ta0318-emi-and-esd-consideration-for-lcd-and-cameras-in-wireless-handsets-stmicroelectronics意法 深圳恒锐丰科技.pdf

TA0318

®TECHNICALARTICLE

EMIandESDconsiderationforLCDandCameras

inwirelesshandsets

1.BringEMIimmunitytoCamerasandLCDsincellularhandsets

Aswirelessmarketcontinuestoevolve,thenextmobilephonegenerationrequiresincreasedfunctionality

withmorecolourfuldisplays,atleasttwoperhandset,andthearrivalofhigh-resolutioncameras

exceeding1Mpixels.

Stilldrivenbycompactdesigntrend,theimplementationofhighresolutionLCDsandcameraswillpose

severalchallengesfordesigners.OneofthemajordesignconsiderationsforcameraandLCDsisthe

electromagneticinterferencessensibilityforthesenewmodules.

Formanypopularhandsets,especiallyclamshell-styleflipphones,thecolorLCDorcamerasCMOS

sensorsareconnectedtothebasebandcontrollerviaaflexibleoralongtracksPCB,connectedin

betweentwomajorpartsofthephone.

Ononeside,thiscableisstillsubjectedtotheparasiticGSM/CDMAfrequenciesradiatedbytheantenna.

Ontheotherside,becauseoftheintroductionofhigh-resolutionCMOSsensorandTFTmodules,data

signalsareclockedathigherfrequencyandtheconnectioncablecan,consequently,behaveasan

antennaforradiatingEMI/RFIorforconductingESDhazardousevents.

Anyway,inbothcase,alloftheseEMIandESDperturbationcandisruptthevideosignalintegrityor

damagedefinitivelythebasebandcontrollercircuitry.

TosuppresstheseEMIradiationwhilepreservingdatatransfers,severalfilter