Home

Understanding electromagnetic effects using PCB demos

1. 4 1 2 6 The Bill of Materials 22s 4 1 3 Board Functional Description 4 14 Lessons Learned rins densis haat eme em RUE He Rue oe 9 1 1 Demonstrations on the Self Induction Board This demonstration board shows that all conductor loops have self induction Cause is the magnetic field that inherently accompanies any current It manifests itself when a step voltage change is applied to the input terminals of the loop Initially the loop generates a voltage proportional to the change in magnetic flux This prevents the current from following the voltage step immediately This is described by Faraday s Law The duration of this transient voltage depends on the area of the loop Induction can be used to delay remove high frequencies in current change CHAPTER 1 SELF INDUCTION BOARD 2 1 2 Self Induction Board Views 1 2 1 The Finished Board The end result of the assembly of the Self Induction Board is shown in Figure 1 1 Ty uction Figure 1 1 The Finished Self Induction Board 1 2 2 The Silkscreen The Silkscreen of the Self Induction Board shown in Figure 1 2 points out which components should be mounted where O Self Mmduction O University of Twente Enschede Metherlands Output Tele g EMC mmunication TEGEN UTwente NL Self Induction De
2. 99 12 2 5 The Board Schematic 100 12 2 6 The Billof Materials 100 12 3 Board Functional Description 2 5 4 ae xx Rees 9o opa eR oq e CBS RR GR 101 T2 4 Lessons Learned sisi uu de tec ux ed a eco e He N 105 13 Ground Bounce Package Type 107 13 1 Demonstrations on the Ground Bounce Package Type Board 107 13 2 Ground Bounce Package Type Board Views 108 13 2 1 The Finished Board 108 13 2 2 The Silkscreen ees 108 19 2 3 Bare Board Top View soe moa awa Pe x bom LO Ren 109 13 2 4 Bare Board Bottom View 109 13 2 5 The Board Schematic 110 13 2 6 The Bill of Materials 110 13 3 Board Functional Description desee bare ete gk ae UR IE Pe eon Hee RI 112 13 4 16550 5 6 8 64 115 14 Ground Bounce Package Type Mk2 117 14 1 Demonstrations on the Ground Bounce Package Type Board Mk2 117 14 2 Ground Bounce Package Type Board Mk2 Views 118 14 2 1 The Finished Board 118 ete ane i eed 118 14 2 3 Bare Board Top VIEW 2s 119 14 2 4 Bare Board Bottom View 119
3. Figure 1 8 Oscilloscope picture for a large loop area Figure 1 9 Oscilloscope picture for a small loop area UNIVERSITY OF TWENTE CHAPTER 1 SELF INDUCTION BOARD Self Induction Demo Board 2 4 6 os o Attenuation dB oo A N 14 16 1 00E 06 1 00E 07 1 00E 08 Frequency Hz 1 00E 09 Wide Loop Small Loop Random Loop Ideal Line Figure 1 10 Attenuation as function of frequency for various wire locations UNIVERSITY OF TWENTE CHAPTER 1 SELF INDUCTION BOARD 9 1 4 Lessons Learned Using the Self Induction experiment we have learned that 1 The Self Induction of a loop formed by the signal and return conductor of an interconnection can disturb the signal integrity by attenuating the higher frequencies 2 This is caused by the energy stored in the magnetic field associated with the signal current over the interconnection The buildup and dissolution of this field takes time 3 The magnetic field generated by the interconnection can affect other systems in the environ ment UNIVERSITY OF TWENTE CHAPTER 1 SELF INDUCTION BOARD UNIVERSITY OF TWENTE Chapter 2 Lenz Law Contents 2 1 Demonstrations on the Le
4. 135 16 4 The Board Schematic rx ee ke ae a gel RR ee OR 136 16 5 The Bill of Materials 0 0200 ee 136 16 6 Board Functional Description ss so Room ek RO Rm 138 16 7 Lessons Learned 22 Ru uer etel on bes fe oou eret patus 140 17 General Remarks 141 17 1 The Future of the PCB Demo Boards 141 17 2 How the boards are built 141 7 2 1 User Expertise Required uoo ome Rum E en Rede 141 17 2 2 Experimenter Case with Finished Boards Cables and Power Supply 141 17 2 3 Do it Yourself m vk Rm Use x EU m XR AY Rh es 142 17 3 Known Issues s dod s woo UAR de o eae dL Se ed e Od es LER 142 15 9 1 Pushb tton Switches siss ue oo or Dt oen Cen e dene o c 142 WF eS a MEM te he Sa eam TCR TEM 142 Bibliography 143 UNIVERSITY OF TWENTE CONTENTS UNIVERSITY OF TWENTE Chapter 1 Self Induction Board Contents 1 1 Demonstrations on the Self Induction Board 1 1 2 Self Induction Board Views 2 12 1 The Finished Board 2 2 ee hae a ee eo 2 tt 2 12 2 The Silkscreen 2 22202 ona ee R4 bbe ee a 2 1 2 3 Bare Board Top Views Re Re a eS 3 1 2 4 Bare Board Bottom View ees 3 1 2 5 The Board Schematic
5. 122 14 4 Lessons Learned ee ee ee ee tnn 124 14 1 Demonstrations on the Ground Bounce Package Type Board Mk2 The Ground Bounce Package Type Board Mk2 shows that large power current surges in a digital device due to simultaneous switching of outputs causes a positive spike on the on chip ground level with respect to the ground level on the Printed Circuit Board PCB This particular board has three identical chips in varying packages from TSSOP to DIL to see if this makes any difference This Mk2 version has an additional ground plane on the component side of the board to further improve reduce the groundbounce effect 117 CHAPTER 14 GROUND BOUNCE PACKAGE TYPE MK2 118 14 2 Ground Bounce Package Type Board Mk2 Views 14 2 1 The Finished Board The end result of the assembly of the Ground Bounce Package Type Mk2 Board is shown in Figure 14 1 Lj ano Ground Bounce x wg Package type PDIP Cio i of Twente ho Hatheriands Wotwers Cioci ow Figure 14 1 The Finished Ground Bounce Package Type Mk2 Board 14 2 2 The Silkscreen The Silkscreen of the Ground Bounce Package Type Mk2 Board shows where which compo nents should be mounted w ek Ground Bounce O is Package type e sonn ez E 5 PDIP 1 B men E i DIP Jom
6. 68 8 2 6 The Bilblof Materials 4 sem oo Pa Aw ee E RR 68 8 3 Board Functional Description 69 8 4 Lessons Learned sssi i usode i e ee ee ee ee s 71 8 1 Demonstrations on the Inductance of Capacitor Dielectrics Board The Inductance of Capacitor Dielectrics Board shows the effect of the dielectric material of a decoupling capacitor on its parasitic properties Equivalent Series Inductance ESI and Equivalent Series Resistance ESR 65 CHAPTER 8 INDUCTANCE OF CAPACITOR DIELECTRICS 66 8 2 Inductance of Capacitor Dielectrics Board Views 8 2 1 The Finished Board The end result of the assembly of the Inductance of Capacitor Dielectrics Board is shown in Figure 8 1 Figure 8 1 The Finished Inductance of Capacitor Dielectrics Board 8 2 2 The Silkscreen The Silkscreen of the Inductance of Capacitor Dielectrics Board shows where which compo nents should be mounted Inductance of Capacitors Part 2 Dielectric See Na ris 1 gt 4 University of Twente B Eosebade Tibe Netherlands Telecommunication Engineering EMC ead x TEBEW UTwente NL 2 5 Bim u 000 med 1 Bluminium Electrolytic 2 Ta lum 3 3 Ceramic Multi Layer l 6 4 Polyphenylene sulphide PPS gt 5S Polyester All 100nF Capacitors a
7. 126 15 2 1 The Finished Board leen 126 I5 2 2 The S ksereem 2 2 DR esku XU EE A 126 15 2 3 Bare Board Top View es 127 15 3 Bare Board Bottom View 127 15 4 The Board Schematic eee eee eee eee ene 128 15 5 The Bill of Materials 128 15 6 Board Functional Description 130 15 7 Lessons L ar n d 4i 2x9 yeh e anne eh ies DRE cee a 131 15 1 Demonstrations on the Ground Bounce Power Pinning Board The Ground Bounce Power Pinning Board shows the same effect as the Ground Bounce Pack age Type Board but focusses on the difference between devices with end and center power pinning layout 125 CHAPTER 15 GROUND BOUNCE POWER PINNING 126 15 2 Ground Bounce Power Pinning Board Views 15 2 4 The Finished Board The end result of the assembly of the Ground Bounce Power Pinning Board is shown in Fig ure 15 1 WEAH Figure 15 1 The Finished Ground Bounce Power Pinning Board 15 2 2 The Silkscreen The Silkscreen of the Ground Bounce Power Pinning Board shows where which components should be mounted QJ Ground Bounce Q AISymmetric IC power pine Power Un versity af Twente 3i A Enschede Wetherlands 2 E Symmetric Telecommunic
8. B amp O a U outi U out2 U_outs U nut4 U outs u_out U out DE w Figure 2 3 The Lenz s Law Bare Board Top View 2 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 2 4 Figure 2 4 The Lenz s Law Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 2 LENZ LAW 14 2 2 5 The Board Schematic The schematic diagram of the Lenz Law board is shown in Figure 2 5 It is drawn in the way the board will be used in the functional description in section 2 3 U out U in 1 Wide Short Trace far from ground plane 500 2 Thin Short Trace far from ground plane g 3 Wide Meandering Trace far from ground plane Pop Uout3 7 72 BES U out4 3 4 Thin Long Trace loop far from ground trace 7 Cc U out5 7 i 5 Trace on Edge of Ground Plane Ground Vias Figure 2 5 The Lenz Law Board Schematic 2 2 06 The Bill of Materials The bill of materials of the Lenz s Law Board is shown below as Table 2 1 Table 2 1 Bill of Materials of the Lenz s Law Board REF DES VALUE PACKAGE FOOTPRINT U in SMB SMB RF SMB V U out1 SMB SMB RF SMB V U out2 SMB SMB RF SMB V U out3 SMB SMB RF SMB V U out4 SMB SMB RF SMB V U out5 SMB SMB RF SMB V U out6 SMB SMB RF SMB V U out7 SMB SMB RF SMB V R1 00 R SM R 1206 R2 notused R SM R 1206 R3 notused HR 1206
9. _ E 32 23 CONN 19 1 1 CONN 20 3 2 23 SMB SMB CONN 17 1 1 CONN 18 45 j 54 SMB SMB Age oda 59 10p riti Inductance Of Capacitors Part 1 ize Document Number lev A 20 Pate Wednesday October 29 2008 Bheet 1 of 1 Figure 7 5 The Inductance of Capacitor Vias and Value Board Schematic 7 2 6 The Bill of Materials The components to complete the Inductance of Capacitor Vias and Value Board are shown in Table 7 1 Table 7 1 Bill of Materials of the Inductance of Capacitor Vias and Value Board REF DES VALUE PACKAGE FOOTPRINT C1 in C 1206 C2 in C SM C 1206 C3 in C SM C 1206 UNIVERSITY OF TWENTE CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 59 Table 7 1 Bill of Materials of the Inductance of Capacitor Vias and Value Board cont d REF DES VALUE PACKAGE FOOTPRINT C4 100n C SM C 1206 C5 10n C SM C 1206 C6 in C SM C 1206 C7 100p C SM C 1206 C8 in C SM C 1206 C10 in C SM C 1206 CONN1 SMB SMB RF SMB V CONN2 SMB SMB RF SMB V CONN3 SMB SMB RF SMB V CONN4 SMB SMB RF SMB V CONN5 SMB SMB RF SMB V CONN6 SMB SMB RF SMB V CONN 7 SMB SMB RF SMB V CONN8 SMB SMB RF SMB V CONN9 SMB SMB RF SMB V CONN 10 SMB SMB RF SMB V CONN 11 SMB SMB RF SMB V CONN 12 SMB SMB RF SMB V CONN 13 SMB SMB RF SMB V CONN 14 SMB SMB RF SMB V CONN 15 SMB SMB RF SMB V CONN 16 SMB SMB RF SMB V CONN 19 SMB SMB RF SMB V CONN 20 SMB SMB RF SMB V
10. 2 Cables generate emit common mode currents through their return conductors due to differ ential mode signals flowing in them 3 If the cable shield is thick enough the skin effect helps to reduce the transfer impedance even further in parts of the frequency spectrum 4 Developers should specify the required transfer impedance for their cable designs over the relevant frequency range UNIVERSITY OF TWENTE CHAPTER 4 TRANSFER IMPEDANCE 34 UNIVERSITY OF TWENTE Chapter 5 Crosstalk Basic Phenomena Contents 5 1 Demonstrations on the Crosstalk Basic Phenomena Board 35 5 2 Crosstalk Basic Phenomena Board 36 5 2 4 The Finished Board oi eke ae ewe A Ree 36 52 2 Thespilkscr enty 22350 6 ewe 36 5 2 8 Bare Board Top View eee ee 37 5 2 4 Bare Board Bottom View 0 0 0 0 00000000004 37 5 2 5 Phe Board Schematic 5 5 mp e bs i 38 5 216 Dhe Bill of Materials 407 0 ob aro Bod Reto de bak RU 38 5 3 Board Functional Description 38 5 4 Lessons Learned 5 oe emos EIE Uo ter pas 45 5 1 Demonstrations on the Crosstalk Basic Phenomena Board The Crosstalk Basic Phenomena Board illustrates the mutual inductance and capacitance effect underlying crosstalk Further it is shown that there is a ceiling to the amount of crosstalk and that the level of this ceiling i
11. 67 8 2 5 The Board Schematic 68 8 2 6 The Billof Materials 68 8 3 Board Functional Description sio Bee WG 69 8 4 Lessons Learned neah o S RI eu ete ne Ge A oh A 71 9 Inductance of Capacitor Packaging 73 9 1 Demo s with the Inductance of Capacitor Packaging Board 73 9 2 Inductance of Capacitor Packaging Board 5 74 9 2 1 The Finished Board 74 9 22 The Silkscreen es 74 9 2 3 Bare Board Top View sw ALS wo OU Se CUR ME ede KE ge Ba Oh ee 75 9 2 4 Bare Board Bottom View 75 9 2 5 TheBoardSchematic n 76 9 2 6 The Bill of Materials 77 9 3 Board Functional Description wo a ee RETRO EE a ees 77 9 4 LessonsLearmned a a a a ao Aaa oE 80 10 Grounding of Filters 81 10 1 Demonstrations on the Grounding of Filters Board 81 10 2 Grounding of Filters Board Views Ree ee ee RSS So Ee ta ee 82 10 2 1 The Finished Board 82 10 2 2 The etis 82 10 2 3 Bare Board Top View s 5 ou duce greed dux Gag 83 10 2 4 Bare Board Bottom View 83 10 2 5 The
12. 2 The way a capacitor is built has an effect on its equivalent series resistance The minimum value the decoupling capacitor impedance can reach is determined by it UNIVERSITY OF TWENTE CHAPTER 8 INDUCTANCE OF CAPACITOR DIELECTRICS 72 UNIVERSITY OF TWENTE Chapter 9 Inductance of Capacitor Packaging Contents 9 1 Demo s with the Inductance of Capacitor Packaging Board 73 9 2 Inductance of Capacitor Packaging Board Views 74 9 2 1 The Finished Board a yv ee do emn 74 9 2 2 The Silkscreen 5o e pure wi qa RR 74 9 2 8 Bare Board Top View 75 9 2 4 Bare Board Bottom View es 75 9 2 5 The Board Schematic 76 9 2 6 The Bill of Materials eee hen 77 9 3 Board Functional Description 2 2 0000 eee 77 9 4 Lessons Learned 1 ee ee ee eee ee 80 9 1 Demo s with the Inductance of Capacitor Packaging Board Capacitors come in different shapes and sizes The packaging affects the device parasitic ele ments and hence its behavior over frequency 73 CHAPTER 9 INDUCTANCE OF CAPACITOR PACKAGING 74 9 2 Inductance of Capacitor Packaging Board Views 9 2 1 The Finished Board The end result of the assembly of the Inductance of Capacitor Packaging Board is shown in Figure 9 1 Inductance of Capac tors and va fo O lO
13. trace between the traces A1 A2 and B1 B2 Any trace could be used as an active trace but the trace between CONN B1 and CONN B2 is used as the active trace for this example The guard trace is connected when both switches SW1 and SW are pressed The spectrum analyzer is connected as shown in Figure 6 6 The results of the measurements are shown in Figure 6 7 Assuming the active signal on connector B1 and measuring the crosstalk on connector A1 four situations are shown in Figure 6 7 The dark blue line B1 to A1 Guard Floating is the situation where the guard trace is not connected on either side The asymptote reached around 100 MHz lies at approximately 10 dB under the level of the active line 0 dB in the graph When both switches are pressed the red line B1 to A1 SW1 amp SW2 closed is measured It is interesting to notice that only the Low Frequencies below 100 MHz are affected 12 dB or a factor of 4 less In the higher frequencies the asymptote still lies around 10 dB If only one of the two switches is closed the purple B1 to A1 SW1 closed and green B1 to A1 SW2 closed lines are found Both a little worse than the original B1 to A1 Guard Floating The extra peaks at 50 MHz are formed because at that frequency the guard trace resonates and in fact increases the crosstalk The measurement B1 to C1 Guard Floating orange UNIVERSITY OF TWENTE CHAPTER 6 CROSSTALK LAYOUT ISSUES 50 line is added to show the cr
14. 141 11 2 3 Do it Yourselt4 o aa d sm er ere b e Pe ete VE ue eres 142 1753 Known Issues 24 Sue rui Se oh n DE atum HL enar er peas eoe d ug 142 11 3 1 Push button Switches xls eek xn RR xs S ORE e G 142 39 Palberg Cua e Ite oe ete EON Sek 142 17 1 The Future of the PCB Demo Boards 14 demonstration boards have been conceived and built so far This however is an ongoing project As the need arises new experiments are sure to come up Also experience with the current boards will probably show how improvements can be made New ways of meeting EMC problems will hopefully flow from it 17 2 How the boards are built 17 2 1 User Expertise Required It is assumed that the user of these demonstration boards has a reasonable knowledge of EMC The boards are primarily intended for educational purposes But the educator might not be inter ested or able to assemble the PCB s 17 2 2 Experimenter Case with Finished Boards Cables and Power Supply The first option therefore is to have the boards assembled and tested by the University of Twente In that case the necessary cables and a power supply for the active boards will also be delivered Everything in a useful carrying case Measuring equipment like an oscilloscope and a spectrum analyzer with tracking generator will have to be provided by the user 141 CHAPTER 17 GENERAL REMARKS 142 17 2 3 Do it Yourself The other option is to ord
15. 7 3 Board Functional Description The Inductance of Capacitor Vias and Value Board is the first part 1 of a three part set It ad dresses the parasitic effects which are caused partly by the way the capacitors are built and partly by the placement and routing on the board Apart from the capacitance for which these devices are sold they come with an Equivalent Series Resistance ESR and Equivalent Series Inductance ESL This inductance will resonate with the capacitance at a frequency determined by the actual value of capacitance and inductance This is a series resonance which has the characteristic fre quency response shown in Figure 7 6 The lowest point in the graph indicates the value of the Equivalent Series Resistor ESR It is clear from Figure 7 6 that the capacitor no longer performs as a capacitor for frequencies over Tresorianees The Inductance of Capacitor Vias and Value Board focusses on the layout of the Board and on the effect of capacitance values The effects are best viewed in the frequency domain On the left hand side of the board it has a number of identical 1 nF capacitors which are connected to the UNIVERSITY OF TWENTE CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 60 return ground plane with traces decreasing in length from the top of the board to the bottom This can be seen in figures 7 1 and 7 3 On the right hand side capacitors with identical shape but with decreasing value are mounted with
16. E SS dut N at UNIVERSITY OF TWENTE ENSCHEDE t TELECOMMUNICATION ENGINEERING GROUP FACULTY OF EEMCS P A Printed Circuit Boards gt N SP for the Education aimed at IN Understanding Electromagnetic Effects User Manual Frits J K Buesink MSc Senior Researcher University of Twente 2009 Version February 1 2010 Faculty of Electrical Engineering Mathematics and Computer Science EMC Chair Building Carr P O Box 217 7500 AE Enschede The Netherlands Tel 053 489 3856 Fax 053 489 5640 E mail te ewi utwente nl website http www ewi utwente nl te UNIVERSITY OF TWENTE Introduction Demos are often used in electromagnetic field courses We have developed many types of demos and used also demos developed by others such as those described in the IEEE EMC ucation Manual IEEE04 and IEEE92 or the demo developed within the ASIAN EU University Network Program ASEU or within PATON Two main drawbacks could be observed 1 We could easily show the fundamental aspects such as Lenz Law or crosstalk in an idealized world but this was not taken for granted by practicing engineers these engineers needed a link to their own world Especially people involved in signal and power integrity issues ground bounce and interconnects Their world is often a printed circuit board 2 The size of many of the demos is huge Transportation of such demos i
17. ON POIP Clock University of Twente s output is 5 SWI Enochede The Metheriands cca Telecommunication Engineering EMC al soic Low EGEWI UTWente NL E Bae Power acci 3 2 z a n a m am sudes uL 1 E En o ON Clock Rio 5015 La CONN 51 T Output a u2 SOIC Clock u J amp D H 5 ms q Brunn founsa Deponsheat on 01C La Fi ntical driver 18 di atkages Output Poe ILS solic and EAM pe ened induch 4 inputa with lacks a chpubEs com EH 4 TESAP CONN T2 0 5 oN TSSOP Clock jim 5 Output R12 1SSOP law Dutput Power 8 izv Pow vere 2005 Istwaan Knijff vere 1 2008 Berala Hoekstra vere 2 2009 M F Brethouner Figure 14 2 The Ground Bounce Package Type Mk2 Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 14 GROUND BOUNCE PACKAGE TYPE 119 14 2 3 Bare Board Top View The etch pattern of the empty Mk2 board seen from the top side is shown in Figure 14 3 Figure 14 3 The Ground Bounce Package Type Mk2 Bare Board Top View 14 2 4 Bare Board Bottom View The etch patte
18. The Wetherlands cat Telecommunication Engineering EMC TEGEWI UTwente NL 50 L Output asc amp Ramer 5 z 4 aue SOIC a us LI cow ss 1 DN Clock JONHz pe goe t 8 oJ CONN 51 u le gl 2 501C Clock EE E e cn H E P conn sa zl 5 Ground cd ounce Demons tratiun PCB solic Law 3 Identical dr rth different packages 3 Output 18516 An E SLM pu Ioa 0 3 Ba to lead inductances 4 DEB NC qraunded ror 5W3 4 TP CONN 12 4 5 DN TSSOP Clock a Lt 5 Dukut EH ML ISSOP law p Co Output ln Bis p input z B i 3 er 2005 Istwaan Knijff ver 1 2008 Gerala Hoekstra Figure 13 2 The Ground Bounce Package Type Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 109 13 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 13 3 e Ground Bouncegg y Package type i mie 9 CONN P2 9 University of Twente Enschede the elecommunication Engineering TEEEUI NL Power PDIP PDIP Clock Dutput conn 52 zi conn 55 ances CONN TI input wer 2005 Istw Ver di 2008 Derald Hae s Power TSSOP Figure 13 3 The Ground Bounce Package Type Bare Board Top View 13 2
19. Figure 9 1 The Finished Inductance of Capacitor Packaging Board 9 2 2 The Silkscreen The Silkscreen of the Inductance of Capacitor Packaging Board shows where which compo nents should be mounted e Inductance of Capacitors S Part 3 Package and value U inl U out U 5 U puts 100nF 100nF University of Twente 10nF Enschede tha Netherlands Telecamm g EMC unication Engineerin TE EW UTwente NL 100pF Package Tyne Radial Leaded Package Types SMD vers Q 20054 Istwaan Kmiiff ver 1 2008 Frank Wiggers vers 2 2008 Eduard Bos Figure 9 2 The Inductance of Capacitor Packaging Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 9 INDUCTANCE OF CAPACITOR PACKAGING 75 9 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 9 3 Jj e Inductance of Capacitors Part 3 Package and value 100nF 100nF University of Twente 188 Enschede Netherlands ORF Telecammunication Engineering EMC TE EW UTwente NL 1 InF 100pF 100pF Package Tyne Radial Leaded pum ver Koad 2895 unu Figure 9 3 The Inductance of Capacitor Packaging Bare Board Top View 9 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the
20. R8 50 RESISTOR SM R_1206 H9 50 RESISTOR SM R 1206 R10 50 RESISTOR SM R 1206 R11 50 RESISTOR SM R 1206 R12 50 RESISTOR SM R_1206 R13 50 RESISTOR SM R_1206 R14 50 RESISTOR SM R_1206 R15 50 RESISTOR SM R_1206 R16 50 RESISTOR SM R_1206 UNIVERSITY OF TWENTE CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 112 Table 13 1 Bill of Materials of the Ground Bounce Package Type Board cont d REF DES VALUE PACKAGE FOOTPRINT SW1 SW KEY SPDT SW KEY SPDT 1 SLIDESWITCH SW2 SW KEY SPDT SW KEY SPDT 1 SLIDESWITCH SW3 SW KEY SPDT SW KEY SPDT 1 SLIDESWITCH U1 LM7805 TO220 L7805 TO2202 TO220AB U2 74ACT244PDIP 74ACT244 DIP 100 20 W 300 L1 050 U3 74ACT244S0IC 74ACT244 SOG 050 20 WG 420 L 500 U4 7TAACT244TSSOP 74ACT244 SOG 65M 20 WG8 20 L6 98 13 3 Board Functional Description The Ground Bounce Package Type Board demonstrates the effect of large power currents due to the simultaneous switching of many outputs of e g a driver IC This is shown in Figure 13 6 On the Ground Bounce Package Type Board the high currents in the output stages of a driver IC are generated by loading some of them with small capacitors 47 pF Four outputs are switched with a 10 MHz clock The other four remain at ground level This same setup is made using three different IC Packages 1 A through hole Dual In Line DIL 2 A Small Outline Integrated Circuit SOIC 3 A Thin Shrink Small Outline Package TSSOP To operate the board a
21. The Crosstalk Basics Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 5 CROSSTALK BASIC PHENOMENA 38 5 2 5 The Board Schematic The schematic diagram of the Crosstalk Basic Phenomena Board is shown in Figure 5 5 Conn Al Conn A2 4 5 SMB 33 e 1 A 32 ConCi Conn C2 5 4 SMB SMB Figure 5 5 The Crosstalk Basics Board Schematic 5 2 6 The Bill of Materials The components to complete the Crosstalk Basic Phenomena Board are shown in Table 5 1 Table 5 1 Bill of Materials of the Crosstalk Basic Phenom ena Board REF DES VALUE PACKAGE FOOTPRINT CONNA1 SMB SMB RF SMB V CONN B1 SMB SMB RF SMB V CONN C1 SMB SMB RF SMB V CONN SMB SMB RF SMB V CONN B2 SMB SMB RF SMB V CONN C2 SMB SMB RF SMB V SW 1 3pos DP DP 3 ALPS STSSS2231 R1 51 RESISTOR SM R 1206 5 3 Board Functional Description The Crosstalk Basic Phenomena Board can be operated both in the time and frequency do main The middle trace on the demo board the active trace transmits a signal from either a square wave generator or from a tracking generator of a spectrum analyzer The active trace load can be switched from characteristic termination to open ended or short circuited Depending on the UNIVERSITY OF TWENTE CHAPTER 5 CROSSTALK BASIC PHENOMENA 39 position of the switch the active line end will or will not reflect the signals on that line The effects crosstalk on the passive lines can be observed at b
22. To see the performance of each mounting a spectrum analyzer with tracking generator is con 12 12 36 12 16 Measures in mm Figure 10 6 Drawing of the brass sheet material needed for filters 3 and 4 nected to measure the attenuation of each filter in sequence The generator is connected to the U inX connector while the analyzer input is connected to the U outX connector on the board The results are plotted together in Figure 10 7 The first ungrounded filter does not work at all It is characterized with the solid blue line around 0 dB The second filters poor performance is shown as Filter Ground through Wire with a green line The third filter behaves much better The attenuation indeed goes to 50 dB but then comes back up again The latter effect is increased if the in and output wires are lifted from the board and the groundplane The fourth filter behaves as it should Note the situations demonstrated on this PCB are simulations of what happens with filters mounted in a cabinet The description for the four cases would then read 1 A filter mounted in a plastic wall 2 Afilter mounted in a plastic wall grounded with a long green yellow wire 3 A filter mounted inside an instrumentation cabinet e g for weather protection on a wide ground plane where in and output wiring can easily crosstalk 4 A filter mounted in the metal wall of a shielded EMC enclosure In and output wiring are completely separated
23. should be better than 50 dB The board has four input and four output connectors Traces run from the connectors towards the middle of the board where the filters have been mounted The bottom of the board has a wide ground plane under all traces The details of the mounting of the filters are 1 The first filter between connectors U in1 and U out1 is only touching the board with its signal in and output terminals In other words it has no ground connection 2 The second filter is connected with long about 5 cm wires but has a ground wire too 3 The third filter has input and output wires but is mounted to a sturdy and relatively wide metal bracket 4 The fourth filter is mounted with the shortest possible wiring and the input section has been completely shielded by a metal enclosure Further this last filter section also has a ground plane on the component side of the board The ground planes on both sides are not only connected at the connectors but also with many via s alongside the signal traces To fabricate the mechanical parts for the latter two filters 0 4 mm brass plate was used Anything between 0 3 and 1 mm is O K Figure 10 6 shows the drawing of the basic shapes These then are bent to form the bracket for the third filter left hand side of Figure 10 6 and the enclosure for the fourth filter right hand side of Figure 10 6 The proposed enclosure is almost shaped like a cube but two sides are missing One open end is direc
24. 11 DISCONTINUITIES STUBS 95 ends of the line at the connectors Due to the different locations of these reflection points the reflected signals have different phases and have an tendency to cancel at specific frequencies the deep valleys in the outputs measured at U out4 5 and 6 The same effects can also be observed in the time domain A fast Time Domain Reflectometer is needed as individual reflections can only be seen if the rise time of the built in generator is shorter than the propagation delay of the line segment to be measured 11 4 Lessons Learned The Discontinuities Stubs experiments show that 1 Ideally the impedance of a PCB trace should be equal to the feeding source and following load For 509 the trace U in1 U out1 is best 2 Ifthe impedance ofthe line differs from the source and or load impedance reflections will occur and the characteristics of the line will be less than ideal Ideal for an interconnection means 0 dB attenuation over the frequency range of interest Example the 1200 line between U in2 and U out2 when driven and loaded by 502 3 The amount of signal distortion depends on the length of the mismatched line section e g U in3 to U out3 4 A high speed interconnection should never be split up into several line segments Use a Daisy Chain instead At the junction into two equal lines the impedance drops a factor of two causing reflections Unequal stub lengths after the junction c
25. 20 v 30 100nF SMD 10nF SMD 1l 5 40 4nF SMD l Y 100pF SMD X X 50 m M 60 1 0 Up p 0 0 p 0 01 0 1 1 10 100 1000 Frequency MHz Figure 7 8 Frequency Response of Capacitors with Decreasing Values UNIVERSITY OF TWENTE CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 63 7 4 Lessons Learned The Inductance of Capacitor Vias and Value Board experiments show that 1 Increasing the length of a connecting trace increases the amount of parasitic inductance of a decoupling capacitor This lowers its inherent resonance frequency and hence the useable frequency range for decoupling purposes 2 A higher value capacitor tends to have a higher parasitic inductance The effect again is resonance at a lower frequency and a lower useable frequency range for decoupling UNIVERSITY OF TWENTE CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 64 UNIVERSITY OF TWENTE Chapter 8 Inductance of Capacitor Dielectrics Contents 8 1 Demonstrations on the Inductance of Capacitor Dielectrics Board 65 8 2 Inductance of Capacitor Dielectrics Board Views 66 8 2 1 The Finished Board 66 8 2 2 Phe Silkscreen 2 ec m RR d ADR Ae eee a ew A 66 8 2 8 Bare Board Top View lees 67 8 2 4 Bare Board Bottom View es 67 8 2 5 The Board Schematic
26. 2005 Istwaan Knijff er 1 2008 Berald Hoekstra Figure 12 3 The Discontinuities Ground Apertures Bare Board Top View 12 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 12 4 Figure 12 4 The Discontinuities Ground Apertures Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 12 DISCONTINUITIES GROUND APERTURES 100 12 2 5 The Board Schematic The schematic diagram of the Discontinuities Ground Apertures Board is shown in Figure 12 5 Figure 12 5 The Discontinuities Ground Apertures Board Schematic 12 2 6 The Bill of Materials The components to complete the Discontinuities Ground Apertures Board are shown in Ta ble 12 1 Table 12 1 Bill of Materials of the Discontinuities Ground Apertures Board REF DES VALUE PACKAGE FOOTPRINT U int SMB SMB RF SMB V U in2 SMB SMB RF SMB V U in3 SMB SMB RF SMB V U out SMB SMB RF SMB V UNIVERSITY OF TWENTE CHAPTER 12 DISCONTINUITIES GROUND APERTURES 101 Table 12 1 Bill of Materials of the Discontinuities Ground Apertures Board cont d REF DES VALUE PACKAGE FOOTPRINT U out2 SMB SMB RF SMB V U out3 SMB SMB RF SMB V SW1 CON4 8 CON49 SWITCH 4PIN TYCO FSM4JH SW2 CONA48 CON49 SWITCH 4PIN TYCO FSM4JH C1 100 nF CAP NP SM C 1206 12 3 Board Functional Description The Ground Stubs Board has three identical
27. 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 13 4 je je e ta Figure 13 4 The Ground Bounce Package Type Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 110 13 2 5 The Board Schematic The schematic diagram of the Ground Bounce Package Type Board is shown in Figure 13 5 F1 45V D1 U1_LM7805 TO220 AN b MINT vin 1n4001 9 FUSEHOLDER POWERJACK 2 c2 le c3 220 Res 220u 100n D2 LED 330 J1 cs aia pppPDIP package ce 29 Clock 23 98 u g n US CONNP il 0 SMB N SA CONN F2 SMB RR DIDAR OW lo mi 5T5S0R 9 gt D o m TSSOP package R13 1 CONN T1 SMB P o 3 T Q 580IC SOIC package 23 u 98 R8 1 CONN 51 50 SMB P 7 c 54 2 Y2 4n CONN T2 SMB 0 B 1144 1 17 CONN S2 SMB 4 5 1 19 74ACT244S0IC 22 B CONN 3 5 SMB 5 5 Title Ground Bounce DIL vs SMD CONN S4 SMB Bize Document Number ev A Date Thursday October 08 2009 Ehest 1 of 1 Figure 13 5 The Ground Bounce Package Type Board Schematic 13 2 6 The Bill of Materials The components to complete the Ground Bounce Package Typ
28. Bounce Power Pinning Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 15 GROUND BOUNCE POWER PINNING 128 15 4 The Board Schematic The schematic diagram of the Ground Bounce Power Pinning Board is shown in Figure 15 5 35y 5V U1_LM7805 TO220 9 ving 8 4x 81 NY VIN D vour 1n4001 o FUSEHOLDER POWERJACK4 2 n 2 a at B w al i ln bbrp wN D bbp 5 o ol nls i Date Thursday October 08 2009 Bheet 1 of 1 Figure 15 5 The Ground Bounce Power Pinning Board Schematic 15 5 The Bill of Materials The components to complete the Ground Bounce Power Pinning Board are shown in Table 15 1 Table 15 1 Bill of Materials of the Ground Bounce Power Pinning Board REFDES VALUE PACKAGE FOOTPRINT C2 220n CAP_NP SM C 1206 C3 100u CAP POL 0 CYL D 275 LS 100 034 C4 22n CAP NP SM C 1206 C5 100p CAP NP SM C 1206 UNIVERSITY OF TWENTE CHAPTER 15 GROUND BOUNCE POWER PINNING 129 Table 15 1 Bill of Materials of the Ground Bounce Power Pinning Board contd REF DES VALUE PACKAGE FOOTPRINT C7 100p CAP_NP SM C_1206 08 100 SM C_1206 C9 100n CAP NP SM C 1206 C10 100n CAP NP SM C 1206 C11 10n CAP_NP SM C_1206 CLOCK SMB SMB RF SMB V CONN A1 SMB SMB RF SMB V CONN SMB SMB RF SMB V CONN B1
29. Mk2 Board cont d REF DES VALUE PACKAGE FOOTPRINT C5 100p CAP_NP SM C 1206 C7 100p CAP_NP SM C_1206 08 100 SM C_1206 C9 100n CAP NP SM C 1206 C10 100n CAP NP SM C 1206 C11 10n CAP NP SM C 1206 CLOCK SMB SMB RF SMB V CONN A1 SMB SMB RF SMB V CONN SMB SMB RF SMB V CONN B1 SMB SMB RF SMB V CONN B2 SMB SMB RF SMB V D1 1n4001 DIODE 0 2 1 4001 4007 REV1 D2 LED RED LED CYL D 225 LS 125 031 D3 LED YEL LED CYL D 225 LS 125 031 D4 LED GRN LED CYL D 225 LS 125 031 F1 FUSEHOLDER FUSEHOLDER BLKCON 200 VH TM1SQ W 100 2 IC1 74AC11244 74AC11244 SOG 050 24 WG 420 L 600 IC2 74ABT541 74ABT541_0 SOG 050 20 WG 420 L 500 J1 CONN PWR 2 J POWERJACK 0 POWERJACK OSC1 10 MHz OSC14 OSC R1 220 RESISTOR SM R 1206 R2 220 RESISTOR 1206 R3 220 RESISTOR SM R 1206 R4 220 RESISTOR 1206 R5 220 RESISTOR SM R_1206 R6 220 RESISTOR SM R 1206 R7 220 RESISTOR 1206 R8 220 RESISTOR SM R 1206 R9 50 RESISTOR SM R 1206 R10 50 RESISTOR SM R 1206 R11 50 RESISTOR SM R 1206 R12 50 RESISTOR SM R 1206 R13 220 RESISTOR SM R 1206 R14 220 RESISTOR SM R 1206 R15 50 RESISTOR SM R 1206 R16 220 RESISTOR SM R 1206 SW1 SW KEY SPDT SW KEY SPDT1 SLIDESWITCH SW2 SWKEYSPDT SW_KEY SPDT 1 SLIDESWITCH U1 L7805 TO220 L7805 T02202 TO220AA RF1 UNIVERSITY OF TWENTE CHAPTER 16 GROUND BOUNCE POWER PINNING MK2 138 16 6 Board Functional Description The Ground Bounce Power Pinnin
30. SMB SMB RF SMB V CONN 2 SMB SMB RF SMB V D1 1n4001 DIODE 0 2 1 4001 4007 REV1 D2 LED RED LED CYL D 225 LS 125 031 D3 LED YEL LED CYL D 225 LS 125 031 D4 LED GRN LED CYL D 225 LS 125 031 F1 FUSEHOLDER FUSEHOLDER BLKCON 200 VH TM1SQ W 100 2 IC1 74AC11244 74AC11244 SOG 050 24 WG 420 L 600 IC2 74ABT541 74ABT541 0 SOG 050 20 WG 420 L 500 J1 CONN PWR2 J PHONEJACK0 POWERJACK OSC1 10 MHz OSC14 OSC R1 220 RESISTOR SM R 1206 R2 220 RESISTOR SM R 1206 R3 220 RESISTOR SM R 1206 R4 220 RESISTOR SM R 1206 R5 220 RESISTOR SM R 1206 R6 220 RESISTOR SM R 1206 R7 220 RESISTOR SM R 1206 R8 220 RESISTOR SM R 1206 R9 50 RESISTOR SM R 1206 R10 50 RESISTOR SM R 1206 R11 50 RESISTOR SM R 1206 R12 50 RESISTOR SM R 1206 R13 220 RESISTOR SM R 1206 R14 220 RESISTOR 1206 15 50 RESISTOR SM R 1206 R16 220 RESISTOR SM R 1206 SW1 SW KEY SPDT SW_KEY SPDT 1 SLIDESWITCH swe SW KEY SPDT SWKEY SPDT 1 SLIDESWITCH U1 L7805 TO220 L7805 T02202 TO220AA RF1 UNIVERSITY OF TWENTE CHAPTER 15 GROUND BOUNCE POWER PINNING 130 15 6 Board Functional Description The Ground Bounce Power Pinning Board is built up as the Ground Bounce Package Type board described in chapter 13 The differences are e Only two IC s are available as test objects e The IC s are functionally for our purpose here identical octal drivers but for the Power pins e The IC 74AC11244 has so called center pinning Powe
31. UNIVERSITY OF TWENTE CHAPTER 2 LENZ LAW 15 Table 2 1 Bill of Materials of the Lenz s Law Board cont d REFDES VALUE PACKAGE FOOTPRINT R4 notused R SM R_1206 R5 notused R SM R 1206 R6 notused R SM R_1206 R7 0 R SM R_1206 R8 notused R SM R_1206 R9 00 R SM R 1206 R10 notused R SM R_1206 R11 notused R SM R 1206 R12 notused R SM R_1206 R13 notused R SM R 1206 R14 notused R SM R_1206 R15 02 R SM R_1206 R16 notused R SM R 1206 R17 not used R SM R_1206 R18 not used R SM R 1206 R19 0 R SM R_1206 R20 0 R SM R 1206 R21 notused R SM R_1206 R22 not used R SM R 1206 R23 notused R SM R_1206 R24 notused R SM R 1206 R25 notused R SM R_1206 R26 notused R SM R_1206 R27 notused R SM R 1206 R28 0 R SM R 1206 Of the 28 resistor positions on the board only seven are used These are zero Ohm jumpers to connect the individual traces to the respective connectors 2 3 Board Functional Description The Lenz Law board is more or less a Frozen version of the Self Induction Board The various locations of the wire in the Self Induction experiment are replaced by fixed etch patterns on the board Some traces have a ground plane underneath others do not The bare board has one input connector U in and seven output connectors U out1 through U out7 Each trace end has a voltage divider built up with four resistors feeding the output connectors as shown in Figure 2 6 These resistors can be used to fine tune the attenuation and i
32. URS ee 29 4 2 4 Bare Board Bottom View 29 4 25 The Board Schematic 30 4 2 6 TheBillof Materials 0 ee 30 4 3 Board Functional Description x 2 6 4 n etsy a 9o Sigs tks Oe Pe eS 31 4 4 IMESSONS LEAN us e tet Pa ae te s VET co oe e aa Pe 33 5 Crosstalk Basic Phenomena 35 5 1 Demonstrations on the Crosstalk Basic Phenomena Board 35 5 2 Crosstalk Basic Phenomena Board Views 36 5 2 4 The Finished Board 36 5 2 2 The Silkscreen naaa ss 36 5 2 3 Bare Board Top View oc ae Ga AU Woe Caw ae ae 37 5 2 4 Bare Board Bottom View 37 5 2 5 TheBoard Schematic 38 5 2 6 The Bill of Materials 38 5 3 Board Functional Description 4 5 ee eee a ask a eee eed 38 5 4 LessonsLearned 22 ee 43 6 Crosstalk Layout Issues 45 6 1 Demonstrations on the Crosstalk Layout Issues Board 45 6 2 Crosstalk Layout Issues Board Views 46 6 2 1 The Finished Board 46 622 The SilKSCreen a See a a yo re b 46 6 2 3 Bare Board Top View a es xou uber es e NUS 47 6 2 4 Bare Board Bottom View 47 6 25 The Board Schem
33. bottom side is shown in Figure 9 4 Figure 9 4 The Inductance of Capacitor Packaging Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 9 INDUCTANCE OF CAPACITOR PACKAGING 76 9 2 5 The Board Schematic The schematic diagram of the Inductance of Capacitor Packaging Board is shown in Figure 9 5 45 54 Conn 5 Conn 9 1 1 Conn 1 SMB SMB SMB 2 2 3 C5 100n 4 5 54 Conn 6 Conn 10 1 1 Conn 14 SMB SMB SMB 2 32 23 j 08 10n ss z 45 5 4 Conn 7 Conn 11 1 1 Conn 15 SMB SMB SMB 3 32 2 3 1n D 5 45 54 Conn 8 Conn 12 1 1 Conn 16 SMB SMB SMB 3 32 2 3 08 100 Title Inductance Of Capacitors part 3 Bize Document Number tev A 2 0 Date Friday August 29 2008 Bheet 1 of 1 Figure 9 5 The Inductance of Capacitor Packaging Board Schematic UNIVERSITY OF TWENTE CHAPTER 9 INDUCTANCE OF CAPACITOR PACKAGING 77 9 2 6 The Bill of Materials The components to complete the Inductance of Capacitor Packaging Board are shown in Ta ble 9 1 9 3 Board Functional Description Table 9 1 Bill of Materials of the Inductance of Capacitor Packaging Board REF DES VALUE PACKAGE FOOTPRINT C1 100n C LEADED CERAMIC C315 C2 10n C LEADED CERAMIC C315 C3 in C LEADED CERAMIC C315 C4 100p C LEADED CERAMIC C317 C5 100n C SM C 1206 C6 10n C 1206 C7 in C SM C 1206 C8 100p C SM C 1206 CONN1 SMB SMB RF SM
34. by the shielding wall UNIVERSITY OF TWENTE CHAPTER 10 GROUNDING OF FILTERS 87 20 25 Attenuation dB 30 35 40 45 50 1 00E 06 1 00E 07 1 00E 08 1 00E 09 Frequency Hz Ungrounded Wire to Ground Wide Plate Plumbers Delight Figure 10 7 Frequency Response of the 4 identical Filters UNIVERSITY OF TWENTE CHAPTER 10 GROUNDING OF FILTERS 88 10 4 Lessons Learned The Filter Grounding experiments show that 1 Filter grounding has a profound impact on the filter s performance 2 The filter ground must be connected to the return of its noise source 3 The path of the filter s input return to the noise source must be such that it does not couple inductively or capacitively to the filter s output circuit This is a delicate matter as the return of the input and output circuits are usually shared Physically it is the metal filter enclosure for the selected filters here 4 The wider the path to the ground plane the better the separation between the filter s input and output Proper attention should also be given to the in and output wire lengths make these as short as possible 5 The best way to mount a filter is to prevent coupling between the input and output circuits using a metal shield In this board example the output line is completely packaged within a metal
35. conductor of this cable is also connected shorted to this same point with a small resistor The generator return conductor is connected to the other end of the return conductor of the cable under test In this way a noise current is fed over the tested cable return The analyzer input is connected to the second end of the cable under test to measure the differential mode signal that is generated on the cable under test A frequency up to 50 or 100 MHz is appropriate The Generator Analyzer output input Transfer Impedance Figure 4 6 Connection Diagram of the Transfer Impedance Board lowest frequency is determined by the analyzer A sample of measurement results is shown in Figure 4 7 The way the demonstration is set up the immunity aspect of the cable under test is measured To demonstrate the opposite emission aspect the connections of the tracking generator output and spectrum analyzer input should be exchanged UNIVERSITY OF TWENTE CHAPTER 4 TRANSFER IMPEDANCE 32 UTP MI S Mc meetabel RGSS RGSS bll Transferi mpedance d Boh m Frequency MHz Figure 4 7 Some Examples of Cable Transfer Impedances with Frequency UNIVERSITY OF TWENTE CHAPTER 4 TRANSFER IMPEDANCE 33 4 4 Lessons Learned The Zr experiments show that 1 Cables generate differential mode noise voltages due to are susceptible to noise currents through their return conductors
36. of Filters Board shows where which components should be mounted OJ Grounding of Filter lO Floating University of Twente Ensehada The Netherlands Grounded by Wire ng EMC Different types of ommunicatiun Engineeri TE EW UTwente NL grounding and shielding U 1 5 U outs Grounded partially shielded u 4 u t4 Grounded and Shielded Q ver 1 2008 Frank Wiggers O Figure 10 2 The Grounding of Filters Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 10 GROUNDING OF FILTERS 83 10 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 10 3 9 Grounding of Filter e Bo Hj U in2 9 U out2 EN Twente Grounded by Ware Telecommunication Engineering EMC TEGEW UTwente NL grounding and shielding Q e Figure 10 3 The Grounding of Filters Bare Board Top View 10 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 10 4 Figure 10 4 The Grounding of Filters Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 10 GROUNDING OF FILTERS 84 10 2 5 The Board Schematic The schematic diagram of the Grounding of Filters Board is shown in Figure
37. packaging of the capacitor has an influence on the parasitic inductance and resistance of the device This influences the useable frequency range for decoupling UNIVERSITY OF TWENTE Chapter 10 Grounding of Filters Contents 10 1 Demonstrations on the Grounding of Filters Board 81 10 2 Grounding of Filters Board Views 82 10 2 1 The Finished Board 82 10 2 2 The Silkscreem odo doe ded hed A deese de ae Lhe ee 82 10 2 3 Bare Board Top View ern 83 10 2 4 Bare Board Bottom View eee 83 10 2 5 The Board Schematic eer 84 10 2 6 The Bill of Materials re 84 10 3 Board Functional Description eee 85 10 4 Lessons Learned 88 10 1 Demonstrations on the Grounding of Filters Board The Grounding of Filters Board demonstrates the effect of the way filters are mounted It shows that induction in the ground return path seriously impairs the filter s effectiveness 81 CHAPTER 10 GROUNDING OF FILTERS 82 10 2 Grounding of Filters Board Views 10 2 1 The Finished Board The end result of the assembly of the Grounding of Filters is shown in Figure 10 1 Grounding of Filter PE EN Floating U an2 University G tm Enschede the M e Figure 10 1 The Finished Grounding of Filters Board 10 2 2 The Silkscreen The Silkscreen of the Grounding
38. power supply of 9 12 VDC is needed center pin positive We used a 9 V 1 33 A Switched Mode Model By the way diode D1 protects the board against wrong polarity There is an LED to indicate the power supply circuit is working properly The three IC s under test can be switched on and off individually using switches SW1 through SW3 LED s indicate the on off state of each section Several outputs have been brought out to an SMB connector to be monitored see schematic diagram in Figure 12 5 A fast at least 200 MHz bandwidth oscilloscope is needed to see the details In Figure 13 7 the measured signals are shown The effects at some non switched outputs of the various IC s are also shown separately in Figure 13 8 UNIVERSITY OF TWENTE CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 113 in 1 bonding wires I CC4 ground lift bonding wires Figure 13 6 The Mechanism of Ground Bounce in an IC package w 1 Amplitude V N 0 eth fis Clock IC out DIL active SOIC active 1 TSSOP active N DIL non active out SOIC non active out TSSOP non active out Lina i UM UP e bm Time ns Figure 13 7 Signals Measured on Several IC Outputs UNIVERSITY OF TWENTE CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 114 x Me Hide he T i eerte Ti
39. predecessor UNIVERSITY OF TWENTE Acknowledgements We wish to thank all who contributed to the realization of the EMC Demonstration PCB set In particular e Prof Dr Frank Leferink MSc Istwaan Knijff MSc Martijn Brethouwer e Christiaan Teerling Eduard Bos e Frank Wiggers Gerald Hoekstra UNIVERSITY OF TWENTE UNIVERSITY OF TWENTE Contents Introductions s deh o BoE A eren T dat dn beo Se RAR tht iii Acknowledgements 1 2 6 4 ae ooh a ee a ee a eS iv 1 Self Induction Board 1 1 1 Demonstrations on the Self Induction Board 1 1 2 Self Induction Board Views 2 1 2 1 gt The Finished Board use xod ek xc a EC Turc e Rr cr 2 1 232 The Silksereen REIR XS bir ERES DR ERES SA 2 1 2 3 Bare Board Top View voe ae Eee Tn ous Even vete ee ee Een 3 1 2 4 Bare Board Bottom View 3 1 25 TheBoardSchematic 4 1 2 6 The Bill of Materials 4 1 3 Board Functional Description OTI CES Rer 4 1 4 Lessons Learned ah e lr Sah es ee ater E rw oe th E s 9 2 Lenz Law 11 2 1 Demonstrations on the Lenz Law 11 2 2 Lenz Law Board 5 12 2 2 1 The Finished Board 12 2 2
40. sample cables 27 CHAPTER 4 TRANSFER IMPEDANCE 28 4 2 Zr Board Views 4 2 1 The Finished Board The end result of the assembly of the Zr Board is shown in Figure 4 1 Transfer Impedance Figure 4 1 The Finished Transfer Impedance Board 4 2 The Silkscreen The Silkscreen of the Zr Board shown in Figure 4 2 points out which components should be mounted where 9 e Transfer Impedance 7 4 1 j rs BMA SMB INE U put Connect cable to be tested University of Twente botnen Enschede the Netherlands GB Bud HOSEIN E 1 r SMA SMB BNC Telecommunication Engineering EMC O ere ver i 2008 Frank Wiggers O Figure 4 2 The Zr Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 4 TRANSFER IMPEDANCE 29 4 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 4 3 9 Figure 4 3 The Zr Bare Board Top View 4 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 4 4 Figure 4 4 The Zr Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 4 TRANSFER IMPEDANCE 30 4 2 5 The Board Schematic The schematic diagram of the Zr board is shown in Figure 4 5 SMA CONN 6 SMB CONN 5 BNC A Figure 4 5 The Transf
41. traces with an impedance of approximately 1200 That implies that it will have reflections if sourced and loaded with 50 equipment As a way to circumvent this trace 2 between connectors U in2 and U out2 is connected to a 502 spectrum analyzer tracking generator combination Initially the generator is connected directly to the ana lyzer and calibrated to 0 dB Then trace 2 is installed in between The result is shown in Figure 12 6 the blue Trace 2 Uncal The the analyzer generator combination is calibrated again with trace 2 in serted After that action the trace 2 response shows as the green line Trace 2 Cal in Figure 12 6 To this line the other two traces will be compared Trace 1 is routed over a wide ground plane aperture of 38 by 35 mm If trace 1 is measured without pressing any of the switches the graph in Figure 12 7 Trace 1 Switches Open appears On the bottom of the board under trace 1 two ground traces are routed The one closest to the edge of the board can be switched on with switch SW1 If we press the SW1 button the graph changes into the pink line Trace 1 SW 1 Closed in Figure 12 7 The other ground trace is switched by SW2 but it has an additional 100 nF capacitor in series If SW2 is pressed the green line in the graph Trace 1 SW2 Closed shows up It lies exactly on top of the pink line found after switching SW1 This shows that at these frequencies a galvanic ground connection is not essential as lo
42. 008 Gerald Hoekstra C C GNO GNO Figure 6 2 The Crosstalk Layout Issues Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 6 CROSSTALK LAYOUT ISSUES 47 6 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 6 3 conn Ci IN 2 University of Twente Enschede the Metherlends Telecommumicaiion Engineering EM TE EW UTwente NL Figure 6 3 The Crosstalk Layout Issues Bare Board Top View 6 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 6 4 Figure 6 4 The Crosstalk Layout Issues Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 6 CROSSTALK LAYOUT ISSUES 48 6 2 5 The Board Schematic The schematic diagram of the Crosstalk Layout Issues Board is shown in Figure 6 5 GNDO GND1 GND2 GND3 Figure 6 5 The Crosstalk Layout Issues Board Schematic 6 2 6 The Bill of Materials The components to complete the Crosstalk Layout Issues Board are shown in Table 6 1 Table 6 1 Bill of Materials of the Crosstalk Layout Issues Board REF DES VALUE PACKAGE FOOTPRINT CONNA1 SMB SMB RF SMB V CONNB1 SMB SMB RF SMB V CONN C1 SM
43. 1 4 2 00E 01 4 Lp 1 00E 06 1 00E 07 1 00E 08 1 00E 09 Frequency Hz 1 1 Wide 50 Ohm line 2 2 Thin 120 Ohm line 3 3 Wide to Thin transition as 4 4 Thin 120 Ohm line with junctions 4 5 Thin line small detour 4 6 Thin line large detour Figure 11 6 The Discontinuities Stubs Interconnections Frequency Response MHz are negligible This is because the size of the interconnection structures are much smaller than the wavelength which is 3 m for 100 MHz When the frequencies go up effects become visible For the four cables the following observations can be made 1 Trace 1 between connector U in1 and U out1 is a 50 trace and minimally disturbs the impedance of the cables to and from the spectrum analyzer generator combination The signal transmission is hence closest to the ideal O dB transmission loss line in Figure 11 6 2 Trace 2 is a thin 1200 This implies that the impedances does not match the feeding lines Reflections will occur and do affect the performance 3 Trace 3 is a combination of line 1 and line 2 Up to half way the line has a 500 impedance The other half is a 1200 line Here reflections do occur The disturbance is shorter and the impact slightly less than in line 2 4 Trace 4 is different Here a 1200 line is split underway to form two separate arms Each junction forms an impedance jump on the line These junctions cause reflections as do the UNIVERSITY OF TWENTE CHAPTER
44. 10 5 CONN At sme A CONN C1 SMB CONN D1 SMa Filter 1 Filter 3 PADS Figure 10 5 The Grounding of Filters Board Schematic 10 2 6 The Bill of Materials The components to complete the Grounding of Filters Board are shown in Table 10 1 Table 10 1 Bill of Materials of the Grounding of Filters Board 4 CONN A2 SMB CONN 82 SMB CONN 5 CONN C2 SMB CONN D2 SMB REF DES VALUE PACKAGE FOOTPRINT U int SMB SMB RF SMB V U in2 SMB SMB RF SMB V U in3 SMB SMB RF SMB V U in4 SMB SMB RF SMB V U out SMB SMB RF SMB V U out2 SMB SMB RF SMB V UNIVERSITY OF TWENTE CHAPTER 10 GROUNDING OF FILTERS 85 Table 10 1 Bill of Materials of the Grounding of Filters Board cont d REF DES VALUE PACKAGE FOOTPRINT U out3 SMB SMB RF SMB V U out4 SMB SMB RF SMB V Filter 1 4 Low Pass Pl several MHz feedthrough e g Oxley FLTM P 1500 Farnell 1570100 Wire AWG 24 40 cm Flexible type Metal Bracket 5x12mm L shape Home made Copper tape 5cm 12mm wide 3M 10 3 Board Functional Description The Grounding of Filters Board intends to show how the way a filter is built into a system or rather the geometry of the return path for signals the filter is supposed to stop affects the behavior of the filter As can be seen in Figure 10 1 the board has four identical filters mounted in different ways According to the manufacturers specification the attenuation of frequencies over 10 MHz
45. 1206 R12 50 RESISTOR SM R_1206 R13 50 RESISTOR SM R_1206 R14 50 RESISTOR SM R_1206 UNIVERSITY OF TWENTE CHAPTER 14 GROUND BOUNCE PACKAGE TYPE MK2 122 Table 14 1 Bill of Materials of the Ground Bounce Package Type Mk2 Board cont d REF DES VALUE PACKAGE FOOTPRINT R15 50 RESISTOR SM R_1206 R16 50 RESISTOR 1206 SW1 SW KEY SPDT SW KEY SPDT 1 SLIDESWITCH SW2 SW KEY SPDT SW KEY SPDT 1 SLIDESWITCH SW3 SW KEY SPDT SW_KEY SPDT_1 SLIDESWITCH U1 LM7805 TO220 L7805 TO2202 TO220AB U2 74ACT244PDIP 74ACT244 DIP 100 20 W 300 L1 050 U3 74ACT244S0IC 74ACT244 SOG 050 20 WG 420 L 500 U4 T4ACT244TSSOP 74ACT244 SOG 65M 20 WG8 20 L6 98 14 3 Board Functional Description The Ground Bounce Package Type Mk2 Board demonstrates the effect of large power currents due to the simultaneous switching of many outputs of e g a driver IC As shown before in Figure 13 6 op Page 113 Apart from the extra ground plane on the component side the operation of the board remains identical to that of the board without it described in Chapter 13 Other minor improvements have led to differences in pin numbering so a new schematic diagram is shown in Figure 14 5 for the Mk2 board On the Ground Bounce Package Type Mk2 Board the high currents in the output stages of a driver IC are generated by loading some of them with small capacitors 47 pF Four outputs are switched with a 10 MHz clock The other four remain at ground l
46. 14 2 5 The Board Schematic eA 120 14 2 6 The Billof Materials 120 14 3 Board Functional Description oo eR ex XX nta hae Sew BB 122 14 4 Lessons Learn d eee ere Rede an te Se ce De OR 124 15 Ground Bounce Power Pinning 125 15 1 Demonstrations on the Ground Bounce Power Pinning Board 125 15 2 Ground Bounce Power Pinning Board Views 126 15 51 the Finished Board oer eo dg v aL Erw RETE nS 126 15 2 2 The Silkscreen ees 126 15 2 3 Bare Board Top View cg bos uU cerea es RO Bee S 127 15 3 Bare Board Bottom 127 15 4 The Board Schematic 128 15 5 The Bill of Materials 128 15 6 Board Functional Description 43605 dog ee doc we E RC Rm ee Se a SA 130 15 7 be ssonsibearned c omae de dec be Re gta cea fea halen de ede a DE ae 131 UNIVERSITY OF TWENTE CONTENTS ix 16 Ground Bounce Power Pinning Mk2 133 16 1 Demonstrations on the Ground Bounce Power Pinning Mk2 Board 133 16 2 Ground Bounce Power Pinning Board Mk2 Views 134 16 2 1 The Finished Board 134 16 2 2 The Silkscreen onnaa 134 16 2 3 Bare Board Top View ue eod xo Sew OO Begs RE ae BE SS 135 16 3 Bare Board Bottom
47. 2 Th SIlKSereen 2 12 2 2 3 Bare Board Top View 4 5 cus o dne Xe ROUX Bh aot ee xr 13 2 2 4 Bare Board Bottom View 13 2 25 TheBoardSchematic 14 2 2 6 I he Billof MaterlalS eo Ree enar oae RT ORC e tele 14 2 3 Board Functional Description Bae a i Get o Donde DOR ond AS 15 2 4 Lessons Learned saer m eur mea i a eee ess 19 3 Coax Cable 21 3 1 Demonstrations on the Coax 21 3 2 Coax Board VIEWS air acsee E Mo ee eU 22 3 2 1 The Finished Board 22 9 The SIlKksereen Be weg ele es a ar Ana he a a ee 22 3 2 3 Bare Board Top View a4 xn des RETE D EE Cae E ec et A een d 23 3 2 4 Bare Board Bottom View 23 3 25 The Board Schematic 24 3 2 6 The Bill of Materials 24 3 9 Board Functional Description ee 24 3 4 Esss ons Learned v sia esce Oe Aa sas o xA ee ech eee 25 CONTENTS vi 4 Transfer Impedance 27 4 1 Demonstrations on the Transfer Impedance Board 27 4 2 Zr Board ViewS 28 4 2 1 The Finished Board le 28 4 2 2 The SIIKSCreen oou Rt a et dd heap ae ee ce aR 28 4 2 3 Bare Board Top View mecca a ee bn axe ee DNE m
48. 4 6 Signals Measured on Several IC Outputs 0 2 4 g 5 v 2 o l 0 25 T T T T T T T T T 1 00E 07 8 00E 08 6 00E 08 4 00E 08 2 00E 08 0 00E 00 2 00E 08 4 00E 08 6 00E 08 8 00E 08 1 00E 07 Time seconds PDIP inactive P2 SOIC inactive 82 SOIC inactive 83 TSSOP inactive T2 Figure 14 7 Ground Lift Spikes Measured on Several IC Outputs UNIVERSITY OF TWENTE CHAPTER 14 GROUND BOUNCE PACKAGE TYPE MK2 124 14 4 Lessons Learned The Ground Bounce Package Type experiments show that 1 Simultaneous switching of outputs of driver IC s can lead to spiking on un switched outputs This Ground Bounce is an inductive effect over the bonding wires of the IC s 2 Choosing a smaller IC package may lead to a reduction of this effect 3 Remember the induction in the ground leads does not stop at the IC power pin It may be continued to a noticeable degree if the board has long ground traces instead of directly con necting to a wide power plane under the IC s And for this Mk2 board 4 Addition of an extra ground plane on the component side can help make the board ground connections shorter and hence reduce their inductance This considerably reduces ground bounce UNIVERSITY OF TWENTE Chapter 15 Ground Bounce Power Pinning Contents 15 1 Demonstrations on the Ground Bounce Power Pinning Board 125 15 2 Ground Bounce Power Pinning Board Views
49. 502 internal impedance is connected via channel 1 of a dual channel oscilloscope to the input connector using a T junction This channel 1 must be high impedance in relation to the characteristic impedance of the connecting 500 cable The output is connected to channel 2 of the oscilloscope with another 50 cable This channel 2 must be switched to 50 or be provided with a 500 feed through load This is shown in Figure 1 6 An oscilloscope with a bandwidth of 200 MHz or more is required while the generator must have a rise time of around 10 ns or less The setup of the oscilloscope and generator for measurements in the time domain described here corresponds to the arrangement of a Time Domain Reflectometer TDR Such an instrument could be used to perform this same experiment The oscilloscope is adjusted to a time base of 100 ns DIV and the amplitude of the channels appropriate for the output level of the generator The oscilloscope picture in Figure 1 8 shows the resulting waveforms for a large loop area After the wire is placed against the ground plane over its full length the picture changes to that in Figure 1 9 Note The trace on the top is the 1 channel input while the trace on the bottom is the output on channel 2 Another experiment option is to analyze the board in the frequency domain For that purpose a spectrum analyzer with tracking generator is used Three wire arrangements have been measured 1 A wide loop the
50. B SMB RF SMB V CONN A2 SMB SMB RF SMB V CONN B2 SMB SMB RF SMB V UNIVERSITY OF TWENTE CHAPTER 6 CROSSTALK LAYOUT ISSUES 49 Table 6 1 Bill of Materials of the Crosstalk Layout Issues Board cont d REF DES VALUE PACKAGE FOOTPRINT CONN C2 SMB SMB RF SMB V CONN D1 SMB SMB RF SMB V CONN E1 SMB SMB RF SMB V CONN F1 SMB SMB RF SMB V CONN D2 SMB SMB RF SMB V CONN E2 SMB SMB RF SMB V CONNF2 SMB SMB RF SMB V CONN G1 SMB SMB RF SMB V CONN H1 SMB SMB RF SMB V CONN I1 SMB SMB RF SMB V CONN 42 SMB SMB RF SMB V CONN H2 SMB SMB RF SMB V CONN 2 SMB SMB RF SMB V SW1 CON4 8 CON49 SWITCH 4PIN TYCO FSM4JH SW2 CONA48 9 SWITCH 4PIN TYCO FSM4JH 6 3 Board Functional Description The Crosstalk Layout Issues Board is best operated in the frequency domain It has three distinct sections that can be operated independently The first section between connectors A1 A2 B1 B2 and C1 C2 has trace lengths around 790 mm routed over a wide ground plane This implies a critical frequency of around 120 MHz where fits the length of the trace The other two sections between connectors D1 D2 E1 E2 and F1 F2 or between connectors G1 G2 H1 H2 and 1 2 are 112 mm long with a corresponding critical frequency of 860 MHz For a short explanation of the critical frequency see the description in Section 5 3 on page 38 Starting with the long traces at the top of the board there are three traces with an additional ground or guard
51. B V CONN2 SMB SMB RF SMB V CONN3 SMB SMB RF SMB V CONN4 SMB SMB RF SMB V CONN5 SMB SMB RF SMB V CONN6 SMB SMB RF SMB V CONN 7 SMB SMB RF SMB V CONN8 SMB SMB RF SMB V CONN9 SMB SMB RF SMB V CONN 10 SMB SMB RF SMB V CONN 11 SMB SMB RF SMB V CONN 12 SMB SMB RF SMB V CONN 13 SMB SMB RF SMB V CONN 14 SMB SMB RF SMB V CONN 15 SMB SMB RF SMB V CONN 16 SMB SMB RF SMB V The Inductance of Capacitor Packaging Board is the third part 3 of a 3 part set Its operation is best viewed in the frequency domain It is focussed on parasitic effects in capacitors as its predecessors The board is operated as the board of chapter 7 described in Section 7 3 on page 59 The board has two rows of capacitors with decreasing values from 100 nF 10 nF 1 nF to 100 pF The left hand row has leaded components while the right hand side features SMD versions The results of the measurements are shown per capacitor value for comparison in Figure 9 6 for the 100 nF Figure 9 7 for the 10 nF Figure 9 8 for the 1 nF and Figure 9 9 for the 100 pF capacitors UNIVERSITY OF TWENTE CHAPTER 9 INDUCTANCE OF CAPACITOR PACKAGING 78 h OOnF radial leaded 100nF SMD Amplitude dB e 0 01 0 1 1 10 100 1000 Frequency MHz Figure 9 6 Inductance of Capacitor Packagin
52. Board Schematic 84 10 2 6 The Billof Materials 84 10 3 Board Functional Description eie esa hue WA Saleen arde 85 TO LESSONS ECA ACOs iu odes dee Mata B 88 11 Discontinuities Stubs 89 11 1 Demonstrations on the Discontinuities Stubs Board 89 11 2 Discontinuities Stubs Board 5 90 11 8 1 The Finishied Board oso ae a en aaa Seat ah 90 11 2 2 The Silkscreen iiri Su i kae ao eta E 90 11 2 3 Bare Board Top View ul e oe ae ee ee ed EG Ae EER petens 91 11 2 4 Bare Board Bottom View 91 11 2 5 The Board Schematic 92 11 2 6 The Bill of Materials 92 11 3 Board Functional Description de o ere Soe A NUR EAD cg Ue 94 T1 4 bessonsiLearned ere cure dea Ot ee ce ETE ea 95 UNIVERSITY OF TWENTE CONTENTS viii 12 Discontinuities Ground Apertures 97 12 1 Demonstrations on the Discontinuities Ground Apertures Board 97 12 2 Discontinuities Ground Apertures Board 98 12 2 1 The Finished Board llle 98 12 2 2 The vaca ee a et hee tee Rr ee ee de 98 12 2 3 Bare Board Top VIGW im rp oe Rei Penh NE eom URS ek 99 12 2 4 Bare Board Bottom View
53. F TWENTE CHAPTER 16 GROUND BOUNCE POWER PINNING MK2 139 0 25 0 2 0 15 0 1 0 05 0 Ael e 1 Q Level volts 0 05 0 1 0 15 0 2 0 25 0 3 T T T T T T T T T T 1 00E 07 8 00E 08 6 00E 08 4 00E 08 2 00E 08 0 00E 00 2 00E 08 4 00E 08 6 00E 08 8 00E 08 1 00E 07 Time seconds Asymm B1 Asymm B2 Symm A1 Symm A2 Figure 16 7 Ground Bounce Spikes on both IC s Outputs Mk2 version UNIVERSITY OF TWENTE CHAPTER 16 GROUND BOUNCE POWER PINNING MK2 140 16 7 Lessons Learned The Ground Bounce Power Pinning Mk2 experiments show that 1 The ground bounce from the center pinned chip is slightly lower than that of the end pinning type But not a factor of 4 less 2 Other factors like the placement and wiring of the decoupling capacitor and ground traces and via s are equally important And for this Mk2 board 3 Addition of an extra ground plane on the component side can help make the board ground connections shorter and hence reduce their inductance This considerably reduces ground bounce UNIVERSITY OF TWENTE Chapter 17 General Remarks Contents 17 1 The Future of the PCB Demo 141 17 2 How the boards are 5 141 17 2 1 User Expertise Required 222r 141 17 2 2 Experimenter Case with Finished Boards Cables and Power Supply
54. SMB SMB SMB 4 5 a 4 i 4 100n 32 3 CONN 2 CONN 5 1 1 CONN 11 SMB SMB SMB 45 4 w 3 32 23 CONN 3 CONN 9 CONN 6 1 1 CONN 12 SMB SMB SMB SMB 5 4 45 54 ce E 400 4 Title Inductsnoe of Capacitors part2 Bize Document Number lev A 20 Bate Tuesday November 04 2008 Ereet 1 of 1 Figure 8 5 The Inductance of Capacitor Dielectrics Board Schematic 8 2 06 The Bill of Materials The components to complete the Inductance of Capacitor Dielectrics Board are shown in Ta ble 8 1 Table 8 1 Bill of Materials of the Inductance of Capacitor Dielectrics Board REF DES VALUE PACKAGE FOOTPRINT C1 100n C SMD ELCO 4MM C2 100n C SMD TANTALUM CASE_A C3 100n C SM C 1206 C4 100n C SM C 1210 UNIVERSITY OF TWENTE CHAPTER 8 INDUCTANCE OF CAPACITOR DIELECTRICS 69 Table 8 1 Bill of Materials of the Inductance of Capacitor Dielectrics Board cont d REF DES VALUE PACKAGE FOOTPRINT C5 100n C SM L 2220 C6 100n C SM C 1210 CONN1 SMB SMB RF SMB V CONN2 SMB SMB RF SMB V CONN3 SMB SMB RF SMB V CONN4 SMB SMB RF SMB V CONN5 SMB SMB RF SMB V CONN6 SMB SMB RF SMB V CONN7 SMB SMB RF SMB V CONN8 SMB SMB RF SMB V CONN9 SMB SMB RF SMB V CONN 10 SMB SMB RF SMB V CONN 11 SMB SMB RF SMB V CONN 12 SMB SMB RF SMB V 8 3 Board Functional Description The Inductance of Capacitor Dielectrics Board is the second part 2 of a 3 part set Its operation is best viewed in the frequency domain As its
55. UNIVERSITY OF TWENTE CHAPTER 12 DISCONTINUITIES GROUND APERTURES 103 Attenuation dB u Ground Slots Trace Attenuation 5 0 5 10 15 20 1 1 00E 06 1 00E 07 1 00E 08 1 00 09 1 00E 10 Frequency Hz Trace 1 Switches Open Trace 1 SW 1 Closed Trace 1 SW2 Closed Figure 12 7 Frequency Responses of Trace 1 with and without Ground Return Traces UNIVERSITY OF TWENTE CHAPTER 12 DISCONTINUITIES GROUND APERTURES 104 Ground Slots Trace 3 w wo GND Plane 3 00E 00 1 00E 00 1 00E 00 3 00E 00 5 00E 00 1007x788 7 00E 00 Attenuation dB 9 00E 00 1 10E 01 1 30E 01 1 50E 01 F i mU 1 1 00E 06 1 00E 07 1 00E 08 1 00E 09 1 00E 10 Frequency Hz Trace 3 over Ground Siot Trace 3 GINS Siot Covered Figure 12 8 Frequency Response of Trace 3 with and without Capacitive Ground Plane under Slot UNIVERSITY OF TWENTE CHAPTER 12 DISCONTINUITIES GROUND APERTURES 105 12 4 Lessons Learned 1 The Discontinuities Ground Apertures experiments show that Apertures in the ground plane underneath signal traces greatly impairs the performance of the in
56. VERSITY OF TWENTE CHAPTER 2 LENZ LAW 17 Trace 1 U out 1 IL SS Ground Plane Figure 2 6 The optional resistive divider one per output connector ensom fs fast e Figure 2 7 Step response of line 1 aasom fash we E tat Figure 2 8 Step response of line 3 UNIVERSITY OF TWENTE CHAPTER 2 LENZ LAW 18 cha Soo mi os sw o me owe Figure 2 9 Step response of line 5 cha Soo mij os sws o me o Figure 2 10 Step response of line 6 cha 500m os sws L me o owe Figure 2 11 Step response of line 7 UNIVERSITY OF TWENTE CHAPTER 2 LENZ LAW 19 2 4 Lessons Learned The message from these Lenz experiments is the same as for the Self Induction demonstration return currents flow as close to their signal path as possible For a printed circuit board this means that the board layout engineer must provide this nearby return path Further it should be noticed from the comparison of traces 5 6 and 7 in figures 2 9 2 10 and 2 11 respectively that it is b
57. aE ee 54 6 1 Demonstrations on the Crosstalk Layout Issues Board The Crosstalk Layout Issues Board focusses on common layout mistakes that may have profound effects on the amount of crosstalk experienced between PCB interconnections 45 46 CHAPTER 6 CROSSTALK LAYOUT ISSUES 6 2 Crosstalk Layout Issues Board Views 6 2 1 The Finished Board The end result of the assembly of the Crosstalk Layout Issues Board is shown in Figure 6 1 Track lenght 790a Crosstalk University of Twente amp Figure 6 1 The Finished Crosstalk Layout Issues Board 6 2 2 The Silkscreen The Silkscreen of the Crosstalk Layout Issues Board shows where which components should be CONN CINN Q Q i 5 1 2 conn 81 conn 67 ON Track Jenght 790mm ii C talk CDM E1 Track lenght U e Tae CONN FI CONN F Crasstalk demonstration PCB Heasure crasstale effecta ave to short distance between University of Twente tracks and groua slote CONN GI COWN G2 Enschede Vibe Metherleads Telecommunicaiion Engineering TEGEWJ liTwente NL conn tonn Hz Track lenght 1i2am agate com 11 cows 12 21 10mm 1 2
58. ard seen from the top side is shown in Figure 7 3 Inductance of Capacitors e Part 1 Vias amp Value 4 gt D University of Twente Eosebedo Tho Netherlands Telecommunication Engineering EMC TEGEMNI UTwente NL 100nF 10nF Inductance of Capacitors Demonstration PCB lt test gt 100pF nF Capacitor ory ver O 2005 Istwaan Knijif BNO ver 1 2008 Frank Wiggers x Figure 7 3 The Inductance of Capacitor Vias and Value Bare Board Top View 7 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 7 4 Figure 7 4 The Inductance of Capacitor Vias and Value Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 58 7 2 5 The Board Schematic The schematic diagram of the Inductance of Capacitor Vias and Value Board is shown in Fig ure 7 5 32 3 32 23 CONN 1 1 1 CONN 4 CONN7 1 1 CONN 11 SMB SMB SMB 45 aa 5 4 45 ae 5 4 100n ee 3 2 2 8 32 23 CONN2 1 1 CONN 5 CONN 8 1 1 12 SMB SMB SMB SMB ina Luca T S t8 e 1 T l y 32 23 32 23 CONN 3 1 1 CONN CONN 9 1 1 CONN 12 SMB SMB SMB SMB 45 al sigs 5 4 45 AM ues 54 C3 08 1 1 E J 32 23 a2 23 CONN 10 1 1 CONN 14 CONN15 1 1 CONN 16 SMB SM8 SM8 SMB 4 5 5 4 4 1 2 5 4 r c7 y 100p
59. atic 48 6 2 6 TheBillof Materials 48 6 3 Board Functional Description COE x Svo Hex ib hot REOR 8 49 6 4 LESSONS Learned Ss eset eek Seg al er o p em e deter er 54 7 Inductance of Capacitor Vias and Value 55 7 1 Demonstrations on the Inductance of Capacitor Vias and Value Board 55 7 2 Inductance of Capacitor Vias and Value Board Views 56 Gea The Finished Board rc arth eee eck alae Ae RUE a 56 7 2 2 The Silkscreen ss 56 7 2 3 Bare Board Top View BG AE ODA RE ee oe ew Bee A G 57 7 2 4 Bare Board Bottom View 57 7 2 5 TheBoard Schematic 58 7 2 6 The Bill of Materials 58 7 3 Board Functional Description oaoa a a 59 74 1 LeSsons Leannedt es do eed bo a ene tede a a a Uode de qd 63 UNIVERSITY OF TWENTE CONTENTS vii 8 Inductance of Capacitor Dielectrics 65 8 1 Demonstrations on the Inductance of Capacitor Dielectrics Board 65 8 2 Inductance of Capacitor Dielectrics Board Views lll sn 66 82 1 The Finished Board 66 82 2 The SiIKSCre ns zo aoe el Eun arcem pis o E ES 66 8 2 3 Bare Board Top View uxisor desee o 67 8 2 4 Bare Board Bottom View
60. ation Engineering EMC TE8ENI UTwente NL CONN At Po 2 i 5 RIS L zU i z oN B n E symmetric E Power LA Iac 5 TE 2 LH Tu ver 0 2005 Istwaan Kmijif vers 1 2008 Gerald Hoekstra 5 CONN B2 Figure 15 2 The Ground Bounce Power Pinning Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 15 GROUND BOUNCE POWER PINNING 127 15 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 15 3 eJ 5 Ground Bounce a power pins amp Symmetric ce Thal University of Twente r5 m m A Enschede Tho Metherlands E Ej Symmetric Telecommunication Engineering TEGEW UTwente NL ee round Bounce Demonstration PCB Power supply pins Symmetric B Asymm 2 r5 e speed same load amp inputs connected to 10MHz clock 2 wath ground nus Mud vere a Istwaan Knij f 2 2008 Gerald Hoekstra Figure 15 3 The Ground Bounce Power Pinning Bare Board Top View 15 3 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 15 4 Figure 15 4 The Ground
61. ause phase differences in the reflections that generate resonances valleys at specific frequencies UNIVERSITY OF TWENTE CHAPTER 11 DISCONTINUITIES STUBS 96 UNIVERSITY OF TWENTE Chapter 12 Discontinuities Ground Apertures Contents 12 1 Demonstrations on the Discontinuities Ground Apertures Board 97 12 2 Discontinuities Ground Apertures Board Views 98 12 241 The Finished Board 98 12 2 2 The Silkscreen 265i Sl ae ce te ee SE aA 98 12 2 3 Bate Board Top View oue a ee ee ae OS Be et eS 99 12 2 4 Bare Board Bottom View een 99 12 2 5 The Board Schematic 100 12 2 6 The Bill of Materials lr 100 12 3 Board Functional Description eee 101 12 4 Lessons Learned y a ee ee ee xXE amu xu 105 12 1 Demonstrations on the Discontinuities Ground Apertures Board The Discontinuities Ground Slots Board demonstrates the effects of irregularities in the signal return paths planes on a PCB The effect of a wide gap in the groundplane under a trace is shown The discontinuity can be repaired by switching in parallel ground traces direct and capacitive The behavior of a trace over a narrow ground aperture can be compared to that of a trace over a wide ground plane 97 CHAPTER 12 DISCONTINUITIES GROUND APERTURES 98 12 2 Discontinuities Groun
62. ck that all traces have a corresponding return conductor plane rather nearby If forgot ten the return current will find a path naturally usually leading to large ground loops These large loops are not only detrimental to signal integrity but also to crosstalk through mutual induction between such loops UNIVERSITY OF TWENTE Chapter 7 Inductance of Capacitor Vias and Value Contents 7 1 Demonstrations on the Inductance of Capacitor Vias and Value Board 55 7 2 Inductance of Capacitor Vias and Value Board Views 56 7 2 1 The Finished Board i g aanraai bie BR ee a RR 56 1 2 2 THe Silkscreen oniani uoa Seen PUR eT te AA Pe dre eet 56 7 2 3 Bare Board Top View 22A 57 7 24 Bare Board Bottom View 0 0 0 0 000002 2 57 7 2 0 The Board Schematic 21x a Oe A 5 7 2 6 The Bill of Materials ox Sb A ws 5 7 3 Board Functional Description 2 2 00 e 59 7 4 Lessons Learned ee ee ee es 63 7 1 Demonstrations on the Inductance of Capacitor Vias and Value Board The Inductance of Capacitor Vias and Value Board demonstrates the effects of parasitic induc tance either caused by layout errors or as a result of component internal conductor geometries The latter usually increase with component size value 55 CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 56 7 2 Inductance of Capacitor Vias and Va
63. d Apertures Board Views 12 2 1 The Finished Board The end result of the assembly of the Discontinuities Ground Apertures Board is shown in Figure 12 1 Figure 12 1 The Finished Discontinuities Ground Apertures Board 12 2 2 The Silkscreen The Silkscreen of the Discontinuities Ground Apertures Board shows where which components should be mounted 7 O 3 O U anl ps U outi Track 1 J F a swe gt 38mm 35mm U an2 G d Sl t U out2 roun CON N Ground Slot Demanstration PCB X si Univers af Twente Show the effect slots in ground planes Enschede The Wothorlands Telecommunication Engineering EMC TEGEW UTwente NL U and U puts Track 3 2 1 8mm ver O 2005 Istwaan Kmijf4 ver 1 2008 Berald Hoekstra Figure 12 2 The Discontinuities Ground Apertures Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 12 DISCONTINUITIES GROUND APERTURES 99 12 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 12 3 ej U ani L 5 Y 1 38mm 358m Ground Slot 5 Blecomm K 1 University of Twente Enschede Tho Wothorlands unicetion Engineering EMC TEGEW UTwente NL U buts ver 0
64. e Board are shown in Table 13 1 Table 13 1 Bill of Materials of the Ground Bounce Package Type Board REFDES VALUE PACKAGE FOOTPRINT C1 330n CAP NP SM C 1206 C2 220u CAP POL 0 CYL D 275 LS 100 034 C3 100n CAP NP SM C 1206 C4 100n CAP NP SM C 1206 C5 100n CAP NP SM C 1206 UNIVERSITY OF TWENTE CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 111 Table 13 1 Bill of Materials of the Ground Bounce Package Type Board cont d REF DES VALUE PACKAGE FOOTPRINT 6 10 CAP_NP SM C_1206 C7 100n CAP_NP SM C_1206 C8 47p CAP_NP SM C_1206 09 47p CAP_NP SM C_1206 C10 47p CAP_NP SM C_1206 C11 47p CAP_NP SM C_1206 C12 47p CAP_NP SM C_1206 C13 47p CAP_NP SM C_1206 C14 47p CAP_NP SM C_1206 C15 47p CAP_NP SM C_1206 C16 47p CAP_NP SM C_1206 CONN P1 SMB SMB RF SMB V CONN P2 SMB SMB RF SMB V CONN 51 SMB SMB RF SMB V CONN 52 SMB SMB RF SMB V CONN S3 SMB SMB RF SMB V CONN 54 SMB SMB RF SMB V CONN SMB SMB RF SMB V CONN T2 SMB SMB RF SMB V D1 1n4001 DIODE 0 DAX2 300X 050 028 D2 LED RED LED CYL D 225 LS 125 031 D3 LED RED LED CYL D 225 LS 125 031 D4 LED GRN LED CYL D 225 LS 125 031 D5 LED YEL LED CYL D 225 LS 125 031 F1 FUSEHOLDER FUSEHOLDER BLKCON 200 VH TM1SQ W 100 2 J1 POWERJACK 0 POWERJACK OSC1 10 MHz OSC14 OSC R1 220 RESISTOR SM R 1206 R2 220 RESISTOR SM R_1206 R4 220 RESISTOR SM R_1206 R5 220 RESISTOR SM R_1206 R6 50 RESISTOR SM R_1206 R7 50 RESISTOR SM R_1206
65. e top side is shown in Figure 16 3 9 Figure 16 3 The Ground Bounce Power Pinning Mk2 Bare Board Top View 16 3 Bare Board Bottom View The etch pattern of the empty Mk2 board seen from the bottom side is shown in Figure 16 4 Figure 16 4 The Ground Bounce Power Pinning Mk2 Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 16 GROUND BOUNCE POWER PINNING MK2 136 16 4 The Board Schematic The schematic diagram of the Ground Bounce Power Pinning Board is shown in Figure 16 5 FT U1 LMT7805 TO220 TN Dy Ins 1 FusEHoLpER 100 Conn A1 Conn SMB Phe pL E5555 8 pp ai to 3 elg ne alo T l 10 GND Ground Bounce Power Layout ize Document Number tev Cust m 2 0 ate Thursday October 08 2009 Bheet 1 of 1 Figure 16 5 The Ground Bounce Power Pinning Mk2 Board Schematic 16 5 The Bill of Materials The components to complete the Ground Bounce Power Pinning Mk2 Board are shown in Table 16 1 Table 16 1 Bill of Materials of the Ground Bounce Power Pinning Mk2 Board REFDES VALUE PACKAGE FOOTPRINT C2 220n CAP_NP SM C_1206 C3 100u 6 0 CYL D 275 LS 100 034 C4 22n CAP_NP SM C_1206 UNIVERSITY OF TWENTE CHAPTER 16 GROUND BOUNCE POWER PINNING MK2 137 Table 16 1 Bill of Materials of the Ground Bounce Power Pinning
66. ed U ani U outi IQ Discontinuities Stubs 5 u t3 U an4 t4 u ut5 University of Twente Enschede The Netherlands U pute Telecommunica tian Engineerin g EME TEGEW UTwente NL Ol ver 1 2008 Frank Wiggers Q Figure 11 2 The Discontinuities Stubs Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 11 DISCONTINUITIES STUBS 91 11 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 11 3 eJ van 6 Discontinuities Stubs 5 B University of Twente Enecheda the Netherlands U pute Telecommunacatian Engineer TE EW UTWente NL e vers 1 2008 Frank Wiggers EMC Figure 11 3 The Discontinuities Stubs Bare Board Top View 11 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 11 4 Figure 11 4 The Discontinuities Stubs Board Bottom View UNIVERSITY OF TWENTE CHAPTER 11 DISCONTINUITIES STUBS 92 11 2 5 The Board Schematic The schematic diagram of the Discontinuities Stubs Board is shown in Figure 11 5 Figure 11 5 The Discontinuities Stubs Board Schematic 11 2 6 The Bill of Materials The components to complete the Discontinuities Stubs Board are shown in Tab
67. ematic 3 2 06 The Bill of Materials The bill of materials of the Coax Cable Board is shown below as Table 3 1 Table 3 1 Bill of Materials of the Coax Cable Board REF DES VALUE PACKAGE FOOTPRINT U in SMB SMB RF SMB V Short SMB SMB RF SMB V R1 51 RESISTOR SM R_1206 R2 51 RESISTOR SM R_1206 3 3 Board Functional Description The Coax Cable Board is an extension of the Lenz Law Board On the Lenz Board we measured what part of the original source signal arrived at the end of an interconnection In the Coax Cable Board the complete return path is laid out close to the signal line The experiment shows the fraction of the signal current that leaks out when a short return path is provided between the ends of the coax line It is connected to a spectrum analyzer with tracking generator as shown for the Transfer Impedance Board in Figure 4 6 on page 31 After calibration of the analyzer generator combination by directly connecting them the Coax Cable Board is inserted The result is shown in Figure 3 6 UNIVERSITY OF TWENTE CHAPTER 3 COAX CABLE 25 If the generator is connected to U in the Coax Cable demonstration is run in the Emission mode What leaks out Exchanging the U in and Short connections results in the Immunity mode What leaks in The result on screen is the same 10 Amplitude dB 40 T T T 0 01 0 1 1 10 100 Frequency MHz Figure 3 6 Frequency response of t
68. enclosure In the graph this way of shielding is called Filter Plumbers Delight a terminology often used by radio amateurs UNIVERSITY OF TWENTE Chapter 11 Discontinuities Stubs Contents 11 1 Demonstrations on the Discontinuities Stubs Board 89 11 2 Discontinuities Stubs Board Views 90 11 2 1 The Finished Board leen 90 11 2 2 The S ksereem te mono RR ee ee ee RA 90 11 2 3 Bare Board Top View 2 0020 eee ee 91 11 2 4 Bare Board Bottom View en 91 11 2 5 The Board Schematic 0 ee 92 11 2 6 The Bill of Materials re 92 11 3 Board Functional Description c eevee 94 11 4 Lessons Learned i eb fe ee Oe A Rd rue dou doo ves a 95 11 1 Demonstrations on the Discontinuities Stubs Board The Discontinuities Stubs Board demonstrates the effects of discontinuities in the signal traces on a PCB A change of width impedance and branching off is demonstrated 89 CHAPTER 11 DISCONTINUITIES STUBS 90 11 2 Discontinuities Stubs Board Views 11 2 1 The Finished Board The end result of the assembly of the Discontinuities Stubs Board is shown in Figure 11 1 Discontinuities Stubs Figure 11 1 The Finished Discontinuities Stubs Board 11 2 2 The Silkscreen The Silkscreen of the Discontinuities Stubs Board shows where which components should be mount
69. er Impedance Board Schematic 4 2 6 The Bill of Materials The bill of materials of the Zr Board is shown below as Table 4 1 Table 4 1 Bill of Materials of the Zr Board REF DES VALUE PACKAGE FOOTPRINT SMB 1 SMB 2 CONN 4 CONN 5 INPUT OUTPUT R1 R2 R3 R4 SMA 1 SMA 2 SMB SMB SMB SMB SMB SMB SMB SMB SMB SMB SMB SMB 1 RESISTOR 1 RESISTOR 1 RESISTOR 1 RESISTOR SMB SMB SMB SMB SMB_JACK SMB_JACK RF SMB V RF SMB V RF SMB V RF SMB V SM R_1206 SM R_1206 SM R_1206 SM R_1206 RF SMA V RF SMA V UNIVERSITY OF TWENTE CHAPTER 4 TRANSFER IMPEDANCE 31 4 3 Board Functional Description This board has provisions to test the transfer impedance of cables as function of frequency For that purpose a spectrum analyzer with tracking generator is used A cable specimen is connected between two two opposite sets of connectors labeled SMA SMB or BNC on the board If you have ordered bare boards you could mount other types of coax connectors The spectrum analyzer is calibrated by connecting the tracking generator output directly to the input to indicate O dB over the entire selected frequency range Then the transfer impedance board with the cable under test is inserted as shown in Figure 4 6 The generator signal conductor is connected through a small resistor to an insulated ground plane island on which the first connector for the cable under test is terminated The signal
70. er empty PCB boards In that case the educator builder has to acquire the necessary components to assemble the boards One of the items not mentioned in the Bills of Materials are the mounting feet the boards will stand on We used nylon bolts and nuts M3 x 12 mm Each board has four mounting holes on the corners where these bolts can be inserted Another option is to used adhesive plastic feet A final note on the connectors used on the demonstrations we use SMB connectors for quick handling but SMA types also fit So if you like you can use your own preference Here too measuring equipment like an oscilloscope and a spectrum analyzer with tracking generator will have to be provided by the user 17 3 Known Issues 17 31 Push button Switches Some of the boards have push button momentary switches After the production of the boards it became apparent that the shape SWITCH 4PIN TYCO FSM4JH used on some of the boards has been placed 90 degrees rotated When placed in the position it fits the connection will always exist whether pushed or not The solution is to mount the switch in the normal way but to cut two of the 4 leads diagonally opposite to each other Affected boards are the Crosstalk Layout Issues board in chapter 6 and the Discontinuities Ground Apertures board in chapter 12 17 3 2 Filters The filters used on the Grounding of Filters board in chapter 10 were not fixed when the board was laid out We used Murata enc
71. erence between forward and backward crosstalk can be ob served if the line is considerably longer than the Length of the Leading Edge Forward crosstalk has a duration equal to the rise or fall time of the signal on the active trace The backward crosstalk in addition has the duration of twice the propagation delay over the total length where the lines crosstalk 5 When reflections occur on the active signal trace backward crosstalk can be observed at both ends of the passive line The only way to avoid backward crosstalk on the far end of the line is to characteristically terminate the active signal line Note that in many digital designs lines can be passive or active depending on the state of the system UNIVERSITY OF TWENTE CHAPTER 5 CROSSTALK BASIC PHENOMENA 44 UNIVERSITY OF TWENTE Chapter 6 Crosstalk Layout Issues Contents 6 1 Demonstrations on the Crosstalk Layout Issues Board 45 6 2 Crosstalk Layout Issues Board Views 46 6 2 1 The Finished Board 46 61212 The Silkscreen 3o e Rue hea ee RS 46 6 2 3 Bare Board Top View ee 47 6 2 4 Bare Board Bottom View een 47 6 2 5 The Board Schematic aoua e 48 6 2 6 The Bill of Materials leeren 48 6 3 Board Functional Description 49 6 4 Lessons Learned coris e d Da aE a ee
72. etter to route a trace in the middle of a wide ground plane trace 6 instead of at the edge of it trace 5 and still better to also surround the trace by grounded guard traces trace 7 UNIVERSITY OF TWENTE CHAPTER 2 LENZ LAW 20 UNIVERSITY OF TWENTE Chapter 3 Coax Cable Contents 3 1 Demonstrations on the Coax Board 21 3 2 Coax Board Views Z2 Sd SAE ey A ey a a a aee Sn 22 3 241 The Finished Board ee 22 32 2 PheSilksereen ee a Be ek 22 3 2 3 Bare Board Top View les 23 3 2 4 Bare Board Bottom View les 23 3 25 The Board Schematic ee eee 24 3 2 6 The Bill of Materials 24 3 3 Board Functional Description 2 2 2000 e 24 3 4 Lessons Learned os 45 2 9325 ak a DE ERE OR ie 25 3 1 Demonstrations on the Coax Board The Coax Cable Board is an extension of the Lenz Law Board see Chapter 2 There we investigated how much of the intended signal reached the end of the interconnection Here we measure the amount of leakage in a situation where the return path is as close to the signal path as possible 21 CHAPTER 3 COAX CABLE 22 3 2 Coax Board Views 3 2 1 The Finished Board The end result of the assembly of the Coax Cable Board is shown in Figure 3 1 Figure 3 1 The Finished Coa
73. evel This same setup is made using three different IC Packages 1 A through hole Dual In Line DIL 2 A Small Outline Integrated Circuit SOIC 3 A Thin Shrink Small Outline Package TSSOP To operate the board a power supply of 9 12 VDC is needed center pin positive We used a 9 V 1 33 A Switched Mode Model By the way diode D1 protects the board against wrong polarity There is an LED to indicate the power supply circuit is working properly The three IC s under test can be switched on and off individually using switches SW1 through SW3 LED s indicate the on off state of each section Several outputs have been brought out to an SMB connector to be monitored see schematic diagram in Figure 14 5 A fast at least 200 MHz bandwidth oscilloscope is needed to see the details In Figure 14 6 the measured signals are shown The effects at some non switched outputs of the various IC s are also shown separately in Figure 14 7 UNIVERSITY OF TWENTE CHAPTER 14 GROUND BOUNCE PACKAGE TYPE 123 2 54 2 1 5 2 E o 2 o l 0 5 0 0 5 T T T T T T T T T 1 1 00E 07 8 00E 08 6 00E 08 4 00E 08 2 00E 08 0 00E 00 2 00E 08 4 00E 08 6 00E 08 8 00E 08 1 00E 07 Time seconds Clock PDIP P1 Clock SOIC S1 Clock TSSOP T1 PDIP inactive P2 SOIC inactive 52 SOIC inactive 55 TSSOP inactive T2 Figure 1
74. g Board is built up as the Ground Bounce Package Type Mk2 board described in chapter 14 The differences are Only two IC s are available as test objects The IC s are functionally for our purpose here identical octal drivers but for the Power pins e The IC 74AC11244 has so called center pinning Power is provided through the pins in the middle of the package The IC 74ABT541 has the traditional end pinning where power is provided via pins diagonally opposite to each other The idea is that the center pinning type has less bonding wire inductance and hence should show less Ground Bounce This is augmented by the fact that the 74AC11244 chip has two parallel Voc and four GND pins This should reduce the GND bonding inductance by a factor of 4 The connection to power supply and oscilloscope and switching on and off the two tested IC sections is as described in chapter 13 Section 13 3 The measured results the Clock and Ground Bounce signals of the two IC s are shown in Figure 16 6 Additionally Figure 16 7 shows the Ground Bounce signals without the clock Level volts 0 5 T T T T T T T T 1 00E 07 8 00E 08 6 00E 08 4 00E 08 2 00E 08 0 00E 00 2 00E 08 4 00E 08 6 00E 08 8 00E 08 1 00E 07 Time seconds Clock Output Asymm B1 Asymm B2 Symm A1 Symm A2 Figure 16 6 Clock and Ground Bounce Spikes Measured on both IC s Outputs Mk2 version UNIVERSITY O
75. g Board Responses of the two 100 nF versions 0 40 10 nF radial leaded 10 nF SMD Amplitude dB 0 01 0 1 1 10 100 1000 Frequency MHz Figure 9 7 Inductance of Capacitor Packaging Board Responses of the two 10 nF versions UNIVERSITY OF TWENTE CHAPTER 9 INDUCTANCE OF CAPACITOR PACKAGING 79 Amplitude dB do eo 1 nF radial leaded inF SMD 0 0 01 Frequency MHz Figure 9 8 Inductance of Capacitor Packaging Board Responses of the two 1 nF versions 100 pF radial leaded 100pF SMD 0 01 0 1 1 10 100 1000 Frequency MHz 0 1 dh 5 S Amplitude dB N o1 Figure 9 9 Inductance of Capacitor Packaging Board Responses of the two 100 pF versions 1 10 100 1000 UNIVERSITY OF TWENTE CHAPTER 9 INDUCTANCE OF CAPACITOR PACKAGING 80 9 4 Lessons Learned The Inductance of Capacitor Packaging experiments show that e The
76. he Coax Board Leakage overe frequency 3 4 Lessons Learned As shown in Figure 3 6 the PCB structure we call Coax here leaks energy in the range of 1 to 100 MHz That means that if other interconnections are routed nearby usually employing the same return path increased crosstalk can be expected The phenomenon is related to Transfer Impedance described in Chapter 4 A wide ground plane under the traces would certainly improve the quality of this interconnection UNIVERSITY OF TWENTE CHAPTER 3 COAX CABLE 26 UNIVERSITY OF TWENTE Chapter 4 Transfer Impedance Contents 4 1 Demonstrations on the Transfer Impedance Board 27 4 2 Zr Beard Views hohes See hoe ey see we Be Ske OR ae ok ee ous 28 4 21 The Finished Board 0 000 ee 28 Add The Silkscteen yg gdh Ak dos ede dedrhe Ba dee ee BE ee AGE s 28 4 2 8 Bare Board Top View 29 4 2 4 Bare Board Bottom View lees 29 4 25 The Board Schematic 30 4 2 6 The Bill of Materials aaa 30 4 3 Board Functional Description 31 4 4 TL ssons Learned oover EG GE cep od at Rod uc RR 33 4 14 Demonstrations on the Transfer Impedance Board Transfer Impedance for short Zr is a basic property of any interconnection This board allows the measurement of the Zr of
77. in Figure 16 1 Figure 16 1 The Finished Ground Bounce Power Pinning Board 16 2 2 The Silkscreen The Silkscreen of the Ground Bounce Power Pinning Mk2 Board shows where which compo nents should be mounted E Ground Bounce mc Difference betwee Asymmetric and Symmetric AC and ABT package 2 FE 2 ER 15 University of Twente L3 A Enschede The Wetherlaads E T Symmetric Ac ON R Telecommunication Engineering EMC al TEGEWN UTwente NL Poner 59 Of Clack Output es sis Ground Baunce Demonstration PCB Ris fi Power supply pins Symmetric and Asymmetric 5 Z 2 drivers same speed same load amp inputs connected to clack 2 inputs to ground CONN Bl DECI z Asymmetric ABT e Le yl Power 1C Ra tO 7 ver 2003 stmaan Knijff ver 1 2008 Geralo Hoekstra ver 2 2009 M F Brethouner Figure 16 2 The Ground Bounce Power Pinning Mk2 Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 16 GROUND BOUNCE POWER PINNING MK2 135 16 2 3 Bare Board Top View The etch pattern of the empty board seen from th
78. in Figure 2 2 points out which components should be mounted where U ain 3 6 5 Lenz s Law 1 2 3 4 wvpe of Track 1l Wide track 2 Thin short track S3 Long track 4 Medium loop m gl Gear Senar Univers f Twente amp Un groundpla Enschede The Netherlands TiWith guardlines Telecommunication Engineering EMC a 2 3 3 z a z 8 E TEGEWI UTNente NL Rud 2d 88 Ra R12 R16 Req 24 ver 0 2005 Jstwaan Knijlf er 1 2008 Frank Wiggers 2 2008 Eduard Bos O U outi U out2 u out3 U nut4 U put U out amp U out Q Figure 2 2 The Lenz Law Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 2 LENZ LAW 13 2 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 2 3 e f Lenz s Law Type of Track Wide track c5 2 Thin short track Long track E 1 1 ur iin Universitat Tuente groundp Enschade Tho Netherlands Telecommunication Engineering ENC ag TEGEWI UTwente NL 4 8 Is 4 0 2005 letwaan Eminit ver 1 2008 Frank Maggers eit 2008
79. le 11 1 Table 11 1 Bill of Materials of the Discontinuities Stubs Board REF DES VALUE PACKAGE FOOTPRINT U int SMB U in2 SMB U in3 SMB U in4 SMB U out SMB SMB RF SMB V SMB RF SMB V SMB RF SMB V SMB RF SMB V SMB RF SMB V UNIVERSITY OF TWENTE CHAPTER 11 DISCONTINUITIES STUBS 93 Table 11 1 Bill of Materials of the Discontinuities Stubs Board cont d REF DES VALUE PACKAGE FOOTPRINT U out2 U out3 U out4 U out5 U out6 SMB SMB SMB SMB SMB SMB SMB SMB SMB SMB RF SMB V RF SMB V RF SMB V RF SMB V RF SMB V UNIVERSITY OF TWENTE CHAPTER 11 DISCONTINUITIES STUBS 94 11 3 Board Functional Description The Discontinuities Stubs Board contains four individual interconnection traces over a ground plane micro striplines Their performance over frequency is shown in Figure 11 6 To measure them each line in turn is connected to a spectrum analyzer between the output of the tracking gen erator and the analyzer input The response of the four traces counting from the input connections is shown in the frequency domain in Figure 11 6 Figure 11 6 shows that the effects below 100 Discontinuities Stubs 5 00 00 wrrr nn 0 00E 00 4 m 2 9 00E 00 4 i z i 9 1 D i 2 i E 1 00E 01 5 o i 5 i E i 1 50E 0
80. losure wall mountable types SMD models could be used just as well Some improvisation is needed when mounting the filters as solder resist may have to be removed at places to provide sufficient access to the ground plane for connection of the return path The L shaped metal bracket will also have to be fabricated from thin brass or copper plate to connect the third filter Finally the Plumbers Delight construction requires complete coverage of one end of the filter with adhesive copper tape Here too solder resist may have to be removed locally UNIVERSITY OF TWENTE Bibliography IEEE04 IEEE92 ASEU KNIJFO5 LEFea08 LEF09 LEF01 HJMG93 BUE809 BUE909 IEEE Experiments Manual http www ewh ieee org soc emcs edu educomms htm rev 2004 IEEE EMC Education Manual http www emcs org pdf EMCman pdf rev date july 1992 ASEAN EU UNIVERSITY NETWORK PROGRAMME User Manual for EMI Toolkit http www kmitl ac th emc emitoolkit htm and http www aunp emctraining polito it index asp july 20 2005 PATON Post Academic EMC course Post Academisch Technisch Onderwijs Neder land The Netherlands 2009 Istvan Knijff Design of Electromagnetic Interference Demos M Sc Thesis University of Twente 2005 Frank Leferink Istvan Knijff Anne Roch Experiments for Educating Electromagnetic Effects EMC Europe 2008 Frank Leferink Educating Electromagnetic Effec
81. lue Board Views 7 2 1 The Finished Board The end result of the assembly of the Inductance of Capacitor Vias and Value Board is shown in Figure 7 1 Inductance of eee 2m O gt Capacitors Figure 7 1 The Finished Inductance of Capacitor Vias and Value Board 7 2 2 The Silkscreen The Silkscreen of the Inductance of Capacitor Vias and Value Board shows where which com ponents should be mounted OJ Inductance of Capacitors 5 Hand HE eat Part Vias amp Value U m U out 1 L 4 l 6 100nF U in2 U out2 cy U U bput7 P University of Twente E Ensebede Metherlaads a Telecammunication Engineering EMC U and U out3 TEGEW UTwente NL U ins U pute 3 L _ Connection to ground B s InF 110mm Track 21 Smm Track U and U out4 3 Imm Track U ing U out 4 Multiple V 5 No Via 4 mo h 100pF Differences n ap x u 5 u t5 i alu u 10 u t10 6 100nF 7 10nF F 3 E 8 Ink ma g 105 3 100pF 10 10pF Al inf Capacitors Q ver O 2005 Istwaan Knijif Q vere 1 2008 Frank Wiggers Figure 7 2 The Inductance of Capacitor Vias and Value Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 57 7 2 3 Bare Board Top View The etch pattern of the empty bo
82. me ns Figure 13 8 Ground Lift Spikes Measured on Several IC Outputs UNIVERSITY OF TWENTE CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 115 13 4 Lessons Learned The Ground Bounce Package Type experiments show that 1 Simultaneous switching of outputs of driver IC s can lead to spiking on un switched outputs This Ground Bounce is an inductive effect over the bonding wires of the IC s 2 Choosing a smaller IC package may lead to a reduction of this effect 3 Remember the induction in the ground leads does not stop at the IC power pin It may be continued to a noticeable degree if the board has long ground traces instead of directly connecting to a wide power plane under the IC s UNIVERSITY OF TWENTE CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 116 UNIVERSITY OF TWENTE Chapter 14 Ground Bounce Package Type Mk2 Contents 14 1 Demonstrations on the Ground Bounce Package Type Board Mk2 117 14 2 Ground Bounce Package Type Board Mk2 Views 118 1421 The Finished Board 2404 Rer 4 vex 118 1232 The Silkser en 2 2 9 2o csse qe bom s bebo Reb ee RU 9 POOR XS E PUR RU ROUES 118 14 2 3 Bare Board Top View c3 bk Ov E Rex we qu beo d 119 14 2 4 Bare Board Bottom View es 119 14 2 5 The Board Schematic 120 14 2 6 The Bill of Materialai BOA RO ee ev 120 14 3 Board Functional Description
83. monstration PCB Bignal Loop Area Determines d dt Figure 1 2 The Self Induction Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 1 SELF INDUCTION BOARD 1 2 9 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 1 3 e Self Inductian e D University of mente Enschede ihe Netherlands Dutput EMC mmunication Engineering TE EN UTwente NL 99 99 amp E 989 ee Self Induction D t t PCB 5 hi re D 1 t e vers 1 2009 Frits Buesink Figure 1 3 The Self Induction Bare Board Top View 1 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 1 4 Figure 1 4 The Self Induction Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 1 SELF INDUCTION BOARD 4 1 2 5 The Board Schematic The schematic diagram of the Self Induction board is essentially two connectors with a connect ing wire see Figure 1 5 Flexible Wire INPUT OUTPUT D e A X Figure 1 5 The Self Induction Board Schematic 1 2 6 The Bill of Materials The bill of materials is shown below as Table 1 1 Table 1 1 Bill of Materials of the Self Induction Board REF DES VALUE Input SMB Output SMB 35 cm of flexible wire 1 9 Board Functional Description The Self Induction board demonstrates Faraday s Law and the Proximity Effect It i
84. mp Pelyethylene na phthalate PEN All 100nF Capacitors Inductan F Cap amp De t t PCB text px ver O 2005 Istwaan Kni ff GNO vers Je 2008 Frank Wiggers Figure 8 2 The Inductance of Capacitor Dielectrics Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 8 INDUCTANCE OF CAPACITOR DIELECTRICS 67 8 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 8 3 v Q Inductance of Capacitors Part 2 Dielectric University of Twente Enschede the Motharlapde Telecammuni cation Engineering EMC TEGEW UTwente NL Multi Layer lyphenylene sulphide PPS i All 100nF Capacitors Polyethylene na phthalate PEN All 100nF Capacitors Inducta dext ver O 2005 Istwaan 1114 GNO ver nk ers 3 i e nf Capacitors Demonstration PCB 1 2008 Frank Wigg Figure 8 3 The Inductance of Capacitor Dielectrics Bare Board Top View 8 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 8 4 Figure 8 4 The Inductance of Capacitor Dielectrics Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 8 INDUCTANCE OF CAPACITOR DIELECTRICS 68 8 2 5 The Board Schematic The schematic diagram of the Inductance of Capacitor Dielectrics Board is shown in Figure 8 5 CONN 1 CONN 4 1 1 CONN 10
85. mpedance of each output During our experiments it turned out that the basic function of the board can be demonstrated just as well and in line with the Self Induction experiment if the output connectors are used as inputs This shows that the PCB demonstration boards are a living collection that is adapted to the needs of the day The resistive voltage divider is hence not used here It is replaced by a jumper 09 In the UNIVERSITY OF TWENTE CHAPTER 2 LENZ LAW 16 Bill of Materials see section 2 2 6 these are indicated as 1206 SMD resistors These do exist But a wire jumper will work just as well The schematic diagram in section 2 2 5 does not show the resistive dividers On the assembled board in Figure 2 1 not all U out connectors have been installed either U out2 and U out4 were left out because the measured signals did not differ much from the neighboring traces This could be different if a faster oscilloscope is used The connectors should be mounted in the latter case The measurement approach is the same as for the Self Induction Board For the time domain the oscilloscope and generator are connected as shown in Figure 1 6 on page 5 with the remark that what is called Input in that figure is now one of the U outx connectors And of course Output now becomes U in The step response results in the time domain for the 5 outputs 1 3 5 6 and 7 are shown in Figures 2 7 2 8 2 9 2 10 and 2 11 UNI
86. ng as there is a path for the return current The improvement attained with these ground traces is not ideal there is still a large loop present that resonates at 800 MHz But as the graphs show the line can now be used up to 600 MHz with an attenuation of less than 2 dB instead of 100 MHz if the ground traces are left open Trace 3 has a narrow ground aperture of 1 8 mm and a length of 35 mm The attenuation graph is shown in Figure 12 8 as the red line Trace 3 over Ground Slot It is clear that the interconnection can be used up to about 1 GHz without to much attenuation Above that frequency the attenuation goes up rapidly As an additional experiment a metal plate of 30 x 60 mm was placed under the board to optically cover the ground slot As the board is covered with a solder resist layer this plate is only capacitively coupled Nevertheless the behavior of the trace is improved to the level of our reference trace 2 This is shown in Figure 12 8 by the green line Trace 3 GND Slot Covered UNIVERSITY OF TWENTE CHAPTER 12 DISCONTINUITIES GROUND APERTURES 102 Ground Slots Calibrate Trace 2 as Reference Attenuation dB A 1 0 F T 1 00E 06 1 00E 07 1 00E 08 1 00E 09 1 00E 10 Frequency Hz Trace 2 Uncal Trace 2 Cal Figure 12 6 Trace 2 Calibrated as Reference in the Frequency Domain
87. ns Learned The Crosstalk Basic Phenomena experiments show that 1 Crosstalk features three aspects best shown in the frequency domain a A low frequency I R resistive effect This is a frequency independent section which can be safely neglected in most cases b Crosstalk increasing proportional with frequency based on inductive and capacitive ef fects c A Transmission Line Effects section where the line lengths are longer than i A The horizontal asymptote in this range of frequencies is independent of frequency The level of crosstalk is determined by the geometry of the cross sections of the signal lines involved These geometries are essentially designable parameters that can be set by the lay out engineer Per unit length line capacitance inductance and inter line capacitance and mutual inductance are parameters that play an important role 2 Given the geometry of the PCB traces and surrounding ground or power planes a maximum level exists for crosstalk in the Transmission Line frequency range The line termination impedances are important here The asymptotic crosstalk ceiling is lowest if the active trace is characteristically terminated Reflections on the active line increase the perceived crosstalk level 3 Crosstalk in the Transmission Line Frequency Range reaches the asymptotic level only if the signal frequencies transmitted contain these frequencies 4 In the time domain a distinct diff
88. nz Law Board 11 2 2 Lenz Law Board Views 12 2 2 1 The Finished Board 0 0 00002 eee 12 2 22 Phe Silkscreen 4 0 4 tek Aha doe OA a het 12 2 4 8 Bare Board Top View 13 2 2 4 Bare Board Bottom View A 13 23 5 The Board Schemiatie 22 2 m ob R URLs EU e EU ee EU 14 2 2 6 The Bill of Materials 14 2 3 Board Functional Description 15 2 4 Lessons Learned terse ie Bi ek os ee AS oe ee a 19 2 1 Demonstrations on the Lenz Law Board The Lenz Law Board demonstrates the same phenomena as the Self Induction Board Instead of a flexible wire loop a number of traces are laid out on the board to show essentially the same aspects currents prefer the path of least inductance If the inductance is high it will take more time to reach the steady state current level after a voltage step at the source connection For a trace over a wide ground plane transmission line the transition is almost instantaneous CHAPTER 2 LENZ LAW 12 2 2 Lenz Law Board Views 2 2 4 The Finished Board The end result of the assembly of the Lenz Law Board is shown in Figure 2 1 Lenz s Law Figure 2 1 The Finished Lenz Law Board 2 2 2 The Silkscreen The Silkscreen of the Lenz Law Board shown
89. oard REF DES VALUE PACKAGE FOOTPRINT C1 330n CAP_NP SM C_1206 C2 220u CAP POL 0 CYL D 275 LS 100 034 C3 100n CAP NP SM C 1206 UNIVERSITY OF TWENTE CHAPTER 14 GROUND BOUNCE PACKAGE TYPE 121 Table 14 1 Bill of Materials of the Ground Bounce Package Type Mk2 Board cont d REF DES VALUE PACKAGE FOOTPRINT C4 100n CAP_NP SM C_1206 C5 100n CAP_NP SM C_1206 6 10 CAP_NP SM C_1206 C7 100n CAP_NP SM C_1206 C8 47p CAP_NP SM C_1206 09 47p CAP_NP SM C_1206 C10 47p CAP_NP SM C_1206 C11 47p CAP_NP SM C_1206 C12 47p CAP_NP SM C_1206 C13 47p CAP_NP SM C_1206 C14 47p CAP_NP SM C_1206 C15 47p CAP_NP SM C_1206 C16 47p CAP_NP SM C_1206 CONN P1 SMB SMB RF SMB V CONN P2 SMB SMB RF SMB V CONN 51 SMB SMB RF SMB V CONN 52 SMB SMB RF SMB V CONN 53 SMB SMB RF SMB V CONN 54 SMB SMB RF SMB V CONN SMB SMB RF SMB V CONN T2 SMB SMB RF SMB V D1 1n4001 DIODE 0 DAX2 300X 050 028 D2 LED RED LED CYL D 225 LS 125 031 D3 LED RED LED CYL D 225 LS 125 031 D4 LED GRN LED CYL D 225 LS 125 031 D5 LED YEL LED CYL D 225 LS 125 031 F1 FUSEHOLDER FUSEHOLDER BLKCON 200 VH TM1SQ W 100 2 J1 POWERJACK PHONEJACK_O POWERJACK OSC1 10 MHz OSC14 OSC R1 220 RESISTOR SM R 1206 R2 220 RESISTOR SM R_1206 R4 220 RESISTOR SM R_1206 R5 220 RESISTOR SM R_1206 R6 50 RESISTOR SM R_1206 R7 50 RESISTOR SM R 1206 H8 50 RESISTOR SM R 1206 H9 50 RESISTOR SM R 1206 R10 50 RESISTOR SM R_1206 R11 50 RESISTOR SM R_
90. of lines D E and F 1000000000 UNIVERSITY OF TWENTE CHAPTER 6 CROSSTALK LAYOUT ISSUES 53 Crosstalk Short Traces No Ground runs via Analyzer Lo I 5 10 m S x 7 o0 2 o 15 20 25 4 1000000 0000000 100000000 1000000000 Frequency Hz hart Area H1 to no SW Figure 6 9 Crosstalk between lines H and G UNIVERSITY OF TWENTE CHAPTER 6 CROSSTALK LAYOUT ISSUES 54 6 4 Lessons Learned The Crosstalk Layout Issues experiments show that 1 Guard traces a grounded trace between two adjacent signal traces can help to reduce crosstalk only below the critical frequency determined by the length of the traces If a guard trace is used it should be connected at least at both ends to ground For frequencies above the critical frequency guard traces should not be used to avoid resonances Rather user a wider separation between the traces e g as if the guard trace had been there three trace widths A greater separation distance between traces reduces crosstalk But this is effective only if the traces are routed over a wide ground plane If the ground return is only a thin trace separating the signal lines will actually increase the loop areas of these lines and hence the mutual induction If ground planes are used under traces to help reduce crosstalk make sure they have no apertures Che
91. osstalk for two traces at the normal trace separation distance in this A B C group The high frequency asymptote lies at 8 dB The middle section of the board has three traces routed close together between two groups of connectors D1 E1 and F1 on the left hand side to D2 E2 and F2 at the right hand side Both connector groups are placed on local ground planes Under the traces there is no ground plane but only a thin ground trace connecting these local planes same width as the signal traces The board is connected as in Figure 6 6 only the signal source is connected to CONN D1 the start of the active trace for this group The 50 load is placed on CONN D2 Crosstalk in then measured on traces E1 E2 and F1 F2 respectively The results are shown in Figure 6 8 as D1 to E1 no SW blue line and D1 to F1 no SW red line The crosstalk between lines E1 E2 and F1 F2 is identical to that between D1 D2 and E1 E2 Finally the bottom section of the board with lines between connectors G H and is explored On the bottom of the board a wide ground plane is placed between the two connector groups But there is a gap in this ground plane of about 10 mm and these two half planes are connected nowhere Using the spectrum analyzer tracking generator combination again it is connected to CONN H1 tracking generator and CONN G1 Spectrum Analyzer with 50 loads on the corresponding CONN H2 and CONN G2 The crosstalk measured is shown in Figu
92. oth the near end closest to the signal gener ator and the far end near the active line termination switch Two passive lines have been routed They have been labeled as a 20 dB trace and a 30 dB trace respectively To see the difference a spectrum analyzer with tracking generator is used The frequency span should be at least 200 MHz preferably 400 MHz starting say at 1 MHz The connection diagram in Figure 5 6 shows the details for measuring the 20 dB line To measure the 30 dB line the Spectrum Analyzer input line is now connected to CONN C1 and the 500 load is transferred to CONN C2 The results Generator Analyzer Load output input Active line terminated Switch to 60 Load Figure 5 6 The Crosstalk Basics Connection Diagram using a Spectrum Analyzer with Tracking Generator of measurements of the 20 and 30 dB passive traces are shown in Figure 5 7 In both cases the active line is terminated with a resistor R1 between 50 and 60 Ohms switch SW 1 in the Zo po sition An interesting phenomenon is the sharp decline in crosstalk on both the 20 and 30 dB lines at almost 200 MHz This appears to be the frequency at which exactly fit the trace Dr Howard Johnson calls this frequency the critical frequency in his book High Speed Digital Design This sharp decline in crosstalk repeats at higher frequencies at multiples of A more practical effect however is that there is a ma
93. out additional trace lengths As done in earlier experiments a spectrum analyzer with tracking generator with two test cables is calibrated to show 0 dB over the frequency range of interest when the cables are directly interconnected We used 1 GHz as highest frequency The the cables are connected at either end of the capacitor to measure its effectiveness as decoupling capacitor The results for the left hand row of identical capacitors is shown in Fig ure 7 7 The results of measurements on the right hand side capacitors with identical shape but decreasing value is shown in Figure 7 8 UNIVERSITY OF TWENTE CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 61 Amplitude dB ZC Wire internal Resr C Resr wire resonance log frequency Figure 7 6 Typical Frequency Response of a Decoupling Capacitor 0 LJ pated EET se Li tH EMI Etpe 2 7 rM ua vj a cw Tri 20 wt PS _ as 4 a i P Pd 30 BUCO WI 1nF 10mm track to via I QU 40 1nF 5mm track to via VE I 1nF 1mm track to via 1nF multiple via s 1 V a 50 sass INF via Y 60 70 1 10 100 1000 Frequency MHz Figure 7 7 Frequency Response of Identical Capacitors with Additional Trace Lengths UNIVERSITY OF TWENTE CHAPTER 7 INDUCTANCE OF CAPACITOR VIAS AND VALUE 62 0 10 m
94. predecessor described in chapter 7 starting on page 55 it addresses the parasitic elements largely inductance inside a capacitor For that purpose it has 6 capacitors of identical value 100 nF but built with different dielectric materials It is operated as the board of chapter 7 described in Section 7 3 on page 59 The results of the measurements are shown in Figure 8 6 Figure 8 6 shows that both the resonant frequency and the equivalent series resistance are affected by the way a capacitor is built UNIVERSITY OF TWENTE CHAPTER 8 INDUCTANCE OF CAPACITOR DIELECTRICS 70 0 10 Hi T 20 saad S EISE H n 2 30 3 a f gn i 40 so 100nF Al electrolytic oy 100nF tantalium 2i X 50 See 100nF ceramic multilayer Y 100nF polyphenylene sulphide 60 100nF polyester s 1OONF polyethylene naphtalate 70 4 0 01 0 1 1 10 100 Figure 8 6 The effect of different dielectrics in 6 100 nF capacitors Frequency MHz UNIVERSITY OF TWENTE CHAPTER 8 INDUCTANCE OF CAPACITOR DIELECTRICS 71 8 4 Lessons Learned The Inductance of Capacitor Dielectrics experiments show that 1 The way a capacitor is built has an effect on its parasitic inductance The resonance frequency and inherent useable frequency range are affected by it
95. r is provided through the pins in the middle of the package e The IC 74ABT541 has the traditional end pinning where power is provided via pins diagonally opposite to each other The idea is that the center pinning type has less bonding wire inductance and hence should show less Ground Bounce This is augmented by the fact that the 74AC11244 chip has two parallel Vcc and four GND pins This should reduce the GND bonding inductance by a factor of 4 The connection to power supply and oscilloscope and switching on and off the two tested IC sections is described in chapter 13 Section 13 3 The measured results the clock and Ground Bounce signals of the two IC s are shown in Figure 15 6 0 2 f 0 15 4 0 1 0 05 d f bl E 0 Y Ay vas ev AE TAa M Y uen T Lo M RPA x 0 V 20 40 W M 100 V 20 140 lt 0 05 4 Clock 0 1 ABT asymmetric AC symmetric 0 15 4 max ABT 167mV max AC 120mV 0 2 Time ns Figure 15 6 Ground Bounce Spikes Measured on both IC s Outputs UNIVERSITY OF TWENTE CHAPTER 15 GROUND BOUNCE POWER PINNING 131 15 7 Lessons Learned The Ground Bounce Power Pinning experiments show that 1 The ground bounce from the center pinned chip is slightly lower than that of the end pinning type But not a factor of 4 less 2 Other factors like the placement and wiring of the decoupling capacitor and ground
96. rd Functional Description 112 13 4 Lessons Learned ee ee ee ee 115 13 1 Demonstrations on the Ground Bounce Package Type Board The Ground Bounce Package Type Board shows that large power current surges in a digital device due to simultaneous switching of outputs causes a positive spike on the on chip ground level with respect to the ground level on the Printed Circuit Board PCB This particular board has three identical chips in varying packages from TSSOP to DIL to see if this makes any difference 107 CHAPTER 13 GROUND BOUNCE PACKAGE TYPE 108 13 2 Ground Bounce Package Type Board Views 13 2 1 The Finished Board The end result of the assembly of the Ground Bounce Package Type Board is shown in Fig ure 13 1 Package Ground RO Figure 13 1 The Finished Ground Bounce Package Type Board 13 2 2 The Silkscreen The Silkscreen of the Ground Bounce Package Type Board shows where which components should be mounted CJ er oung Bounce 9 ckage conn P2 5 PDIP la E sam E goe umi of Twente i rem oft Bu Ivers NB BS Enschede
97. re 6 9 As the two ground plane sections on the board are not connected the ground connection is now via the connectors of the spectrum analyzer tracking generator This creates a huge ground loop That is reflected in the crosstalk which now extends all the way to the low frequency border of the graph in Figure 6 9 UNIVERSITY OF TWENTE CHAPTER 6 CROSSTALK LAYOUT ISSUES 51 Generator L1 output 22 JU T DE Switches to connect Guard Trace to Ground Plane Figure 6 6 The Crosstalk Layout Issues Connection Diagram using a Spectrum Analyzer with Track ing Generator Crosstalk Long Trace E Crosstalk dB 50 LETT FET ET 1000000 10000000 100000000 1000000000 Frequency Hz to A1 Guard Floating B1 to A1 SW1 closed B1 to A1 SW2 closed B1 to A1 SW1 8 SW2 closed B1 to C1 Guard Floating Figure 6 7 Frequency Response of crosstalk from line B to lines A and C UNIVERSITY OF TWENTE CHAPTER 6 CROSSTALK LAYOUT ISSUES 52 Crosstalk Short traces over Thin Groundline 10 Crosstalk dB 35 4 1000000 10000000 100000000 Frequency Hz D1 to F1 no SW D1 to E1 no SW Figure 6 8 Crosstalk between combinations
98. ristics of the far end crosstalk can be explored UNIVERSITY OF TWENTE CHAPTER 5 CROSSTALK BASIC PHENOMENA Comparison 20 and 30 dB Passive lines Active line terminated 20 20 dB line 30 30 dB line Crosstalk 40 50 60 i 1 00E 06 00E 07 00E 08 00E 09 Frequency Figure 5 7 Comparison of Crosstalk on 20 and 30 dB lines Active line terminated Crosstalk 2 20 dB trace Source Line Terminated Zo Source Line Open E Source Line Shorted H Crosstalk e e 40 60 1 00E 06 1 00E 07 1 00E 08 1 00E 09 Frequency Figure 5 8 Crosstalk on 20 dB line Active line terminated open and shorted UNIVERSITY OF TWENTE CHAPTER 5 CROSSTALK BASIC PHENOMENA 42 Crosstalk 2 30 dB Trace 20 Source Line Terminated Zo Source Line Open E Source Line Shorted H 30 Crosstalk 40 50 60 1 1 00E 06 1 00E 07 1 00E 08 1 00E 09 Frequency Figure 5 9 Crosstalk on 30 dB line Active line terminated open and shorted UNIVERSITY OF TWENTE CHAPTER 5 CROSSTALK BASIC PHENOMENA 43 5 4 Lesso
99. rn of the empty Mk2 board seen from the bottom side is shown in Figure 14 4 Mee ejeje Figure 14 4 The Ground Bounce Package Type Mk2 Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 14 GROUND BOUNCE PACKAGE TYPE MK2 120 14 2 5 The Board Schematic The schematic diagram of the Ground Bounce Package Type Mk2 Board is shown in Figure 14 5 5 sv V rusEHoLpeR 409 POWERJACK 1 CERA 220 E uS 41 52 LED 3 5V OSC osc14 c7 ce 8 8 Clock 23 rid 1 eS CONNP lon 56 E chet SMB 54 R14 Clock em 7 CONN P2 SMB 5TSSOR o9 TSSOP package 4 g R12 1 CONN T1 o SMB 2 At v1 Clow R18 tia 9 v2 7 clod 9 a3 Y3 550C 60 B lua 76 SOIC package 25 H AS Y5 3 g R8 CONN 81 i545 X9 SMB az z CONN T2 4 4 amp Ext o 5 5 9 Clock RIS ipe 1 Tp Se 20E 50 51 Md T4ACT244TSSOR A aab CONN 2 gt MB CONN 53 SME itle Ground Bounce DIL vs SMD CONN S4 SMB ize Document Number lev 4 A 20 ste Thursday October 08 2009 Eheet 1 of 1 Figure 14 5 The Ground Bounce Package Type Mk2 Board Schematic 14 2 6 The Bill of Materials The components to complete the Ground Bounce Package Type Mk2 Board are shown in Ta ble 14 1 Table 14 1 Bill of Materials of the Ground Bounce Package Type Mk2 B
100. s a basic intro duction to the Lenz s Law Board described in Chapter 2 Faraday s Law describes the phenomenon that a voltage is induced in a wire loop due to a change in the magnetic flux that is enclosed by the loop The Self Induction Board and the Lenz Law Board both show this phenomenon in the opposite direction if a voltage step is applied to the input terminals of an interconnection it takes some time before current starts to flow For this demonstration the interconnection formed by a single signal wire plus return ground plane is loaded with 500 A generator with again 50 is used to feed a voltage step actually a square wave into the wire ground loop The 502 impedances imply a equilibrium signal voltage of 50 of the unloaded source amplitude The loop self induc tance provides a reverse voltage initially equal to the source voltage As the current and magnetic field in the loop builds up the voltage reduces as a decaying exponential toward the equilibrium UNIVERSITY OF TWENTE CHAPTER 1 SELF INDUCTION BOARD 5 voltage determined by the source and load internal impedances At the load side initially no cur rents flows and the voltage over the load resistor hence starts out at zero After that this voltage increases as a mirror image of the voltage at the source end towards the equilibrium voltage The physical loop is formed by a flexible wire over a ground plane see Figure 1 1 A square wave generator with
101. s set by designable board layout parameters 35 36 CHAPTER 5 CROSSTALK BASIC PHENOMENA 5 2 Crosstalk Basic Phenomena Board Views 5 2 1 The Finished Board The end result of the assembly of the Crosstalk Basic Phenomena Board is shown in Figure 5 1 Crosstalk 2 University of Twente Wotherlands Telecommunication Engineering TE EWI UTwente NL Figure 5 1 The Finished Crosstalk Basic Phenomena Board 5 2 2 The Silkscreen The Silkscreen of the Crosstalk Basic Phenomena Board shows where which components should be mounted Crosstalk 2 University of Twente Eosebede The Wotharlanda 30 dB Trace g EMC Telecommumication Engineerin Active Trace TE EWI UTwente NL CONN 82 20 dB Trace ack lenght 430mm ver 1995 Fe Buesink er 1 2009 M F Brethouner Figure 5 2 The Crosstalk Basics Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 5 CROSSTALK BASIC PHENOMENA 37 5 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 5 3 gs 9 CONN Bi University of Twente fnceheda The Netharlands dB Passive Traces CONN 82 conn Figure 5 3 The Crosstalk Basics Bare Board Top View 9 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 5 4 Figure 5 4
102. s therefore a problem Hence we decided to develop a series of demos on Eurocard 100x160mm printed circuit boards PCB KNIJFO5 Test equipment consists in most cases of a basic generator a dual channel oscilloscope and if available a basic spectrum analyzer The demo kit has been presented at several EMC conferences LEFea08 LEF09 BUE809 and BUE909 and many many people were interested Therefore a new generation was developed The detailed description of these new demo PCBs is presented in this document in Chapters 1 through 9 Table 1 shows where the descriptions can be found in this manual Table 1 Survey of Currently Available EMC Demo Boards Demonstration Subject Chapter Page Self Inductance 1 1 Lenz s Law 2 11 Coax Cable 3 21 Transfer Impedance 4 27 Crosstalk Basic phenomena 5 35 Crosstalk Layout Issues 6 45 Inductance of Capacitors Via s and Value 7 55 Inductance of Capacitors Different dielectrics 8 65 Inductance of Capacitors Package and Value 9 73 Grounding of Filter 10 81 Discontinuities Stubs 22 22 Discontinuities Ground Slot 12 97 Ground Bounce Package Type 13 107 Ground Bounce Package Type Mk2 14 117 Ground Bounce End or Center Pinning Power 15 125 Ground Bounce End or Center Pinning Power Mk2 16 133 Over time new experiments will emerge The Ground Bounce experiments as an example now exist in two versions The second version is labelled Mk2 Mark 2 to distinguish it from its
103. ted to connector U out4 The filter output wire must be connected to the PCB inside the enclosure The other open side is the bottom of the cube It is closed by the ground plane s on the PCB It is important that the bottom edge makes good contact with the top ground plane If you are assembling the empty board scratch of the solder resist under the edges of the enclosure and solder these edges to the PCB ground plane This is easier if the brass material is thin The bracket of the third filter has a small hole A copper wire should be used to connect the bracket to the grounding hole in the PCB The filters the version mentioned in the bill of materials Table 10 1 are of the symmetrical r type So the direction they UNIVERSITY OF TWENTE CHAPTER 10 GROUNDING OF FILTERS 86 are mounted in is not important The input wire black in Figure 10 1 has some inductance and is needed to make the low frequency characteristics of the filters identical Only the fourth filter has no output wire The connection from this filter to the board should be as short as possible The output of this latter filter should be completely enclosed by shielding metal The remaining open end could also be closed with e g copper tape But even without this the performance is acceptable see Figure 10 7 This is because the remaining aperture size in the shielding enclosure is much smaller than a half wavelength of the highest frequency of interest
104. terconnection for high frequencies The message is do not route traces over return plane gaps The presence of a nearby ground return trace can greatly improve the performance even if it has just the same width as the signal trace Itis not necessary to connect a ground trace or strip we still prefer wide grounds galvanically A capacitive connection is sufficient This can be useful if the two return planes do not have the same DC level e g connecting Ground to a Vcc plane The capacitive connection could be a capacitor or just capacitive overlap of the two planes The latter solution is preferred if the planes are wide enough A gap in a ground plane can be covered with an insulated ground plane nearby The overlap needed depends on the frequencies involved UNIVERSITY OF TWENTE CHAPTER 12 DISCONTINUITIES GROUND APERTURES 106 UNIVERSITY OF TWENTE Chapter 13 Ground Bounce Package Type Contents 13 1 Demonstrations on the Ground Bounce Package Type Board 107 13 2 Ground Bounce Package Type Board Views 108 13 2 1 The Finished Board 5 cce SRB R n BG BUR RR 108 13 22 The Silkscreen b RT ee GRR ox BE Sod BUE E EUER Pen 108 13 2 3 Bare Board Top View ers 109 13 2 4 Bare Board Bottom View 109 13 2 5 The Board Schematic osaa 110 13 2 6 The Bill of Materials 2 re 110 13 3 Boa
105. traces and via s are equally important UNIVERSITY OF TWENTE CHAPTER 15 GROUND BOUNCE POWER PINNING 132 UNIVERSITY OF TWENTE Chapter 16 Ground Bounce Power Pinning Mk2 Contents 16 1 Demonstrations on the Ground Bounce Power Pinning Mk2 Board 133 16 2 Ground Bounce Power Pinning Board Mk2 Views 134 16 2 1 The Finished Board 0 ee 134 16 2 2 The Silkscreen ge bb BOS ek OS AS RE ee EGER 134 16 2 3 Bare Board Top View es 135 16 3 Bare Board Bottom View 135 16 4 The Board Schematic eee ee ee eee ee ene 136 16 5 The Bill of Materials 136 16 6 Board Functional Description 138 16 7 bessons Learned ae ed BE ARE kere es 140 16 1 Demonstrations on the Ground Bounce Power Pinning Mk2 Board The Ground Bounce Power Pinning Board Mk2 shows the same effect as the Ground Bounce Package Type Mk2 Board but focusses on the difference between devices with end and center power pinning layout Mk2 has an additional ground plane on the component side of the board to try to further reduce Ground Bounce 133 CHAPTER 16 GROUND BOUNCE POWER PINNING MK2 134 16 2 Ground Bounce Power Pinning Board Mk2 Views 16 2 1 The Finished Board The end result of the assembly of the Ground Bounce Power Pinning Mk2 Board is shown
106. ts using Printed Circuit Board Demos Kyoto EMC Conference Japan 2009 Frank Leferink Reduction of Radiated Electromagnetic Fields by Creation of Geomet rical Asymmetry PhD Thesis University of Twente 2001 ISBN 90 365 1689 7 Howard Johnson Martin Graham High Speed Digital Design A Handbook of Black Magic Prentic Hall PTR Upper Saddle River NJ07458 ISBN 0 13 395724 1 Frits Buesink Basic EMI Effects at the PCB level Experiment Session at the IEEE EMC Symposium Austin TX Aug 2009 Frits Buesink Educating Electromagnetic Effects using Printed Circuit Board Demos Presentation at the SOFTCOM 2009 Symposium HVAR Croatia Sept 2009 143
107. wire is far removed from the ground plane 2 A minimal loop the wire is meandering on the surface of the board close to the ground plane 3 A random loop the wire is left as it rests on the board sometimes touching at other places floating in space The spectrum analyzer is calibrated to show a horizontal 0 dB line if the tracking generator is con nected directly to the input The results for the three situations are shown in Figure 1 10 For the Scope 200 MHz BW Generator Tise 10 ns Figure 1 6 Connection Diagram for Self Induction Experiment UNIVERSITY OF TWENTE CHAPTER 1 SELF INDUCTION BOARD 6 7 Large Loop Area Small Loop Area Figure 1 7 Two possible ways to reduce loop area interpretation of the graph it is important to remember that the wire ground plane combination is actually intended as an interconnection a transmission line The ideal transmission line passes all frequencies with 0 dB attenuation For comparison this ideal O dB line has been added to the graph in Figure 1 10 It is obvious from the measurements that the position of the wire with the smallest loop area approaches this ideal line best The largest wire loop has the worst performance maximum attenuation The randomly positioned wire ends up somewhere between the best and the worst case UNIVERSITY OF TWENTE CHAPTER 1 SELF INDUCTION BOARD 7
108. x Cable Board 3 2 2 The Silkscreen The Silkscreen of the Coax Cable Board shown in Figure 3 2 points out which components should be mounted where Oo O Coax Cable University of Twente Epgebada etherlands Telecomm unication Engineering EMC Short TEBEMWI UTwente NL Coax Cable Demanstratian PCB 2 O ver d 2008 Frank Wiggers Q ver 2 2009 M F Brethouwer Figure 3 2 The Coax Cable Board Silk Screen UNIVERSITY OF TWENTE CHAPTER 3 COAX CABLE 23 3 2 3 Bare Board Top View The etch pattern of the empty board seen from the top side is shown in Figure 3 3 e Coax Cable Univarcity of Twen Basehade Tho Metherlaods Telecommunication Engineering EMC TE EW UTwente NL Coax Cable Demanstration PCB 2 e ver la 2008 Frank Wiggers e Figure 3 3 The Coax Cable Bare Board Top View 3 2 4 Bare Board Bottom View The etch pattern of the empty board seen from the bottom side is shown in Figure 3 4 Figure 3 4 The Coax Cable Bare Board Bottom View UNIVERSITY OF TWENTE CHAPTER 3 COAX CABLE 24 3 2 5 The Board Schematic The schematic diagram of the Coax board is shown in Figure 3 5 Figure 3 5 The Coax Cable Board Sch
109. ximum crosstalk level Figure 5 7 shows two of them at 100 and 300 MHz frequencies at which A and 3 If these maxima are interconnected with an imaginary line an asymptote is found The level at which this asymptote lies depends on the distance between the active and passive lines For this board the two passive traces were designed to have a maximum crosstalk level of 20 and 30 dB respectively Whether these levels are reached depends on the frequency spectrum of the source connected to the active trace To see the effects of an untermi nated source active line in the frequency domain the switch SW 1 can be set to H middle position active line is shorted to ground at the switch or to E bottom position active line is open circuit at the switch The results are shown in Figure 5 8 for the 20 dB passive line and in Figure 5 9 for the 30 dB passive line The passive lines were terminated in 500 in both situation While measuring the 30 dB line an experiment can be added by terminating the 20 dB line on one or both sides That will show the influence of a more or less floating line near the active line If desired any of the passive lines can be used as active line using the other two to monitor crosstalk The experiment described above measures crosstalk at the near end By exchanging the position of the 50 load UNIVERSITY OF TWENTE CHAPTER 5 CROSSTALK BASIC PHENOMENA 40 and the spectrum analyzer input the characte

Understanding electromagnetic effects using PCB demos

Contents

Download Pdf Manuals

Related Search

Related Contents