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1. A Offs O 260 RETURN DS335 Synthesized Function Generator 3 14 Programming Examples DS335 Synthesized Function Generator Troubleshooting 4 1 TROUBLESHOOTING If Nothing Happens on Power On Cold Boot ERROR MESSAGES Operational Errors Message AC Error AC DC Error Freq Error No GPIB No RS232 Off Error Out q err Range Er Rate Err Rcl Err Span Err StrtF Er Stop F Er Make sure that the power entry module on the rear panel is set for the proper ac line voltage for your location that the correct fuse is installed and that the line cord is inserted all the way into the power entry module The selected line voltage may be seen through the clear window just below the fuse When the unit is plugged in and turned ON the unit s firmware version number and serial number will be briefly displayed Then the self tests should execute If the unit displays no sensible message the cold boot procedure may fix the problem To do a cold boot turn the unit off Then while holding the button turn the unit ON This procedure initializes the RAM and recalls all factory calibration values The following lists explain all of the error messages that the DS335 can generate The messages are divided into operational errors errors in using the instrument and self test errors The messages are listed alphabetically These error messages may appear during normal front panel operation and gene
2. sine 500 kHz 3 Vrms sine 1 0 MHz 3 Vrms sine 1 5 MHz 3Vrms sine 2 0 MHz 3 Vrms DS335 Synthesized Function Generator 4 14 Performance Tests sine 2 5 MHz 3 Vrms sine 3 0 MHz 3 Vrms square 10 Vpp Pass DC Offset Accuracy DC only 5 0 V 4 940 V 5 0 V 5 060 V 0 0 V 0 0002 V DC Offset Accuracy DC AC 1 kHz 10 Vpp 0 Vdc 0 08 V 100 kHz 10 Vpp 0 Vdc 0 08 V 1 MHz 10 Vpp 0 Vdc 0 08 V 3 1 MHz 10 Vpp 0 Vdc 0 08 V Subharmonics sine 102 kHz 10 Vpp sine 1 002 MHz 10 Vpp sine 3 1 MHz 10 Vpp Spurious Signals sine 100 kHz sine 2 MHz Harmonic Distortion sine 100 Hz 1 Vpp sine 1 kHz 1 Vpp sine 10 kHz 1 Vpp sine 50 kHz 1 Vpp sine 500 kHz 1 Vpp sine 1 MHz 1 Vpp sine 3 1 MHz 1 Vpp Phase Noise noise Square Wave Rise Time square 1 MHz 10 Vpp 10 to 90 rise time square 1 MHz 10 Vpp Overshoots Square Wave Symmetry square 1 MHz 5 Vpp pulse width square 1 MHz 5 Vpp pulse width asymmetry width width Fail 5 060 V 4 940 V 0 0002 V 70dBc 70dBc 70dBc 65 dBc 55 dBc 60 dBc 60 dBc 60 dBc 60 dBc 50 dBc 50 dBc 40 dBc 60 db 18 ns 200 mV 13 ns DS335 Synthesized Function Generator CALIBRATION Introduction Calibration Enable Calbytes Calibration 4 15 The calibration of the DS335 is composed of two parts adjustment and calibration Adjustments are actual physical adjustment
3. 002U Capacitor Ceramic Disc 50V 1096 SL C 515 5 00271 532 56P Capacitor Ceramic Disc 50V 10 NPO C 516 5 00271 532 56P Capacitor Ceramic Disc 50V 1096 NPO C 517 5 00269 501 300P Capacitor Ceramic Disc 50V 1096 SL C 518 5 00269 501 300P Capacitor Ceramic Disc 50V 1096 SL C 519 5 00131 501 560P Capacitor Ceramic Disc 50V 1096 SL C 520 5 00131 501 560P Capacitor Ceramic Disc 50V 1096 SL C 521 5 00272 532 39P Capacitor Ceramic Disc 50V 10 NPO C 522 5 00272 532 39P Capacitor Ceramic Disc 50V 10 NPO C 523 5 00274 532 180P Capacitor Ceramic Disc 50V 1096 NPO C 524 5 00274 532 180P Capacitor Ceramic Disc 50V 1096 NPO C 525 5 00264 513 0015U Capacitor Mylar Poly 50V 596 Rad C 526 5 00264 513 0015U Capacitor Mylar Poly 50V 5 Rad C 527 5 00133 532 150P Capacitor Ceramic Disc 50V 10 NPO C 528 5 00133 532 150P Capacitor Ceramic Disc 50V 10 NPO C 529 5 00021 501 82P Capacitor Ceramic Disc 50V 10 SL C 530 5 00264 513 0015U Capacitor Mylar Poly 50V 5 Rad C 531 5 00021 501 82P Capacitor Ceramic Disc 50V 10 SL C 532 5 00264 513 0015U Capacitor Mylar Poly 50V 5 Rad C 533 5 00275 532 120P Capacitor Ceramic Disc 50V 10 NPO C 534 5 00131 501 560P Capacitor Ceramic Disc 50V 1096 SL C 535 5 00268 532 270P Capacitor Ceramic Disc 50V 10 NPO C 536 5 00131 501 560P Capacitor Ceramic Disc 50V 1096 SL DS335 Synthesized Function Generator DS335 Component Parts
4. 5 0 or 5E1 The variables i and j usually take integer values while the variable x take real number values Function Output Control Commands AECL The AECL command sets the output to the ECL levels of 1 V peak to peak with a 1 3 V offset That is from 1 8V to 0 8V AMPL x The AMPL command sets the output amplitude to x The value x must consist of the numerical value and a units indicator The units may be VP Vpp or VR Vrms For example the command AMPL 1 00VR will set the output to 1 0 Vrms Note that the peak AC voltage Vpp 2 plus the DC offset voltage must be less than 5 Volts for 500 source Setting the amplitude to 0 Volts will produce DC only no AC function output controlled by the OFFS command The AMPL query will return the amplitude in the currently displayed units For example if the display is 3 0 Vrms the AMPL query will return 3 0VR If a units indicator is sent with the AMPL query such as AMPL VP the displayed units will be changed to match the units indicator and the amplitude returned in those units ATTL The ATTL command sets the TTL output levels of 5V peak to peak with a 2 5V offset That is from OV to 5V FREQ x The FREQ command sets the output frequency to x Hertz The FREQ query returns the current output frequency The frequency is set and returned with 1uHz resolution If the current waveform is NOISE an error will be generated and the frequency will not be changed FUNC 2
5. Radial C 1004 5 00192 542 22U MIN Cap Mini Electrolytic 50V 20 Radial C 1005 5 00192 542 22U MIN Cap Mini Electrolytic 50V 20 Radial C 1006 5 00192 542 22U MIN Cap Mini Electrolytic 50V 20 Radial C 1013 5 00007 501 220P Capacitor Ceramic Disc 50V 10 SL D 906 3 00062 340 KBP201G BR 81D Integrated Circuit Thru hole Pkg J 1000 1 00160 162 IEEE488 STAND Connector IEEE488 Standard R A Femal JP1000 1 00032 130 14 PIN DIL Connector Male 3 00446 340 63137 Integrated Circuit Thru hole Pkg Ol 3 00446 340 6N137 Integrated Circuit Thru hole Pkg Ol2 3 00446 340 6N137 Integrated Circuit Thru hole Pkg 3 00446 340 63137 Integrated Circuit Thru hole Pkg Ol4 3 00446 340 6N137 Integrated Circuit Thru hole Pkg OI5 3 00446 340 6N137 Integrated Circuit Thru hole PRg OI6 3 00446 340 6N137 Integrated Circuit Thru hole PRg P 1000 1 00016 160 RS232 25 PIN D Connector D Sub Right Angle PC Female R 1000 4 00076 401 390 Resistor Carbon Film 1 4W 5 R 1001 4 00076 401 390 Resistor Carbon Film 1 4W 5 R 1002 4 00076 401 390 Resistor Carbon Film 1 4W 5 R 1003 4 00076 401 390 Resistor Carbon Film 1 4W 5 R 1004 4 00081 401 470 Resistor Carbon Film 1 4W 5 R 1005 4 00076 401 390 Resistor Carbon Film 1 4W 5 R 1006 4 00076 401 390 Resistor Carbon Film 1 4W 5 R 1007 4 00076 401 390 Resistor Carbon Film 1 4W 5 R 1008 4 00034 401 10K Resistor Carbon Film 1 4W 5 R 1009 4 00034 401
6. ibrd dds335 stop 20 read back stop frequency printf n n n n DS335 Setup Demo printf n n n nDS335 Sweep Start Frequency Ve Hz n n atof start printf DS335 Sweep Stop Frequency e Han atof stop DS335 Synthesized Function Generator Programming Examples 3 13 EXAMPLE 2 RS232 COMMUNICATION BASIC LANGUAGE BASIC Program to demonstrate communication with the DS335 via RS232 Program assumes the RS232 option is enabled use SHIFT 2 and the BAUD rate is set to 9600 10 OPEN com2 9600 n 8 2 cs ds cd FOR RANDOM AS 1 Set up com2 20 PRINT 1 30 PRINT 1 Reset the DS335 40 GOSUB 190 Query DS335 and diplay result 50 PRINT 1 freg1234567 Set new frequency 60 GOSUB 190 Query DS335 and diplay result 70 PRINT 1 rst Reset the DS335 80 FORI 4 Step through all functions 90 PRINT 1 func 100 GOSUB 190 Query DS335 and diplay result 110 NEXT I 120 PRINT 1 rst Reset the DS335 130 PRINT 1 ampl Ovp Set amplitude to O volts 140 FORI2 5TO5 Set 05335 offset from 5V to 5V 150 PRINT 1 offs and query each time 160 GOSUB 190 Query DS335 and diplay result 170 NEXT 180 END Routine to query the DS335 frequency 190 PRINT 1 freq offset and amplitude and display them 200 INPUT 1 F 210 PRINT 1 ampl 220 INPUT 1 A 230 PRINT 1 offs 240 INPUT 1 O 250 PRINT Frequ F
7. the DS335 at least 1 2 hour to warm up Set the DS335 to sine wave 1 kHz 3 00 Vrms and 500 Load Impedance Allow the thermal converter 15 seconds to stabilize and record the result as the 1RHz reference value Step the DS335 s frequency in 500kHz steps from OHz to 3 1 MHz Allow the thermal converter to stabilize at each frequency and record the results Verify that the readings are within 1 2 96 of the 1 kHz reading for frequencies above 1kHz Square Waves specification 5 frequency 3 1MHz 1 2 3 Connect the DS335 s output to the oscilloscope with a 500 terminator Set the DS335 to square wave 1 kHz 10Vpp and 500 Load Impedance Set the scope to 2V div and 0 1ms div Step the DS335 s frequency in 100kHz steps from OkHz to 3 1 MHz Verify that the DS335 s output is within 5 of the 1kHz amplitude This test measures the accuracy to the DS335 s DC offset function specification 1 2 of setting 2mV 1 Connect the DS335 s output to the voltmeter with a 50Q terminator Set the DS335 to 0 0V amplitude and 50Q Load Impedance DS335 Synthesized Function Generator 4 10 Performance Tests DC AC SUBHARMONICS SPURIOUS SIGNALS 2 Set the DS335 to 5V offset Read the voltmeter and record the result The result should be between 4 94V and 5 06V 3 Set the DS335 to 5V offset Read the voltmeter and record the result The result should be between 5 06V and 4 940V 4 Set the DS335 to OV o
8. 00196 335 HS 2128 5 3 00270 340 74HC4051 3 00066 340 CA3140E 3 00066 340 CA3140E 3 00487 340 LM1458 3 0041 1 340 74 273 3 00195 340 082 3 00196 335 HS 2128 5 3 00196 335 HS 2128 5 3 00196 335 HS 2128 5 3 00196 335 HS 2128 5 3 00114 329 7815 3 00120 329 7915 DESCRIPTION Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit STATIC RAM I C Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg ORS Rp pe GR ns ie Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg STATIC RAM I C Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg EPROM PROM I C Integrated Circuit Thru hole Pkg EPROM PROM I C Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Relay Relay Integrated Circuit Thru hole Pkg Integrated Cir
9. 00201 526 2200U 5 00201 526 2200U 5 00196 520 6800U 5 00196 520 6800U 5 00027 503 01U 5 00262 548 01U AXIAL 5 00262 548 01U AXIAL 3 00012 306 GREEN 3 00012 306 GREEN 3 00885 306 YELLOW 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00455 310 GREEN COATED 3 00455 310 GREEN COATED 3 00455 310 GREEN COATED 3 00455 310 GREEN COATED DESCRIPTION Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Cer
10. 11 5 4 00777 407 11 5 4 00777 407 11 5 4 00031 401 100 4 00031 401 100 4 00130 407 1 00K 4 00193 407 499 4 00193 407 499 4 00193 407 499 4 00193 407 499 4 00158 407 2 00K 4 00158 407 2 00K 4 00166 407 200K 4 00165 407 200 4 00441 401 9 1 4 00472 407 806 4 00138 407 10 0K 4 00138 407 10 0K 4 00142 407 100K 4 00353 441 100 4 00158 407 2 00K 4 00716 407 1 40K 4 00158 407 2 00K 4 00716 407 1 40K 4 00779 407 133 4 00779 407 133 4 00771 407 66 5 4 00771 407 66 5 4 00165 407 200 4 00512 407 80 6 4 00048 401 2 2K 4 00048 401 2 2K 4 00165 407 200 4 00512 407 80 6 4 00165 407 200 4 00142 407 100K 4 00714 401 2 7 4 00714 401 2 7 4 00525 407 7 5 4 00714 401 2 7 4 00786 439 49 9 4 00714 401 2 7 4 00141 407 100 4 00141 407 100 4 00322 407 316 4 00141 407 100 4 00141 407 100 4 00165 407 200 4 00525 407 7 5 4 00322 407 316 4 00780 407 255 4 00055 401 20K 4 00056 401 22 4 00056 401 22 DESCRIPTION Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 596 Resistor Carbon Film 1 4W 596 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor C
11. 127 Nom 0 Value added to 12 bit Offset DAC 8 OdB OFF 127 Nom 0 Value added to 12 bit Offset DAC 9 2dB OFF 127 Nom 0 Value added to 12 bit Offset DAC 10 4dB OFF 127 Nom 0 Value added to 12 bit Offset DAC 11 6dB OFF 127 Nom 0 Value added to 12 bit Offset DAC 12 8dB OFF 127 Nom 0 Value added to 12 bit Offset DAC 13 10dB OFF 127 Nom 0 Value added to 12 bit Offset DAC 14 12dB OFF 127 Nom 0 Value added to 12 bit Offset DAC 15 14dB OFF 127 Nom 0 Value added to 12 bit Offset DAC Pre attenuator gain calibration values These values are linear in the measured gain for the pre attenuator 16 PRE OdB Always set to 2 16 1 65535 The reference gain 17 PRE 2dB 5 from nominal value of 52057 18 PRE 4dB 5 from nominal value of 41350 19 PRE 6dB 5 from nominal value of 32845 20 PRE 8dB 5 from nominal value of 26090 21 PRE 10dB 5 from nominal value of 20724 22 PRE 12dB 5 from nominal value of 16461 23 PRE 14dB 5 from nominal value of 13076 Post attenuator gain calibration values These values are linear in the measured gain for the post amplifier attenuator There are two of these tables corresponding to the measured gains in the 50 Ohm and High Impedance load conditions These tables compensate for attenuator errors finite amplifier output resistance internal 50 Ohm resistor tolerances and reflects the fact that the output amplitude of high impedance loads is twice th
12. 3 54 Vrms 10Vpp and 50Q Load Impedance 2 Read the AC voltage on the voltmeter Repeat at 1kHz and 10kHz and 100 kHz The readings should be between 3 498 and 3 582 Vrms 1 2 Record the results 3 Set the DS335 to 1 kHz Set the amplitude to 1 Vrms Read the voltmeter and record the results The amplitude should be between 0 988 and 1 012 Vrms Repeat at 0 5 Vrms 0 25 Vrms 120 mVrms 70 mVrms 40 mVrms and 20 mVrms Record the results They should be within 1 2 of the set values Square Wave specification 1 290 1 Set the DS335 to square wave 100 2 5Vrms 10 Vpp and 500 Load Impedance DS335 Synthesized Function Generator Frequency 100 kHz DC OFFSET ACCURACY DC Only 2 Performance Tests 4 9 Read the AC voltage on the voltmeter Repeat at 1 kHz and 10kHz The readings should be between 4 94 and 5 06 Vrms Triangle Ramp Waves specification 1 2 1 Set the DS335 to triangle wave 100Hz 2 89Vrms 10 Vpp and 500 Load Impedance 2 Read the AC voltage on the voltmeter Repeat at 1 kHz and 10kHz The readings should be between 2 85 and 2 93 Vrms Sine Waves specification 0 1 dB 1 2 frequency gt 100kHz 1 4 Connect the DS335 s output to the thermal converter because the convertor has a 50Q impedance no terminator is needed Connect the thermal converter output to the voltmeter using the most sensitive voltmeter range since the nominal signal level is about 7mV DC Allow
13. 62V 0 01Vrms Range into a high impedance load limited such that Vac peak IVacl lt 10 V Vpp Vrms Function Max Min Max Min Sine 20V 100 mV 7 07V 0 04Vrms Square 20V 100 mV 10V 0 05Vrms Triangle 20V 100 mV 5 77V 0 03Vrms Ramp 20V 100 mV 5 77V 0 03Vrms Noise 20V 100 mV 3 24V 0 02Vrms Resolution 3 digits Accuracy with OV DC Offset 500 terminated Sine Accuracy 0 1 dB Square Accuracy 2 Triangle Ramp Accuracy 2 DS335 Synthesized Function Generator vi Specifications DC OFFSET Range Limitation Resolution Accuracy WAVEFORMS 5V into 50 Q limited such that Vac Mac 5 V 10V into hi Z limited such that V Vac lt 10 V 2xVpp in all cases 3 digits 1 2 of setting DC only 0 8 mV to 80 mV depending on AC and DC settings ac peak Sinewave Spectral Purity Spurious non harmonic Phase Noise Subharmonic 65 dBc to 1 MHz 55 dBc to 3 1 MHz 60dBc in a 30 KHz band centered on the carrier exclusive of discrete spurious signals lt 70 dBc lt lt lt Harmonic Distortion Harmonically related signals will be less than Square Wave Rise Fall Time Asymmetry Overshoot Ramps and Triangle Rise Fall Time Linearity Settling Time FREQUENCY SWEEP Type Waveform Rate Span Level Frequency Range lt 60 dBc DC to 100 KHz lt 50 dBc 1 to 1 MHz 40 dBc 1 to3 1 MHz
14. AC to 100 kHz Input Impedance 50 Q Ballantine 1395A 3 Input Voltage 3 Vrms Frequency DC to 10 MHz Accuracy 0 05dB Frequency 10 MHz 001 ppm SRS FS700 Phase Noise 130 dBc 100Hz 50 Q 0 2 1 Watt HP 11048C ADJUSTMENTS Output Amplifier Bandwidth The following adjustments set the values of all of the variable components in the DS335 After an adjustment has been made the associated calibrations must be made All adjustments must be complete before calibration is started First remove the DS335 s top cover by removing the four retaining screws Set the cal enable jumper JP200 switch 2 between pins 1 and 2 NOTE The chassis ground and circuit ground float relative to each other For voltage measurements use the FUNCTION output BNC shield as a ground reference These adjustments correct the bandwidth of the output amplifier A complete calibration must be performed if these adjustments are changed All of the adjustments are on the bottom PCB Use an insulated adjusting screwdriver 1 Connect the output of the DS335 to the oscilloscope with a 50W terminator Set the DS335 to square wave 8 Vpp 100 Hz Set the scope to 2 V div vertical and 5 ms div horizontal Adjust R703 for the squarest output waveform 2 Set the scope to 200ns div Adjust C707 for the fastest output risetime without excessive overshoots 3 Doa complete calibration of the DS335 DS335 Synthesized Function Generator 4 20 Cal
15. List 5 11 REF SRS PART VALUE DESCRIPTION C 537 5 00268 532 270P Capacitor Ceramic Disc 50V 1096 NPO C 538 5 00275 532 120P Capacitor Ceramic Disc 50V 1096 NPO C 539 5 00151 501 680P Capacitor Ceramic Disc 50V 1096 SL C 540 5 00151 501 680P Capacitor Ceramic Disc 50V 1096 SL C 542 5 00257 530 20 90P Capacitor Variable 200V 5m C 600 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 601 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 602 5 00027 503 01U Capacitor Ceramic Disc 50V 20 Z5U C 603 5 00225 548 AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 604 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 605 5 00100 517 2 2U Capacitor Tantalum 35V 20 Rad C 606 5 00027 503 01U Capacitor Ceramic Disc 50V 20 Z5U C 607 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 608 5 00022 501 001U Capacitor Ceramic Disc 50V 10 SL C 700 5 00002 501 100P Capacitor Ceramic Disc 50V 10 SL C 701 5 00022 501 001U Capacitor Ceramic Disc 50V 10 SL C 702 5 00100 517 2 2U Capacitor Tantalum 35V 20 Rad C 703 5 00267 526 1000U Capacitor Electrolytic 35V 20 Rad C 704 5 00100 517 2 2U Capacitor Tantalum 35V 20 Rad C 705 5 00267 526 1000U Capacitor Electrolytic 35V 20 Rad C 707 5 00107 530 1 8 6P Capacitor Variable 200V 5m C 708 5 00003 501 10P Capacitor Ceramic Disc 50V 10 SL C 709 5 00017 501 47P Capacitor Ceramic D
16. Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 0 1 25ppm Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Comp 1 2W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM DS335 Synthesized Function Generator 5 16 _DS335 Component Parts List REF R 653 R 654 R 655 R 656 R 657 R 660 R 661 R 662 R 663 R 664 R 665 R 666 R 667 R 668 R 669 R 670 R 700 R 701 R 702 R 703 R 704 R 705 R 706 R 707 R 708 R 709 R 711 R 713 R 714 R 716 R 717 R 718 R 720 R 721 R 722 R 723 R 727 R 728 R 729 R 730 R 731 R 733 R 736 R 737 R 740 R 741 R 742 R 744 R 745 R 746 R 747 R 748 R 749 R 750 DS335 Synthesized Function Generator SRS PART VALUE 4 00777 407
17. STYP query returns the current sweep type Refer to the SDIR command for sweep direction Waveform 0 LIN SWEEP 1 LOG SWEEP SPFR x The SPFR command sets the sweep stop frequency to x Hertz An error will be generated if the sweep frequency is less than or equal to zero or greater than allowed by the current function The SPFR query returns the current sweep stop frequency If the stop frequency is less than the start frequency the STFR command a downward sweep from maximum to minimum frequency will be generated The stop frequency is also used in the FSK mode SRAT x The SRAT command sets the trigger rate for internally triggered single sweeps and FSK to x Hertz x is rounded to two significant digits and may range from 0 01 Hz to 1 kHz for sweeps and 0 01Hz to 50kHz for FSK The SRAT query returns the current trigger rate If the rate is set to OHz and FSK is enabled SDIR 2 then the external FSK BNC is used to toggle between the start and stop frequencies STFR x The STFR command sets the sweep start frequency to x Hertz An error will be generated if the sweep frequency is less than or equal to zero or greater than allowed by the current function The STFR query returns the current sweep start frequency If the start frequency is greater than the stop frequency the SPFR command a downward sweep from maximum to minimum frequency will be generated The stop frequency is also used in the FSK mode SWEN i Enable
18. URQ Set by any key press 7 PON Set by power on This status byte is defined by IEEE 488 2 1987 and is used primarily to report errors in commands received over the communications interfaces The bits in this register stay set once set and are cleared by reading them or by the CLS command DDS Status Byte bit name usage 0 Trig d Set when a sweep is triggered 1 Trig Error Set when a trigger rate error occurs 2 Unused 3 Unused 4 Warmup Set after the warmup period has expired 5 Test Error Set if a self test error occurs 6 Unused 7 the stored setting were corrupt on power up The Warmup bit will be set and remain set after the warmup period has expired The rest of the bits in this register are set when the corresponding event occurs and remain set until cleared by reading this status byte or by the CLS command DS335 Synthesized Function Generator 3 10 Programming Commands DS335 Synthesized Function Generator Programming Examples 3 11 Program Examples Introduction The following examples demonstrate interfacing the DS335 via RS232 and the GPIB interface using the National Instruments GPIB card Using a different brand of card would be similar except for the program lines that actually send the data These examples are intended to demonstrate the syntax of the DS335 s command set To successfully interface the DS335 to a PC via the GPIB interface the instrument interface card and interface drivers must all be
19. be disabled and enabled with the SHIFT 0 and SHIFT keys FUNCTION SELECTION The DS335 s output function is selected using the FUNCTION UP DOWN arrow keys Simply press the keys until the desired function LED is lit If the programmed frequency is outside of the range allowed for the selected DS335 Synthesized Function Generator 2 10 Function Setting Ramps FREQUENCY Setting the Frequency AMPLITUDE function an error message will be displayed and the frequency will be set to the maximum allowed for that function Ramp functions usually ramp up in voltage downward ramps may be set entering a negative amplitude see AMPLITUDE section To display the DS335 s output frequency press the FREQ The frequency units can be Hz kHz or MHz and are indicated by the LEDs on the right of the display The DS335 has 1 uHz frequency resolution at all frequencies for all functions The maximum frequency depends on the function selected as shown below Function Frequency Range Sine 1 uHz 3 100000000000 MHz Square 1 uHz 3 100000000000 MHz Triangle 1 uHz 10 000 000000 Hz Ramp 1 uHz 10 000 000000 Hz Noise 3 5 MHz White Noise fixed Frequency is usually displayed by the DS335 with the highest resolution possible However if the frequency is below 100 Hz the DS335 will display the frequency with 1 uHz resolution At frequencies greater than 1 MHz the digits below 0 1 Hz cannot be displayed but
20. configured properly To configure the DS335 the GPIB address must be set in the GPIB menu The default GPIB address is 22 use this address unless a conflict occurs with other instruments in your system Make sure that you follow all the instructions for installing the GPIB card The National Instruments card cannot be simply unpacked and put into your computer To configure the card you must set jumpers and switches on the card to set the I O address and interrupt levels You must run the program IBCONF to configure the resident GPIB driver for your GPIB card Please refer to the National Instruments manual for information In this example the following options must be set with IBCONF Device name dds335 Device address 22 EOS character OAh linefeed Once all the hardware and GPIB drivers are configured use IBIC This terminal emulation program allows you to send commands to the DS335 directly from your computer s keyboard If you cannot talk to the DS335 via IBIC then your programs will not run Use the simple commands provided by National Instruments Use IBWRT and IBRD to write and read from the DS335 After you are familiar with these simple commands you can explore more complex programming commands The RS232 program assumes the RS232 option is enabled SHIFT 2 and the BAUD rate is set to 9600 BAUD The GPIB example was written in C and the RS232 example was written in BASIC DS335 Synthesized Function Gener
21. i The FUNC command sets the output function type to i The correspondence of i and function type is shown in the table below If the currently selected frequency is incompatible with the selected function an error will be generated and the frequency will be set to the maximum allowed for the new function The FUNC query returns the current function Function SINE SQUARE TRIANGLE AUON OT INVT 2 i INVT command turns output inversion on i21 and off i 0 The INVT query returns the current inversion status This function is used with the ramp waveform to set it for positive or negative slope DS335 Synthesized Function Generator 3 4 Programming Commands REYS 2 i OFFS 2 x SYNC I TERM i The KEYS command simulates the pressing of a front panel key The KEYS query returns the keycode of the most recently pressed key Keycodes are assigned as follows Key Name Key Code FREQ 1 AMPL 2 OFFSET 3 START FREQ 4 STOP FREQ 5 SWEEP RATE 6 0 7 1 8 2 9 3 10 Vrms HZ DOWN 11 SEL FNC 12 Decimal Point 13 4 14 5 15 6 16 Vpp kHz UP 17 19 7 20 8 21 9 22 MHz SHIFT 23 The OFFS command sets the output s DC offset to x volts The OFFS query returns the current value of the DC offset The DC offset voltage plus the peak AC voltage must be less than 5 Volts into 500 Turns the SYNC output on i 1 or off i 0 Sets the output source impedance to 500 i20 or hi Z i21 The TERM query returns the cur
22. i21 or off i0 Valid only if SDIR2 is sent first Triggers single sweeps if in single trigger mode Sets the sweep direction 0 Ramp 1 Triangle 2 FSK Sets the sweep stop frequency to x Hz Sets the sweep rate to x Hz Sets the sweep start frequency to x Hz Sets the sweep type 0 linear sweep 1 logarithmic sweep Turns sweeps on i21 or off iO Sets the trigger source for sweeps 0 single 1 internal sweep rate Returns the device identification Recalls stored setting i Clears instrument to default settings Stores the current settings in storage location i Clears all status registers Sets reads the standard status byte enable register Reads the standard status register or just bit j of register Sets the power on status clear bit This allows SRQ s on power up if desired Sets reads the serial poll enable register Reads the serial poll register or just bit n of register Reads the DDS status register or just bit n of register Sets reads the DDS status enable register DS335 Synthesized Function Generator x Abridged Command List Hardware Test Control TST Starts self test and returns status when done Status Byte Definitions Serial Poll Status Byte bit name usage 0 Sweep Done set when no sweeps in progress 1 Sweep Enable set when sweep or FSK is enabled 2 User SRQ set when the user issues a front panel SRQ 3 DDS set when an unmasked bit in DDS status byte is set 4 MAV set
23. is filtered by 470 Ohm resistor networks before being latched into the 12 bit waveform DAC U500 a TDC1012 by the rising edge of the 10 MHz CONV clock The differential current outputs from the DAC have a range from 0 to 40 mA Value OUT OUT 0 0 40 000 mA 1 01 39 990 7FF 19 995 20 005 800 20 005 19 995 FFE 39 990 00 010 FFF 40 000 0 Because the DAC outputs can only sink current part of the output termination network is connected to a positive voltage source which tracks the DAC reference input This arrangement keeps both outputs centered on 0 Vdc This improves the performance of the DAC and eliminates any dc current from the output filters DS335 Synthesized Function Generator Circuitry 5 5 Output Filters DS335M5 There are two output filter types a Bessel filter and a Cauer filter Both filters have a characteristic impedance of 50 Ohms they are driven by and terminated into 50 Ohms The filters are differential filters they have complementary inputs and outputs and are closely phase matched between the inputs because they share the same physical core The Bessel filter is a 5th degree filter with the 3 dB point set to 3 5 MHz This filter is used when ramps triangles or noise functions are selected The Bessel filter has excellent phase linear response so that there will be no overshoot or ringing of the output waveform The Cauer filter is a 7th degree filter with a passband to 3 4 MHz and a stopband attenu
24. j are integers Variable x is a real number in integer real or exponential notation Commands which may be queried have a in parentheses after the mnemonic The are not sent Commands that may only be queried have a 2 after the mnemonic Commands which may not be queried have Optional parameters are enclosed by 1 Function Output Control Commands AECL AMPL x ATTL FREQ x FUNC i INVT 2 i KEYS i OFFS x SYNC i TERM i Sweep control commands TRG SDIR 2 i SPFR 2 x SRAT 2 x STFR 2 x STYP 2 i SWEN i TSRC i Setup Control Commands IDN RCLi RST SAV i Status Reporting Commands CLS ESE j ESR j PSC j SRE j STB j STAT j DENA j Sets the output amplitude offset to ECL levels 1Vpp 1 3V offset Sets the output amplitude to x x is a value plus units indicator The units can be VP Vpp VR Vrms Example AMPL 1 00VR sets 1 00 Vrms Sets the output amplitude offset to TTL levels 5 Vpp 2 5 V offset Sets the output frequency to x Hz Sets the output function 0 sine 1 square 2 triangle 3 ramp 4 noise Sets the output inversion on i21 or off i 0 Used with the ramp function Simulates a key press or reads the most recently pressed key Sets the output offset to x volts Turns the Sync output on i21 or off i20 Sets the output source impedance to 500 i0 Hi Z i21 Enables FSK on
25. lt 15 nS 5 nS 10 to 90 at full output 1 of period 3 nS 590 of peak to peak amplitude at full output 100 20 nS 3 5MHz Bessel Filter 0 1 of full scale output lt 200 ns to settle within 0 5 of final value at full output Linear or Log phase continuous Up down up down single sweep 0 01 Hz to 1 kHz 1 uHz to 3 1 MHz 10 kHz for triangle or ramp FREQUENCY SHIFT KEYING FSK Type Waveform Rate Shift Span External Internal rate or External control phase continuous Sine Square Triangle Ramp 0 01 Hz to 50 kHz internal 1 uHz to 3 1 MHz 10 kHz for triangle or ramp TTL input 1MHz maximum DS335 Synthesized Function Generator Specifications vii SYNC amp SWP FSK OUTPUTS SYNC TTL level active with all functions SWP FSK TTL level synchronous with internal Sweeps and FSK rates TIMEBASE Accuracy 25 ppm 0 to 70 C Aging 5 ppm year Optional Timebase Type Temperature Compensated Crystal Oscillator Stability 2 0 ppm 0 to 50 C Aging 5 ppm first year 2 ppm per year thereafter GENERAL Interfaces RS232 C 300 to 9600 Baud DCE and GPIB All instrument functions can be controlled over the interfaces Weight 8 165 Dimensions 8 5 x 3 5 x 13 W x H x L Power 25 Watts 100 120 220 240 Vac 50 60 Hz DS335 Synthesized Function Generator viii Specifications DS335 Synthesized Function Generator Abridged Command List ix Abridged Command List Syntax Variables i
26. of the square wave It should be less than 20ns This test provides a visual indication of the sine wave amplitude flatness 1 2 Connect the DS335 s output to the oscilloscope input and terminate in 500 Set the DS335 to sine wave 10Vpp and 500 Load Impedance Set to linear sweep with a Unidirectional waveform Set the start frequency to 1Hz stop frequency to 3MHz and the rate to 100Hz Turn the DS335 s sweep ON Set the scope to 2V div vertical and 1ms div horizontal Trigger the scope on the falling edge of the DS335 s SWEEP output Rear Panel The scope should show a sweep that is essentially flat The peak to peak variations should be less than 1 2 Ignore any dc variations using the peak to peak measurements for flatness comparison This test provides a visual check of the DS335 s output level control 1 Connect the DS335 s output to the oscilloscope input and terminate in 500 Set the DS335 to sine wave 1MHz 10Vpp and 500 Load Impedance Set the scope to 2V div vertical and 1us div horizontal Verify that the DS335 s output is about 10V pk to pk Set the DS335 to 5Vpp verify the output Repeat step 4 at 1Vpp 0 5 Vpp 0 1 Vpp and 0 05 Vpp Adjust the Scope as necessary THIS COMPLETES THE FUNCTIONAL TESTS DS335 Synthesized Function Generator 4 8 Performance Tests PERFORMANCE TESTS These tests are intended to measure the DS335 s conformance to its published specifications The test result
27. output into 50 ohms Turn the DS335 on and wait until the message TEST PASS is displayed if the self tests fail refer to TROUBLESHOOTING section of the manual 1 Press SHIFT This recalls the DS335 s default settings 2 Press AMPL Then press 5 Vpp Displays the amplitude and sets it to 5 Vpp The scope should show a 5 Vpp 1 MHz sine wave 3 Press FUNC DOWN ARROW twice The function should change to a square wave and then a triangle wave The 05335 automatically performs frequency adjustment to match the maximum triangle frequency 10kHz 4 Press FREQ and then 1 kHz Displays the frequency and sets it to 1 kHz The scope should now display a 1 kHz triangle wave 5 Press UP ARROW The frequency will increment to 1 0001 kHz The flashing digit indicates a step size of 0 1 Hz DS335 Synthesized Function Generator 1 2 Getting Started 6 Press SHIFT UP ARROW twice 7 Press UP ARROW three times Observe that the blinking digit is shifted twice to the left indicating a step size of 10 Hz We ve changed the output frequency to 10 0301 kHz Frequency Sweep The next example demonstrates a linear frequency sweep The DS335 can sweep the output frequency of any function over the entire range of allowable output frequencies There are no restrictions on minimum or maximum sweep span The sweep is phase continuous and may range from 0 01Hz to 1000 kHz Attach the FUNCTION output BNC to the oscill
28. question mark to the command mnemonic and omitting the desired parameter from the command If multiple queries are sent on one command line separated by semicolons of course the answers will be returned in a single response line with the individual responses separated by semicolons The default response terminator that the DS335 sends with any answer to a query is carriage return linefeed ecrselfs on RS232 and linefeed plus EOI on GPIB All commands return integer results except as noted in individual command descriptions Examples of Command Formats FREQ 1000 0 lt Sets the frequency to 1000 Hz FREQ If Queries the frequency IDN lt lf gt Queries the device identification query no parameters TRG lt Triggers a Sweep no parameters FUNC 1 FUNC lt lf gt Sets function to square wave 1 then queries the function The DS335 reports two types of errors that may occur during command execution command errors and execution errors Command errors are errors in the command syntax For example unrecognized commands illegal queries lack of terminators and non numeric arguments are examples of command errors Execution errors are errors that occur during the execution of syntactically correct commands For example out of range parameters and commands that are illegal for a particular mode of operation are classified as execution errors The NO COMMAND bit is a bit in the serial poll register that indicates that
29. received All commands function identically on GPIB and RS232 Command mnemonics beginning with an asterisk are IEEE 488 2 1987 defined common commands These commands also function identically on RS232 Commands may require one or more parameters Multiple parameters are separated by commas Multiple commands may be sent on one command line by separating them by semicolons The difference between sending several commands on the same line and sending several independent commands is that when a command line is parsed and executed the entire line is executed before any other device action proceeds DS335 Synthesized Function Generator 3 2 Programming Commands Programming Errors No Command Bit DETAILED COMMAND LIST There is no need to wait between commands The DS335 has a 256 character input buffer and processes commands in the order received If the buffer fills up the DS335 will hold off handshaking on the GPIB and attempt to hold off handshaking on RS232 If the buffer overflows the buffer will be cleared and an error reported Similarly the DS335 has a 256 character output buffer to store output until the host computer is ready to receive it If the output buffer fills up it is cleared and an error reported The GPIB output buffer may be cleared by using the Device Clear universal command The present value of a particular parameter may be determined by querying the DS335 for its value A query is formed by appending a
30. the frequency still has 1 uHz resolution and may be set via the computer interfaces If the function is set to NOISE the character of the noise is fixed with a band limit of 3 5 MHz The frequency is not adjustable and the FREQ display will read noise instead of a numerical value To set the frequency of any function simply type a new value on the keypad and complete the entry with the appropriate units Hz kHz or MHz Also the UP and DOWN arrow keys may be used to increment or decrement the frequency by adding or subtracting one from the flashing digit Press AMPL to display the amplitude of the output function The amplitude may be set and displayed in units of Vj and Vins The current units are indicated by the LEDs at the right of the display The amplitude range is limited by the DC offset setting since peakl 5 V into 500 If the DC offset is zero the amplitude range for each of the functions is shown below Note The rms value for NOISE is based on the total power in the output bandwidth about 3 5 MHz at a given peak to peak setting Vpp Vrms Function Max Min Max Min Sine 10V 50 mV 3 54V 0 02Vrms Square 10V 50 mV 5 00V 0 03Vrms Triangle 10V 50 mV 2 89V 0 01Vrms Ramp 10V 50 mV 2 89V 0 01Vrms Noise 10V 50 mV 1 62V 0 01Vrms 500 Load Impedance DS335 Synthesized Function Generator Function Setting 2 11 Vpp Vrms Function Max Min Max Min Sine 20V
31. user service request is in addition to the usual service requests based on status conditions see PROGRAMMING section for details Press SHIFT 2 three times to display the last 256 characters of data that have been received by the DS335 This display is a 3 character window into the DS335 s input data queue that could be scrolled to view the previous 256 characters The data is displayed in ASCII hex format with each input character represented by 2 hexadecimal digits The most recently received character has a decimal point indicator Pressing DOWN ARROW scrolls the display to the beginning of the queue and UP ARROW scrolls to later in the queue The DS335 has a built in test routine that allows the user to test a large portion of instrument functionality quickly and easily Self test starts every time the DS335 is turned ON The DS335 s self test is always executed on power up The test checks most of the digital circuitry in the DS335 and should end with the display test pass If the self test encounters a problem it will immediately stop and display a warning message See the TROUBLESHOOTING section for a list and explanation of the error messages If the DS335 fails its test it still may be operated The DS335 tests its CPU and data memory ROM program memory calibration constant integrity the computer interfaces and the modulation program memory Items not tested are the connections from the PC boards to the BNC connecto
32. 0 4 00056 401 22 4 00302 407 82 5 4 00685 408 100 4 00031 401 100 4 00132 407 1 10R 4 00215 407 909 4 00030 401 10 4 00081 401 470 4 00081 401 470 4 00112 402 47 4 00477 407 432 4 00777 407 11 5 4 00778 407 44 2 4 00777 407 11 5 4 00777 407 11 5 4 00777 407 11 5 4 00777 407 11 5 4 00777 407 11 5 4 00777 407 11 5 4 00778 407 44 2 4 00777 407 11 5 4 00777 407 11 5 4 00777 407 11 5 4 00777 407 11 5 DESCRIPTION Resistor Metal Film 1 8W 1 5OPPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor
33. 0 CTS and DTR should be passed Occasionally pins 6 and 8 DSR and CD will be needed these lines are always asserted by the DS335 DS335 Synthesized Function Generator 4 4 Troubleshootin DS335 Synthesized Function Generator Performance Tests 4 5 PERFORMANCE TESTS INTRODUCTION NECESSARY EQUIPMENT Instrument Analog Oscilloscope Time Interval Counter FFT Spectrum Analyzer RF Spectrum Analyzer DC AC Voltmeter Thermal Converter 10 MHz Frequency Standard 500 Terminator Doubly Balanced Mixer The procedures in this section test the performance of the DS335 The first set tests the basic functionality of the DS335 from the front panel The second set of tests actually measures the DS335 s specifications The results of each test may be recorded on the test sheet at the end of this section The following equipment is necessary to complete the tests The suggested equipment or its equivalent may be used Critical Specifications Recommended Model 350 MHz Bandwidth Tektronix 2465 Frequency Range 20 MHz minimum SRS SR620 Time Interval Accuracy 1ns minimum Frequency Range DC to 100 kHz SRS SR760 Amplitude Accuracy 0 2 dB Distortion 75 dB below reference Frequency Range 1 kHz to 100 MHz Anritsu MS2601 HP4195A Amplitude 0 5 dB Distortion and Spurious 70 dB 5 1 2 Digit DC accuracy Fluke 8840A True RMS AC to 100 kHz Input Impedance 500 Ballantine 1395A 3 Input Voltage 3 Vrm
34. 0 1V 7 07V 0 04Vrms Square 20V 0 1V 10 0V 0 05Vrms Triangle 20V 0 1V 5 77V 0 03Vrms Ramp 20V 0 1V 5 77V 0 03Vrms Noise 20V 0 1V 3 24V 0 02Vrms HIGH Z Load Impedance Output Inversion The DS335 s output may be inverted for ramp functions This is useful for turning positive ramps into negative ramps Entering a negative amplitude inverts the ramp output D C Only The output of the DS335 may be set to a DC level by entering an amplitude of 0 V When the amplitude is set to zero the A C waveform will be completely shut off and the DS335 may be used as a DC voltage source DC OFFSET When the OFFS key is pressed the DC offset is displayed and the indicator LED will be lit new value may be entered numerically with amplitude unit key In general the DC offset may range between 5V but is restricted such that Vac Vacl lt 5 V into 50 Ohms or Vac peak IVgel 10 V into HIGH Z The DC offset is also restricted such that V4 lt 2x When the offset is changed the output signal will briefly go to zero as the output attenuators are switched and then back to the set offset value SYNC ENABLE Pressing the SHIFT key enables the SYNC OUT function The SHIFT O disables the output by highly attenuating the output function signal DS335 Synthesized Function Generator 2 12 Function Setting DS335 Synthesized Function Generator Sweeps amp FSK 2 13 FREQUENCY SWEEP
35. 0 20dB 5 from nominal value of 3276 51 50 22dB 5 from nominal value of 2602 52 50 24dB 5 from nominal value of 2067 53 50 26dB 5 from nominal value of 1642 54 50 28dB 5 from nominal value of 1304 55 50 30dB 5 from nominal value of 1036 Spare calbytes unused 56 Unused 57 Unused 58 Unused 59 Unused 60 Unused 61 Unused 62 Unused 63 Unused 64 Unused 65 Unused 66 Unused 67 Unused 68 Unused 69 Unused 70 Unused 71 Unused The following three tables have a length of 160 entries and contain sine and square wave leveling values and squarewave symmetry values as a function of frequency 72 SINE 0 Fixed at 127 This is the reference value for dc 73 SINE 1 0 to 255 Nominal 127 For 19 531 to 39 062 Hz 74 SINE 2 0 to 255 Nominal 127 For 39 063 to 58 593 Hz 231 SINE 159 0 to 255 Nominal 127 For 3105468 to 3125000 Hz The next table of 160 words contains amplitude leveling data for square wave outputs This data is used to modify squarewave amplitude control values as a function of frequency there is no hardware accommodation for amplitude leveling of squarewave sweeps 232 SQ 0 Fixed at 2 15 32 768 The dc reference level 233 SQ 1 For 19 531 to 39 062 Hz 10 from nominal 234 SQ 2 For 39 063 to 58 593 Hz 10 from nominal 391 SQ 159 For 3105468 to 3125000 Hz 10 from nominal DS335 Synthesized Function Generator 4 18 Calibration The last table of 160 words contains sync
36. 00128 610 DS335 340 6 00131 623 10MHZ 6 00212 630 1 X 25 CYL 7 00217 735 PS300 40 7 00447 709 DS335 1 7 00449 709 DS335 7 00451 720 DS335 4 amp 5 7 00452 720 DS335 6C 9 00458 917 DS335 340 345 9 00552 924 COPPERFOIL 1 DESCRIPTION Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package Varistor Zinc Oxide Nonlinear Resistor Power_Entry Hardware Lugs Nut Kep Nut Kep Cable Coax amp Misc Standoff Tie Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Screw Black All Types Heat Sinks Screw Flathead Phillips Screw Panhead Phillips Insulators Screw Flathead Phillips Washer nylon Power Button Insulators Screw Panhead Phillips Wire 22 UL1007 Wire 22 UL1007 Washer nylon Insulators Termination Hardware Misc Connector Amp MTA 156 Connector Amp MTA 100 Connector Female Cable Assembly Ribbon Cable Assembly Multiconductor Varistor Zinc Oxide Nonlinear Resistor Fuse Transformer Temp Controlled Crystal Osc Ferrite Beads Injection Molded Plastic Lexan Overlay Lexan Overlay Fabricated Part Fabricated Part Product Labels Tape All types Miscellaneous and chassis Assembly Parts List REF U 104 20 20 SRS PART VALUE 3 00449 342 27C256 120 0 00179 000 RIGHT FOOT 0 00180 000 LEFT FOOT DESCRIPTION EPROM PROM I C Hardware Misc Hardware Misc DS33
37. 0138 407 10 0K Resistor Metal Film 1 8VV 196 SOPPM R 318 4 00210 407 9 09R Resistor Metal Film 1 8VV 196 SOPPM R 400 4 00309 407 3 32K Resistor Metal Film 1 8VV 196 SOPPM R 401 4 00130 407 1 00K Resistor Metal Film 1 8VV 196 SOPPM R 402 4 00138 407 10 0K Resistor Metal Film 1 8VV 196 SOPPM R 403 4 00165 407 200 Resistor Metal Film 1 8VV 196 SOPPM R 406 4 00034 401 10K Resistor Carbon Film 1 4W 596 R 407 4 00021 401 1 0K Resistor Carbon Film 1 4W 5 DS335 Synthesized Function Generator DS335 Component Parts List 5 15 REF R 500 R 501 R 502 R 503 R 504 R 505 R 506 R 507 R 508 R 509 R 510 R 511 R 512 R 513 R 601 R 602 R 603 R 604 R 605 R 606 R 607 R 608 R 609 R 610 R 611 R 612 R 613 R 614 R 615 R 616 R 617 R 618 R 619 R 620 R 621 R 622 R 623 R 624 R 625 R 626 R 627 R 628 R 635 R 636 R 637 R 638 R 639 R 640 R 641 R 648 R 649 R 650 R 651 R 652 SRS PART VALUE 4 00138 407 10 0K 4 00141 407 100 4 00141 407 100 4 00141 407 100 4 00141 407 100 4 00506 407 35 7K 4 00702 407 1 78K 4 00702 407 1 78K 4 00776 407 178 4 00776 407 178 4 00724 407 226 4 00719 401 4 7 4 00719 401 4 7 4 00724 407 226 4 00473 407 11 0K 4 00473 407 11 0K 4 00166 407 200K 4 00142 407 100K 4 00021 401 1 0K 4 00191 407 49 9 4 00031 401 100 4 00031 401 100 4 00031 401 100 4 00031 401 100 4 00130 407 1 00R 4 00141 407 100 4 00141 407 100 4 00132 407 1 10R 4 00215 407 909 4 00030 401 1
38. 10K Resistor Carbon Film 1 4W 5 R 1010 4 00034 401 10K Resistor Carbon Film 1 4W 5 R 1011 4 00081 401 470 Resistor Carbon Film 1 4W 5 R 1012 4 00081 401 470 Resistor Carbon Film 1 4W 5 R 1013 4 00081 401 470 Resistor Carbon Film 1 4W 5 R 1014 4 00081 401 470 Resistor Carbon Film 1 4W 5 R 1015 4 00021 401 1 0K Resistor Carbon Film 1 4W 5 R 1016 4 00021 401 1 0K Resistor Carbon Film 1 4W 5 U 900 3 001 12 329 7805 Voltage Reg TO 220 TAB Package U 1000 3 00303 340 74HC164 Integrated Circuit Thru hole Pkg U 1001 3 00045 340 74HC32 Integrated Circuit Thru hole Pkg U 1002 3 00434 340 74HC299 Integrated Circuit Thru hole Pkg U 1003 3 00039 340 74HC14 Integrated Circuit Thru hole Pkg U 1004 3 00036 340 74HC00 Integrated Circuit Thru hole PRg U 1005 3 00645 340 NAT9914BPD Integrated Circuit Thru hole PRg U 1006 3 00078 340 DS75160A Integrated Circuit Thru hole Pkg U 1007 3 00079 340 DS75161A Integrated Circuit Thru hole Pkg U 1008 3 00493 340 UPD71051C Integrated Circuit Thru hole Pkg DS335 Synthesized Function Generator 5 10 DS335 Component Parts List REF SRS PART VALUE DESCRIPTION U 1009 3 00217 340 MAX232 Integrated Circuit Thru hole Pkg Z0 0 00299 000 1 8 ADHES TAPE Hardware Misc 70 1 00048 171 14 COND Cable Assembly Ribbon Front Panel and Main PC Board Parts List REF SRS PART VALUE DESCRIPTION BT1 6 00001 612 BR 2 3A 2PIN PC Battery C 100 5 00225 548 1U AX
39. 5 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 821 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 822 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 823 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 824 5 00225 548 AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 825 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 826 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 827 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX DS335 Synthesized Function Generator 5 12 DS335 Component Parts List REF C 828 C 829 C 830 C 831 C 832 C 833 C 834 C 835 C 836 C 837 C 838 C 839 C 840 C 841 C 842 C 843 C 844 C 845 C 846 C 847 C 848 C 849 C 850 C 851 C 852 C 900 C 944 C 945 C 953 D 21 D 22 D 23 DS335 Synthesized Function Generator SRS PART VALUE 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00259 501 002U 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00225 548 1U AXIAL 5 00259 501 002U 5 00225 548 1U AXIAL 5
40. 5 Synthesized Function Generator 5 20 05335 Component Parts List DS335 Synthesized Function Generator SRS PART VALUE 0 00204 000 REAR FOOT 0 00248 026 10 32X3 8TRUSSP 0 00315 021 6 32X7 16 PP 0 00326 026 8 32X1 4PP 0 00396 000 BE CU DDS 0 00590 066 0097 0555 02 7 00122 720 DG535 36 7 00259 720 SR560 28 7 00260 720 SR560 27 DESCRIPTION Hardware Misc Screw Black All Types Screw Panhead Phillips Screw Black All Types Hardware Misc Copper Foil Tape Self Adhesive Fabricated Part Fabricated Part Fabricated Part
41. 6 130 3 PIN SI 1 00080 130 8 PIN SI 1 00080 130 8 PIN SI 6 00120 630 FB64 101 6 00120 630 FB64 101 6 00120 630 FB64 101 4 00498 421 680X4 4 00498 421 680X4 4 00498 421 680X4 4 00498 421 680X4 4 00774 421 39X4 4 00774 421 39X4 4 00707 425 2 2KX7 4 00293 421 470X4 4 00244 421 10KX4 4 00293 421 470X4 4 00293 421 470X4 4 00293 421 470X4 4 00775 419 220X13 4 00717 421 22X4 4 00717 421 22X4 4 00717 421 22X4 4 00717 421 22X4 7 00457 701 DS335 MAIN 7 00453 701 DS335 340 FP 7 00450 701 DS335 40 PS OPT 3 00021 325 2N3904 3 00022 325 2N3906 DESCRIPTION LED Coated Rectangular LED Coated Rectangular LED Rectangular Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Integrated Circuit Thru hole Pkg Diode Diode Diode Diode Diode Connector Male Connector Male Connector BNC Connector BNC Connector BNC Connector BNC Connector Male Connector Male Connector Male Connector Male Ferrite Beads Ferrite Beads Ferrite Beads Res Network Res Network Res Network Res Network Res Network Res Network SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated Resistor Network SIP 1 4W 2 Common Res Network Res Network Res Network Res Network Res Network Res Network Res Network Res Network Res Network Res Network SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated S
42. A IA 1 Connect the DS335 to the RF spectrum analyzer Set the DS335 to sine wave 1Vpp OV offset and 50Q Load Impedance 2 Setthe DS335 to 100 kHz Set the spectrum analyzer to 100 kHz center frequency 100 kHz span Measure the amplitude of the spurious signals and verify that they are lt 65 dBc Increase the span and check again 3 Set the DS335 to 2 MHz Set the spectrum analyzer to 2 MHz center frequency 100 kHz span Measure the amplitude of the spurious signals and verify that they are lt 55 dBc Increase the span and check again DS335 Synthesized Function Generator HARMONIC DISTORTION PHASE NOISE SQUARE WAVE RISE TIME SQUARE WAVE SYMMETRY Performance Tests 4 11 This test measures the DS335 s sine wave harmonic distortion specification lt 60 dBc frequency lt 100 kHz lt 50 dBc frequency 0 1 to 1 MHz lt 40 dBc frequency 1 to 3 1 MHz 1 Connect the DS335 output to the FFT analyzer input with a 50W terminator Set the DS335 to sine wave 100Hz 1 Vpp and 50Q Load Impedance 2 Adjust the FFT analyzer to view the fundamental and its harmonics Verify that all harmonics are below 60 dBc 3 Repeat step 2 at 1 kHz and 10 kHz 4 Connect the DS335 output to the RF spectrum analyzer input Set the DS335 to 50 kHz Verify that the harmonics are at least 60 dBc 5 Set the 05335 to 500 kHz and 3 MHz and verify that all harmonics are at least 50 dBc and 40 dBc respectively Record
43. Component Parts List 5 17 REF R 751 R 752 R 800 R 801 R 802 R 803 R 804 R 805 R 806 R 807 R 808 R 809 R 810 R 8111 R 812 R 813 R 814 R 815 R 817 R 818 R 900 R 901 R 902 50104 50408 SP100 SW1 SW900 T 500 T 501 T 502 T 503 T 504 T 505 T 600 T 800 T 801 T 900 TP100 TP101 TP102 TP103 TP500 SRS PART VALUE 4 00056 401 22 4 00056 401 22 4 00749 439 432 4 00749 439 432 4 00777 407 11 5 4 00750 439 221 4 00750 439 221 4 00751 439 23 7 4 00752 439 232 4 00752 439 232 4 00752 439 232 4 00752 439 232 4 00753 439 52 8 4 00754 439 154 4 00755 439 137 4 00755 439 137 4 00755 439 137 4 00755 439 137 4 00272 407 221 4 00202 407 698 4 00022 401 1 0M 4 00034 401 10R 4 00032 401 100R 1 00026 150 28 PIN 600 MIL 1 00108 150 PLCC 68 TH 6 00096 600 MINI 7 00448 740 DS335 340 2 00023 218 DPDT 6 00138 601 T37 15 8 6 00139 601 T37 15 12 6 00141 601 T37 15 14 6 00140 601 T37 15 13 6 00139 601 T37 15 12 6 00141 601 T37 15 14 6 00157 601 DS335 6 00157 601 DS335 6 00157 601 DS335 1 00036 116 7 PIN VVHITE 1 00143 101 TEST JACR 1 00143 101 TEST JACR 1 00143 101 TEST JACR 1 00143 101 TEST JACR 1 00143 101 TEST JACR 3 00288 340 HDSP H101 3 00288 340 HDSP H101 3 00288 340 HDSP H101 3 00288 340 HDSP H101 3 00288 340 HDSP H101 3 00288 340 HDSP H101 3 00288 340 HDSP H101 3 00288 340 HDSP H101 3 00298 340 Z80H 3 00049 340 74HC74 3 00155 340 74HC04 DESCRIPTION Resistor Carbon Film 1 4W 596 Resistor C
44. Function Generator Programming Commands 3 7 Hardware Test and Calibration Commands NOTE These commands are primarily intended for factory calibration use and should never be needed during normal operation Incorrect use of some of these commands can destroy the calibration of the DS335 CLK The CLK command queries the DS335 for the status of its calibration jumper Shown below are the different status values that the DS335 can return Status value Meaning 0 Calibration disabled 1 Calibration enabled FCL The FCL command recalls the factory calibration bytes This command will generate an error if calibration is not enabled TST The TST common query runs the DS335 internal self tests After the tests are complete the test status is returned The status may have the following values see the TROUBLESHOOTING section for more details Status value Meaning 0 No Error 1 CPU Error The DS335 has detected a problem in its CPU 2 Code Error The DS335 s ROM firmware has a checksum error 3 Sys RAM Error The system RAM failed its test 4 Cal Data Error The DS335 s calibration data has become corrupt 5 Unused 6 Program Data Error The modulation program RAM failed its test 7 DS335 not warmed up At least 2 minutes must elapse between power on and calibration PRE 2 i The PRE command sets the DS335 s pre amplifier attenuators to range i The integer i is the attanuation value in dB and ranges from 0 t
45. IAL Capacitor Ceramic 50V 80 20 Z5U AX C 101 5 00192 542 22U MIN Cap Mini Electrolytic 50V 20 Radial C 102 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 103 5 00040 509 1 0U Capacitor Electrolytic 50V 20 Rad C 200 5 00027 503 01U Capacitor Ceramic Disc 50V 20 Z5U C 301 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 303 5 00225 548 AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 304 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 305 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 306 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 400 5 00002 501 100P Capacitor Ceramic Disc 50V 10 SL C 500 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 501 5 00065 513 01U Capacitor Mylar Poly 50V 5 Rad C 502 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 503 5 00178 501 62P Capacitor Ceramic Disc 50V 10 SL C 504 5 00178 501 62P Capacitor Ceramic Disc 50V 10 SL C 505 5 00273 532 100P Capacitor Ceramic Disc 50V 10 NPO C 506 5 00273 532 100P Capacitor Ceramic Disc 50V 10 NPO C 509 5 00151 501 680P Capacitor Ceramic Disc 50V 10 SL C 510 5 00151 501 680P Capacitor Ceramic Disc 50V 10 SL C 511 5 00270 532 51P Capacitor Ceramic Disc 50V 10 NPO C 512 5 00270 532 51P Capacitor Ceramic Disc 50V 10 NPO C 513 5 00259 501 002U Capacitor Ceramic Disc 50V 1096 SL C 514 5 00259 501
46. INE FUSE Verify that the correct line fuse is installed before connecting the line cord For 100V 120V use a 1 2 Amp slow blow fuse and for 220V 240V use a 1 4 Amp slow blow fuse LINE CORD The DS335 has a detachable three wire power cord for connection to the power source and to a protective ground The exposed metal parts of the instrument are connected to the outlet ground to protect against electrical shock Always use an outlet which has a properly connected protective ground DS335 Synthesized Function Generator iv SRS Symbols Symbols you may find on SRS products Description EUM Alternating current Caution risk of electric shock Frame or chassis terminal A Caution refer to accompanying documents Earth ground terminal El Pee DS335 Synthesized Function Generator Specifications v SPECIFICATIONS FREQUENCY RANGE Waveform Maximum Freq Resolution Accuracy Sine 3 1 MHz 1 uHz 25 Square 3 1 MHz 1 uHz 25ppm Ramp 10 KHz 1 uHz 25ppm Triangle 10 KHz 1 uHz 25ppm Noise 3 5 MHz Gaussian Weighting OUTPUT Source Impedance 50 Q Output may float up to 40V AC DC relative to earth ground AMPLITUDE Range into 500 load limited such that Vac peak Vac lt 5 V Vpp Vrms Function Max Min Max Min Sine 10V 50 mV 3 54V 0 02Vrms Square 10V 50 mV 5 00V 0 03Vrms Triangle 10V 50 mV 2 89V 0 01Vrms Ramp 10V 50 mV 2 89V 0 01Vrms Noise 10V 50 mV 1
47. IP 1 4W 2 Isolated SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated Dip 1 4W 2 Common SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated SIP 1 4W 2 Isolated pp eS es Printed Circuit Board Printed Circuit Board Printed Circuit Board Transistor TO 92 Package Transistor TO 92 Package DS335 Synthesized Function Generator 5 14 05335 Component Parts List REF SRS PART VALUE DESCRIPTION Q 103 3 00026 325 2N5210 Transistor TO 92 Pachage Q 104 3 00026 325 2N5210 Transistor TO 92 Pachage Q 200 3 00022 325 2N3906 Transistor TO 92 Package Q 201 3 00022 325 2N3906 Transistor TO 92 Package Q 202 3 00022 325 2N3906 Transistor TO 92 Package Q 203 3 00022 325 2N3906 Transistor TO 92 Package Q 500 3 00021 325 2N3904 Transistor TO 92 Package Q 600 3 00021 325 2N3904 Transistor TO 92 Package Q 601 3 00022 325 2N3906 Transistor TO 92 Package Q 602 3 00021 325 2N3904 Transistor TO 92 Package Q 603 3 00022 325 2N3906 Transistor TO 92 Package Q 604 3 00022 325 2N3906 Transistor TO 92 Package Q 700 3 00024 325 2N5086 Transistor TO 92 Package Q 701 3 00027 325 2N5770 Transistor TO 92 Package Q 702 3 00027 325 2N5770 Transistor TO 92 Package Q 703 3 00022 325 2N3906 Transistor TO 92 Package Q 704 3 00028 325 2N5771 Transistor TO 92 Package Q 705 3 00028 325 2N5771 Transistor TO 92 Package Q 706 3 00021 325 2N3904 Transistor TO 92 Package Q 707 3 00025 325 2N5088 Transistor
48. MODEL DS335 Synthesized Function Generator RS Stanford Research Systems 1290 D Reamwood Avenue Sunnyvale California 94089 Phone 408 744 9040 Fax 408 744 9049 email info QthinkSRS com www thinkSRS com Copyright 1993 2002 2013 by SRS Inc All Rights Reserved Revision 1 7 11 2013 DS335 Synthesized Function Generator Table of Contents Condensed Information Safety and Use SRS Symbols Specifications Abridged Command List Getting Started Introduction CW Function Generation Frequency Sweep Operation Introduction to DDS DS335 Features Front Panel Features Rear Panel Features Function Setting Setting the Function Frequency Amplitude DC Offset Sweeps FSK Frequency Sweeps Sweep Type Sweep Frequencies Sweep FSK Output FSK Intput Instrument Setup Default Settings Store and Recall GPIB and RS232 Setup Self Test Programming Programming the DS335 Communications GPIB Communication RS 232 Communication Data Window Command Syntax Detailed Command List Function Output Commands Sweep Control 2 5 2 7 2 9 2 9 2 9 2 9 2 11 2 13 2 13 2 13 2 14 2 14 2 14 2 17 2 17 2 17 2 17 2 18 Table of Contents Setup Control Commands Status Reporting Commands Test and Calibration Commands Status Byte Definitions Programming Examples Introduction GPIB and C Example RS232 and BASIC example Test and Calibration Troubleshooting Operation Error Messages Self Te
49. S amp FSK Introduction The DS335 can perform frequency sweeps of the sine square triangle and ramp waveforms The sweeps may be up or down in frequency and may be linear or logarithmic in nature The frequency changes during the sweep are phase continuous and the sweep rate may be set between 0 01 Hz and 1000Hz The DS335 has a SWEEP output that may be used to trigger an oscilloscope The DS335 is also capable of Frequency Shift Keying FSK FSK can be implemented either through the internal rate generator or the back panel external input to toggle between two preset frequencies mam Ti IT EB q eT AED m LE WIL TREY Sweep FSK Enable Sweeps are enabled by pressing SHIFT START FREQ in the Frequency Sweeps menu The DS335 displays the CONT SNGL menu which allows the user to choose between continuous and single sweeps The DS335 will immediately start a continuos sweep unless the user presses the UP DOWN arrow key to select SINGLE sweep Once a single sweep is selected the SHIFT START FREQ key triggers the sweep If the user has selected the FSK function from the UNI BI Unidirectional Bidirectional FSK menu the single continuous sweep option is disabled and the FS OFF menu appears giving the user the choice to enable or disable the FSK function Once the FSK function is selected and enabled the FSK output signal appears at the Function Out BNC Sw
50. SRE i STB i DENA i STAT i The CLS common command clears all status registers This command does not affect the status enable registers The ESE command sets the standard event status byte enable register to the decimal value i The ESR common command reads the value of the standard event status register If the parameter i is present the value of bit i is returned 0 or 1 Reading this register will clear it while reading bit i will clear just bit i The PSC common command sets the value of the power on status clear bit If i2 1 the power on status clear bit is set and all status registers and enable registers are cleared on power up If i 0 the bit is cleared and the status enable registers maintain their values at power down This allows the production of a service request at power up The SRE common command sets the serial poll enable register to the decimal value of the parameter i The STB common query reads the value of the serial poll byte If the parameter i is present the value of bit i is returned 0 or 1 Reading this register has no effect on its value as it is a summary of the other status registers The DENA command sets the DDS status enable register to the decimal value i The STAT query reads the value of the DDS status byte If the parameter i is present the value of bit i is returned Reading this register will clear it while reading bit i will clear just bit i DS335 Synthesized
51. T FSK Input The duration of the sweep is set by RATE and the value is entered or modified with the keypad The sweep rate may be set over the range of 0 01 Hz to1 kHz The sweep rate is the inverse of the sweep time a 0 01 Hz rate is equal to a 100s sweep time and a1 kHz rate is equal to a 1 ms sweep time For a TRIANGLE sweep the sweep time is the total time to sweep up and down If FSK is selected from the UNI BI menu then the Sweep Rate button sets the FSK Rate If the rate is set to 0 Hz then the rear panel FSK BNC input toggles between the two preset frequencies For any non zero rate the DS335 will toggle between the two preset frequencies at the specified rate The maximum internal FSK rate is 50 kHz The DS335 may sweep over any portion of its frequency range 1 uHz to 3 1 MHz for sine and square waves 1 uHz to 100 kHz for triangle and ramp waves The sweep span is limited to six decades for logarithmic sweeps The DS335 s sweep range is set by entering the start and stop frequencies In FSK mode the DS335 will toggle between any two frequencies 1uHz to 3 1 MHz for sine and square waves and 1 uHz to 100 kHz for triangle and ramp waves There are no restrictions on the values of the start and stop frequencies for linear sweeps To enter the start and stop frequency press the START FREQ and STOP FREQ keys The span value is restricted to sweep frequencies greater than zero and less than or equal to the maximum allowed freque
52. T 1 twice to view the GPIB address The entry keys or the UP DOWN ARROW keys may be used to set the GPIB address The DS335 will ignore its front panel key pad when Remote Enable REN has been asserted by the GPIB This REMOTE state is indicated by the REMOTE LED To return to LOCAL operation ie to enable the front panel press 3 Controlling programs may inhibit the ability to return to LOCAL operation by asserting the Local Lockout state LLO A linefeed character is sent with and End or Identify EOI to terminate strings from the DS335 Be certain that your GPIB controller has been configured to accept this sequence First make sure that the RS232 interface is enabled Press SHIFT 2 to display the enable status line RS232 should be ON If not turn RS232 on using the UP DOWN ARROW keys Second the RS 232 baud rate must be set to match that expected by the controlling computer The default baud DS335 Synthesized Function Generator Troubleshooting 4 3 rate is 9600 baud The DS335 always sends two stop bits 8 data bits and no parity and will correctly receive data sent with either one or two stop bits When connecting to a PC use a standard PC serial cable not a null modem cable The DS335 is a DCE Data Communications Equipment device and so should be connected with a straight cable to a DTE device Data Terminal Equipment The minimum cable will pass pins 2 3 and 7 For hardware handshaking pins 5 and 2
53. TO 92 Package Q 708 3 00028 325 2N5771 Transistor TO 92 Package Q 709 3 00027 325 2N5770 Transistor TO 92 Package Q 710 3 00022 325 2N3906 Transistor TO 92 Package Q 711 3 00022 325 2N3906 Transistor TO 92 Package Q 712 3 00022 325 2N3906 Transistor TO 92 Package Q 713 3 00447 322 2N5943 Transistor TO 39 Package Q 714 3 00015 322 2N5583 Transistor TO 39 Package Q 715 3 00021 325 2N3904 Transistor TO 92 Package Q716 3 00021 325 2N3904 Transistor TO 92 Package Q 717 3 00021 325 2N3904 Transistor TO 92 Package R 101 4 00027 401 1 5K Resistor Carbon Film 1 4W 596 R 102 4 00027 401 1 5K Resistor Carbon Film 1 4W 5 R 103 4 00081 401 470 Resistor Carbon Film 1 4W 5 R 104 4 00081 401 470 Resistor Carbon Film 1 4W 5 R 105 4 00031 401 100 Resistor Carbon Film 1 4W 5 R 106 4 00034 401 10K Resistor Carbon Film 1 4W 5 R 107 4 00032 401 100K Resistor Carbon Film 1 4W 5 R 108 4 00034 401 10K Resistor Carbon Film 1 4W 5 R 109 4 00021 401 1 0K Resistor Carbon Film 1 4W 5 R 110 4 00032 401 100K Resistor Carbon Film 1 4W 596 R 229 4 00022 401 1 0M Resistor Carbon Film 1 4W 596 R 300 4 00218 408 10 00K Resistor Metal Film 1 8W 0 196 25ppm R 302 4 00034 401 10K Resistor Carbon Film 1 4W 596 R 303 4 00185 407 4 02K Resistor Metal Film 1 8VV 196 SOPPM R 304 4 00130 407 1 00K Resistor Metal Film 1 8VV 196 SOPPM R 305 4 00218 408 10 00K Resistor Metal Film 1 8W 0 196 25ppm R 316 4 0
54. To refresh a particular sample and hold the analog multiplexer U304 a 74HC4051 is inhibited by writing a one to the MSB Q8 of the DAC MPX latch 0305 a 74HC273 Next the address of the desired S H is written to bits Q5 Q6 and Q7 of the DAC MPX latch along with the four LSB s of the desired 12 bit DAC value to Q1 4 Then the 8 MSB s of the 12 bit DAC value is written along with the port strobe DAC STB to load the 12 bit value into the DAC Finally the inhibit to the DAC multiplexer is removed by writing a zero to the MSB Q8 of the DAC MPX latch A different sample and hold is refreshed with each new RTI The refresh interval is two milliseconds The square wave symmetry control voltage may be set over 5V with zero being nominal This voltage controls the duty cycle of the SYNC and square wave outputs and varies with frequency to maintain the output at 5096 duty cycle per the contents of a calibration table The square wave amplitude control voltage may be set over 5V The actual output square wave amplitude is linear in the DAC value and zero when the DAC value is zero This voltage is set to 5V if a square wave is not selected in order to reduce cross talk in the function select relay The output offset control voltage may be set over the range of 10 5 to 10 5V The higher output levels are due to the gain of x2 1 of the sample and hold amplifier for this control voltage The front panel function output will have an dc offse
55. amic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Electrolytic 35V 20 Rad Capacitor Electrolytic 35V 20 Rad Capacitor Electrolytic 16V 20 Rad Capacitor Electrolytic 16V 20 Rad Capacitor Ceramic Disc 50V 20 Z5U Capacitor Ceramic 50V 80 20 Z5U AX Capacitor Ceramic 50V 80 20 Z5U AX LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Coated Rectangular LED Coated Rectangular LED Coated Rectangular LED Coated Rectangular DS335 Component Parts List 5 13 REF D 24 D 25 PC3 Q 101 Q 102 SRS PART VALUE 3 00455 310 GREEN COATED 3 00455 310 GREEN COATED 3 00884 306 RED 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00485 301 1N5237B 3 00485 301 1N5237B 3 00062 340 KBP201G BR 81D 3 00226 301 1N5822 3 00226 301 1N5822 3 00226 301 1N5822 3 00226 301 1N5822 3 00203 301 1N5711 1 00038 130 40 PIN DIL 1 00038 130 40 PIN DIL 1 00003 120 BNC 1 00003 120 BNC 1 00073 120 INSL 1 00073 120 INSL 1 00032 130 14 PIN DIL 1 0008
56. arbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Pot Multi Turn Trim 3 8 Square Top Ad Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 4W 1 50ppm Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 DS335
57. arbon Film 1 4W 596 Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 8W 196 50PPM Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 4W 196 50ppm Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Socket THRU HOLE Socket THRU HOLE Misc Components Keypad Conductive Rubber Switch Panel Mount Power Rocker Inductor Inductor Inductor Inductor Inductor Inductor Inductor Inductor Inductor Header Amp MTA 156 Vertical Test Jack Vertical Test Jack Vertical Test Jack Vertical Test Jack Vertical Test Jack Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Th
58. at of the 50 Ohm cases High Impedance table goes first as its first entry is the reference gain for all other measurements 24 HI OdB Fixed at 2 16 1 65535 Reference gain level 25 HI 2dB 5 from nominal value of 52057 26 HI 4dB 5 from nominal value of 41350 27 HI 6dB 5 from nominal value of 32845 28 HI 8dB 5 from nominal value of 26090 29 HI 10dB 5 from nominal value of 20724 30 HI 12dB 5 from nominal value of 16461 31 HI 14dB 5 from nominal value of 13076 32 HI 16dB 5 from nominal value of 10386 33 HI 18dB 5 from nominal value of 8250 34 HI 20dB 5 from nominal value of 6553 35 HI 22dB 5 from nominal value of 5205 36 24dB 5 from nominal value of 4135 37 HI 26dB 5 from nominal value of 3284 38 HI 28dB 5 from nominal value of 2609 39 HI 30dB 5 from nominal value of 2072 DS335 Synthesized Function Generator Calibration 4 17 Now the post amplifier attenuator gains for 50 Ohm case 40 50 OdB 5 from nominal value of 32768 41 50 2dB 5 from nominal value of 26028 42 50 4dB 5 from nominal value of 20675 43 50 5 from nominal value of 16422 44 50 8dB 5 from nominal value of 13045 45 50 10dB 5 from nominal value of 10362 46 50 12dB 5 from nominal value of 8230 47 50 14dB 5 from nominal value of 6538 48 50 16dB 5 from nominal value of 5193 49 50 18dB 5 from nominal value of 4125 50 5
59. ata and commands are shifted to and from the interface with the port strobe DATA CLK Commands are executed a register read for example when the port strobe CMD STB is asserted A separate ground referenced power supply is generated on the interface PCB by rectifying and regulating the 9 Vac which is supplied to the header GPIB and RS232 interrupts can assert the maskable interrupt to the Z80 If no interface is present this interrupt will not be asserted The CPU tests for the presence of the interface on power up by shifting data though the interface and looking for its return with a 16 cycle delay of course Data to the interface is buffered by a D type flip flop 74HC74 U107A The MSB of the data bus is clocked into the flip flop on the leading edge of the DATA CLK and clocked into the interface s shift register on the trailing edge of the DATA CLK This is done to eliminate processor noise on the ribbon cable when there are no communications A byte is transferred to the interface with eight outputs and eight left shift instructions Battery Back up The contents of the 32Kx8 CMOS RAM are preserved when the power is turned off by a Lithium battery The CS to the RAM is disabled on power down by the RESET which turns off the NPN transistor Q101 a 2N3904 Display Driver DS335M2 The front panel display is time multiplexed two digits and seven indicators may be refreshed and six keys read during each of four successi
60. ation of 86 dB The Cauer filter is used when sines or square wave outputs are selected Cauer filters provide steep roll offs and flat passband characteristics A Sin x x compensator precedes the Cauer filter This circuit compensates for the reduced signal level of the sampled waveform as the frequency of the output approaches the Nyquist limit The circuit increases the amplitude to compensate for the effect by increasing the termination impedance of the DAC output for higher frequencies A pair of DPDT relays U501 and U502 HS 212 s select between the Bessel and Cauer filters These relays are controlled by the LSB of the RELAY CTL latch U800 a 74HC374 and are driven by an emitter follower U801 a CA3082 Pre attenuator DS335M5 The output from the selected filter is terminated by a O to 14 dB resistive differential attenuator This attenuator must be used when an output offset other than zero is selected The peak ac amplitude plus offset must not exceed 10 V at the output of the amplifier The attenuator will also be used for outputs of less that 0 3 Vpp A pair of 1 8 analog multiplexers U600 and U604 74HC4051 s select the attenuation factor in 2 dB steps The analog multiplexers are controlled by the MISC OUT latch 0109 a 4HC273 The multiplexers are inhibited by SQ SINE if a square wave output is selected This will reduce crosstalk in the function select relay U603 a HS 212 SYNC Generator DS335M6 The un at
61. ator 3 12 Programming Examples EXAMPLE 1 GPIB COMMUNICATION C LANGUAGE This program communicates with the DS335 via GPIB The program is written in C C Program to demonstrate communication with the DS335 via GPIB Written in Microsoft C and uses National Instruments GPIB card Assumes DS335 is installed as device name DDS335 Refer to National Instruments for Device Name setup include lt stdio h gt include lt string h gt include lt stdlib h gt include lt dos h gt include lt decl h gt National Instruments header files void main void function declaration int dds335 void main char 40 char start 20 char stop 20 if dds335 ibfind DDS335 lt 0 open National driver printf Cannot find DDS335 n exit 1 Now that the driver is located reset the DS335 sprintf cmd RST n ibwrt dds335 cmd strlen cmd send command Setup the DS335 as follows 500 kHz Square Wave 1 5 Vpp 1 0 Volt offset display offset sprintf cmd FREQ500000 AMPL1 5VP OFFS 1 0 KEYS3 n ibwrt dds335 cmd strlen cmd send commands Now query the DS335 for the sweep start and stop frequencies sprintf cmd STFRAn ask for start rate ibwrt dds335 cmd strlen cmd send query ibrd dds335 start 20 read back start frequency sprintf cmd SPFRAn ask for stop rate ibwrt dds335 cmd strlen cmd send query
62. ber and the serial number should be displayed for about 3 seconds The self tests will execute and the message TEST PASS should be displayed If an error message appears see the TROUBLESHOOTING section for a description of the errors This procedure visually checks the sine wave output for the correct frequency and any visible irregularities 1 2 3 Connect the DS335 s output to the oscilloscope input and terminate in 500 Set the DS335 to sine 1 MHz 10 Vpp and 500 Load Impedance Set the scope to 2 V div vertical and 1us div horizontal The scope should display a sine vvave vvith one cycle per horizontal division and about five divisions peak to peak There should be no visible irregularities in the waveform This procedure checks the square wave output for frequency rise time and aberrations 1 2 3 Connect the DS335 s output to the oscilloscope input and terminate in 500 Set the DS335 to square vvave 1 MHz 10 Vpp and 50Q Load Impedance Set the scope to 2V div vertical and 200ns div horizontal The scope should show two square waves about 5 division peak to peak DS335 Synthesized Function Generator Amplitude Flatness Output Level Performance Tests 4 7 Increase the scope sensitivity to 1V div and measure the size of the overshoot at the beginning of the square wave It should be less than 0 2V peak to peak Adjust the scope to 2V div and 5ns div Measure the 10 to 90 rise time
63. cuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Relay Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Relay Relay Relay Relay Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg NEN Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg po Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package 05335 Component Parts List 5 19 REF U 809 U 810 U 811 U 812 VR900 SRS PART VALUE 3 00141 329 LM337T 3 00112 329 7805 3 001 12 329 7805 3 001 12 329 7805 4 00723 435 82V 2500A 0 00014 002 6J4 0 00025 005 3 8 0 00043 01 1 4 40 KEP 0 00050 01 1 8 32 KEP 0 00051 056 RG174 0 00079 031 4 40X3 16 M F 0 00089 033 4 0 00111 053 1 3 4 24B 0 00112 053 1 3 4 24R 0 00150 026 4 40X1 4PF 0 00163 007 TO 5 0 00181 020 6 32X1 4PF 0 00187 021 4 40X1 4PP 0 00207 003 TO 5 0 00208 020 4 40X3 8PF 0 00231 043 4 SHOULDER 0 00237 016 F1404 0 00243 003 TO 220 0 00259 021 4 40X1 2 PP 0 00267 052 6 1 2 22 RED 0 00268 052 6 1 2 22 BL 0 00304 043 7 8X3 8X1 16 0 00386 003 BNC BUSHING 0 00407 032 SOLDR SLV RG174 0 00500 000 554808 1 1 00034 113 PIN 18AWG OR 1 00072 112 8 PIN 28AWG GR 1 00087 131 2 PIN JUMPER 1 00134 171 40 COND 1 00172 170 9535 4 00541 435 130V 1200A 6 00003 61 1 5A 3AG 6
64. d with the message TST PASS If the self test fails the DS335 will display an error message indicating the nature of the problem see the TROUBLESHOOTING section for more details The DS335 will still attempt to operate normally after a self test failure pressing any key will erase the error message SETTING THE FUNCTION UT As m um a EE Ed OUTPUTS The FUNCTION and SYNC BNCs are the DS335 s main outputs Both of these outputs are fully floating and their shields may be floated relative to earth ground by up to 40V Both outputs also have a 500 output impedance If the outputs are terminated into high impedance instead of 50W the signal levels will be twice those programmed the FUNCTION output may also show an increase in waveform distortion The output impedance should be set properly from the front panel using the SHIFT 5 or SHIFT 6 keys Incorrect impedance matching may result in output voltages that do not correspond to the displayed amplitudes and offsets For example if the DS335 is set for a 50 Ohms source impedance and the output is connected to a scope without a 50 Ohms terminator then the scope waveform will be twice the amplitude displayed on the DS335 The programmed waveform comes from the FUNCTION output while the SYNC output generates a TTL compatible 2 5 V into 500 signal that is synchronous with the function output The SYNC signal is suppressed if the function is set to NOISE or ARB The SYNC signal can
65. e DS335 is a 10 MHz crystal clock The 10 MHz clock controls the DDS ASIC waveform ROM and high speed 12bit DAC Sampling theory limits the frequency of the waveform output from the DAC to about 40 of 10 MHz or 3 MHz The 48 bit length of the ASIC s PIR s sets the frequency resolution to about 36 nHz These parameters and the DAC s 12 bit resolution define the performance limits of the DS335 The reconstruction filter is key to accurately reproducing a waveform in a sampled data system The DS335 contains two separate filters For sine wave generation the output of the DAC goes through a 7 order Cauer filter while ramps and triangles pass instead through a 3 5 MHz 5 order Bessel filler The Cauer filter has a cutoff frequency of 3 4 MHz and a stopband attenuation of 86 dB and includes a peaking circuit to correct for the sin x x amplitude response characteristic of a sampled system This filter eliminates any alias frequencies from the waveform output and allows generation of extremely pure sine waves However the Cauer filter has very poor time response and is only useful for CW waveforms Therefore the Bessel filter was chosen for its ideal time response eliminating rings and overshoots from stepped waveform outputs The output from the filter passes through pre amplifier attenuators with a O to 14 dB range The attenuators are followed with a wide bandwidth power amplifier that outputs a 10 V peak to peak into a 50 ohm load with a ri
66. e Frequency Shift Keying input allows the user to toggle between the start frequency and the stop frequency The BNC takes a TTL level input When the input is low the start frequency is active and when the input is high the stop frequency is active This input is sampled at 10 MHz If the DS335 has the optional GPIB RS232 interface this connector is used for IEEE 488 1 and 2 compatible communications The shield of this connector is connected to earth ground If the DS335 has the optional GPIB RS232 interface this connector is used for RS232 communication The DS335 is a DCE and accepts 8 bits no parity 2 stop bits at between 300 and 9600 Baud The shield of this connector is connected to earth ground DS335 Synthesized Function Generator 2 8 Features DS335 Synthesized Function Generator Function Setting 2 9 DS335 OPERATION Introduction The following sections describe the operation of the DS335 The first section describes the basics of setting the function frequency amplitude and offset The second section explains sweeps and FSK The third section explains storing and recalling setups running self test and autocalibration and setting the computer interfaces Power On When the power is first applied to the DS335 the unit will display its serial number and ROM version for about three seconds Then the DS335 will initiate a series of self tests of the circuitry and stored data The test should take about three seconds and en
67. e modulation RAM is addressed by the ASIC To load modulation op codes and data the start address for the modulation program is written to the ASIC s MODSTHT registers and loaded into the modulation address counters Op codes and data are written sequentially to the modulation RAM as outputs to MOD RAM port The MOD RAM port strobe writes data to the modulation RAM and increments the modulation address There is one eight bit DAC which is loaded as if it were an ASIC register The DAC U402 a AD7524 controls the reference voltage to the waveform DAC and so the output amplitude DAC values from 0 to 255 control the reference from minus 0 75 to minus 1 25 Vdc This DAC is used to level the output amplitude during frequency sweeps There is a 74HC273 U413 that is also loaded as if it were an ASIC register its output goes directly to the SWEEP FSK rear panel BNC When the DS335 is performing a sweep this output provides a pulse that is synchronous with the sweep rate When the DS335 is performing internal FSK the SWEEP FSK ouptut voltage toggles at the FSK rate The waveform addresses generated by the ASIC access one of four 8k long tables in waveform ROMs U409 0411 These tables contain sine ramp saw and noise data The tables are selected by the two MSB s of the ASIC CTL latch U404 a 74HC273 Data from the ROMs is latched into two 8 bit latches U410 and U412 74F374 s Waveform DAC DS335M5 Latched waveform data WDO to 011
68. ed The RS232 interface baud rate may be set in the second line of the RS232 menu type SHIFT 2 twice The interface is fixed at 8 data bits no parity and 2 stop bits Front Panel LEDs To assist in programming the DS335 has 4 front panel status LEDs The RS232 and GPIB LEDs flash whenever a character is received or sent over the corresponding interface The ERROR LED flashes when an error has been detected such as an illegal command or an out of range parameter The REMOTE LED is lit whenever the DS335 is in a remote state front panel locked out Data Window To help find program errors the DS335 has an input data window which displays the data received over either the GPIB or RS232 interfaces This window is activated by typing SHIFT 2 or SHIFT 1 three times The menu displays the received data in hexadecimal format The last 256 characters received can be scrolled through using the MODIFY up down arrow keys A decimal point indicates the most recently received character Command Syntax Communications with the DS335 use ASCII characters Commands may be in either UPPER or lower case and may contain any number of embedded space characters A command to the DS335 consists of a four character command mnemonic arguments if necessary and a command terminator The terminator may be either a carriage return cr or linefeed lf on RS232 or a linefeed If or EOI on GPIB No command processing occurs until a command terminator is
69. eep Type Pressing the SHIFT STOP FREQ key sets the sweep to either a linear or log mode The UP DOWN arrow toggles between the two sweep types The output frequency of a linear sweep changes linearly during the sweep time The output frequency in a logarithmic sweep changes exponentially during the sweep time spending equal time in each decade of frequency For example in a sweep from 1 kHz to 100 kHz the sweep will spend half the time in the 1 kHz to 10 kHz range and half the time in the 10 kHz to 100 kHz range It should be noted that these are digital sweeps and that the sweep is actually composed of 1500 to 3000 discrete frequency points depending on the sweep rate Sweep Waveform The type of sweep waveform may be set to UNidirectional ramp or Bldirectional triangle by pressing the SHIFT SWEEP RATE key and then pressing the UP DOWN arrow keys If FSK is selected Frequency Shift keying is enabled and the sweeps are disabled If the waveform is UNI Ramp the DS335 sweeps from the start to the stop frequency returns to the start frequency and repeats continuously For BI directional sweeps the DS335 sweeps from the start to the stop frequency then sweeps from the stop frequency to the start frequency and repeats If the DS335 is set for a single sweep the sweep occurs only once DS335 Synthesized Function Generator 2 14 Sweeps amp FSK Sweep FSK RATE Sweep FSK FREQUENCIES Start and Stop Frequencies Sweep FSK OUTPU
70. es 2 2 Output Attenuator 5 6 Option Board 5 7 Front Panel Component Placement Power Supplies 5 7 Main PC Board Component Placement GPIB and RS232 Interfaces 5 7 Option Board Component Placement DS335 Synthesized Function Generator Safety and Preparation for Use iii Safety and Preparation for Use WARNING Dangerous voltages capable of causing death are present in this instrument Use extreme caution whenever the instrument covers are removed This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong ac line voltage or if the wrong fuse is installed LINE VOLTAGE SELECTION The DS335 operates from a 100V 120V 220V or 240V nominal ac power source having a line frequency of 50 or 60 Hz Before connecting the power cord to a power source verify that the LINE VOLTAGE SELECTOR card located in the rear panel fuse holder is set so that the correct ac input voltage value is visible Conversion to other ac input voltages requires a change in the fuse holder voltage card position and fuse value Disconnect the power cord open the fuse holder cover door and rotate the fuse pull lever to remove the fuse Remove the small printed circuit board and select the operating voltage by orienting the board so that the desired voltage is visible when it is pushed firmly back into its slot Rotate the fuse pull lever back into its normal position and insert the correct fuse into the fuse holder L
71. eter Display 11 Units LEDs 12 Load Impedance LEDs These keys control the different sweep parameters including Start and Stop Frequencies Sweep Rate Continuous or Single Sweep Linear or Log Sweep Unidirectional or Bidirectional Sweeps and FSK These keys control the main function output The Func DOWN ARROW key and SHIFT UP ARROW key select between the output functions If the output frequency is set beyond the range allowed for a waveform 10kHz for triangle and ramp an error message will be displayed and the frequency will change to the maximum allowed for that function This output has an impedance of 500 The shield of this output may be floated up to 40V relative to earth ground This output is a TTL square wave synchronized to the main function output and has a 50Q output impedance The shield of this output may be floated up to 40V relative to earth ground These four LEDs indicate the DS335 s status They are name function REMOTE The DS335 is in GPIB remote state The 3 key returns local control GPIB Flashes on GPIB activity RS232 Flashes on RS232 activity ERROR Flashes on an error in the execution of a remote or local command including range errors The 8 digit display shows the value of the currently displayed parameter The LEDs below in the DISPLAY section indicate which parameter is being displayed Error messages also appear on the display When an error message is displayed you can re
72. face Press SHIFT 1 again to display the GPIB address Enter the address desired using the numeric keypad or arrow keys The range of valid addresses is 0 30 NOTE If the DS335 does not have the optional GPIB RS232 interfaces the message no GPIB will be displayed when the GPIB menu is accessed Only one of the GPIB and RS232 interfaces may be active at a given time the RS232 interface is automatically disabled when GPIB is enabled DS335 Synthesized Function Generator 2 18 Sweeps 8 FSK RS232 Setup User Service Requests Communications Data AUTO TEST Introduction SELF TEST CALIBRATION BYTES To set the DS335 s RS232 interface press SHIFT 2 The RS232 enable selection will be displayed Use the UP DOWN ARROW keys to enable the RS232 interface Press SHIFT 2 again to display the RS232 baud rate selection The available baud rates of 300 600 1200 2400 4800 or 9600 baud can be set with the UP DOWN ARROW keys NOTE If no interface option is present the message no RS232 will be displayed when the RS232 menu is accessed Only one of the GPIB and RS232 interfaces may be active at a given time the GPIB interface is automatically disabled when RS232 is enabled While the GPIB is enabled the user may issue a service request SRQ by pressing SHIFT 4 The message srq sent will be displayed and the GPIB LED will light The GPIB LED will go off after the host computer does a serial poll of the DS335 Note the
73. ffset Read the voltmeter and record the result The result should be between 0 2 mV and 0 2mV specification lt 80mV at full output 1 Connect the DS335 s output to the voltmeter with a 50W terminator Set the DS335 to sine wave 1 kHz 10Vpp OV offset and 500 Load Impedance Set the voltmeter to measure DC voltage 2 Measure the offset voltage and verify that it is between 80mV and 80mV Record the result 3 Repeat step 2 at 100kHz 1MHz and 3 1MHz Record the results and verify that the offset is between 80mV and 80mV at all of the frequencies This test measures the subharmonic content of the DS335 s sinewave output The frequencies in this test are picked such that spurious frequencies from the DDS process do not fall on the carrier position specification lt 70 dBc 1 Connect the DS335 to the RF spectrum analyzer Set the DS335 to sine wave 10Vpp OV offset and 50Q Load Impedance 2 Set the DS335 to 102 kHz Set the spectrum analyzer to 51 kHz center frequency 10 KHz span The carrier amplitude at 51 kHz should be less than 70 dBc Record the result 3 Set the DS335 to 1 002 MHz and the spectrum analyzer to 501 kHz Measure and record the amplitude of the 501 kHz carrier It should be less that 70 dBc Repeat for 3 1MHz These tests measure the spurious signals on the DS335 s sine wave outputs They check both close in and wide band spurs 65 dBc to 1MHz 55 dBc to 3 1MHz specification I
74. he attenuators are switched in The relays are controlled by bits written to the 8 bit latch U800 a 74HC273 Outputs from the latch are buffered by npn emitter followers U801 a CA3082 which drive the relay coils Each 2 dB attenuator can reduce the output by a factor of 0 794 Output levels between these steps are obtained by adjusting the reference level to the waveform DAC The total attenuation is 30 dB or a factor of 0 0316 which will reduce the 7 94 Vpp level from the output amplifier to 0 25 Vpp For ac levels below this the pre attenuator will be used Sheet FG6 to provide up to 14 dB additional attenuation for levels down to 50 mVpp DS335 Synthesized Function Generator Circuitry 5 7 Povver Supplies DS335PS9 A transformer with multiple primary taps accommodates operation from 100 120 220 and 240 Vac mains The secondaries are full wave rectified filtered and regulated Linear power supplies which float with the ground applied to the BNC shields provide 15 5 and 5 2 Vdc There are three separate regulators for the 5 supplies so as to reduce noise in critical circuits 5 LOGIC 45 CLOCK and 5 ANALOG There is a 9 4 Vac tap on the secondary of the transformer which is rectified filtered and regulated on the optional communications interface to provide a 5 Vdc which is referenced to the line cord ground See sheet DS340PS10 A power up power down reset circuit asserts RESET signals to the system whenever t
75. he unit is turned on or off Clean resets are important for starting the CPU and for RAM protection on power down Communications Interface DS335PS10 Optional The design of the communications interface is dictated by the requirement that it must be ground referenced while the rest of the system must float with the BNC shield This requires a separate power supply and opto isolators for data and clock To avoid using large numbers of opto isolators it is necessary to transfer data and commands between the CPU and the communications interface serially The RS232 interface is handled by a 8251 UART the GPIB interface uses a TMS9914A GPIB controller Both of these devices have a bi directional data bus and several internal registers for data and control To write to a register in one of these devices sixteen bits must be shifted serially Eight bits of data and eight command bits This requires sixteen OUT instructions and sixteen shift instructions Only the MSB of the OUT will be transferred to the communications interface with each OUT instruction Consider a write to a register in the UART to illustrate the operation of the communications interface First the eight data bits will be sent with the MSB going first Next the command byte 10h will be sent MSB first Both bytes will be clocked serially through the to shift registers U1000 and U1002 with the data byte ending up in U1002 and the command byte in U1000 The command b
76. ibration Bessel Filter Adjustment CALIBRATION Clock Calibration This adjustment sets the bandpass of the DS335 s Bessel waveform filter 1 Set the DS335 to RAMP waveform 8 Vpp 10 kHz frequency Connect the DS335 s output to an oscilloscope with a 50W terminator Set the DS335 for 500 Load Impedance Set the scope to 2 V div vertical and 200 ns div horizontal 2 Adjust C542 to make the output rise time as fast as possible while minimizing the peak to peak ripple The DS335 is fully calibrated at the factory with all calibration bytes secured in ROM and RAM The user can change the calibration bytes in RAM after changing the position of the calibration jumper JP200 The list of calibration bytes on page 6 2 shows the address and function of every byte The only calibration byte that might need adjustment as the instrument ages is the frequency reference byte The following procedure describes the adjustment of the DS335 s clock calibration calbyte In the case where the calibration bytes in RAM get corrupted the user can recall the factory calibration bytes Please refer to page 6 1 for that procedure Allow the DS335 at least 1 2 hour warmup before beginning calibration All calibrations should be done with the DS335 completely assembled and 1 2 hour of warmup after reassembly When the new calbyte values are determined they should be entered into the DS335 s RAM This procedure sets the frequency of the DS335 s internal 10 MHz c
77. isc 50V 10 SL C 710 5 00017 501 47P Capacitor Ceramic Disc 50V 10 SL C711 5 00022 501 001U Capacitor Ceramic Disc 50V 10 SL C712 5 00022 501 001U Capacitor Ceramic Disc 50V 10 SL C 800 5 00100 517 2 2U Capacitor Tantalum 35V 20 Rad C 801 5 00100 517 2 2U Capacitor Tantalum 35V 20 Rad C 802 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 803 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 804 5 00100 517 2 2U Capacitor Tantalum 35V 2094 Rad C 805 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 806 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 807 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 808 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 809 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 810 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 811 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 812 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 813 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 814 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 815 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 816 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 817 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 818 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 819 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 820 5 0022
78. lock The procedure is identical for standard and optional oscillators Be sure that the DS335 has been completely reassembled and warmed up for at least 1 2 hour before this calibration is started 1 Connect the DS335 s Function output to the frequency counter input with a 50W terminator Use the frequency standard as the counter s timebase 2 Adjust the value of calbyte O so that the frequency is within 1 Hz of 10 MHz 0 01 Hz for optional oscillators The range of calbyte O is O to 4095 DS335 Synthesized Function Generator Circuitry 5 1 DS335 Circuit Description Front Panel DS3350FP The front panel pcb has 8 seven segment displays 26 LED indicators and 22 heys The displays are refreshed by a time multiplexing there are four strobe lines vvhich enable tvvo digits a column of seven LEDs and six keys The display refresh is synchronized by the Real Time Interrupt RTI The RTI occurs at a 500 Hz rate The display refresh is the first task in the RTI routine so as to avoid display flicker Five RTI s are required to refresh the entire display four to refresh all of the displays and indicators and to look for key contacts and a fifth to intensify a particular digit in the eight digit display Each LED and display has a 1 5 duty cycle When intensified the selected display will have a 2 5 duty cycle making that digit twice as bright The intensity of the selected digit will blink between 1 5 and 2 5 duty cycle at a 1 Hz ra
79. lose to the waveform DAC For the DDS to work well it is imperative that this clock be kept clean hence the oscillator is operated from a separate supply 4 5 CLOCK and its output is passed directly to the waveform DAC The 10 MHz is buffered to provide clocks to the rest of the system DS335 Synthesized Function Generator 5 2 Circuitry There is a TCXO option for the 10 MHz clock When present the TCXO may be tuned to exactly 10 MHz The frequency is calibrated by altering the constant used to compute the PIR value for the ASIC phase accumulator The buffered 10 MHz is divided by two by a D type flip flop 74HC74 U101A to provide a 5 MHz clock to the CPU A second flip flop U101B divides the 5 MHz by two to provide a 2 5 MHz clock to the 8253 counter timer and to the UART and GPIB controller on the communications interface board The 8253 provides three additional clocks by dividing its 2 5 MHz input a 500 Hz RTI is generated by dividing by 5000 a 1 kHz tone for the speaker is generated by dividing by 2500 and a 16x clock for 9600 baud is generated by dividing by 16 which will have a 1 7 error Communications Interface Header 18 pin header to the optional GPIB RS232 interface is shown on sheet DS335FP The computer interface must be ground referenced while the function generator and so its CPU etc must float To accommodate this communications between the CPU and the interface are done serially via opto isolators D
80. nction Generator DS335 Setup 2 17 INSTRUMENT SETUP Introduction This section describes the DS335 s default settings storing and recalling settings setting the computer interfaces and running self test Default Settings Press SHIFT to recall the DS335 s default settings The 053355 default settings are listed below Setting Default Value Frequency 1 MHz Function SYNC ON OFF Load Impedance Display Frequency Amplitude 1 Vpp Offset 0 0 V Inversion Off Sweeps Off Start Frequency 1Hz Stop Frequency 3 1MHz Trigger Source Continuous Sweep FSK Rate 100 Hz Interface RS232 Baud Rate 9600 GPIB Address 22 Storing Setups To store the DS335 s current setup press SHIFT 7 followed by a location number in the range O 9 After pressing any UNITS key to enter the location number the message sto done will be displayed indicating that the settings have been stored Recalling Stored Settings To recall a stored setting press SHIFT 8 followed by a location number in the range O 9 After pressing any UNITS key to enter the location number the message rcl done will be displayed indicating that the settings have been recalled If nothing is stored in the selected location or the settings are corrupted the message rcl err will be displayed GPIB Setup To set the DS335 s GPIB interface press SHIFT 1 The GPIB enable selection will be displayed Use the UP ARROW and DOWN ARROW keys to enable the GPIB inter
81. ncy If the stop frequency is greater than the start frequency the DS335 will sweep up If the start frequency is larger the DS335 will sweep down If FSK is enabled the DS335 toggles between the Start and Stop frequencies at the Sweep FSK Rate If the rate has been set to zero then the rear panel FSK input is active A TTL low level activates the start frequency and a TTL high level activates the stop frequency The rear panel SWP FSK output is synchronous with the sweep rate This output emits a TTL pulse at the beginning of every sweep cycle and can be used to trigger an oscilloscope When the start frequency is selected the Sweep output is at 0 Volts and when the Stop frequency is selected the Sweep level is at 5 Volts The Sweep output is synchronous with the frequency shifts The FSK input accepts TTL level signals When enabled FSK mode with 0 Hz rate it is sampled at a 10 MHz frequency by the DS335 A low TTL level selects the start frequency and a high TTL level selects the stop frequency see example below When the FSK Input is being used the Sweep output is disabled and stays at O Volts DS335 Synthesized Function Generator Sweeps amp FSK 2 15 mx ITT 1L 1 WU V V UU V V V VV 20k Hz TORHE GORHE 12 20KHE Start Freg 2 4 2 Stop Freq 10kHz Sweep Fate OH External Frequency Shift Keying FSK Example DS335 Synthesized Function Generator 2 16 Sweeps amp FSK DS335 Synthesized Fu
82. no sweeps are in progress Sweep Enable set when sweep is enabled 2 User SRQ set if the user sends a SRQ from the front panel 3 DDS An unmasked bit in the DDS status register has been set 4 The gpib output queue is non empty 5 ESB An unmasked bit in the standard status byte has been set 6 RQS MSS SRQ Service Request bit 7 No Command There are no unexecuted commands in the input queue The DDS and ESB bits are set whenever any unmasked bit bit with the corresponding bit in the byte enable register set in their respective status registers is set They are not cleared until the condition which set the bit is cleared Thus these bits give a constant summary of the enabled status bits A service request will be generated whenever an unmasked bit in the serial poll register is set Note that service requests are only produced when the bit is first set and thus any condition will only produce one service request Accordingly if a service request is desired every time an event occurs the status bit must be cleared between events Standard Event Status Byte bit name usage 0 unused 1 unused 2 Query Error Set on output queue overflow 3 unused 4 Execution err Set by an out of range parameter or non completion of some command due to a condition such as an incorrect waveform type 5 Command err Set by a command syntax error or unrecognized command DS335 Synthesized Function Generator Programming Commands 3 9 6
83. o 14 in increments of two Resetting the amplitude will return the attenuators to their normal position The PRE query returns the current attenuator position PST i The PST command sets the DS335 s post amplifier attenuators to range i The integer i is the attenuation value in dB and ranges from 0 to 30 in increments of two Resetting the amplitude will return the attenuators to their normal position The PST query returns the current attenuator position WRD j k The WRD command sets the value of calibration word j to k Parameter j may have a value from 0 to 554 while may range from 127 to 65535 This command will generate an error if calibration is not enabled NOTE this command will alter the calibration of the DS335 To correct the calibration the factory calibration bytes may be recalled see the FCL command The calibration bytes cannot be altered unless the warm up bit has been set DS335 Synthesized Function Generator 3 8 Programming Commands STATUS BYTE DEFINITIONS Status Reporting The DS335 reports on its status by means of three status bytes the serial poll byte the standard status byte and the DDS status byte On power on the DS335 may either clear all of its status enable registers or maintain them in the state they were in on power down The action taken is set by the PSC command and allows things such as SRQ on power up Serial Poll Status Byte bit name usage 0 Sweep Done set when
84. oscope terminating the output into 50 ohms Set the scope to 2V div Attach the SWEEP rear panel BNC to the scope and set to 2V div The scope should be set to trigger on the rising edge of this signal 1 Press SHIFT 2 Press AMPL then 5 Vpp 3 Press SHIFT STOP FREQ 4 Press SWEEP RATE then 1 0 0 Hz 5 Press START FREQ then 110101 2 6 Press STOP FREQ then 1 MHz 7 Press SHIFT START FREQ This recalls the DS335 s default settings Sets the amplitude to 5Vpp Verify linear sweep Lin should be blinking now Set the sweep rate to 100 Hz The sweep will take 10 ms 1 100Hz Set the scope time base to 1ms div Set the sweep start frequency to 100 kHz Set the stop frequency to 1 MHz The SWP LED will light indicating that the DS335 is sweeping The scope should show the SWEEP output as a TTL pulse synchronous with the start of the sweep The FUNCTION output is the swept sine wave The DS335 also displays the option to switching to single shot sweeps at this time Pressing the up or down arrows at this time switches the sweeps to single shot Pressing SHIFT START FREQ triggers one sweep DS335 Synthesized Function Generator Introduction 2 1 Introduction to Direct Digital Synthesis Introduction Traditional Generators DDS Figure 1 Block diagram of SRS DDS ASIC Direct Digital Synthesis DDS is a method of generating very pure waveforms with extraordinary fre
85. phase continuously in only one clock cycle And the fixed clock eliminates phase jitter requiring only a simple fixed frequency anti aliasing filter at the output The DS335 uses a custom Application Specific Integrated Circuit ASIC to implement the address generation in a single component The frequency resolution is equal to the resolution with which the Phase Increment can be set In the DS335 the phase registers are 48 bits long resulting in an impressive 1 1014 frequency resolution The ASIC also contains a modulation control CPU that operates on the Phase Accumulator Phase Increment and external circuitry to allow digital synthesis and control of waveform sweeps The Modulation CPU uses data stored in the Modulation RAM to produce frequency sweeps All modulation parameters such as rate and frequency deviation are digitally programmed Direct Digital Synthesis dul al M ie CAJ Phases ori equal AB Hite DS335 Synthesized Function Generator 2 2 Introduction DDS gives the DS335 greater flexibility and power than conventional synthesizers without the drawbacks inherent in PLL designs DS335 Description Modulation TOMH Clock Wayvelonm Dp85345 ASIC ROM Square Wave Comparator Amplitude DAC Amplitude Attenuatore Figure 2 DS335 Block Diagram Function Output Souma Impedance A block diagram of the DS335 is shown in Figure 2 The heart of th
86. quency resolution low frequency switching time crystal clock like phase noise and flexible sweeping capabilities As an introduction to DDS let s review how traditional function generators work Frequency synthesized function generators typically use a phase locked loop PLL to lock an oscillator to a stable reference Wave shaping circuits are used to produce the desired function It is difficult to make a very high resolution PLL so the frequency resolution is usually limited to about 1 106 some sophisticated fractional N PLLs do have much higher resolution Due to the action of the PLL loop filter these synthesizers typically have poor phase jitter and frequency switching response In addition a separate wave shaping circuit is needed for each type of waveform desired and these often produce large amounts of waveform distortion DDS works by generating addresses to a waveform ROM to produce data for a DAC However unlike earlier techniques the clock is a fixed frequency reference Instead of using a counter to generate addresses an adder is used On each clock cycle the contents of a Phase Increment Register are added to the contents of the Phase Accumulator The Phase Accumulator output is the address to the waveform ROM see diagram below By changing the Phase Increment the number of clock cycles needed to step through the entire waveform ROM changes thus changing the output frequency Frequency changes now can be accomplished
87. rally are warnings of illegal parameter entries Meaning Amplitude entered is out of allowable range The output V4 gt 5V Adjust either the offset or amplitude Attempt to set output frequency outside of range allowed for current function lt 0 Hz or gt 3 1 MHz or attempting to set frequency for NOISE function Cannot access GPIB menus if option board is not installed Cannot access RS232 menus if option board is not installed DC output offset outside of 5V range into 500 Output queue error The DS335 output queue is full due to too many queries that have not been read back Parameter in command is out of allowed range for that command Sweep rate out of range 0 01 Hz to 1kHz Parameter memory corrupt on power up stored setting corrupt Not a worry unless this error occurs frequently Check the battery if so Logarithmic sweep span error The start and stop frequencies are apart by more than six decades The sweep start frequency is out of range 0 lt Freq lt max for function The sweep stop frequency is out of range 0 lt Freq lt max for function DS335 Synthesized Function Generator 4 2 Troubleshootin Syn Err UART Error Uni Err Self Test Errors The command syntax is invalid See PROGRAMMING section for correct command syntax The DS335 has detected an error on its computer interface option board The units set with AMPL command are not V or Vims These erro
88. rent source impedance setting Note that all amplitude and offset display settings get doubled when switching from 50 Ohm to High Impedance Similarly when switching from high impedance to 50 Ohm all amplitude and offset display values get halved The actual BNC output is not affected by this change Sweep amp FSK Control Commands note All sweep amp FSK parameters may be set at any time For the changes to have an effect be sure that the sweep or FSK type is set correctly and that sweep or FSK is enabled see the STYP and SWEN commands FSEN i Enables FSK on i21 or off i0 This function is valid only if FSK has been selected with the SDIR command SDIR2 or from the front panel If the FSK rate has been set between 0 01Hz and 50 kHz then the FSK starts following the FSEN1 command If the rate has been set to OHz and FSK selected the command FSEN1 would enable the FSK BNC input on the rear panel This TTL signal is sampled at a 10MHz rate and toggles between the Start frequency and the Stop frequency DS335 Synthesized Function Generator Programming Commands 3 5 TRG The TRG command triggers a single sweep The trigger source must be set to SINGLE see the TSRC command below SDIR i Sets the sweep direction 0 Ramp unidirectional 1 Triangle bidirectional 2 enable FSK disable sweeps STYP i The STYP command sets the sweep type to i The correspondence of i to type is shown in the table below The
89. rs the 12 bit waveform DAC the output amplifier the offset and amplitude control circuits and the output attenuators It is possible to recall and modify the DS335 factory calibration bytes Please refer to the Test and Calibration Chapter for more detail DS335 Synthesized Function Generator Programming Commands 3 1 PROGRAMMING THE DS335 The DS335 Function Generator may be remotely programmed via either the RS232 or GPIB IEEE 488 interfaces Any computer supporting either of these interfaces may be used to program the DS335 Only one interface is active at a time All front and rear panel features except power may be controlled GPIB Communications The DS335 supports the IEEE 488 1 1978 interface standard It also supports the required common commands of the IEEE 488 2 1987 standard Before attempting to communicate with the DS335 over the GPIB interface the DS335 s device address must be set The address is set in the second line of the GPIB menu type SHIFT 1 twice and may be set between 0 and 30 The default address is 22 RS232 Communications The DS335 is configured as a DCE transmit on pin 3 receive on pin 2 and supports CTS DTR hardware handshaking The CTS signal pin 5 is an output indicating that the DS335 is ready while the DTR signal pin 20 is an input that is used to control the DS335 s transmitting If desired the handshake pins may be ignored and a simple 3 wire interface pins 2 3 and 7 may be us
90. rs may occur during the DS335 s self test In general these messages indicate DS335 hardware problems If the errors occur repeatedly the unit may have an electrical problem The messages are listed alphabetically also listed is the status value returned by the TST command The RAM calibration data has become corrupt The factory values will be reloaded from ROM This message is not a problem unless it occurs frequently which could indicate a problem with the battery backup circuits The DS335 s ROM has a checksum error XX is the checksum value The DS335 has detected a problem in its Z80 CPU Read write test of modulation RAM U400 failed Can be bad RAM ASIC or bus problem CPU RAM U206 failed read write test Message Status Value Meaning Cald Err 4 Code Err XX 2 CPU Error 1 Prgd Err 6 Sysd Err 3 Cal Dly Err 7 GPIB PROBLEMS RS 232 PROBLEMS The DS335 is not warmed up Wait until warmed up for at least two minutes before starting autocal First make sure that the GPIB interface is enabled Press SHIFT 1 to display the enable status line GPIB should be ON If not turn GPIB on using the UP DOWN ARROW keys Second the GPIB address of the DS335 must be set to match that expected by the controlling computer The default GPIB address is 22 and so it is a good idea to use this address when writing programs for the DS335 Any address from 0 to 30 may be set in the GPIB menu To check the GPIB address press SHIF
91. ru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg DS335 Synthesized Function Generator 5 18 05335 Component Parts List REF U 103 U 106 U 107 U 108 U 109 U 110 U 111 U 200 U 201 U 202 U 203 U 204 U 206 U 300 U 301 U 302 U 303 U 304 U 305 U 306 U 400 U 401 U 402 U 404 U 405 U 406 U 407 U 408 U 409 U 410 U 411 U 412 U 413 U 500 U 501 U 502 U 503 U 504 U 600 U 601 U 602 U 603 U 604 U 605 U 700 U 701 U 800 U 801 U 802 U 803 U 804 U 805 U 807 U 808 DS335 Synthesized Function Generator SRS PART VALUE 3 00045 340 74HC32 3 00491 340 UPD71054C 3 00049 340 74HC74 3 00158 340 74HC154N 3 0041 1 340 74 273 3 00044 340 74 244 3 00039 340 74HC14 3 00046 340 74HC374 3 00046 340 74HC374 3 00046 340 74HC374 3 00046 340 74HC374 3 00044 340 74HC244 3 00366 341 32KX8 35 3 00319 340 AD586JN 3 00088 340 LF353 3 00105 340 LM741 3 00415 340 AD7845 3 00270 340 74HC4051 3 0041 1 340 74 273 3 00087 340 LF347 3 00366 341 32KX8 35 3 00088 340 LF353 3 00058 340 AD7524 3 0041 1 340 74HC273 3 00165 340 74HC08 3 00045 340 74HC32 3 00261 340 74LS245 3 00421 340 F107563FN 3 00528 342 U409 27C256 PRO 3 00486 340 74F273 3 00529 342 U411 27C256 PRO 3 00486 340 74F273 3 0041 1 340 74HC273 3 00482 340 TDC1012N7C2 3 00196 335 HS 2128 5 3 00196 335 HS 2128 5 3 00105 340 LM741 3 00190 340 10MHZ 25PPM 3 00270 340 74HC4051 3 00437 340 AD9696KN 3 00044 340 74HC244 3
92. s Frequency DC to 10 MHz Accuracy 0 05dB Frequency 10 MHz 001 ppm SRS FS700 Phase Noise 130 dBc 2 100Hz 500 0 2 1 Watt HP 11048C Impedance 500 Mini Circuits ZAD 3SH Frequency 1 20 MHz DS335 Synthesized Function Generator 4 6 Performance Tests FUNCTIONAL TESTS These simple tests verify that the DS335 s circuitry is functional They are not intended to verify the DS335 s specifications Front Panel Test Internal Self Tests Sine Wave Square Wave This test verifies the functionality of the front panel digits LED s and buttons 1 2 Turn on the DS335 while holding down FREQ Press the UP ARROW and a single segment of the leftmost digit should light Use DOWN ARROW to light each segment 7 of them and the decimal point of the left most two digits Only a single segment should be on at a time UP ARROW will step backward through the pattern Push the down arrow key again and all of the segments of all 8 digits should light Press the down arrow key repeatedly to light each front panel indicator LED in turn top to bottom left to right At any time only a single LED should be on After all of the LEDs have been lit further pressing of the front panel keys will display the key code associated with each key Each key should have a different keycode The internal self tests test the functionality of the DS335 circuitry 1 Turn on the DS335 The ROM firmware version num
93. s may be recorded on the test sheet at the end of this section Allow the DS335 at least 1 2 hour to warm up run the DS335 s self test procedure and proceed with the tests FREQUENCY ACCURACY This test measures the accuracy of the DS335 s frequency If the frequency is out of specification the DS335 s timebase frequency should be adjusted see CALIBRATION section Tolerance 50 ppm of selected frequency 1 Turn the DS335 on and allow it to warm up for at least 1 2 hour Set the DS335 for sine wave 1 MHz 1 Vpp and 500 Load Impedance 2 Attach the output of the DS335 to the frequency counter Terminate into 500 Attach the reference frequency input of the counter to the frequency standard Set the counter for a 1s frequency measurement 3 The counter should read 1MHz 50Hz Record the result AMPLITUDE ACCURACY The following tests measure the accuracy of the DS335 output amplitude There are separate tests for sine square and ramp triangle The tests measure the accuracy of the amplitude as a function of frequency The sine wave test also measures the performance of the attenuators There is only a single test for triangle and ramp functions because they have the same signal path Frequency 100 kHz Connect the DS335 output to the voltmeter through the 50Q terminator After the DS335 has had at least 1 2 hour to warm up perform the following tests Sine Wave specification 0 1 dB 1 2 1 Set the DS335 to sine wave 100Hz
94. s sweeps on i 1 or off i 0 If the continuous sweep is selected enabling sweeps will start the sweep with the specified rate If triggered single sweep is selected and sweeps are enabled then the DS335 waits for a front panel trigger or a TRG command to start the sweep TSRC i The TSRC command sets the trigger source for sweeps to i The correspondence of i to source is shown in the table below The TSRC query returns the current trigger source i Waveform 0 SINGLE 1 INTERNAL RATE For single sweeps the TRG command triggers the sweep DS335 Synthesized Function Generator 3 6 Programming Commands Setup Control Commands IDN RCLi RST SAV i The IDN common query returns the DS335 s device configuration This string is the format StanfordResearchSystems DS335 serial number version number Where serial number is the five digit serial number of the particular unit and version number is the 3 digit firmware version number The RCL command recalls stored setting number i where i may range from 0 to 9 If the stored setting is corrupt or has never been stored an execution error will be generated The RST common command resets the DS335 to its default configurations The SAV command saves the current instrument settings as setting number i Status Reporting Commands See tables at the end of the Programming section for Status Byte definitions CLS ESE i ESR i PSC i
95. s to variable resistors and capacitors to correct the DS335 s filters and output amplifier response Calibration is the process of determining the calibration constants calbytes that the DS335 firmware uses to correct the output amplitude etc The settings of the adjustments are in general very stable and should rarely require change If the adjustments are changed the corresponding calibrations must be performed However the DS335 rarely requires complete recalibration to maintain its performance It is recommended that the unit be sent back to the manufacturer in the case where a full recalibration is required The DS335 is shipped with calibration byte editing disabled When calibration is disabled direct access to the calbytes is prevented The internal calibration enable jumper must be set to enable calibration To set the jumper remove the DS335 s top cover by removing its four retaining screws this will break the calibration seal In the center of the bottom circuit board is a three pin jumper labeled JP200 Setting JP200 between pins 1 and 2 enables calibration setting it between pins 2 and 3 disables calibration The DS335 s calibration is controlled by calibration constants calbytes that the firmware uses to adjust the various output parameters These calbytes are stored in the DS335 s RAM Recalibration of the DS335 involves determining the values of the calbytes and storing the new values in RAM The calbyte values a
96. s writing to the other and the adder can shift between the two PIR s without missing a single add cycle In addition to the PIR s there are lots of other registers in the ASIC The other registers are used for mode control setting prescalers and setting modulation sweep addresses Three of these registers are located off the ASIC strobes are generated which will allow modulation data to be latched into external devices This allows amplitude leveling during sweeps etc by the modulation program The FSK BNC input goes directly to the ASIC and allows the user to select between PIRA and PIRB by changing the input level DS335 Synthesized Function Generator 5 4 Circuitry To set an output frequency Fout the PIR is set to PIR Fout x 2 48 Fclk where Fclk is the 10 MHz ASIC clock Math operations to compute the PIR must be done to 48 bit precision So a 48x48 bit multiply is required to compute a PIR value The ASIC registers are loaded by providing an op code which tells which and how many registers to load and data which is loaded into the target registers These op codes and data may be provided directly by the CPU after a REQ is issued and a HOST ACR received Or a series of op codes and data may be stored in the 32K x 8 modulation RAM U400 a 62256 The modulation RAM is used to store data for frequency sweeps Sweeps can consist of up to 4000 different frequencies together with amplitude leveling data Th
97. se time of less than 15 ns The output of the power amplifier passes through a series of four step attenuators 2 4 8 and 16 dB that set the 053355 final output DS335 Synthesized Function Generator Introduction 2 3 amplitude The post amplifier attenuators allow internal signal levels to remain as large as possible minimizing output noise and signal degradation Square waves and waveform sync signals are generated by discriminating the function waveform with a high speed comparator The output of the comparator passes to the SYNC OUTPUT and in the case of square waves to the amplifier input Generating square waves by discriminating the sine wave signal produces a square wave output with rise and fall times much faster than allowed by either of the signal filters DS335 Synthesized Function Generator 2 4 Introduction DS335 Synthesized Function Generator Features 2 5 Front Panel Features GPS STANFORD RESEARCH SYSTEMS MODEL D5335 3 1 MHz SYNTHESIZED FUNCTION GENERATOR 261260 1 nay IU LU ULIL LU E MC QU 1 Power Switch 2 Data Entry Keys 3 Units Keys 4 Shift Key The power switch turns the DS335 on and off The DS335 has a battery backed up system RAM that remembers all instrument settings The numeric keypad allows for direct entry of the DS335 s parameters To change a parameter value simply type the new value Entries are terminated by the UNITS keys A typing error may be corrected by pres
98. sing the corresponding function key For example if the wrong numeric key is pressed while entering a new frequency pressing the FREQ key will backspace over the last entered digit If there are no digits left the current frequency value is displayed The key may be selected at any time during numeric entry The UNIT keys are used to terminate numeric entries Simply press the key with the desired units to enter the typed value Some parameters have no particular units and any of the unit keys may be used The unit keys also increase and decrease the numeric value in the DS335 s display Pressing the UPARROW key adds one to the flashing digit value the DOWN ARROW key subtracts one from the flashing digit value To change the position of the flashing digit press SHIFT LEFT ARROW or SHIFT RIGHT ARROW A few of the display menus have more than one parameter displayed at a time The SHIFT LEFT ARROW and SHIFT RIGHT ARROW keys select between left and right The shift key selects the function printed above the keys Pressing SHIFT and then the desired key to select the specific function for example SHIFT 50Q sets the source impedance to 500 When the SHIFT key is pressed the SHIFT LED will light Pressing SHIFT a second time will deactivate shift mode DS335 Synthesized Function Generator 2 6 Features 5 Sweep Key 6 Function Keys 7 Main Function BNC 8 Sync Output BNC 9 Status LEDs 10 Param
99. ss the SHIFT key and then the labeled key SHIFT STOP FREQ for example to display the type of waveform sweep set Values are changed by the DATA ENTRY keys To directly enter a value simply type the new value using the keypad and complete the entry by hitting one of the UNITS keys If the value has no particular units any of the UNITS keys may be used otherwise select the appropriate units key If an error is made pressing the corresponding function key will backspace the cursor If the key is pressed repeatedly the display will eventually show the previous value For example if a new frequency is being entered and the wrong numeric key is pressed then pressing the FREQ key will backspace the cursor If the FREQ key is pressed until the new entry is erased then the last valid frequency value will be displayed The current parameter value may also be incremented or decremented using the UP and DOWN ARROW keys Pressing the UP ARROW key will increment the flashing digit value by one while pressing the DOWN ARROW key will decrement the flashing digit value by one If the parameter value cannot be incremented or decremented the DS335 will beep and display an error message Pressing SHIFT UP ARROW or SHIFT DOWN ARROW changes the position of the blinking digit CW Function Generation Our first example demonstrates a CW waveform using the DS335 s data entry functions Connect the front panel FUNCTION output to an oscilloscope terminating the
100. st Error Messages Performance Tests Necessary Equipment Functional Tests Front Panel Test Self Tests Sine Wave Square Wave Amplitude Flatness Output Level Performance Tests Frequency Accuracy Amplitude Accuracy DC Offset Accuracy Subharmonics Spurious Signals Harmonic Distortion Phase Noise Square Wave Rise Time Square Wave Symmetry Test Scorecard Calibration Introduction Calibration Enable Calbytes Necessary Equipment Adjustments Output Amplifier Bandwidth Bessel Filter Adjustment 4 1 4 1 4 2 4 5 4 6 4 6 4 6 4 6 4 7 4 7 4 8 4 8 4 9 4 9 4 10 4 10 4 11 4 11 4 11 4 13 4 19 4 20 DS335 Synthesized Function Generator ii Table of Contents Calibration 4 20 Component Parts List 5 9 Clock Calibration 4 20 Schematic Circuit Diagrams Sheet No DS335 Circuitry Front Panel Circuit Description 5 1 Keypad and LED Display 1 1 Front Panel Board 5 1 Main Bottom PC Board Microprocessor 1 8 Main Board 5 1 Display Reyboard and Cable 2 8 Microprocessor System 5 1 System DACs 3 8 Display and Reyboard 5 2 DDS ASIC Memory and Sweep 4 8 System DAC and S H s 5 3 DDS Waveform DAC and Filters 5 8 DDS ASIC and Memory 5 3 SYNC and Pre Attenuators 6 8 DDS Waveform DAC 5 4 Output Amplifier 7 8 DDS Output Filters 5 5 Regulators and Attenuators 8 8 Pre Attenuator 5 5 SYNC Generator 5 5 Option Top PC Board Function Selection 5 6 Power Supply and Cable 1 2 Output Amplifier 5 6 GPIB and RS232 Interfac
101. symmetry values as a function of frequency when sines or squares are selected There are three values which precede the table these are used to control the sync duty cycle for triangles ramps and noise 392 TRI SYM 393 RAMP SYM 394 NOISE SYM 395 SYM 0 396 SYM 1 397 SYM 2 554 SYM 159 DS335 Synthesized Function Generator Triangle sync symmetry 0 to 4095 Nominal 2048 Ramp sync symmetry 0 to 4095 Nominal 2048 Noise sync duty O to 4095 Nominal 2048 0 to 4095 Nominal 2048 For dc to 19530 Hz 0 to 4095 Nominal 2048 For 19 531 to 39 062 Hz 0 to 4095 Nominal 2048 For 39 063 to 58 593 Hz 0 to 4095 Nominal 2048 For 3105468 to 3125000 Hz NECESSARY EQUIPMENT Calibration 4 19 The following equipment is necessary to complete the adjustments and calibrations The suggested equipment or its equivalent may be used Instrument Critical Specifications Recommended Model Analog Oscilloscope 350 MHz Bandwidth Tektronix 2465 Time Interval Counter Frequency Range 20 MHz min SRS SR620 FFT Spectrum Analyzer RF Spectrum Analyzer DC AC Voltmeter Thermal Converter 10 MHz Frequency Standard 50 W Terminator Time Interval Accuracy 1ns max Frequency Range DC to 100 kHz SRS SR760 Amplitude Accuracy 0 2 dB Distortion 75 dB below reference Frequency Range 1 kHz to 100 MHz Anritsu MS2601 HP4195A Amplitude 0 5 dB Distortion and Spurious 70 dB 51 2 Digit DC accuracy Fluke 8840A True RMS
102. t equal to this control voltage Calibration values will offset and gain correct this control voltage so that the actual output offset equals that set from the front panel The waveform amplitude control sample and hold output is level shifted and attenuated to a 3 to 5 Vdc range This control voltage is used as a reference to the 8 bit amplitude leveling DAC which is controlled by the ASIC during frequency sweeps The the weighted sum of the leveling DAC output and amplitude control voltage is scaled to the range of 75 to 1 25 for the nominal leveling DAC value of 128 DDS ASIC DS335M4 Waveforms are generated in the DS335 by updating a 12 bit DAC at a rate of 10 million samples per second The waveform sine ramp saw or noise is stored in ROM and the ROM is addressed by a phase accumulator which is implemented in a CMOS ASIC The ASIC s phase accumulator is a 48 bit adder with the top 15 bits of the accumulated result serving as the address to the ROM The frequency of the output waveform is proportional to the rate at which ROM addresses change so the larger the number added to the phase accumulator the higher the frequency The 48 bit number resides in six 8 bit registers in the ASIC This 48 bit number is called the phase increment register or PIR To facilitate seamless frequency changes there are two phase increment registers PIRA and PIRB The adder will use one of the PIR s while the host processor or modulation RAM i
103. t signal is applied The base of Q701 goes up while Q702 s base goes down This increases Q701 s collector current pulling down the base of the emitter follower Q709 which pulls the base of Q710 and Q711 down increasing their collector currents This current will cause the collector voltage of Q710 to slew very quickly and with lots of gain because the collector load is a very high impedance The Darlington pair Q712 and Q713 buffer this node to drive the output which is a 100 Ohm load The current imbalance at the high impedance node will cause the output to continue to slew until the feedback current though R703 and R747 brings the input differential pair back into balance The ac gain is adjusted by setting R703 The ac gain is adjusted to match the dc gain which is controlled by the op amp and its feedback resistor network The ac gain is determined by the ratio of the feedback resistors to the emitter resistors The op amp U700 a CA3140 and its feedback resistors R700 701 702 and R723 stabilize the dc characteristics The op amp is externally compensated so that it will only correct low frequency errors and so will not affect high frequency performance The output of U700 is buffered for extra current drive by U701A and U701B Output Attenuator DS335M8 The output attenuator is a relay controlled 50 Ohm attenuator which allows attenuation in a binary sequence of 2 dB steps When the power is removed or on RESET all of t
104. t the time of the DS335 s production are also stored in ROM and may be recalled at any time Direct access to the DS335 s calbytes is allowed from both the front panel and computer interfaces after calibration is enabled From the front panel press SHIFT 9 once to display the calbyte menu line There are two displayed parameters on the left is the calbyte number and on the right is the calbyte value The calbyte number and value may be modified with either the keypad or the UP DOVVN ARROW keys To select an item use the SHIFTI DOWN ARROW and SHIFT UP ARROW keys calbyte number may be set between 0 and 554 The calbyte value may be set between 127 and 65536 The complete set of factory calbyte values may be recalled by pressing SHIFT 9 twice to bring up the Clear Cal menu and then pressing any of the unit keys The tables on the following pages lists the DS335 calbytes Shown is the calbyte number name and meaning DS335 Synthesized Function Generator 4 16 Calibration DS335 CALBYTES Number Name Meaning 0 OSC FREQ Sets 10 MHz clock 0 to 4095 Nom 2048 1 SINE AMP L F Sine amplitude 29 000 to 36 000 Nom 2 15 2 SQ AMP L F Square amplitude 29 000 to 36 000 Nom 2 15 3 TRI AMP L F Triangle amplitude 29 000 to 36 000 Nom 2 15 4 RAMP AMP L F Ramp amplitude 29 000 to 36 000 Nom 2 15 5 NOISE AMP L F Noise amplitude 29 000 to 36 000 Nom 2 15 6 OFFS GAIN Adjusts gain for output offsets 29k 36k Nom 2 15 7 SW OFF
105. te Microprocessor DS335M1 The CPU is a CMOS Z80 TMPZ84C00AP 0100 clocked at 5 MHz The CPU s 64k memory space is divided in two the lower 32k is occupied by a CMOS ROM 27256 U104 the top 32k has a battery backed up CMOS RAM HM62256LP U105 All other devices in the system are mapped as I O I O port strobes active low are provided by the 1 16 decoder 74HC154 U108 Port strobes are separated by eight addresses leaving room to access registers within particular devices Address Name Definition 00 CS 8253 CS to RD or VVR to 8253 triple counter timer 08 LED STB WR to assert display strobe and speaker enable 10 LED EVEN WR for segment enables for EVEN display digits 18 LED ODD WR for segment enables for ODD display digits 20 LED LAMP WR for LED indicator enables 28 KEY RD RD to read keypad matrix 30 DAC MPX WR to select channel for system DAC and 4 LSB s 38 DAC STB WR for 8 MSB s to 12 bit system DAC 40 RLY CTL WR to set position of 7 system relays 48 ASIC CTL WR to set state of ASIC control lines 50 ASIC WR VVR to strobe opcodes and data into ASIC 58 MOD RAM CS to RD or WR to modulation RAM 60 CMD STB Command strobe to GPIB RS232 interface 68 DATA CLK Serial data clock to RD WR to interface 70 MISC IN RD eight bit port of miscellaneous inputs 78 MISC OUT WR eight bit port of miscellaneous outputs Timing A 10 MHz crystal oscillator is the source of all timing This oscillator is on page DS335M5 c
106. tenuated signal from the filters is buffered by emitter followers Q600 and Q602 2N3904 s The buffered differential signal drives a differential comparator U601 an AD9696 to generate a SYNC signal The positive feedback provides lots of hysterisis and additional resistive feedback to the emitter followers cancels the kick back from the comparator The comparator output is buffered by an octal driver U602 a 74HC244 which has seven of its outputs wire in parallel to drive the front panel SYNC output The SYNC output is driven though a 47 Ohm resistor provide reverse termination of reflected pulses The comparator also drives a pnp differential pair Q603 and Q604 2N3906 s to generate a differential square wave at their collectors The amplitude of the square wave is controlled by the analog voltage SW AMPL which controls the pnp constant current source Q601 a 2N3906 The externally compensated op amp U605 a CA3140 maintains a voltage across the emitter resistor which is proportional to SW AMPL 5 00Vdc As SW AMPL varies from 5 to 5V the constant current source varies from 0 to 11 mA generating from O to 1 1 Vpp square wave output DS335 Synthesized Function Generator 5 6 Circuitry Function Selection DS335M6 The DPDT relay U603 an HS212 selects between the filtered and perhaps attenuated waveform DAC output and the output of the square wave generator If the square wave output is not being used then the square wa
107. the results This test measures the integrated phase noise of the DS335 s output in a 15 kHz band about carrier This test is performed at 1 MHz to minimize the contribution of discrete spurs to the measurement specification 60 dBc in a 30 kHz band centered about the carrier exclusive of discrete spurious signals 1 Setthe DS335 to sine wave 10 001 MHz 1Vrms 2 Record the Phase noise reading from the FFT screen This test measures the rise time and aberrations of the square wave output specification rise time lt 20 ns overshoot 296 of peak to peak output 1 Connect the output of the DS335 to the 350 MHz oscilloscope with a 50W terminator Set the DS335 to square wave 1 MHz 10 Vpp and 500 Load Impedance 2 Setthe oscilloscope to 2 V div vertical and 5 ns div horizontal Measure the time between the 1096 and 9096 points and verify that it is less than 20ns Record the results 3 Set the oscilloscope to 1 V div vertical and 100 ns div horizontal Verify that the overshoots and undershoots are less than 200 mV Record the results This test measures the symmetry of the square wave output specification 1 of period 3ns 1 Connect the output of the DS335 to the A input of the time interval counter and terminate into 50W Set the 05335 to square wave 1 MHz 5 Vpp and 500 Load Impedance DS335 Synthesized Function Generator 4 12 Performance Tests 2 Setthe time interval counter to measure the positive
108. there are no commands waiting to be executed in the input queue This bit is reset when a complete command is received in the input queue and is set when all of the commands in the queue have been executed This bit is useful in determining when all of the commands sent to the DS335 have been executed This is convenient because some commands such as setting the function or sweep take a long time to execute and there is no other way of determining when they are done The NO COMMAND bit may be read while commands are being executed by doing a GPIB serial poll There is no way to read this bit over RS232 Note that using the STB query to read this bit will always return the value 0 because it will always return an answer while a command is executing the STB command itself The four letter mnemonic in each command sequence specifies the command The rest of the sequence consists of parameters Multiple DS335 Synthesized Function Generator Programming Commands 3 3 parameters are separated by commas Parameters shown in are optional or may be queried while those not in are required Commands that may be queried have a question mark in parentheses after the mnemonic Commands that may ONLY be queried have a after the mnemonic Commands that MAY NOT be queried have no Do not send or as part of the command All variables may be expressed in integer floating point or exponential formats i e the number five can be either 5
109. turn to the normal display by pressing any key The Units LEDs indicate the units of the displayed parameter If no LED is lit the value has no units The SWP LED indicates that a sweep or FSK is in progress These LEDs indicate the load impedance value as set by the user The amplitude and offset display values will change according to the load impedance setting DS335 Synthesized Function Generator Features 2 7 Rear Panel Features STANFORD RESEARCH SYSTEME MODEL 31 SYNTHESIZED FLNC TION GENERATOR MADE de LE 1 Power Entry Module 2 Sweep FSK Output 3 FSK Input 4 GPIB Connector 5 RS232 Connector FES 3 2 This contains the DS335 s fuse and line voltage selector Use a 1 amp slow blow fuse for 100 120 volt operation and a 1 2 amp fuse for 220 240 volt operation To set the line voltage selector for the correct line voltage first remove the fuse Then remove the line voltage selector card and rotate the card so that the correct line voltage is displayed when the card is reinserted Replace the fuse This output generates a TTL pulse that is synchronous with the DS335 s frequency sweep When the DS335 is in FSK mode the output voltage reflects the present frequency at the FUNCTION output BNC TTL LOW Start Frequency TTL HIGH Stop Frequency The shield of this output is tied to that of the function output and may be floated up to 40V relative to earth ground Th
110. ve amplitude will be set to zero SW AMPL 5 Vdc so as to reduce crosstalk in the function select relay The selected function is passed to the differential output amplifier Output Amplifier DS335M7 The output amplifier is a high speed low distortion discrete transistor differential amplifier The gain is x 10 for the inverting input and x12 for the non inverting input and the 3 dB bandwidth is 35 MHz it has a phase linear response to about 175 MHz and a THD of about 0 05 to 50 kHz The amplifier has a very low offset drift as its dc characteristics are stabilized by an external compensated op amp The amplifier has a very symmetric design This together with it class A operation and high open loop bandwidth keeps it distortion very low In this circuit description only the top half will be described as the bottom half of the amplifier operates in a completely symmetrical and complimentary manner The signal is applied to the input differential pair Q701 and Q702 2N5770 s The input pair run in a constant current configuration with the constant current source Q706 with R741 and D701 The pnp transistor Q700 provides an ac current to absorb the feedback current from R705 Since the input differential pair runs at constant current independent of the input signal their base emitter voltages are constant and so are not a source of distortion To understand the operation of the amplifier consider events when a positive inpu
111. ve strobe periods To refresh a part of the front panel display one STROBE column is pulled high by writing a zero to the corresponding position in the LED STB latch U203 a 74HC374 For example writing a zero to QO will saturate the PNP transistor 0200 and pull STROBE O to 5 volts Digit segments and LED indicators within a particular STROBE column are turned on by writing a zero to the corresponding position in the LED EVEN LED ODD or LED LAMP latches U200 201 74HC374 s For example writing a zero to QO of the LED EVEN latch will cause the a segment of the even digit display in the selected strobe column to turn on There is a watch dog circuit U111 D200 C200 and R229 which will turn off the front panel displays if the processor stops refreshing the LED STROBE latch The circuit pumps charge onto C200 with every output to the LED STROBE latch C200 is discharged by R229 if the port strobes cease removing the output enable from the 74HC374 display drivers DS335 Synthesized Function Generator Circuitry 5 3 System DAC and S H s DS335M3 There are four analog voltages which may be set by the CPU These four voltages control the output square wave symmetry square wave amplitude output offset and waveform amplitude These analog voltages are on sample and hold amplifiers which are maintained by a 12 bit system DAC U303 an AD7845 The DAC can output voltages from 5 00 to 5 00V with input values from 0 to 4095
112. when GPIB output queue is non empty 5 ESB set when an unmasked bit in std event status byte is set 6 RQS SRQ bit 7 No Command set when there are no unexecuted commands in input queue Standard Event Status Byte bit name usage 0 unused 1 unused 2 Query Error set on output queue overflow 3 unused 4 Execution Err set on error in command execution 5 Command Err set on command syntax error 6 URQ set on any front panel key press 7 PON Set on power on DDS Status Byte bit name usage 0 Trig d set on sweep trigger 1 Not in use 2 Not in use 3 Not in use 4 Warmup set when the DS335 is warmed up 5 Test Error set when self test fails 6 Not in use 7 mem err set on power up memory error DS335 Synthesized Function Generator Getting Started 1 1 Getting Started Introduction This section is designed to familiarize you with the operation of the DS335 Synthesized Function Generator The DS335 is a powerful flexible generator capable of producing both continuous and swept waveforms of exceptional purity and resolution The DS335 is also relatively simple to use and the following examples will lead you step by step through some typical uses Data Entry Setting the DS335 s operational parameters is done by pressing the key with the desired parameters name on it FREQ for example to set the frequency The current value will be displayed Some of the parameters are labeled above the keys in light gray To display those values first pre
113. width of the A input Record the reading 3 Set the time interval counter to measure the negative width of the A input This reading should be equal to the reading in step 2 13 ns Record the result THIS COMPLETES THE PERFORMANCE TESTS DS335 Synthesized Function Generator Performance Tests 4 13 DS335 PERFORMANCE TEST RECORD Serial Number Date Tested By Comments Pass Fail Functional Tests Front Panel Test Self Test at power up Sine Wave Square Wave Amplitude Flatness Output Level Minimum Actual Maximum Performance Tests Frequency Accuracy 999 950 Hz 1 000 050 Hz Amplitude Accuracy sine 100 Hz 3 54 Vrms 3 498 Vrms 3 582 Vrms sine 1 kHz 3 54 Vrms 3 498 Vrms 3 582 Vrms sine 10 kHz 3 54 Vrms 3 498 Vrms 3 582 Vrms sine 100 kHz 3 54 Vrms 3 498 Vrms 3 582 Vrms sine 1 kHz 1 Vrms 0 988 Vrms 1 012 Vrms sine 1 kHz 0 5 Vrms 0 494 Vrms 0 506 Vrms sine 1 kHz 0 25 Vrms 0 247 Vrms 0 253 Vrms sine 1 kHz 120 mVrms 118 mVrms 122 mVrms sine 1 kHz 70 mVrms 69 1 mVrms 70 9 mVrms sine 1 kHz 40 mVrms 39 5 mVrms 40 5 mVrms sine 1 kHz 20 mVrms 19 7 mVrms 20 3 mVrms square 100 Hz 5 Vrms 4 94 Vrms 5 06 Vrms square 1 kHz 5 Vrms 4 94 Vrms 5 06 Vrms square 10 kHz 5 Vrms 4 94 Vrms 5 06 Vrms triangle 100 Hz 2 89 Vrms 2 85 Vrms 2 93 Vrms triangle 1 kHz 2 89 Vrms 2 85 Vrms 2 93 Vrms triangle 10 kHz 2 89 Vrms 2 85 Vrms 2 93 Vrms sine 1 kHz 3 Vrms reference X Tolerance 1 2 of X 0 980X 1 020X
114. yte 10h indicates that this will be a WRITE to the RS232 register 0 Finally a single OUT instruction will assert CMD STB the command strobe generating a CS and WR to the UART writing the data byte to register 0 To read a register only the command byte and command strobe need be sent For example if the command byte 49h is shifted into the command shift register U1000 and the command strobe asserted then register 01 in the GPIB controller will be read into the shift register U1002 The contents of the data shift register may then be clocked down to the CPU with eight IN and eight shift instructions DS335 Synthesized Function Generator 5 8 Circuitry DS335 Synthesized Function Generator DS335 Component Parts List 5 9 Power Supply Parts List REF SRS PART VALUE DESCRIPTION C 955 5 00201 526 2200U Capacitor Electrolytic 35V 2096 Rad C 956 5 00100 517 2 2U Capacitor Tantalum 35V 2096 Rad C 957 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 958 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 959 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 960 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 961 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 962 5 00225 548 1U AXIAL Capacitor Ceramic 50V 80 20 Z5U AX C 1002 5 00192 542 22U MIN Cap Mini Electrolytic 50V 20 Radial C 1003 5 00192 542 22U MIN Cap Mini Electrolytic 50V 20

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