Texas Instruments THS3115 EVM User manual

THS3115/25 EVM
May 2002 HPL
User’sGuide
SLOU126

IMPORTANTNOTICE
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enhancements,improvements,and otherchangestoitsproductsand servicesatanytime and to discontinue
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accordancewithTI’s standardwarranty.Testing and otherquality controltechniquesare used tothe extentTI
deemsnecessarytosupportthiswarranty.Exceptwheremandatedbygovernmentrequirements,testing ofall
parametersofeach productisnotnecessarilyperformed.
TIassumesno liabilityforapplicationsassistance orcustomerproductdesign.Customersareresponsiblefor
theirproductsandapplicationsusingTIcomponents.Tominimizethe risks associated withcustomerproducts
and applications,customers should provide adequate design and operating safeguards.
TIdoesnotwarrantorrepresent thatanylicense,eitherexpressorimplied,isgrantedunderanyTIpatentright,
copyright,maskworkright,orotherTIintellectualpropertyrightrelatingtoanycombination,machine,orprocess
inwhichTIproductsorservicesareused.InformationpublishedbyTIregardingthird--partyproductsorservices
doesnotconstitutealicensefromTI to usesuch productsorservicesorawarrantyorendorsement thereof.
Useofsuchinformationmayrequirealicensefromathird partyunderthepatentsorotherintellectualproperty
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Mailing Address:
TexasInstruments
PostOfficeBox655303
Dallas,Texas75265
Copyrightã2002,TexasInstrumentsIncorporated

EVMIMPORTANTNOTICE
TexasInstruments(TI)providesthe enclosed product(s)underthe following conditions:
ThisevaluationkitbeingsoldbyTIisintendedforuseforENGINEERINGDEVELOPMENTOREVALUATION
PURPOSES ONLYandisnotconsidered byTI tobefitforcommercialuse.Assuch, thegoodsbeingprovided
maynotbe completeintermsofrequired design-,marketing-,and/ormanufacturing-related protective
considerations,including productsafetymeasurestypicallyfound inthe end productincorporating the goods.
Asa prototype, thisproductdoesnot fall withinthe scope of the European Union directive on electromagnetic
compatibilityand thereforemaynotmeet the technicalrequirementsof the directive.
ShouldthisevaluationkitnotmeetthespecificationsindicatedintheEVMUser’sGuide,thekitmaybereturned
within 30 days fromthe date ofdeliveryforafull refund.THEFOREGOINGWARRANTYISTHE EXCLUSIVE
WARRANTYMADE BY SELLERTOBUYERAND ISINLIEUOFALL OTHERWARRANTIES,EXPRESSED,
IMPLIED,ORSTATUTORY, INCLUDINGANYWARRANTYOFMERCHANTABILITYORFITNESS FORANY
PARTICULARPURPOSE.
The userassumesall responsibilityand liabilityforproperand safe handling of the goods.Further, the user
indemnifiesTI fromall claimsarising fromthe handling oruse of the goods.Please be awarethat the products
receivedmaynotberegulatorycompliantoragencycertified (FCC,UL,CE,etc.).Duetotheopenconstruction
oftheproduct,itistheuser’sresponsibilitytotakeanyandallappropriateprecautionswithregardtoelectrostatic
discharge.
EXCEPT TOTHE EXTENTOF THEINDEMNITY SET FORTHABOVE,NEITHERPARTY SHALL BE LIABLE
TOTHEOTHERFORANYINDIRECT,SPECIAL, INCIDENTAL,OR CONSEQUENTIALDAMAGES.
TIcurrentlydealswithavarietyofcustomersforproducts,and therefore ourarrangementwiththe userisnot
exclusive.
TIassumesno liabilityforapplicationsassistance,customerproductdesign,softwareperformance,or
infringementofpatentsorservices described herein.
Pleaseread the EVMUser’sGuide and,specifically, the EVMWarningsand Restrictionsnoticeinthe EVM
User’sGuidepriortohandlingtheproduct.Thisnoticecontainsimportantsafetyinformationabouttemperatures
and voltages.Forfurthersafety concerns,pleasecontact the TIapplication engineer.
Personshandling the productmusthave electronics training and observe good laboratorypracticestandards.
Nolicenseisgranted underanypatentrightorotherintellectualpropertyrightofTIcovering or relating to any
machine,process,orcombination inwhichsuchTIproductsorservicesmightbe orare used.
Mailing Address:
TexasInstruments
PostOfficeBox655303
Dallas,Texas75265
Copyrightã2002,TexasInstrumentsIncorporated

EVMWARNINGSAND RESTRICTIONS
It isimportant to operatethisEVMwithinthe specified inputand outputrangesdescribed in
the EVMUser’sGuide.
Exceeding the specified inputrange may cause unexpected operation and/orirreversible
damage tothe EVM. If there are questions concerning the inputrange,pleasecontactaTI
fieldrepresentative priortoconnecting the inputpower.
Applyingloadsoutsideofthespecifiedoutputrangemayresultinunintendedoperationand/or
possible permanentdamage tothe EVM.Pleaseconsult the EVMUser’sGuide priorto
connecting anyload tothe EVMoutput. If thereisuncertaintyastothe load specification,
pleasecontactaTI fieldrepresentative.
Duringnormaloperation,somecircuitcomponentsmayhavecasetemperaturesgreaterthan
60°C.TheEVMisdesignedto operateproperlywithcertaincomponentsabove60°Caslong
astheinputandoutputrangesaremaintained.Thesecomponentsincludebutarenotlimited
tolinearregulators,switchingtransistors,passtransistors,andcurrentsenseresistors.These
typesofdevicescanbeidentifiedusingtheEVMschematiclocatedintheEVMUser’sGuide.
When placing measurementprobesnearthese devicesduring operation,please be aware
that these devicesmaybe verywarmtothe touch.
Mailing Address:
TexasInstruments
PostOfficeBox655303
Dallas,Texas75265
Copyrightã2002,TexasInstrumentsIncorporated

Information AboutCautionsand Warnings
iii
Preface
Read This First
AboutThisManual
Thismanualprovidesinformation about the evaluation module of the current
feedback amplifierundertest. Additionally, thisdocumentprovidesa good ex-
ample ofPCBdesign forhigh-speed applications.The usershouldkeep in
mind the following points.
-The design of the high-speed amplifierPCBisa delicate process.
-The usermustapproachthe PCBdesign withcare and awareness.
-Itisrecommendedthattheuserinitiallyreviewthedatasheetofthedevice
undertest.
-It isalso helpfultoreviewthe schematicand layoutof the THS3115/25
EVMto determine the design techniquesused inthe evaluation board.
-It isrecommended that the user reviewthe application notesCurrent
Feedback AmplifierAnalysisand Compensation,(literature number
SLOA021A)and Voltage Feedback vs CurrentFeedback OpAmps,
(literature numberSLVA051)to gainmoreinsightaboutcurrent feedback
amplifiers.
HowtoUse ThisManual
Thisdocumentcontainsthe following chapters:
-Chapter1—Introduction and Description
-Chapter2—Using the THS3115/25 EVM
-Chapter3—CircuitDesign Examples
-Chapter4—GeneralHigh-Speed AmplifierDesign Considerations
-Chapter5—EVMHardwareDescription
Information AboutCautions and Warnings
Thisbookmay containcautionsand warnings.
Thisis anexampleofa caution statement.
Acaution statementdescribes a situation thatcould potentially
damage yoursoftwareorequipment.

Trademarks
iv
Thisis anexampleofawarning statement.
Awarning statementdescribes a situation thatcould potentially
cause harmtoyou.
The information in a caution orawarning isprovided foryourprotection.
Pleaseread eachcaution and warning carefully.
RelatedDocumentation FromTexas Instruments
TheURL’sbelowarecorrectasofthe dataofpublication ofthismanual.Texas
Instrumentsapplicationsapologizesif they change overtime.
-THS3115/25 datasheet(literature numberSLOS382)
-Application report(literature numberSLOA021A),CurrentFeedback
AmplifierAnalysisand Compensation,
http://www--s.ti.com/sc/psheets/sloa021a/sloa021a.pdf
-Application report(literature numberSLVA051),Voltage Feedback Vs
CurrentFeedback OpAmps,
http://www--s.ti.com/sc/psheets/slva051/slva051.pdf
-Application report(literature numberSLOA069),How(Not)toDecouple
High Speed OpAmpCircuits,
http://www--s.ti.com/sc/psheets/sloa069/sloa069.pdf
-Application report(literature numberSLOA072),SingleSupply
DifferentialOpAmpTechniques,
http://www--s.ti.com/sc/psheets/sloa072/sloa072.pdf
FCC Warning
Thisequipmentisintendedforuseinalaboratorytestenvironmentonly.Itgen-
erates,uses,and canradiateradiofrequency energyand hasnotbeen tested
forcompliancewiththe limitsofcomputing devicespursuant tosubpartJof
part15 ofFCC rules,which are designed to provide reasonable protection
againstradiofrequency interference.Operation of thisequipmentin otheren-
vironmentsmay causeinterferencewithradiocommunications,inwhichcase
the userathisown expensewill be required totakewhatevermeasuresmay
be required tocorrect thisinterference.
Trademarks
PowerPADisatrademarkofTexasInstruments.

Contents
v
Contents
1Introduction and Description 1-1....................................................
1.1Description 1-2................................................................
1.2Evaluation ModuleFeatures1-2.................................................
1.3THS3115/25 EVMOperating Conditions1-2.......................................
1.4EVMDefaultConfiguration 1-2..................................................
2Using theTHS3115/25 EVM2-1......................................................
2.1Required Equipment2-2........................................................
2.2PowerSupplySetup for±15 Vdc2-2.............................................
2.3Inputand OutputSetup forChannel1 2-3.........................................
2.4Operating the EVMon Channel1 2-4............................................
2.5Inputand OutputSetup forChannel2 2-6.........................................
2.6Operating the EVMon Channel2 2-7............................................
3CircuitDesign Examples 3-1........................................................
3.1Inverting Stage (Channel1)Operation 3-2........................................
3.2Noninverting Stage (Channel2)Operation 3-4.....................................
3.3ShutDownOperation (Channels1 and 2)3-4.....................................
4GeneralHigh-SpeedAmplifierDesign Considerations 4-1.............................
5EVMHardwareDescription 5-1......................................................
5.1Bill ofMaterials5-2............................................................
5.2CircuitBoard Layout5-4........................................................
5.3Schematic5-6................................................................

Contents
vi
Figures
1--1Schematicof the Populated Circuiton the EVM(DefaultConfiguration)1-3..............
2--1PowerSupplyConnection for±15 Vdc2-3...........................................
2--2SignalConnectionsforChannel1 2-4...............................................
2--3Oscilloscope Output forChannel1 2-5..............................................
2--4Oscilloscope Output forChannel1WithShutdownActivated 2-5.......................
2--5SignalConnectionsforChannel2 2-6...............................................
2--6Oscilloscope Output forChannel2 2-7..............................................
2--7Oscilloscope Output forChannel2WithShutdownActivated 2-8.......................
3--1Inverting GainStage 3-2..........................................................
3--2Noninverting GainStage 3-4......................................................
5--1Top Layer1(Signals)forTHS3115 EVM5-4.........................................
5--2Bottom(Layer2) (Ground and SIgnal)forTHS3115 EVM5-5..........................
5--3Full Schematicof the EVM5-6.....................................................
Tables
5--1THS3115 EVMBill ofMaterials5-2.................................................
5--2THS3125 EVMBill ofMaterials5-3.................................................

1-1
Introduction and Description
Introduction and Description
The TexasInstrumentsTHS3115/25 evaluation module(EVM)helps
designersevaluatethe performance of the THS3115/25 current feedback
operationalamplifier (CFA).ThisEVMisalso a good example ofhigh-speed
PCBdesign.
ThisdocumentdetailstheTHS3115/25EVM.ItincludesalistofEVMfeatures,
a briefdescription of the moduleillustrated with a seriesofschematic
diagrams,EVMspecifications,detailson connecting and using the EVM,and
a discussion ofhigh-speed amplifierdesign considerations.
ThisEVMenablestheusertoimplementvariouscircuitstoclarifytheavailable
configurationspresented inthe schematicof the EVM. In addition,when the
customer receivesthe EVM, the schematicof the defaultcircuithasbeen
added to depict the componentsmounted on the EVM.
Othersamplecircuitsare presented foruserimplementation.The userisnot
limited tothe circuitconfigurationspresented inthisuser’sguide.The EVM
providesenough hardware hooks that the onlylimitation isthecreativityof the
user.
TopicPage
1.1Description 1-2...................................................
1.2Evaluation ModuleFeatures 1-2...................................
1.3THS3115/25 EVMOperating Conditions 1-2.........................
1.4EVMDefaultConfiguration 1-2.....................................
Chapter1

Description
1-2
1.1Description
The THS3115/25 EVMprovidesa platformfordeveloping high-speed CFA
application circuits.Itcontainsthe THS3115/25 high-speed CFA,a numberof
passivecomponents,and variousfeaturesand footprintsthatenablethe user
to experiment, test, and verify variousoperationalamplifiercircuit
implementations.The PCboardmeasures3.52 by2.81 inches.
1.2Evaluation ModuleFeatures
THS3115/25 high-speed operationalamplifierEVMfeaturesinclude:
-Wideoperatingsupplyvoltagerange:dualsupply±5to±15Vdcoperation
(see the device datasheet).
-Unitygaininverting stage (channel1 of the IC).The usercan reconfigure
gain asrequired.
-Noninverting stage with a gain of2(channel2 of the IC).The usercan
reconfigure gain asrequired.
-Nominal50-Winputtermination resistors(R2and R8).Termination canbe
configured according tothe application requirement.
-Nominal50-W,1watt outputmatching resistors(R5Band R11B).Foot-
printsare provided forlowerpower resistors(R5Aand R11A).
-100-W,1watt outputload resistors(R6Band R12B).Footprintsare
provided forlowerpower resistors(R6Aand R12A).
-Shutdown(SD)pincontrol,J10
-Powersupplyripplerejection capacitors(C1 and C2)
-Decoupling capacitors(C3,C4)populated with 0.1-mFcapacitors.Design
finaldecoupling in accordancewithSLOA069
-Agood example ofhigh-speed amplifierPCBdesign and layout
1.3THS3115/25 EVMOperating Conditions
-Supply voltage range,±VS ±5Vto±15V(seethedevicedatasheet)
-Supply current, IS(see the device datasheet)
-Outputdrive, IO,atVS =±15 (see the device datasheet)
ForcompleteTHS3115/25 amplifierICspecifications,parameter
measurementinformation,and additionalapplication information,see the
THS3115/25 datasheet, TIliterature numberSLOS382.
1.4EVMDefaultConfiguration
Asdelivered, the EVMhasafullyfunctionalexamplecircuit, justadd power
supplies,asignalsource,and monitoring instrument. See Figure 1--1forthe
defaultschematicdiagram.The usercan change the gain by changing the
ratiosof the feedback and gainresistors(see the device datasheet for
recommended resistorvalues).The completeEVMschematic—showing all
componentlocations—is showninChapter5.