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3211 Hi-V Amp RevB

1. Feussner Polarizer 45V 14344 9 Lom Function Lock in Generator Amplifier 0 1 MHz Signal Out 11 12 Appendix 1 Bandwidth Limitations Vv When driving capacitive loads with a high voltage amplifier such as the Model 3211 there are several factors which determine the bandwidth of the system Closed Loop Bandwidth The closed loop bandwidth of the high voltage operational amplifier in the Model 3211 deter mines the maximum bandwidth attained by the Model 3211 this bandwidth is at least 1 MHz Other factors such as slew rate current limiting and RC filtering can limit the bandwidth even fur ther as described below Slew Rate The slew rate of the Model 3211 is at least 700 V s Thus the maximum frequency of operation is dependent on the peak voltage With a peak voltage of 200 V the maximum frequency and therefore the largest signal bandwidth is given by Wu sin 27 7 out di y dt 2n4V cos 2m f lt 700 Vis fax large signal 111x10 V where V is the peak voltage fis the frequency in Hz is time and Vis the output voltage Therefore when the peak voltage is 200 V and the amplifier is not current limited as described in the section below the maximum frequency on the high voltage output is 555 kHz Vv Current Limit The maximum current that can be provided by the amplifier Model 3211 is 120 mA For this rea
2. bandwidth and the calculated RC bandwidth determines the maximum bandwidth of the Model 3211 Four examples illustrating how to determine the maximum bandwidth follow Example 1 slew rate limited case Peak voltage 200 V Load capacitance 10 pF 1 Slew rate limited bandwidth 111 MHz 200 555 kHz 2 Current limited bandwidth 0 0191 10x10 12x200 9 55 MHz 3 Closed loop bandwidth 1 MHz 4 RC bandwidth 1 272510x10 2 637 MHz Therefore the maximum bandwidth is the small est of the four or 555 kHz Example 2 current limited case Peak voltage 200 V Load capacitance 100 nF 1 Slew rate limited bandwidth 111 MHz 200 555 kHz 2 Current limited bandwidth 0 0191 100x10 9x200 955 Hz Vv 3 Closed loop bandwidth 1 MHz 4 RC bandwidth 1 27tx25x100x10 9 63 7 kHz Therefore the maximum bandwidth is the small est of the four or 955 Hz Example 3 closed loop bandwidth limited case Peak voltage 100 V Load capacitance 100 pF 1 Slew rate limited bandwidth 111 MHz 100 1 11 MHz 2 Current limited bandwidth 0 0191 100x10 2 100 1 91 MHz 3 Closed loop bandwidth 1 MHz 4 RC bandwidth 1 2 X25x100x10 2 63 7 MHz Therefore the maximum bandwidth is the small est of the four or 1 MHz Example 4 RC bandwidth limited case Peak voltage 1 V Load capacitance 100 nF 1 Slew rate limited bandwidth 111 MHz 1 111 MHz 2 Current limited bandwidth 0 0191 100x10 91 191 kHz 3 Closed loop
3. selection slot selection wheel Fuse holder 17 Specifications 18 Performance Bandwidth 3 dB C lt 100 pF Slew Rate Output Voltage Voltage Gain Input Impedance Output Impedance Max Load Capacitance Max Output Current Max Input without Damage Operating AC Voltage Vv 1 MHz 700 V ps 200 V 40 5 75 KQ 25 Q 0 1 pF 120 mA 10 V peak 100 120 220 or 240 VAC Warranty Service amp Support Vv Warranty New Focus guarantees its products to be free of defects for one year from the date of shipment This is in lieu of all other guarantees expressed or implied and does not cover incidental or conse quential loss Technical Support Information and advice about the operation of your New Focus products are available from our technical support engineers Engineers are on duty from 8 00 5 00 PST Monday through Friday excluding holidays For quickest response ask for Technical Support and know the model number for your product Phone 408 980 8088 Fax 408 980 8883 Support is also available by email Email techsupport newfocus com We typically respond to email within one business day Service In the event that your amplifier malfunctions or becomes damaged please contact New Focus for a return authorization number and instructions on shipping the unit back for evaluation and repair 19
4. bandwidth 1 MHz 4 RC bandwidth 1 27x25x100x10 63 7 kHz Therefore the maximum bandwidth is the small est of the four or 63 7 kHz 15 16 Appendix 2 Operating Voltages and Fuses Vv The Model 3211 can operate from 100 120 220 or 240 V AC with AC frequencies of 47 63 Hz The unit is configured at the factory for the standard AC voltage in the user s country To select a differ ent operating voltage please refer to Fig 4 and fol low the directions below 1 Disconnect the power cord 2 Open the cover of the power entry module on the rear panel with a small blade screwdriver or similar tool 3 Insert the tool into the voltage selection slot and remove the wheel from the unit 4 Turn the wheel and re insert into the module so the desired voltage is shown NOTE Do not attempt to rotate the wheel while it is still in the power entry module the wheel must be removed turned and then re inserted 5 Close the cover 6 Verify that the proper voltage is showing through the module s window The power entry module requires two 5x20 mm slow blow fuses such as Littlefuse s Slo Blo 239 Series one for the hot line and the other for the neutral line Replacement fuses should be as follows AC Voltage Fuse Rating Little Fuse 100 V AC 16A 239 01 6 120 V AC 16A 239 01 6 220 V AC 0 8A 239 800 240 V AC 0 8A 239 800 Vv Fig 4 Model 3211 Amplifier voltage selection Voltage
5. of the Model 3211 High voltage Amplifier DC Offset Input 1 Input 2 High Voltage On Off 20 0V itch Vv Current 200 V Out Limit High Voltage Output Current 200 V Out Limit Switch G y Monitor Vv The 200 V outputs nominally 212 V are designed to be used as bias voltages for electro optic modulators or piezo electric transducers They are current limited at DC with 2 mA maxi mum DC out but at higher frequencies act as an AC return The front panel BNC inputs can be used indepen dently or together in a summing configuration The input resistance is 5 75 KQ and the output resistance is 25 Q The total gain from input to output is 40 and the maximum output voltage is 200 V The maximum input voltage is therefore 5 V for linear operation The absolute maxi mum voltage at Input 1 and Input 2 with out damage is 10 V peak NOTE OPERATING PRECAUTIONS The high voltage operational amplifier in the Model 3211 can be permanently damaged if ther mally stressed Thermal stress occurs only if the unit is operated well into its current limited mode for at least 5 10 minutes the unit is adequately protected for all other conditions To avoid the pos sibility of overheating the amplifier and reducing its lifetime you should ensure that it doesn t oper ate in the current limited mode for more than a couple of minutes T
6. Model 3211 User s Manual High Voltage Amplifier Vv The VY symbol and NEW FOCUS Inc are registered trademarks of New Focus Inc Copyright 1999 New Focus Inc All rights reserved 321101 Rev B 2 Vv Contents Introduction Safety Operation Applications Appendix 1 Bandwidth Limitations Appendix 2 Operating Voltages amp Fuses Specifications Warranty Service amp Support Vv 10 12 16 18 19 Introduction Vv The New Focus Model 3211 High voltage Amplifier can be used as a versatile gain block in applica tions involving high speed and high voltage sig nals The amplifier is extremely linear and can be used to drive capacitive loads up to 100 nF with peak voltages up to 200 V These features make the device useful for driving electro optic modula tors and piezo electric transducers For instance with the Model 400X Electro optic Phase Modula tors the Model 3211 can be used to provide a lin ear phase modulation of greater than 7 for fre quencies up to 1 MHz The amplifier can also pro vide output current up to 120 mA Vv Safety The Model 3211 is a high voltage amplifier capa ble of putting out 200 V at 120 mA Because of the high voltage capabilities of the amplifier proper precautions should be taken to avoid electrical shock The unit is equipped with a High Voltage On Off switch which acts independently of the AC power switch The three high voltage outputs H
7. he amplifier will operate in this mode under certain combinations of peak voltage frequency and load capacitance Please refer to the Appendix 1 Bandwidth Limitations for a discussion on calculating the frequency at which current limiting occurs given the load capacitance and the signal s peak voltage Vv Fig 2 Front panel view of the Model 3211 Amplifier a p High Voltage Amplifier 3211 Made in U S A High Voltage DC Offset Outputs On Off Monitor Power Input 1 Input 2 High Voltage Output O O A Do not exceed 10 V peak on inputs Caution Up to 200 V NEW FOCUS Inc Mountain View California 94041 10 Applications Vv The Model 3211 was designed primarily to drive electro optic modulators and piezo electric transducers However you can use it as a general purpose amplifier to drive any capacitive load less than 100 nE The amplifier can be used in con junction with a low voltage source to create a broad bandwidth low voltage modulator driver To prevent undesirable external signals from appearing on the High voltage Output the user should terminate any unused inputs Fig 3 Vv Driving an electro optic amplitude modulator with the Model 3211 Amplifier Amplitude Modulator V 200 V Model 3211 High voltage Amplifier Optically Chopped Signal Models 1801 1811 2001 or 2001 Photoreceivers
8. igh voltage Output 200 V and 200 V will not operate unless the front panel rocker Power switch is on and the green LED light is indicated on the High Voltage On Off switch In the typical application the user may not want to use the 200 V outputs Since these outputs are turned on when the High voltage Output is en abled New Focus recommends putting dust covers over these 200 V outputs which are DC current limited to 2 mA when they are not being used to avoid electrical shock NOTE Your safe and effective use of this product is of utmost importance to New Focus Please read through the entire manual before attempting to operate the amplifier Vv Operation The Model 3211 consists of a current limited high voltage operational amplifier used in a summing amplifier configuration As shown in Fig 1 three signals are summed together at the input and amplified DC offset Input 1 and Input 2 The DC offset is adjustable from the front panel potentiometer and Input 1 and Input 2 come from the front panel BNC jacks The outputs consist of a high voltage output a monitor output which is high voltage output 30 or 1 5 times the sum of the inputs a 200 V DC current limited output and a 200 V DC current limited output NOTE Before connecting the AC power cable ver ify the the line voltage setting in the amplifier agrees with the local voltage See Appendix 2 Operating Voltages amp Fuses Fig 1 Block diagram
9. son when driving capacitive loads the maximum frequency is capacitance dependent The displace ment current drawn by a capacitor is given by I CdV dt lt 0 12 A ddt 20V Therefore Trax current limit 0 0191 CV If the peak voltage into the capacitor is 200 V then the maximum frequency in Hz is given by Fray current limit large signal 9 55x10 C Therefore if the capacitive load is 100 nF 0 1 pF the maximum frequency before current limiting begins to distort a 200 V waveform is 955 Hz RC Filter The Model 3211 has an output resistance of approximately 25 This resistance along with the capacitive load forms a low pass RC filter with the 3 dB point at a frequency of 1 27RC This RC filter can limit the bandwidth performance of the Model 3211 for large capacitive loads and very small peak voltages Summary When determining the maximum bandwidth of the Model 3211 for a known capacitive load and a desired peak voltage the user must calculate the bandwidth determined by the slew rate dominates 13 14 Vv for small on the order of 100 pF or less capac itive loads and large voltages the current limit dominates for large on the order of tens of nanofarads capacitive loads and the RC filter dominates for large capacitive loads and very small peak voltages The smallest of the 1 MHz closed loop bandwidth the calculated slew rate limited bandwidth the calculated current limited

3211 Hi-V Amp RevB

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