Analysis of Internal RF Interferences in Mobile Phones

Transcription

1 Anlysis of Inernl RF Inerferences in Mobile Phones SEVAG BALKORKIAN & HAO ZHANG Mser of Science Thesis in Rdio Elecronics Sockhol, Sweden 2005 IMIT/LECS

2 Absrc Nowdys, obile phones hve reer funcionliy; cer, color LCD screen, wireless LAN, Blueooh, IrDA nd ohers. In he ner fuure wider vriey of new funcionliies will be dded, fro hih quliy voice, hih definiion video o hih d re wireless chnnels. As consuer elecronics inere reer funcionliy nd hih operin frequencies, heir eissions will exceed he specified liis, os of hese eissions will be resul of he inernl inerferences in he obile phone. Moreover hiher operin frequencies will be required o iprove he quliy of hese funcionliies, soehin h will ke i ore difficul o conrol hese inerferences. Inernl or exernl sources of elecroneic inerference cn derde he perfornce of sensiive nlo/diil circuis inside he obile phone. Moreover he elecronic device us sisfy hos of lobl reulions h lii i s suscepibiliy o hese inerferences, s well s he inerference eied by he device iself. Therefore desinin new elecronic device o perfor new nd exciin funcions will no be plesn sk if i cn no ee cerin specificions nd funcion s required o dhere o cerin lobl reulions. This hesis projec invesies he sources of inerference inside obile phone; inly he elecroneic inerferences nd is effec on he rdio rnsceiver focusin on he GSM receiver sensiiviy. This repor is resul of inensive reserch, n invesiion of possible sources of inerference, lso cul esureens were perfored; RSSI, OTA nd sniffin esureens; o idenify he physicl sources of inerferences, nd heir effec on he receiver sensiiviy. Finlly soluions were recoended nd ipleened o suppress he inerferences due o differen sources, inly hrouh filerin, shieldin or proper roundin of sinls nd coponens/subsyses in he obile phone. 2

3 Acknowledens We would like o express our riude o he followin people: Zreh Mhdessin, our dvisor Sony Ericsson Mobile Counicions AB for proposin he projec nd for he uidnce. Professor Håkn Olsson, our exiner KTH, for oivion nd dvice. We would like o hnk he sff Sony Ericsson Kis h helped us ke his projec successful, hnk you ll for he suppor. Finlly we would like o hnk Sören Krlsson Sony Ericsson Mobile Counicion s AB for his coninuous suppor for our projec. 3

4 Abbreviions 3GPP ARFCN ASIC BER CISPR CTIA DUT EGSM EMC EMI ESD ETSI FCC GSM IC IRDA LAN LCD MS OTA PCB PDA RFI RSSI SAM WLAN 3rd Generion Prnership Projec Absolue Rdio Frequency Chnnel Nuber Applicion Specific Inered Circui Bi Error Re Coie Inernionl Specil des Perurbions Rdioelecriques Cellulr Telecounicions nd Inerne Associion Device under Tes Exended GSM Elecroneic Copibiliy Elecroneic Inerference Elecrosic Dischre Europen Telecounicions Sndrds Insiue Federl Counicions Coission Globl Syse for Mobile Counicions Inered Circui Infrred D Associion Locl Are Nework Liquid Crysl Disply Mobile Sion Over he ir Prined Circui Bord Personl Diil Assisn Rdio Frequency Inerference Received Sinl Srenh Indicor Sndrd Anhropoorphic Model Wireless Locl Are Nework 4

5 Tble of Conens ABSTRACT...2 ACKNOWLEDGMENTS...3 ABBREVIATIONS...4 TABLE OF CONTENTS INTRODUCTION RELATED WORK TRANSCEIVER STANDARDS GSM STANDARD GSM 900 / EGSM GSM 1800 / DCS GSM 1900 / PCS SOURCES OF RF INTERFERENCE THERMAL NOISE ELECTROMAGNETIC INTERFERENCE POWER SUPPLY INTERFERENCE IC / PACKAGE DESIGN PCB AND COMPONENT PLACEMENT CLOCK AND DATA GROUNDING DESIGN Sinle Poin Ground Syse Mulipoin Ground Syse INTERFERENCE DETECTION PROCEDURES POSSIBLE SOLUTIONS LAYOUT & PLACEMENT OF COMPONENTS GROUNDING SOLUTIONS EMI SUPPRESSION BY FILTERING Noise Suppression usin Hiher Order Filers Disorion suppression usin filers SHIELDING SOLUTIONS RSSI MEASUREMENTS MEASUREMENT SCENARIOS MEASUREMENTS WHERE CAMERAS ACTIVE/INACTIVE & ANALYSIS MEASUREMENTS IN PRESENCE OF WLAN & ANALYSIS OTA SENSITIVITY MEASUREMENTS MEASUREMENT PROCEDURE MEASUREMENT RESULTS AND ANALYSIS SNIFFING MEASUREMENTS MEASUREMENT PROCEDURE MEASUREMENT CASES MEASUREMENT RESULTS AND ANALYSIS SOURCES OF UNCERTAINTY RECOMMENDED SOLUTIONS LCD DISPLAY DATA/CONTROL LINES RADIATED EMISSIONS FROM FLEX CABLES IMPROPER GROUNDING OF SHIELD BOXES MPX CAM SUBSYSTEM INTERFERENCES

6 9.4.1 Siulions Oscilloscope Mesureens RSSI Resuls & Anlysis VGA CAM SUBSYSTEM INTERFERENCES Siulions Oscilloscope Mesureens RSSI Resuls & Anlysis RADIATED EMISSIONS FROM DIODES Audio subsyse inerferences Power subsyse inerferences...45 CONCLUSION...47 FUTURE WORK...47 APPENDIX A...48 APPENDIX B...49 REFERENCES

7 1 Inroducion Nowdys, obile phones hve reer funcionliy; cer, color LCD screen, wireless LAN, Blueooh, IrDA nd ohers. In he ner fuure wider vriey of new funcionliies will be dded, fro hih quliy voice, hih definiion video o hih d re wireless chnnels. As consuer elecronics inere reer funcionliy nd hih operin frequencies, heir eissions will exceed he specified liis, os of hese eissions will be resul of he inernl inerferences in he obile phone. Moreover hiher operin frequencies will be required o iprove he quliy of hese funcionliies which will ke i ore difficul o conrol hese inerferences. Inernl/exernl sources of elecroneic inerference cn derde he perfornce of sensiive nlo/diil circuis inside he obile phone. Moreover he elecronic device us sisfy hos of lobl reulions h lii is suscepibiliy o hese inerferences, s well s he inerference eied by he device iself. Therefore desinin new elecronic device o perfor new nd exciin funcions will no be plesn sk if i cn no ee cerin specificions nd funcion s required o dhere o cerin lobl reulions (3GPP, FCC, ETSI, nd CISPR). This hesis repor is rouhly divided ino he followin prs: An inroducion in chper 1, reled work or bckround inforion bou he projec described in chpers 2, 3, 4 nd 5. Mesureen seups nd resuls nlysis described in chpers 6, 7 nd 8. Soluions o inernl inerferences described in chper 9. Ler in he repor here is conclusion nd fuure work proposed, coonly used erinoloies in Appendix A, hiher order filer siulions in Appendix B, nd finlly he references. 2 Reled Work Throuhou he yers elecronics nufcurers hve pu serious effor o idenify possible cuses of inernl inerference in obile phones nd oher consuer elecronic devices, nd wys o solve hese issues. The bi pr of his work ws reled o elecroneic inerference cused by he PCB, hih re clocks nd oher inernl coponens of devices like oscillors on he nlo/diil circuiry. The uhors of [1] discuss rdio frequency effecs on elecronics syses inered wih hih perfornce chips. Unwned inerferences when superiposed on he syse sinls h cuse spurious se chnes on loic devices nd syse level brekdown. The uhors of [2] discuss he es requireens h cover OTA perfornce of obile phone nenns; hey describe ypicl OTA es syse nd key preers exrced fro such es. 7

8 3 Trnsceiver Sndrds 3.1 GSM Sndrd The Globl Syse for Mobile counicions is second enerion cellulr elecounicion syse which ws firs plnned in he erly 1980s. Unlike firs enerion syses operin he ie, GSM ws diil nd hus inroduced reer enhnceens such s securiy, cpciy, quliy nd he biliy o suppor inered services. [11] Copred wih he exisin nlo syses, he new syse ws required o hve hiher cpciy, coprble or lower operin coss nd coprble or beer speech quliy. Sndrd Lower Bnd Frequency RFCN Upper Bnd Frequency E-GSM 900 Fl(n) = *n 0 n 124 Fu(n) = Fl(n) + 45 Fl(n) = *(n-1024) 975 n 1023 Fu(n) = Fl(n) + 45 DCS 1800 Fl(n) = *(n-512) 512 n 885 Fu(n) = Fl(n) + 95 PCS 1900 FI(n) = *(n-512) 512 n 810 Fu(n) = FI(n) + 80 Tble 1: ARFCN nd Correspondin Frequency Rne of Chnnels [3] The crrier spcin is 200 KHz nd frequency is desined by he bsolue rdio frequency chnnel nuber is ARFCN. If we cll Fl(n) he frequency vlue of he crrier ARFCN n in he lower bnd, nd Fu(n) he correspondin frequency vlue in he upper bnd. Noe h ll frequencies in he ble bove re in. [3] GSM 900 / EGSM The specru rne for he GSM 900 operion is beween 890 nd 915 for uplink operion nd 935 nd 960 for downlink operion. EGSM is n exension o he GSM 900 specru, i hs ddiionl 10 h provides n ddiionl 50 chnnels. Thus he specru rne for EGSM operion is beween 880 nd 915 for uplink operion nd 925 nd 960 for downlink operion GSM 1800 / DCS GSM 1800 lso known s DCS1800 or DCS is diil nework workin on frequency of The specru rne for he GSM 1800 operion is beween 1710 nd 1785 for uplink operion nd 1805 nd 1880 for downlink operion GSM 1900 / PCS The specru rne for he GSM 1900 operion is beween 1850 nd 1910 for uplink operion nd 1930 nd 1990 for downlink operion. 8

9 4 Sources of RF Inerference In obile phone here re ny sources of inerference which cn be in he for of rdied or conduced elecroneic inerferences nd could ffec he quliy of sinl perceived he rnsceiver. These inerferences cuse sinl ineriy issues nd iproper funcionliy of sensiive nlo/diil circuis inside he obile phone. Therl noise, fro power supply or IC pckin, PCB rces, roundin nd crosslk should be considered s sources of inerference inside obile phone. In his secion we will discuss he differen sources of inerference independenly; in ler chpers we will propose soluions for hese disurbnces. 4.1 Therl Noise Generlly, noise is considered o be n elecroneic inerference. Unwned voles nd currens induced by exernl neic fields, elecric fields nd round currens fll ino he ceory of noise nd ofen cuse serious errors in low power circuis. Usully conducin edi eneres inernl noise wihou curren flow. [4] One coon noise ceory is resisor herl noise, which is he noise developed in resisor in he bsence of curren flow, ofen referred o s Johnson noise. This noise is enered in resisor independen of ny curren flow nd hs en-squre vole 4 KTR BW. vlue of ( ) In his expression k is Bolzn s consn, T is eperure in derees Kelvin, R is resisnce in Ω, nd BW is bndwidh, in Hz. In prcice, here is lwys soe prsiic cpcince cross he leds of resisor due o he prined circui bord or led wire connecions. For his siuion, when he herl noise in resisor is shuned by non-zero cpcince, he en-squre vole vlue is iven by KT. C Teperure nd resisor vlues cn no lwys be iniized; however, usin sinl condiionin odules wih sll bndwidh uli-pole low-pss filers will ensure h exernl herl resisor is essenilly eliined. [4] 9

10 4.2 Elecroneic Inerference RFI is n elecroneic rdiion or inerference which is eied by elecricl circuis crryin rpidly chnin sinls s by-produc of heir norl operion. I cuses unwned sinls in he for of inerference or noise which in urn is o be induced in oher circuis. This inerrups, obsrucs derdes or liis he effecive perfornce of hose oher circuis inside he syse. EMI cn be induced inenionlly, or uninenionlly, s resul of spurious eissions nd responses, iner-odulion producs, nd he like. Fiure 1: EMI Propion Model: (1) Conducion ode, (2) Rdiion ode, (3) Conducion ode Rdiion ode nd (4) Rdiion ode Conducion ode The efficiency of he rdiion is dependn on he heih bove he round or power plne; RF one is s ood s he oher, nd he lenh of he conducor in relionship o he wvelenh of he sinl coponens eiher he fundenl, hronic or rnsien (overshoo, undershoo or rinin). A lower frequencies, such s 133, rdiion is los exclusively vi I/O cbles; RF noise es ono he power plnes nd is coupled o he line drivers vi he V CC nd round pins. The RF is hen coupled o he cble hrouh he line driver s coon ode noise. Since he noise is coon ode, shieldin hs very lile effec, even wih differenil pirs. The RF enery is cpciively coupled fro he sinl pir o he shield nd he shield iself does he rdiin. A hiher frequencies, usully bove 500, rces e elecriclly loner nd hiher bove he plne. Two echniques re used hese frequencies: wve shpin wih series resisors nd ebeddin he rces beween he wo plnes. If ll hese esures sill leve oo uch RFI, shieldin such s RF skes nd copper pe cn be used. 4.3 Power Supply Inerference Swichin power supplies cn be source of RFI, bu hve becoe less of proble s desin echniques hve iproved. Noise which is conduced or rdied should be prevened fro reurnin o he inpu source, where i cn poenilly cuse hvoc on oher devices operin fro he se inpu power. Here EMI filers re uilized o block his noise nd provide low-ipednce ph bck o he noise source. The lrer he noise inerference; he reer is he size, expense, nd difficuly of he filer o be desined. Power supplies h opere fixed frequency hve heir lres EMI eission his fundenl, fixed frequency. Eissions lso occur uliples of he swichin frequency bu diinished pliudes. 10

11 4.4 IC / Pcke Desin The IC pckin of coponen or n ASIC could cuse cerin ouns of herl noise. The IC pcke desin ffecs he equivlen herl resisnce enered noise. Below is ble h shows differen pckin desins nd coprison beween differen herl resisnces. Pcke RhJC RhJC Sill Air RhJC 0.5 /s RhJC 2.0 /s (K/W) (K/W) (K/W) (K/W) DIP SOIC PLCC QFP BGA Tble 2: IC Pckin nd Therl Resisnces [5] 4.5 PCB nd Coponen Plceen The PCB connecs elecronic pssive/cive coponens such s rnsisors, diodes, cpciors resisors, oscillors nd ICs. The rouin of he rces on he PCB lrely ffecs he elecroneic copibiliy perfornce of he PCB wih respec o boh elecroneic rdiions nd suscepibiliy o elecroneic fields. In order o e PCB on which he circuis funcion properly, he rce rouin, he plceen of coponens/connecors nd he decouplin used wih cerin ICs will hve o be opiized. Elecroneic inerference cn be rnsferred by elecroneic wves, conducion, nd inducive/cpciive couplin. This inerference us rech he conducors in order o disurb he coponens. This ens h he loops, lon lenh nd lre surfce of he conducors re vulnerble o EMI, kin he PCB he principle subjec of EMC iproveens. The followin equion shows he relionship of curren, is loop re, nd he frequency o elecric field which is in (V/): 2 1 E = kiaf sinθ r Where k is he consn of proporionliy, I is he curren in peres, A is he loop re in 2, f is frequency in, r is he disnce nd θ is he nle. And since he disnce o he round plne is usully fixed due o bord sckup requireens, iniizin rce lenh on he bord lyou is crucil o decresin eissions. [6] 11

12 4.6 Clock nd D Conrollin clock nd d EMI issues hs reined chllene for he elecronics desiner, look he oriin of his noise shows h he diil syse clock is he lres conribuor. This is undersndble boh becuse he frequency of he syse clock is ofen he hihes of ll he sinls in he syse, nd becuse i is usully periodic squre wve. The frequency specru of such sinl consiss of fundenl one of hiher pliude hn he hronic ones, whose pliudes diinish s frequency increses. Oher sinls wihin he syse (e.., hose on he d nd ddress buses) re upded he se frequency s he clock, bu occur irreulr inervls nd re uncorreled. This resuls in brodbnd noise specru of uch lower pliude hn he clock. Alhouh he ol enery in his specru is uch lrer hn he clock enery, i hs lile effec on he EMI ess. In hese ess, he hihes specrl pliude is wh is looked nd no he ol rdied enery. The clock or d sinl y cuse n elecroneic inerference, rnsiion ie of he pulse fro off o on nd vise vers is he os iporn fcor in deerinin he specrl conen of he pulse. Fs rnsiion ies enere wider rne of frequencies hn do slower rnsiion ies. The specrl conen of diil devices enerlly occupies wide rne of frequencies nd cn lso cuse inerference in elecricl nd elecronic devices. [7] 4.7 Groundin Desin I is iporn o relize h here re severl purposes of round syse. The concep of round s bein zero-poenil surfce y be pproprie dc or low frequencies, bu i is never in hiher frequencies, since conducors hve sinificn ipednce (inducnce) nd hih frequency currens flow hrouh hese ipednces, resulin in poins on he round hvin differen hih frequency poenils. There re bsiclly wo jor philosophies rerdin sinl round schees: sinle poin round syses nd uli-poin round syses, here re oher ypes of round syses h re used less frequenly nd in specil cses. These re referred o s hybrid round syses, nd re cobinion of he previous wo syses over differen frequency rnes Sinle Poin Ground Syse A sinle poin round syse is one in which subsyse round reurns re ied o sinle poin wihin he subsyse. The inen in usin sinle poin round syse is o preven currens of wo differen subsyses fro shrin he se reurn ph nd producin coon-ipednce couplin. [7] Typiclly, sinle poin round syses re used in nlo sub-syses, where low-level sinls re involved. In hese cses, illi-vol nd icrovol round drops cree sinificn coon-ipednce couplin inerference probles for hose circuis. Diil 12

13 sub-syses on he oher hnd re inherenly iune o noise fro exernl sources; however hey re suscepible o inernl noise. In order o iniize his coonipednce couplin, he round syse in diil sub-syses ends o be uli-poin, usin lre round plne such s in inner plne such s in inner plne bord or plcin nuerous lerne round phs in prllel such s wih round rid, hus reducin he ipednce of he reurn ph. I is lso iporn o roue he sinl conducors in close proxiiy o he round reurns, since his will lso reduce he ipednce of he reurn. Fiure 2: Sinlpoin round syse: Coon Ipednce Couplin in disy chin connecion Fiure 3: Sinlpoin round syse: Uninenionl couplin beween round wires Mulipoin Ground Syse The oher ype of round syse philosophy is he ulipoin round syse. Typiclly lre conducor, ofen he round plne, serves s he reurn in ulipoin round syse. In such syse he individul rounds of he sub-syses re conneced differen poins o he round conducor. In usin ulipoin round syse i is ssued h he round reurn o which he individul rounds re erined hve very low ipednce beween ny wo poins he frequency of ineres. [7] Fiure 4: Mulipoin round syse: Idel cse 13

14 4.8 Inerference Deecion Procedures There re severl ehods used o deerine rdied EMI in syse. Soe coon ehods eployed in indusry re OTA esureens, EMI screenin, probin or sniffin nd cul sofwre ess perfored by he obile phone. Below is buled sury of he possible esureen nd invesiion scenrios proposed for his projec. On he rih side of ech esureen or invesiion scenrio is he reson why i should be perfored. Mesureens nd Invesiions Resons Screenin for EMI To loce possible sources of elecroneic rdiion nd reions of hih EMI. A ehod used o deerine which coponens conribue o EMI in differen odes. Exinin CLK/D sinls on PCB To deerine possible loops, sources of crosslk, sinl couplin coponens nd oscillor/clock sinl hronic inerferences. Specrl nlysis of inerferences in differen odes To find ou rdied frequencies nd physiclly loce coponens; he sources of inerferences. This ehod is lso clled sniffin. OTA Mesureens (BER RX / Sensiiviy) To find he effec of inerference on RX sensiiviy / BER in rel life scenrios where he phone is conneced o nework. Tble 3: Differen Mesureen nd Invesiion Scenrios 14

15 5 Possible Soluions This chper describes uidelines on how o ckle he proble of EMI inernl o he syse. EMC describes he biliy of elecronic nd elecricl syses or coponens o funcion correcly when hey re close oeher. In prcice his ens h he elecroneic inerference fro ech device us be liied nd lso h ech device us hve n deque level of iuniy o he inerference in is environen he se holds in icro-level where coponens inside he device iself inerfere wih ech oher. There re soe eiers whose eissions cn serve uninenionl rdiion; hese eied sinls re rerded s inerference sinls or EMI. In enerl here re hree in ehods o preven his inerference; oher ehods re described in he followin secions nd in ore deil: Suppress he eission Mke couplin ph s efficien s possible. Mke he recepor less suscepible o he eission. The os iporn concep is o suppress he eission s uch s possible he source. For exple, we cn deerine h fs rise/fll ies re priry conribuors o he hih-frequency specrl conen of hese sinls. In enerl hiher he frequency of he sinl o be pssed hrouh he couplin ph he ore efficien he couplin ph. So we should slow he rise/fll ies of he diil sinls o iprove he efficiency of he couplin ph hus reduce EMI. One cn no slow he rise/fll ies wihou considerin he norl operion sinlin condiions required by vrious devices dependn on hose sinls. By reducin he hih-frequency specrl conen of n eission ends o inherenly reduce he efficiency of he couplin ph nd hence reduces he sinl level he recepor. Oher brue force ehods re vible, bu he cos-effeciveness is quesionble. For exple, plcin he recepor in el enclosure or shield will serve o reduce he efficiency of he couplin ph. Bu shielded enclosures re ore expensive hn reducin he rise/fll ie of he eier, nd soeies he resulin perfornce is fr less hn he idel. [7] 5.1 Lyou & Plceen of Coponens Durin he PCB desin phse, he lyou desiner should foresee he need of suppression for soe clock hronics in he fuure when he produc is evenully esed for coplince. If he PCB desiner plces pds he oupu of he clock on he PCB, cpcior cn be esily insered, cross he clock erinls, hus reducin he eissions of he clock. Also pds y be plced in series wih he rce of clock oupu o provide for ler inserion of series resisor o ddiionlly reduce he clock 15

16 rise/fll ies nd furher reduce he hih frequency eissions of he clock sinl. In he iniil desin he cpcior pds cn be lef vcn nd he series resisor pds cn be wired cross wih 0 Ω resisor. If probles wih he clock eissions occur durin esin, cpcior cn be insered nd only he PCB rwork nd he produc prs lis needs o be chned. If his is no done, he enire PCB would need o be rlid ou, hus by dherin o cerin desin principles nd ininin he necessry EMC insih hrouhou he desin will end o ke he necessry suppression esy o pply nd inil expense. For echnicl resons, i is bes o use uli-lyer prined circui bord wih sepre lyer dediced o he round nd noher one o he V DD supply, which resuls in ood decouplin, s well s ood shieldin effec. For ny pplicions, econoicl requireens prohibi he use of his ype of bord. In his cse, he os iporn feure is o ensure ood srucure for he round nd power supply. [7] The lyou of diil loic bord cn hve sinificn effec on is perfornce. The edes of he wvefors bein very fs, he frequencies h re conined wihin wvefors re priculrly hih. Accordinly leds should be kep s shor s possible if he circui is o be ble o perfor correcly. A preliinry lyou of he PCB us sepred he differen circuis ccordin o heir EMI conribuion in order o reduce cross couplin on he PCB, i.e. noisy, hih-curren circuis, low vole circuis nd diil coponens. There re lso soe enerl uidelines o iniize EMI wih ood coponen plceen, like: Plce ll coponens ssocied wih one clock rce closely oeher o reduce he rce lenh nd reduce rdiion. Keep oscillors, nd clock enerors wy fro I/O pors nd bord edes, EMI fro hese devices cn be coupled ono he I/O pors. Plce hih-curren devices s closely s possible o he power sources. [6] 5.2 Groundin Soluions For circui bord rounds, i is los ipossible o e ood low-ipednce rounds on wo-sided circui bords, so i is criicl o keep ESD currens nd hih-level rdiofrequency inerference off such bords. On he oher hnd, i is esy o chieve low ipednces wih he round plne underneh he rces on ulilyer bords. Circuis buil iediely bove he round plne re well proeced, rerdless of he hre. EMI probles re frequenly he resul of hih-ipednce inerconnecs. Ain, desiners need o keep he round ipednce low; eiher by connecin he circui bords or odules o coon round plne or by providin very-low-ipednce round inerconnecs, usully by llocin s ny connecor pins o rounds s possible. Alhouh he connecor spce is n iporn concern, so is funcionliy. [8] 16

17 5.3 EMI Suppression by Filerin The os iporn ens of reducin elecroneic inerference re: he use of bypss or decouplin cpciors on ech cive device conneced cross he power supply, s close o he device s possible, or conrol he rise ie of hih speed sinls usin series resisors nd V CC filerin. Shieldin is usully ls resor fer oher echniques hve filed becuse of he dded expense of RF skes nd he like. EMI suppression filers re used o suppress noise produced by conducors. Noise rdiion cn be suppressed, if i is eliined wih filer in dvnce. Generlly, such noise suppression is chieved wih DC EMI suppression filers, ccordin o he cpciive nd inducive frequency chrcerisics of he respecive conducors in he circui. Filers of his kind cn be rouhly divided ino hose; eployin cpcior, n inducor or cpcior nd inducor cobinion. When decouplin cpcior is conneced fro noisy sinl line or power line o round; he circui ipednce decreses s he frequency increses. Since noise is hih frequency phenoenon, i flows o round if cpcior hs been conneced o round, hereby kin i possible o eliine noise, see fiure below. EMI suppression filers eployin cpcior in his wy re used o eliine his ype of noise (See Fiure 6). Fiure 5: Cpciive Noise Suppression Z = 1 2πfC where f is he frequency nd C is he vlue of he cpcince. When n inducor is insered in series in noise producin circui, see fiure below, is ipednce increses wih frequency. In his confiurion i is possible o enue nd eliine noise coponens which re he hih frequency coponens found in he sinl. (See Fiure 7) Fiure 6: Inducive Noise Suppression Z = 2πfL where f is he frequency nd L is he vlue of he inducnce. If cpciive nd inducive suppression chrcerisics re cobined, i is possible o confiure uch hiher perfornce filer. In sinl circui pplicions where his 17

18 cobinion is pplied, noise suppression effecs which hve lile influence on he sinl wve for becoe possible. This ype of filer is lso effecive in he suppression of hih-speed sinl circui noise. When used in DC power circuis, cpciivinducive filers preven resonnce fro occurrin in peripherl circuis, hus kin i possible o chieve sinificn noise suppression under norl service condiions Noise Suppression usin Hiher Order Filers The order of he filer deerines he shrpness of he risin ede of he processed sinl, ccordin o he siulions perfored i urned ou h he hiher he filer order, he slower is he risin ede, hus hiher order filers ih cuse inpu/oupu driver no ee specificions nd hve sinl ineriy probles. Also in hiher order filer siulions he bes risin ie in cerin order of filer is differen for differen odels of he se filer ype (e.. for 3 rd order filers: he risin ie ws he bes for he Buerworh Pi-odel filer, while for he T-odel filer he Chebyshev I filer ws he bes.) To hve n ide bou differen filerin opoloies, sinl wvefors nd EMI Suppression effec. [See Appendix B] The ble below describes differen filerin soluions on rnsission line hvin specific lenh nd driver echnoloy drivin he inpu/oupu of he rnsission line: Type of Filer Sinl Wvefor EMI Suppression Effec Sinl Risin/Fllin Ede & Noise Specru before/fer filer Mounin 1s Order Chebyshev I PB Ripple = 1dB GHz Sinl Risin/Fllin Ede & Noise Specru before/fer filer Mounin 3rd Order Chebyshev I PB Ripple = 1dB GHz Sinl Risin/Fllin Ede & Noise Specru before/fer filer Mounin 5h Order Chebyshev I PB Ripple = 1dB Tble 4: Differen Chebyshev Filerin Soluions GHz

19 5.3.2 Disorion suppression usin filers There re ny ehods h cn be used o reduce disorion in sinl. The ble below describes bsic ehods for disorion suppression: series resisive erinion nd RC filerin soluions h reduce he rinin effec nd disorion of clock sinl iprovin is sinl ineriy. Type of Sinl EMI Suppression Effec P P Iniil wvefor V Series resisor erinion pplied / wvefor rinin effec reduced. V RC filerin soluion pplied / wvefor disorion is suppressed V Tble 5: Differen Disorion Suppressin Soluions 19

20 5.4 Shieldin Soluions I is for of coninen used o prevenin RF enery fro exiin n enclosure, enerlly by shieldin produc wihin el enclosure or by usin plsic housin wih RF conducive pin. By reciprociy, we cn lso spek of coninen s prevenin RF enery fro enerin he enclosure. Therefore shield is, concepully, brrier o rnsission of elecroneic fields, see fiures below. Fiure 7: Shield h Conins Rdied Eission Fiure 8: Shield h Excludes Rdied Eission In order o relize n effecive shieldin, he shield us enclose he elecronics, nd us hve no penerions such s holes, ses or slos. [7] 20

21 6 RSSI Mesureens In his chper we exine he criicl inerference scenrios in differen operion odes; esureen resuls re presened in he noise specru plos. Vrious possible scenrio cobinions were enuered; ol of 52 cses were invesied; nd only he criicl scenrios re presened in noise specru plos. 6.1 Mesureen Scenrios Differen esureens scenrios were invesied; soe cses were discrded since hey do no occur in rel life. So fer filerin ou ll he non-occurrin scenrios nd he ones h cn no be esured OTA, only hree cses reined hvin criicl levels of inerference in he GSM bnd in ddiion o he reference scenrios. 21

22 6.2 Mesureens where Cers Acive/Incive & Anlysis EGSM 900 Specru EGSM 900 Specru RSSI of chnnel X: 936 Y: RSSI of chnnel X: 936 Y: Chnnel Frequency in Fiure 9: Noise Specru (Cers Incive Bcklih ON Flsh OFF) EGSM 900 Specru Chnnel Frequency in Fiure 10: Noise Specru (Cers Incive Bcklih OFF Flsh OFF) EGSM 900 Specru RSSI of chnnel X: 936 Y: -101 X: 949 Y: -107 RSSI of chnnel X: 936 Y: X: 949 Y: X: Y: Chnnel Frequency in Fiure 11: Noise Specru (VGA CAM Acive - Bcklih OFF - Flsh OFF) Chnnel Frequency in Fiure 12: Noise Specru (2MPx CAM Acive Bcklih Off Flsh OFF) EGSM 900 Specru RSSI of chnnel X: 936 Y: -101 X: 949 Y: -103 X: Y: Chnnel Frequency in Fiure 13: Noise Specru (2MPx CAM Acive Bcklih On Flsh Off) In he firs wo cses here were no hih levels of inerference, only sinle 13 hronic ppered 936 bu i hd neliible inerference srenh. Fro severl scenrios only hese hree cses were chosen o perfor furher invesiions on. (See fiures 12, 13 nd 14) 22

23 6.3 Mesureens in presence of WLAN & Anlysis In presence of WLAN rnsissions n inerference ws noiced in he DCS bnd lower WLAN rnsission chnnels (chnnels 1 o 7), his inerference level diinished in srenh s rnsission ws hiher chnnels. The levels of inerference re uch below he hreshold level. EGSM 900 Specru -80 DCS 1800 Specru RSSI of chnnel RSSI of chnnel in db X: 1872 Y: Chnnel Frequency in Fiure 14: Noise Specru (WLAN TX1 - Bcklih OFF - Flsh OFF in EGSM900) Chnnel Frequency in Fiure 15: Noise Specru (WLAN TX1 - Bcklih OFF - Flsh OFF in DCS1800) EGSM 900 Specru DCS 1800 Specru -85 RSSI of chnnel X: 936 Y: -111 RSSI of chnnel in db X: 1872 Y: Chnnel Frequency in Fiure 16: Noise Specru (WLAN TX7 - Bcklih OFF- Flsh OFF in EGSM900) Chnnel Frequency in Fiure 17: Noise Specru (WLAN TX7 - Bcklih OFF - Flsh OFF in DCS1800) EGSM 900 Specru DCS 1800 Specru RSSI of chnnel X: 936 Y: -109 RSSI of chnnel in db X: 1872 Y: Chnnel Frequency in Chnnel Frequency in Fiure 18: Noise Specru (WLAN TX13 - Bcklih OFF - Flsh OFF in EGSM900) 23 Fiure 19: Noise Specru (WLAN TX13 - Bcklih OFF - Flsh OFF in DCS1800)

24 7 OTA Sensiiviy Mesureens In his chper we invesie he sensiiviy of he receiver in he hree differen scenrios s seleced in he previous chper where hih levels of inerference exis. Over-hir ess deerine how specific nework will influence he conneciviy perfornce of obile hndse. I cn yield d h cn be used o deonsre h produc ees perfornce crieri. Over-hir perfornce ess esure he niude nd direcion of rnsied/received enery, sensiiviy nd BER o deerine he perfornce of he wireless device. A ypicl polr pern confiurion is obined wih he esureen nenn(s) fixed he nenn under es is roed hrouh 360. [9] In OTA ess i is iporn o deerine he influence of he user s body on he rnsceiver properies nd perfornce nd he differences beween frespce nd he sndrd nhropoorphic odel. SAM phno ess deerine he blockin effec of he hun hed on he nenn pern, bu do no ddress rdiion bsorpion, hzrd or helh nd sfey issues [9]. Below is ypicl OTA es syse. Nework Anlyzer Specru Anlyzer Device Under Tes (DUT) Dionl dul polrized horn Universl Rdio Counicion Teser Rely Swich Uni wlkwy ` MAPS Conroller Fibre Opics MAPS syse Fiure 20: DUT in Typicl OTA Tes Syse To hve relible chnnel sensiiviy scn, we cquired he vere of 5000 sples of d; hreshold BER of percen in order for he cll no o be disconneced. Trnsission fro he MS ws perfored inil power o reduce bery consupion for loner hours of esureen. The sr level of scnnin ws db for he sofwre o be ble o loce inerference peks below his level in fser seek ie. 24

25 The DUT ws posiioned in lk posiion so s o eule cul siuion where here re reflecions fro he hun hed, lhouh we could no perfor esureens considerin he hun hnd effec. We cn ssue h he obined resuls in lk posiion will be he wors cse, since reflecions will be direcly hedin owrds he nenn, so no need o consider he oher cse. Fiure 21: DUT in Tlk Posiion 7.1 Mesureen Procedure Iniilly we sred wih bsic scn of every enh chnnel of he EGSM bnd, fer obinin he resuls of he firs pss we de second pss kin ore sples djcen o he inerference chnnels. Finlly we scnned exr chnnels s resul of he sniffin resuls discussed in he followin chper. We obined bou 42 chnnels ou of 174 chnnels which consiues 24 percen of he ol chnnels for he firs cse. We hd 27 chnnels which consiue 16 percen of he chnnels in he bnd nd for he second cse, bu for he ls cse only 17 chnnels which consiue bou 10 percen of he chnnels were required since his cse is reference. These percenes were fir enouh o cover ll he possible inerference frequencies. The firs nd second cses hd he 2MPx cer cive, nd he bcklih on or off respecively. The hird ws reference cse used o deerine he vere sensiiviy of he bnd when he cers nd bcklih re off. 25

26 7.2 Mesureen Resuls nd Anlysis For differen DUTs we obined differen inerference levels frequency on he EGSM900 bnd (Fiures 24 & 25). This ws due o he loose shield of he 2MPx cer, which ws no coninin rdied eissions of he cer MCLK_2M nd is inernl oscillor. Resisnce esureens were perfored beween he shielded boxes nd he inerference disppered when ore pressure ws pplied or 2MPx shield box chned. This inerference nd he oher 13 hronic frequency inerferences were blocked nd suppressed in he soluions chper. EGSM 900 Specru EGSM 900 Specru X: Y: X: 936 X: 936 Y: Y: Sensiiviy of chnnel X: Y: X: 949 Y:.8 Sensiiviy of chnnel X: Y: X: 949 Y:.8 X: Y: Chnnel Frequency in Chnnel Frequency in Fiure 22: Noise Specru wih Good Shield (2MPx CAM Acive Bcklih ON Flsh OFF) Fiure 23: Noise Specru wih Loose Shield (2MPx CAM Acive Bcklih ON Flsh OFF) EGSM 900 Specru Sensiiviy of chnnel X: 936 Y: X: 948 Y: X: Y: Chnnel Frequency in Fiure 24: Noise Specru (Cers Incive Bcklih ON Flsh OFF) In he esureen resuls bove hih levels of inerference were noiced 936 nd 949 ; he bcklih hd soe conribuion in he inerference hese frequencies. 26

27 EGSM 900 Specru RSSI of chnnel X: 936 Y: Chnnel Frequency in Fiure 25: Noise Specru (Cers Incive Bcklih OFF Flsh OFF) This cse is reference used o deerine he vere sensiiviy levels he receiver when he cers, bcklih nd flsh re off. 27

28 8 Sniffin Mesureens In n elecronic syse, he priry eission sources re currens flowin in circuis like clocks, d drivers, oscillors nd oher coponens h re ouned on prined circui bords. Alhouh he rdied esureens in he lborory environen cn no be ccure enouh, i is possible o esblish iniu sup in he lb which one cn perfor eissions dinosis nd crry ou coprive ess. Anlyzin he d obined fro he sniffin esureens, we noiced h severl coponens eiin inerference sinls bove cerin hreshold level. In his chper we ry o hihlih hese coponens nd describe he key inerferences. Probin or sniffin is esureen ehodoloy used o physiclly loce he source of eissions fro produc. Afer dechin exernl echnics of he DUT, nd scnnin is inernl coponens usin probe or sniffer loop nenn. The eission specru cn be observed hrouh he specru nlyzer, nd relive eission srenh cn be concluded. The dvne of sniffin is h he source of inerference cn be direcly loced on he PCB, he disdvne is h he inerference pliude is dependn on he disnce beween he probe nd he coponen, so ny vriion in he disnce cuses n unceriny in he pliude of he cul inerference, cusin he pek vlue of he inerferin sinl vry. Fiure 26: Specru Anlyzer A ner-field or sniffer probe ws used o physiclly loce he source of eissions fro he produc, since we only wn o deec he field srenhs in he ner field. The probe is conneced o he specru nlyzer for frequency doin disply. desin is rdoff beween sensiiviy nd specil ccurcy. The sller he probe, he ore ccurely i cn loce sinls bu he less sensiive i will be. The sensiiviy cn be incresed wih preplifier if workin wih low power circuis. The su of rdiin sources will differ beween ner nd fr fields nd he probe will iself disor he field i is esurin. Perhps one ih iske priculr ho spo 28

29 found on he circui bord for he cul rdiin poin, wheres he rdiion is in fc coin fro cbles or oher srucures h re coupled o his poin vi n ofen coplex ph. Thus probes re bes used for rcin nd for coprive rher hn bsolue esureens [10]. 8.1 Mesureen Procedure Sniffin esureens re perfored in shielded chber o void exernl inerferences. The device hs is exernl echnics deched o expose he priry nd secondry lyers. Before he deiled sniffin esureens, fs prscn hrouh is perfored o loce jor peks or inerference frequencies. This enorously speeds up he sweep re for whole frequency scn. 8.2 Mesureen Cses Bsed on he RSSI esureen resuls of he previous phses of he projec, nd fer droppin he unnecessry cses, we were lef wih hree cses for he secondry lyer nd wo cses for he priry lyer s shown in he ble below. Device sides Secondry Priry 2MPx Cer Bcklih Flsh Incive ON OFF Incive OFF OFF Acive ON OFF Incive ON OFF Acive ON OFF Tble 6: Sniffin Mesureens on Priry nd Secondry Sides 29

30 8.3 Mesureen Resuls nd Anlysis On he priry side of he PCB new frequency of inerference ws found h did no pper in he previous esureen resuls, his frequency ppered fer he prscn perfored on differen coponens of his side of he PCB. Thus he new sniffin specrl scns were bsed on four frequencies, 936, 943.6, 949 nd On his side os of coponens were covered wih shieldin boxes which were quie effecive o block eissions of inernl coponens o he exerior nd vice vers. So he esureens were inly done on he uncovered coponens loced on he PCB nd he flex cbles. Mny djcen peks pper round he cener frequency, especilly 936 nd in (2MPx C cive Bcklih On Flsh OFF) cse. Bu hose djcen peks disppered when cers nd bcklih were off. Also on his lyer, new pek frequency ws lso found This inerference ws inly conribued by cpcior, n inducor nd he flex cble beween PCB /LCD nd he cpciors h re plced on he flex cble. The wo e pixel cer s shieldin box ws loose, so while sniffin hih levels of eission were observed. While on he secondry side nd fer exinin he obined resuls we noiced h he 2 pixel cer when cive will cuse ore inerference; no only on he key inerference chnnels, bu lso is djcen chnnels. Siilrly he bcklih will conribue in risin he inerference o hiher levels, bu will no inroduce oher inerference frequencies in he specru. On he secondry side here re wo key coponens h conribue o hih levels of inerference, hese coponens re diodes. The firs one cuses very hih pek 936 (-88.56dB ~.03dB) for ll hree cses, hih pek (-93.29dB ~ dB) 949 nd lso hih pek (.73dB) The second one cuses very hih pek nd noise floor in cerin cses. Only when cer, bcklih nd flsh re ll off, he noise floor flls bck o norl vlue (round db). Noe h he noise floor cn no be esured fro he specru nlyzer direcly, so his vere vlues re only esies. 30

31 8.4 Sources of Unceriny Rdied inerference, wheher inenionl or no, decreses in srenh wih disnce fro he source. For rdied fields in free spce, he decrese is inversely proporionl dis n ce < λ o he disnce provided h he esureen is de in he ner field 2 π. EMC esureens re inherenly less ccure hn os oher ypes of esureens. I is lwys wise o llow rin of bou 10dB beween esureens nd he specificion liis, no only o cover esureen unceriny bu lso olernces risin in producion. These uncerinies could rise fro differen fcors such s: insruen nd cble errors, isch errors in cble ipednce, nenn clibrion issues, reflecions no only fro DUT bu lso fro he round plne nd nenn cble. Thus we cn sy h he rdied esureens in he lborory environen cn no be ccure enouh, bu i is possible o perfor eissions dinosis nd crry ou coprive ess bsed on he resuls obined hrouh hese esureens. Perforin sniffin esureens on he produc helps o physiclly loce he sources of eission. Alhouh he rdied esureens cn no be ccure enouh, one cn crry ou coprive ess nd observe he key inerference coponens. [10] 31

32 9 Recoended Soluions 9.1 LCD Disply D/Conrol lines A cuse of EMI could be he CLK sinl oin in/ou of connecor fro PCB o flex cble. For his cse we ried o pu decouplin cpciors on he d lines, bu he EMI conribuion of his secion seeed o be quie neliible on he GSM receiver due o he disnce fro he receiver nenn. Thus his soluion did no solve he inerference proble. Also we ried o use copper pe o shield he flex cble, bu no iproveen in he sensiiviy of he receiver ws noiced. Fiure 27: A soluion for D/Conrol lines beween PCB nd LCD disply 9.2 Rdied Eissions fro Flex Cbles While sniffin he LCD, VGA CAM nd 2MPx CAM flex cble, hih levels of inerference ws found on 936 frequency. The inerference conribuion of he flex cbles ws noiceble in OTA sensiiviy esureens lso. The soluions provided could no be ipleened on he flex cbles, only soluions were done on he PCB. 32

33 9.3 Iproper Groundin of Shield Boxes For he esureens perfored in he ble below we used diil uli-eer, wo probes nd he DUT. We hd he exernl echnicl cover of he device reoved in order o ccess he inernl shield boxes nd perfor deiled esureens. Copred o he older DUTs he new shields required ore pressure o be pplied in order o e beer conc wih round, hus for ny reson lesser pressure resuled in hiher inerference levels cerin frequencies. DUT 1 Hih resisnce beween he wo poins: 22.5 Ω (2 MPx Cer Shield box RF Shield box) DUT 2 Hih resisnce beween he wo poins: 46 ~ 68 Ω (2 MPx Cer Shield box RF Shield box) DUT 3 Lower resisnce beween he wo poins:2 ~ 3 Ω (2 MPx Cer Shield box RF Shield box) Tble 7: Iproper Groundin of 2MPx CAM Shield Box The proble of inerference ws solved by chnin he shield box in ler ses. 33

34 9.4 2MPx CAM Subsyse Inerferences This secion includes siulion resuls usin Menor Grphics Hyperlynx sofwre, possible soluions o he MCLK_2M rce line were proposed nd hese soluions were ipleened nd verified o be consisen wih he siulion resuls. Meein he specificions of he wo e pixel cer (risin ie/slew re liiions) ws he chllene. In his cse he specificions were no e fer pplyin soluions, bu he cer ws funcionl. CAM_DAT[i] CAM_DAT[i] CAM_DAT[i] CAM_DAT[i] CAM_DAT[i] CAM_DAT[i] CAM_DAT[i] CAM_DAT[i] n MCLK_2M PIX_CLK Oher_CLK Fiure 28: D/CLK lines beween PCB nd 2MPx CAM We ried o pply differen filerin soluions o he MCLK_2M in order o reduce he EMI resulin fro he clock line nd is hronics. The ppendix includes differen filerin ypes (Buerworh, Chebyshev, Bessel nd Leendre filers), opoloies (-odel nd pi-odel) nd orders (1 s, 3 rd nd 5 h ). These resuls were copred nd conclusion ws de in secion

35 9.4.1 Siulions Type of Filer Sinl Wvefor EMI Suppression Effec MCLK_2M wih decouplin cpcior of 33pF GHz MCLK_2M wih series erinion of 22 Ω nd decouplin cpcior of pF GHz Pr Pr MCLK_2M wih resisive erinion of 220 Ω GHz Tble 8: Soluions Verificion for MCLK_2M 35

36 9.4.2 Oscilloscope Mesureens The oscilloscope esureens resuls were siilr o he siulion resuls, only he fllin ede hd 1ns dely. In he fiure below he fses risin ede resebles he oriinl MCLK_2M sinl; he oher wo re he risin edes fer pplyin he 33 pf cpcior nd he one wih he 22 Ω nd 22 pf RC filerin soluions. Fiure 29: Oscilloscope Mesureens of MCLK_2M Rise Ties 36

37 9.4.3 RSSI Resuls & Anlysis Oriinl MCLK_2M Sinl EGSM 900 Specru EGSM 900 Specru X: 936 Y: -98 X: 936 Y: -99 X: Y: -101 RSSI of chnnel X: Y: -104 RSSI of chnnel X: Y: -106 X: Y: Chnnel Frequency in Chnnel Frequency in Fiure 30: Noise Specru (2MPx CAM Acive Bcklih Off Flsh OFF) Fiure 31: Noise Specru (2MPx CAM Acive Bcklih ON Flsh OFF) For boh cses he inerference level 936 ws -98 ~ -99 db nd 949 ws -104 ~ -106 db, he inerference Mhz ws excluded since he shield box coverin he 2MPx cer olly discrds i when properly rounded. MCLK_2M wih Decouplin Cpcior EGSM 900 Specru EGSM 900 Specru RSSI of chnnel X: 936 Y: -106 RSSI of chnnel X: 936 Y: -107 X: 949 X: 949 Y: X: 957 Y: -111 Y: X: Y: Chnnel Frequency in Chnnel Frequency in Fiure 32: Noise Specru (2MPx CAM Acive Bcklih Off Flsh OFF) Fiure 33: Noise Specru (2MPx CAM Acive Bcklih On Flsh OFF) For boh cses he inerference level 936 ws -106 ~ -107 db nd 949 ws db, hus resulin in inerference reducion of 8dB 936 nd 4 ~ 6 db

38 MCLK_2M wih series Resisive Terinion nd Decouplin Cpcior EGSM 900 Specru EGSM 900 Specru RSSI of chnnel X: 936 Y: -106 X: 949 RSSI of chnnel X: 936 Y: -107 Y: -108 X: 949 Y: Chnnel Frequency in Chnnel Frequency in Fiure 34: Noise Specru (2MPx CAM Acive Bcklih Off Flsh OFF) Fiure 35: Noise Specru (2MPx CAM Acive Bcklih On Flsh OFF) For boh cses he inerference level 936 ws -106 ~ -107 db nd 949 ws -108 ~ -109 db, hus resulin in inerference reducion of 6dB 936 nd 3 ~ 6 db 949. MCLK_2M wih series erinion EGSM 900 Specru EGSM 900 Specru X: 936 RSSI of chnnel Y: -104 X: 949 Y: -108 X: 936 Y: -103 RSSI of chnnel X: 949 Y: Chnnel Frequency in Chnnel Frequency in Fiure 36: Noise Specru (2MPx CAM Acive Bcklih Off Flsh OFF) Fiure 37: Noise Specru (2MPx CAM Acive Bcklih On Flsh OFF) For boh cses he inerference level 936 ws -103 ~ -104 db nd 949 ws -108 db, hus resulin in inerference reducion of 3 db 936 nd 3 ~ 5 db 949. Accordin o he experienl resuls obined, he soluion of hvin decouplin cpcior of 33pF ws found o be he bes. Noe h he relive esureens were perfored on wo differen devices. 38

39 9.5 VGA CAM Subsyse Inerferences A cuse of EMI could be he CLK sinls oin in/ou of connecor fro PCB o flex cble. Fiure 38: D/CLK lines beween PCB nd VGA CAM Filerin is n efficien wy o decrese clock risin ede, since loner he risin ie, lesser he inerference hiher frequencies bove 500. I is iporn o choose suible vlues for he resisor nd cpcior, since here is rdoff beween risin ie nd noise specru of he sinl. Below is he scheic of he VGA CAM connecor, nd he proposed soluion o suppress he EMI. Fiure 39: A Soluion for D/CLK lines beween PCB nd VGA CAM 39

40 9.5.1 Siulions Fiures 41, 42, 43 nd 44 presen coprison of he noise specru before nd fer ddin RC filerin soluions o he rce involved GHz Fiure 40: Noise Specru before ddin RC filer GHz Fiure 41: Noise Specru fer ddin RC filer (R=33Ω, C=22pf) GHz Fiure 42: Noise Specru fer ddin RC filer (R=220Ω, C=22pf) GHz Fiure 43: Noise Specru fer ddin RC filer (R=0Ω, C=33pf) 40

41 9.5.2 Oscilloscope Mesureens Fiures 45, 46, 47 nd 48 presen he resuls of he oscilloscope esureen of MCLK / PCLK, i is eviden how he resisor nd cpcior vlues effec he risin ie of boh clocks. Noe h he risin ie is red fro 10% ~ 90% risin ie of he sinl. Fiure 44: VGA_MCLK on es poin ¾ (R = 0Ω, C = 33pf) Fiure 45: VGA_MCLK on es poin 4 (R = 33Ω, C = 22pf) Fiure 46: VGA_MCLK on es poin 4 (R = 220Ω, C = 22pf) Fiure 47: VGA_MCLK on es poin ¾ (R = 0Ω, C = 22pf) Tes poin Risin ie(ns) R = 0Ω, C = 33pf Risin ie(ns) R = 33Ω, C = 22pf Risin ie(ns) R = 220Ω, C = 22pf Tble 9: Risin Tie Sury of MCLK_VGA Risin ie(ns) R = 0Ω, C = 22pf

42 Fiure 48: VGA_PCLK on es poin ½ (Iniilly R = 0Ω, no cpcior) Fiure 49: VGA_PCLK on es poin 2 (R = 33 Ω, no cpcior) Fiure 50: VGA_PCLK on es poin 2 (R = 220 Ω, no cpcior) Fiure 51: VGA_PCLK on es poin ½ (R = 0Ω, C = 22 pf) Fiure 52: VGA_PCLK on es poin 2 (R = 220Ω, C = 22pf) Tes poin Risin Tie(ns) R = 0Ω, C = 0pf Risin ie(ns) R = 33Ω, C = 0pf Risin ie(ns) R = 220Ω, C = 0pf Risin ie(ns) R = 0Ω, C = 22pf Risin ie(ns) R = 220Ω, C = 22pf Tble 10: Risin Tie Sury of PCLK_VGA 42

43 9.5.3 RSSI Resuls & Anlysis EGSM 900 Specru EGSM 900 Specru X: 936 Y: -99 RSSI of chnnel X: 949 Y: -107 RSSI of chnnel X: 936 Y: -104 X: 949 Y: Chnnel Frequency in Fiure 53: Noise Specru of Reference Chnnel Frequency in Fiure 54: Noise Specru fer ddin RC filer_1 (MCLK-R 33Ω & C 22pf, PCLK-R 33Ω & C 22pf) EGSM 900 Specru EGSM 900 Specru RSSI of chnnel X: 936 Y: X: 949 Y: RSSI of chnnel X: 936 Y: -103 X: 949 Y: Chnnel Frequency in Fiure 55: Noise Specru fer ddin RC filer on PCLK (MCLK-R 0Ω&C 33pf, PCLK-R 220Ω&C 22pf) Chnnel Frequency in Fiure 56: Noise Specru (2M pixel cer incive VGA cer ON Bcklih OFF) Pek/chnnel Pek(dB)/chnnel Reference -99dB / 5-107dB / 70 Afer decouplin R = 33Ω&C = 22pf -104dB / 5-108dB / 70 Afer decouplin R = 220Ω&C = 22pf db / 5 db / 70 Afer decouplin on PCLK Rpclk = 220Ω&Cpclk = 22pf -103dB / 5 db / 70 Tble 11: Sury of MCLK_VGA & PCLK_VGA Soluions Lrer resisor vlues cn ke ore effecive EMI suppression, by furher dpin he risin ede of he sinl o reduce hiher frequency inerference. Thouh, he iin requireens for he clock risin ede should be ccepble. Accordin o he oscilloscope plos, los no iin rin ws lef for boh clocks wih 220 Ω resisor h will led o he difficuly o ee hold / seup ie requireens for he sensor. 43

44 Fro he noise specru esureen plos we cn deduce h, lower resisor vlues will be beer choice, he 33Ω for resisor nd 22pf for cpcior is fesible choice. This RC filer cn cuse reducion of 5dB Rdied Eissions fro Diodes While sniffin he PCB for rdied eissions, wo diodes ner he RF nenn were suspeced o be possible sources of inerference. By perforin over he ir esureens of he receiver sensiiviy, he rdiion frequencies fro he device were deeced, nd by sniffin he pproxie locion of he eiin coponens were verified Audio subsyse inerferences As resul of he sniffin esureens, wo oher sources of inerference were loced which indiced he presence of RF rdiion proble on he udio circuiry which connecs he bck spekers o he udio power plifier. (Fiure 59) Fiure 57: A Soluion for he Audio Subsyse Inerference These wo diodes re used for voidin ESD. A proposed soluion ws o dd four cpciors C1, C2, C3 nd C4 of 33 pf on he diodes in prllel. These four cpciors re supposed o work o keep he frequency s oriinl becuse hih frequency sinl will o hrouh cpcior insed of diode. Th will be helpful o decrese inerference on hih frequency. 44

45 EGSM 900 Specru EGSM 900 Specru X: 949 Y: -102 RSSI of chnnel X: 936 Y: -104 RSSI of chnnel X: 936 Y: -106 X: 949 Y: Chnnel Frequency in Chnnel Frequency in Fiure 58: Noise Specru of Reference Fiure 59: Noise Specru fer decouplin Pek/chnnel Pek(dB)/chnnel Reference -104dB / 5-102dB / 70 Afer decouplin -106dB / 5 db / 70 Tble 12: Sury of Audio Diode Soluion Before ddin hese cpciors, os of he pek levels of inerference were below -102 db. Afer ddin cpciors, boh he noise floor nd pek vlue decresed by 2~3 db Power subsyse inerferences A proposed soluion ws o dd one decouplin cpcior C5 of 33 pf nd ler o pu series resisor 33 Ω. Fiure 60: A Soluion for Bcklih DC-DC Converer Inerference 45

46 EGSM 900 Specru EGSM 900 Specru RSSI of chnnel X: 936 Y: -102 X: 949 Y: X: Y: -107 RSSI of chnnel X: 936 Y: -102 X: 949 Y: Chnnel Frequency in Fiure 61: Noise Specru of Reference Chnnel Frequency in Fiure 62: Noise Specru fer Soluion Pek/chnnel Pek(dB)/chnnel Reference -102dB / 5 db / 70 Afer decouplin -102dB / 5-103dB / 70 Tble 13: Sury of Power Diode Soluion (2MPx CAM Acive VGA CAM OFF Bcklih OFF) EGSM 900 Specru EGSM 900 Specru RSSI of chnnel X: 936 Y: -104 X: 949 Y: -108 RSSI of chnnel X: 936 Y: -106 X: 949 Y: Chnnel Frequency in Fiure 63: Noise Specru of Reference Chnnel Frequency in Fiure 64: Noise Specru fer Decouplin Pek/chnnel Pek(dB)/chnnel Reference -104dB / 5-108dB / 70 Afer decouplin -106dB / 5-108dB / 70 Tble 14: Sury of Power Diode Soluion (2MPx CAM Incive VGA CAM OFF Bcklih ON) For his priculr soluion, no obvious iproveen ws noiced by ddin decouplin cpcior. 46

47 Conclusion Deecin nd solvin inernl inerference issues in obile phone is foridble nd ineresin sk. I is foridble since i involves n overhed of esureens nd physicl ipleenion of soluions. I is lso ineresin since he pproch of deecin nd suppressin hese inerferences requires undersndin of he overll receiver funcionliy nd requireens. This repor is resul of inensive reserch, heoreicl bckround of possible sources of inerference. Acul esureens were prefored; RSSI esureens were used o quickly deerine he key inerference frequencies, OTA esureens uses ore coplex seup o deerine he receiver sensiiviy hrouh BER evluion of he received sinl nd sniffin esureens o physiclly loce he sources of inerference; o idenify he physicl sources of inerferences, heir effec on he receiver sensiiviy nd overll receiver perfornce. Finlly soluions were recoended nd ipleened o suppress hese inerferences. Soe of he soluions resuled in ood inerference suppression, while ohers hd no obvious iproveen in he sensiiviy of he receiver. Lower order filers were preferred since hey hd beer EMI suppression resuls, wih less EMI he resonnce frequencies. There is lwys rdeoff beween he sinl ineriy nd EMI suppression, one should keep in ind o ee he overll syse requireens nd provide soluions ccordinly. Specil enion should be iven o lyou, he lyou enineer hs o dhere o cerin desin uidelines, nd be ble o foresee fuurisic EMI suppression needs. Shield boxes should be verified o be well rounded so s no o c s nenns. Fuure Work In he fuure invesiions, siulions nd experienion on newer echnoloies wih fser nd ore ressive driver inpus/oupus should be perfored o deerine sinl ineriy, couplin nd EMI issues risin due o dvnces in echnoloy. Also oher funcionliies of he obile phone should be invesied, like he IrDA, Blueooh, USB inerfce nd ohers. 47

48 Appendix A Conduced suscepibiliy The relive inbiliy of produc o wihsnd elecroneic enery h reches i hrouh exernl cbles, power cords, nd oher I/O inerconnecs. Coninen Prevenin RF enery fro exiin n enclosure, enerlly by shieldin produc wihin el enclosure (frdy ce) or by usin plsic housin wih RF conducive pin. By reciprociy, we cn lso spek of coninen s prevenin RF enery fro enerin he enclosure. Elecroneic copibiliy (EMC) The biliy of produc o coexis in is inended elecroneic environen wihou cusin or sufferin funcionl derdion or de. Elecroneic inerference (EMI) A process by which disrupive elecroneic enery is rnsied fro one elecronic device o noher vi rdied or conduced phs or boh. In coon use, he er refers priculrly o RF sinls, bu EMI cn occur in he frequency rne fro DC o dylih. Iuniy A relive esure of device or syse s biliy o wihsnd EMI exposure. Rdied suscepibiliy The relive inbiliy of produc o wihsnd EMI h rrives vi free spce propion. Rdio frequency (RF) The frequency rne wihin which coheren elecroneic rdiion is useful for counicion purposes: rouhly fro 10 KHz o 100GHz. This enery y be enered inenionlly, s by rdio rnsier, or uninenionlly s byproduc of n elecronic device s operion. RSSI Received Sinl Srenh Indicion is esureen of he srenh; no necessrily he quliy; of he received sinl srenh in wireless environen; i is represened in rbirry unis. Suppression Desinin produc o reduce or eliine RF enery he source wihou relyin on secondry ehod such s el housin or chssis. Suscepibiliy A relive esure of device or syse s propensiy o be disruped or ded by EMI exposure. 48

49 Appendix B Buerworh Filer Preers Buerworh Filer Preers in Hyperlynx 1 s Order Buerwo rh Frequen cy = rd Order Buerwo rh Frequen cy = h Order Buerwo rh Frequen cy = s Order Buerwo rh Frequen cy = rd Order Buerwo rh Frequen cy = h Order Buerwo rh Frequen cy = 245 PI - Model Filer T - Model Filer 49

50 Chebyshev I Filer Preers Chebyshev I Filer Preers in Hyperlynx 1 s Order Chebyshev I Frequency = 245 Pss bnd Ripple = 1 db 3 rd Order Chebyshev I Frequency = 245 Pss bnd Ripple = 1 db 5 h Order Chebyshev I Frequency = 245 Pss bnd Ripple = 1 db 1 s Order Chebyshev I Frequency = 245 Pss bnd Ripple = 1 db 3 rd Order Chebyshev I Frequency = 245 Pss bnd Ripple = 1 db 5 h Order Chebyshev I Frequency = 245 Pss bnd Ripple = 1 db PI - Model Filer T - Model Filer R 11.2 ph R L 50

51 Bessel Filer Preers Bessel Filer Preers in Hyperlynx 1 s Order Bessel Frequenc y = rd Order Bessel Frequenc y = h Order Bessel Frequenc y = s Order Bessel Frequenc y = rd Order Bessel Frequenc y = h Order Bessel Frequenc y = 245 PI - Model Filer T - Model Filer 51

52 Leendre Filer Preers Leendre Filer Preers in Hyperlynx 1 s Order Bessel Leendre Frequenc y = rd Order Leendre Frequenc y = h Order Leendre Frequenc y = s Order Leendre Frequenc y = rd Order Bessel Frequenc y = h Order Leendre Frequenc y = 245 PI - Model Filer T - Model Filer 52

53 Buerworh Filer Sinl (Risin Tie of 40 CLK) 1 s Order Buerwo rh Frequen cy = rd Order Buerwo rh Frequen cy = PI - Model Filer h Order Buerwo rh Frequen cy = T - Model Filer

54 PI - Model Filer T - Model Filer Chebyshev I Filer Sinl (Risin Tie of 40 CLK) 1 s Order Chebysh ev I Frequen cy = rd Order Chebysh ev I Frequen cy = h Order Chebysh ev I Frequen cy =

55 PI - Model Filer T - Model Filer Bessel Filer Sinl (Risin Tie of 40 CLK) 1 s Order Bessel Frequen cy = rd Order Bessel Frequen cy = h Order Bessel Frequen cy =

56 PI - Model Filer T - Model Filer Leendre Filer Sinl (Risin Tie of 40 CLK) 1 s Order Leendr e Frequen cy = rd Order Leendr e Frequen cy = h Order Leendr e Frequen cy =

57 PI - Model Filer T - Model Filer Buerworh Filer (EMI Levels) Chebyshev I Filer (EMI Levels) 1 s Order Buerworh Frequency = rd Order Buerworh Frequency = h Order Buerworh Frequency = s Order Chebyshev I Frequency = rd Order Chebyshev I Frequency = h Order Chebyshev I Frequency = GHz GHz GHz PI - Model Filer GHz GHz GHz GHz GHz GHz T - Model Filer 00ns nsghz GHz GHz 57

58 Bessel Filer (EMI Levels) Leendre Filer (EMI Levels) 1 s Order Bessel Frequency = rd Order Bessel Frequency = h Order Bessel Frequency = s Order Leendre Frequency = rd Order Leendre Frequency = h Order Leendre Frequency = 245 PI - Model Filer GHz GHz GHz PI - Model Filer GHz GHz GHz T - Model Filer 0 0 ns GHz 75 ns 0 0ns ns GHz GHz T - Model Filer 0 0 ns GHz 75 ns GHz GHz 58

59 References [1] Honxi Wn e Al., Rdio Frequency Effecs on he Clock Neworks of Diil Circuis, IEEE 2004 [2] Min Wiles, CTIA es requireens cover over he ir perfornce, Wireless Europe, Ocober Noveber 2004 [3] 3rd Generion Prnership Projec; Technicl Specificion Group GSM/EDGE V8.17.0, [4] Willi J. Dlly & John W. Poulon, Diil Syse Enineerin, Cbride Universiy Press 1998 [5] Krl Rinne, Dep. Elecronics nd Copuer Enineerin, Universiy of Lierick, hp:// Auus 2005 [6] Inel, Desin for EMI Applicion Noe AP-589, Februry, [7] Clyon R. Pul, Inroducion o Elecroneic Copibiliy, Wiley-Inerscience Publicion, 1992 [8] Willi D. Kiel nd Dryl D. Gerke re principls in he EMI consulin fir Kiel Gerke Associes, Ld., bsed in S. Pul, MN. [9] Mrin Wiles, CTIA es requireens cover over-hir perfornce, Insiue of Physics nd Insiue of Physics Publishin Ld [10] Ti Willis, EMC for Produc Desiners, Third Ediion, Newnes, 2001 [11] Sieund M. Redl e Al, GSM nd Personl Counicions Hndbook, Arech House,