AMMC-5024 datasheet(8/10 Pages) AVAGO

8 / 10 page

Biasing and Operation

AMMC-5024isbiasedwithasinglepositivedrainsupply

(Vdd)anegativegatesupply(Vg1)andhasapositivecontrol

gatesupply(Vg2).

For best overall performance the recommended bias

conditionfortheAMMC-5024isVdd =7VandIdd=200

mA.Toachievethisdraincurrentlevel,Vg1istypically

between–2.5to–3.5V.Typically,DCcurrentflowforVg1

is–10mA.OpencircuitisthedefaultsettingforVg2when

notutilizinggaincontrol.

Usingthesimplestformofassembly(Figure20),thedevice

iscapableofdeliveringflatgainovera2–50GHzrange

withaminimumofgainslopeandripple.However,this

deviceisdesignedwithDCcoupledRFI/Oports,and

operationmaybeextendedtolowerfrequencies(<2

GHz)throughtheuseofoff-chiplow-frequencyextension

circuitryandproperexternalbiasingcomponents.With

lowfrequencybiasextensionitmaybeusedinavariety

oftime-domainapplications(through40Gb/s).

Figure21showsatypicalassemblyconfiguration.

WhenbypasscapacitorsareconnectedtotheAUXpads,

thelowfrequencylimitisextendeddowntothecorner

frequencydeterminedbythebypasscapacitorandthe

combinationoftheon-chip50ohmloadandsmallde-

queingresistor.Atthisfrequencythesmallsignalgain

willincreaseinmagnitudeandstayatthiselevatedlevel

downtothepointwheretheCauxbypasscapacitoractsas

anopencircuit,effectivelyrollingoffthegaincompletely.

Thelowfrequencylimitcanbeapproximatedfromthe

followingequation:

fCaux =

πCaux(Ro + RDEQ)

where:

Roisthe50Ωgateordrainlineterminationresistor.

RDEQisthesmallseriesde-queingresistorand10Ω.

Cauxisthecapacitanceofthebypasscapacitorconnect-

edtotheAUXDrainandAUXGatepadinfarads.

WiththeexternalbypasscapacitorsconnectedtotheAUX

gateandAUXdrainpads,gainwillshowaslightincrease

between1.0and1.5GHz.Thisisduetoaseriescombina-

tionofCauxandtheonchipresistancebutisexaggerated

bytheparasiticinductance(Lc)ofthebypasscapacitorand

theinductanceofthebondwire(Ld).Thereforethebond

wirefromtheAuxpadstothebypasscapacitorsshould

bemadeasshortaspossible.

InputandoutputRFportsareDCcoupled;therefore,DC

decouplingcapacitorsarerequiredifthereareDCpaths.

(Donotattempttoapplybiastothesepads.)

RFbondconnectionsshouldbekeptasshortaspossible

toreduceRFleadinductancewhichwilldegradeperfor-

manceabove20GHz.

Anoptionaloutputpowerdetectornetworkisalsopro-

vided.Detectorsensitivityisoptimizedbybiasingthe

diodeswithtypicaldrainvoltageVdd=7volts.Simplycon-

nectingDet-BiastotheVddsupplyisaconvenientmethod

ofbiasingthisdetectornetwork.Thedifferentialvoltage

betweentheDet-RefandDet-Outpadscanbecorrelated

withtheRFpoweremergingfromtheRFoutputport.A

>0.5µFcapacitorisrequiredfortheDet_Outpadtoex-

pandpowerdetectionperformancebelow100MHz.

Groundconnectionsaremadewithplatedthrough-holes

tothebacksideofthedevice;therefore,groundwiresare

notneeded.

Assembly Techniques

Thechipshouldbeattacheddirectlytothegroundplane

usingeitherafluxlessAuSnsolderpreformorelectrically

conductiveepoxy[1].Forconductiveepoxy,theamount

shouldbejustenoughtoprovideathinfilletaroundthe

bottomperimeterofthedie.Thegroundplaneshould

befreeofanyresiduethatmayjeopardizeelectricalor

mechanical attachment. Caution should be taken to

notexceedtheAbsoluteMaximumRatingforassembly

temperatureandtime.

Thermosonicwedgebondingisthepreferredmethodfor

wireattachmenttothebondpads.TheRFconnections

shouldbekeptasshortaspossibletominimizeinduc-

tance.Goldmesh[2]ordouble-bondingwith0.7milgold

wireisrecommended.

Meshcanbeattachedusinga2milroundtrackingtool

andatoolforceofapproximately22gramswithanultra-

sonicpowerofroughly55dBforadurationof76±8mS.

Aguidedwedgeatanultrasonicpowerlevelof64dBcan

beusedforthe0.7milwire.Therecommendedwirebond

stagetemperatureis150±2°C.

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