Texas Instruments THS4121 User manual


    
  
July 2001 Mixed-Signal Products
User’s Guide
SLOU118

IMPORTANT NOTICE
Texas Instrumentsand itssubsidiaries(TI) reservetheright tomakechanges totheirproducts ortodiscontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its products to the specifications applicable at the time of sale in accordance with
TI’sstandardwarranty.TestingandotherqualitycontroltechniquesareutilizedtotheextentTIdeemsnecessary
to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except
those mandated by government requirements.
Customers are responsible for their applications using TI components.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TIassumesno liabilityforapplications assistanceorcustomerproduct design.TIdoes notwarrantor represent
thatanylicense,eitherexpressorimplied,isgrantedunderanypatentright,copyright,maskworkright,orother
intellectual property right of TI covering or relating to any combination, machine, or process in which such
products or services might be or are used. TI’s publication of information regarding any third party’s products
or services does not constitute TI’s approval, license, warranty or endorsement thereof.
Reproduction of information in TI data books or data sheets is permissible only if reproduction is without
alterationand isaccompaniedby allassociatedwarranties,conditions,limitations andnotices. Representation
or reproduction of this information with alteration voids all warranties provided for an associated TI product or
service, is an unfair and deceptive business practice, and TI is not responsible nor liable for any such use.
Resale of TI’s products or services with statements different from or beyond the parameters stated by TI for
that product or service voids all express and any implied warranties for the associated TI product or service,
is an unfair and deceptive business practice, and TI is not responsible nor liable for any such use.
Also see: Standard Terms and Conditions of Sale for Semiconductor Products. www.ti.com/sc/docs/stdterms.htm
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2001, Texas Instruments Incorporated

EVM IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:
This evaluation kit being sold by TI is intended for use for ENGINEERING
DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered by TI to
befitforcommercialuse.Assuch,thegoodsbeingprovidedmaynotbecompleteinterms
of required design-, marketing-, and/or manufacturing-related protective considerations,
including product safety measures typically found in the end product incorporating the
goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may not meet the technical
requirements of the directive.
Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide,
the kit may be returned within 30 days from the date of delivery for a full refund. THE
FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY SELLER TO
BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR
STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE.
Theuserassumesallresponsibilityandliabilityforproperandsafehandlingofthegoods.
Further, the user indemnifies TI from all claims arising from the handling or use of the
goods. Please be aware that the products received may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.). Due to the open construction of the product, it is
the user’s responsibility to take any and all appropriate precautions with regard to
electrostatic discharge.
EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER
PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL,
INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
TIcurrentlydealswithavarietyofcustomersforproducts,andthereforeourarrangement
with the user is not exclusive.
TI assumes no liability for applications assistance, customer product design,
software performance, or infringement of patents or services described herein.
PleasereadtheEVM User’sGuideand,specifically,theEVMWarningsand Restrictions
notice in the EVM User’s Guide prior to handling the product. This notice contains
important safety information about temperatures and voltages. For further safety
concerns, please contact the TI application engineer.
Personshandlingtheproductmusthaveelectronicstrainingandobservegoodlaboratory
practice standards.
No license is granted under any patent right or other intellectual property right of TI
covering or relating to any machine, process, or combination in which such TI products
or services might be or are used.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2001, Texas Instruments Incorporated

EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the specified input and output ranges described in
the EVM User’s Guide.
Exceeding the specified input range may cause unexpected operation and/or irreversible
damage to the EVM. If there are questions concerning the input range, please contact a TI
field representative prior to connecting the input power.
Applyingloadsoutsideofthespecifiedoutputrangemayresultinunintendedoperationand/or
possible permanent damage to the EVM. Please consult the EVM User’s Guide prior to
connecting any load to the EVM output. If there is uncertainty as to the load specification,
please contact a TI field representative.
Duringnormaloperation,somecircuitcomponentsmayhavecasetemperaturesgreaterthan
60°C.TheEVM is designed to operateproperlywithcertain components above 60°C as long
astheinput andoutputranges are maintained.Thesecomponents includebutarenot limited
tolinearregulators,switchingtransistors,passtransistors,andcurrentsenseresistors.These
typesof devicescan beidentifiedusingtheEVMschematiclocated inthe EVMUser’sGuide.
When placing measurement probes near these devices during operation, please be aware
that these devices may be very warm to the touch.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2001, Texas Instruments Incorporated

How to Use This Manual
v
Read This First
Preface
Read This First
About This Manual
This manual is written to provide information about the evaluation module of
the fully differential amplifier under test. Additionally, this document provides
a good example of PCB design for high speed applications. The user should
keep in mind the following points.
Thedesign ofthe high-speedamplifier PCBis asensitive process.Therefore,
the user must approach the PCB design with care and awareness. It is
recommended that the user initially review the data sheet of the device under
test. It is also helpful to review the schematic and layout of the THS4121 EVM
to determine the design techniques used in the evaluation board. In addition,
it is recommended that the user review the application note Fully-Differential
Amplifiers (literature number SLOA054B) to gain more insight about
differential amplifiers. This application note reviews the differential amplifiers
and presents calculations for various filters.
How to Use This Manual
-Chapter 1—Introduction and Description
-Chapter 2—Using the THS4121 EVM
-Chapter 3—General High-Speed Amplifier Design Considerations

Trademarks
vi
Information About Cautions and Warnings
This book may contain cautions and warnings.
This is an example of a caution statement.
A caution statement describes a situation that could potentially
damage your software or equipment.
This is an example of a warning statement.
A warning statement describes a situation that could potentially
cause harm to you.
The information in a caution or a warning is provided for your protection.
Please read each caution and warning carefully.
Related Documentation From Texas Instruments
-THS4121 data sheet (literature number SLOS319A)
-Application report (literature number SLOA054B),
Fully-Differential Amplifiers
FCC Warning
Thisequipmentisintendedforuseinalaboratorytestenvironmentonly.Itgen-
erates,uses,and canradiate radio frequencyenergy andhasnot beentested
for compliance with the limits of computing devices pursuant to subpart J of
part 15 of FCC rules, which are designed to provide reasonable protection
against radio frequency interference. Operation of this equipment in other en-
vironmentsmay cause interferencewith radio communications,in whichcase
the user at his own expense will be required to take whatever measures may
be required to correct this interference.
Trademarks
PowerPAD is a trademark of Texas Instruments.

Running Title—Attribute Reference
vii
Chapter Title—Attribute Reference
Contents
1 Introduction and Description 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Description 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Evaluation Module Features 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 THS4121 EVM Specifications 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Schematic of the Populated Circuit (Default Configuration) 1-3. . . . . . . . . . . . . . . . . . . . . . .
1.5 THS4121 EVM Schematic 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 Additional Sample Schematics 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7 THS4121 EVM Layout 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Using the THS4121 EVM 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Required Equipment 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Power Supply Setup 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Input and Output Setup 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 Testing the EVM Setup 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5 Power Down Verification 2-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6 Measuring the Frequency Response 2-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.7 Butterworth Filter 2-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.8 THS4121 EVM Bill of Materials 2-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 General High-Speed Amplifier Design Considerations 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Running Title—Attribute Reference
viii
Figures
1–1 Schematic of the Populated Circuit on the EVM (Default Configuration) 1-3. . . . . . . . . . . . . .
1–2 Schematic 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–3 Fully-Differential In/Fully-Differential Out, Without Transformer 1-5. . . . . . . . . . . . . . . . . . . . . .
1–4 Fully-Differential In/Fully-Differential Out, Utilizing Transformer 1-5. . . . . . . . . . . . . . . . . . . . . .
1–5 VICR Level Shifter 1-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–6 Butterworth Filter With Multiple Feedback 1-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–7 Top Layer (Silkscreen) 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–8 Top (Layer 1) (Signals) 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–9 Internal Plane (Layer 2) (Ground Plane) 1-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–10 Internal Plane (Layer 3) (±Power Plane) 1-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–11 Bottom (Layer 4) (Ground and Signal) 1-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–1 Power Supply Connection 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–2 Signal Connections 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–3 Driver 1 Output Signal 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–4 Multiple Feedback Filter Circuit 2-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–5 Gain vs Phase 2-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tables
2–1 THS4121 EVM Bill of Materials 2-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
Introduction and Description
Introduction and Description
This document details the Texas Instruments THS4121 high-speed
operational amplifier evaluation module (EVM). It includes a list of EVM
features,abriefdescriptionofthemoduleillustratedwithaseriesofschematic
diagrams, EVM specifications, details on connecting and using the EVM, and
a discussion of high-speed amplifier design considerations.
The Texas Instruments THS4121 evaluation module (EVM) helps designers
evaluate the performance of the THS4121 operational amplifier. Also, this
EVM is a good example of high-speed PCB design.
ThisEVMenablestheusertoimplementvariouscircuitstoclarifytheavailable
configurations presented by the schematic of the EVM. In addition, the
schematic of the default circuit has been added to depict the components
mounted on the EVM when it is received by the customer. This configuration
correlates to the single input/differential output signal.
Othersamplecircuitsarepresentedtoshowhowtheusercanimplementother
circuit configurations such as differential input/differential output signal,
transformer utilization on the input and output terminals, VICR level shifter,
and Butterworth filter with multiple feedback. The user may be able to create
and implement circuit configurations in addition to those presented in this
document using the THS4121 EVM.
Topic Page
1.1 Description 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Evaluation Module Features 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 THS4121 EVM Specifications 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Schematic of the Populated Circuit (Default Configuration) 1-3. . . . . . .
1.5 THS4121 EVM Schematic 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 Additional Sample Schematics 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7 THS4121 EVM Layout 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1

Description
1-2 Introduction and Description
1.1 Description
ThisEVMismadeoftheTHS4121high-speedoperationalamplifier,anumber
of passive components, and various features and component footprints that
enable the user to experiment and verify various operational amplifier circuit
configurations. Initially, this board is populated for a single-ended
input/differential-output amplifier (see Figure 1-2 for populated circuits). The
outputs(VO+ andVO–) canbe tested differentiallyorsingleended. Gainisset
to one and can be changed by changing the ratios of the feedback and gain
resistors (see the device datasheet for recommended resistor values). Each
input is terminated with a 50-Ωresistor to provide correct line-impedance
matching.
This EVM is optimized to work with ±1.65 power supplies. If the user tests the
deviceinasinglesupplymode(VDD=3.3V),thenthepropergroundingshould
be applied. The VOCM voltage level would be set at the mid rail (1.65-V when
VDD = 3.3 V). In general, the mid rail is the optimal area of the operation for
amplifiers. Therefore, if the device is operating at VDD = 3.3 V, it is
recommended that a dc offset be added to the input signal to shift it to the mid
rail.Havingtheinputsignalcenteredatthemidrailreducesthepeakingeffect.
RPU resistors in this EVM work as input signal level shifters. Therefore, they
canbe used toshift theinput signal level.To calculatethe RPU valuesuse the
following equation.
V(p) = V(pullup), RPU = R pullup (see EVM schematic)
RPU +V(p)*VDD
Ă(VI*V(P)) 1
Rg)(VO*V(p)) 1 Rf
The above equation is a good estimation tool for RPU. The user should
considerthe component error contribution tothe system. As a result,the RPU
number generated by the above equation could be changed slightly to
compensate for the error to provide the optimal result.
HavingVOCMlevelat1.65VabovetheGNDcausesacurrentflowfromVOCM
to GND. Consideration should be given to this current flow which will increase
the IDD.
1.2 Evaluation Module Features
THS4121 high-speed operational amplifier EVM features include:
JSingle and differential input and output capability
JNominal 50-Ωinput and output termination resistors. They can be
configured according to the application requirement.
JVOCM direct input control (see schematic and the device data sheet)
JVOCM pin can be controlled via transformer center-tap (see
schematic)
JShutdown pin control, JU1 (if applicable to the device, see the device
data sheet)
JInput and output transformer footprints for changing single-ended
signals to differential signals

THS4121 EVM Specifications
1-3
Introduction and Description
JFootprints for high-precision, balanced feedback and gain resistors
(0.01% or better)
JFootprints for low-pass filter implementation (see application note
SLOA054A)
JFootprints for antialiasing filter implementation (see application note
SLOA054A)
JDifferential probe terminals on input and output nodes for differential
probe insertion
JVarious GND and signal test points on the PCB
JCircuit schematic printed on the back of the EVM
JA good example of high-speed amplifier PCB design and layout
1.3 THS4121 EVM Specifications
Supply voltage range (see the device data sheet). . . . . . . . . . . . . . . . . . . . . . .
Supply current, ICC (see the device data sheet). . . . . . . . . . . . . . . . . . . . . . . .
Output drive, IO(see the device data sheet). . . . . . . . . . . . . . . . . . . . . . . . . . .
For complete THS4121 amplifier IC specifications, parameter measurement
information, and additional application information, see the THS4121 data
sheet, TI literature number SLOS319.
1.4 Schematic of the Populated Circuit (Default Configuration)
For verification of jumper locations and other bypass components, see the
complete EVM schematic in Figure 1–2.
Figure 1–1.Schematic of the Populated Circuit on the EVM (Default Configuration)
150 Ω
+
–
–
+
VDD
VSS
150 Ω
0 Ω
0 Ω
VIN
AC 0 Ω
0 Ω
RX1
0 Ω
R1b
R1a 150 Ω
R3b
R3a
R6a
C1 VOCM
C4
C6
R4b
R4a 0 Ω
0 Ω
Rx4
Rx5 49.9 Ω
49.9 Ω
R10
Rx6
50 Ω
Source
NOTE: Default populated footprints on the EVM from the input nodes to the output terminals Gain = 1
150 Ω
R6B
RX3
49.9 Ω
JU4
JU3
Rx0
24.9 Ω

THS4121 EVM Schematic
1-4 Introduction and Description
1.5 THS4121 EVM Schematic
Figure 1–2.Schematic
150 150 150
150
VDD VDD
VSS VSS
VDD
VSS
VDD
VSS
VDD
VDD

Additional Sample Schematics
1-5
Introduction and Description
1.6 Additional Sample Schematics
For verification of jumper locations and other bypass components, see the
complete EVM schematic in Figure 1–2.
Figure 1–3.Fully-Differential In/Fully-Differential Out, Without Transformer
+
–
–
+
VDD
VSS
VIN
AC 0 Ω
0 Ω
RX1
0 Ω
RX2
R1b
R1a
R6a
C1 VOCM
C4
C6
R4b
R4a 0 Ω
0 Ω
Rx4
Rx5
R10
Rx6
50 Ω
Source
R3B
0 Ω
0 Ω
0 Ω
R16 Termination
Resistor
R3a
R6b
Note: Fully-differential in / fully-differential out signal path. See the Texas Instruments February 2001Analog Applications
Journal for the information on the termination resistors.
Figure 1–4.Fully-Differential In/Fully-Differential Out, Utilizing Transformer
+
–
–
+
VDD
GND
VIN
AC 0 Ω
0 Ω
R1B
R1A
R3b
R3a
R6a
C1 VOCM
C4
C6
R4b
R4a 0 Ω
0 Ω
R14
R15
R10
Rx6
50 Ω
Source
R6b
R5
R9
T1 T2
Note: Utilizingtheinputandoutputtransformerstocreateafully-differentialsignalinput/differentialor singleoutputandisolate
the amplifier from the rest of the front-end and back-end circuits.

Additional Sample Schematics
1-6 Introduction and Description
Figure 1–5.VICR Level Shifter
+
–
–
+
VDD
24.9 Ω
0 Ω
VIN
AC 0 Ω
0 Ω
RX1
0 Ω
R1b
Rx0
R3b
R3a
R6a
C1 VOCM
C4
C6
R4b
R4a 0 Ω
0 Ω
Rx4
Rx5 49.9 Ω
49.9 Ω
R10
Rx6
50 Ω
Source
R6B
RX3
49.9 Ω
VDD
RPU1
RPU2
VSS
Note: ShiftingtheVICRwithinthespecifiedrangeinthedatasheetviaRPU1andRPU2iftheVICRisoutofthespecifiedrange.
See the Application section of the data sheet for the THS4121 for more information.
Figure 1–6.Butterworth Filter With Multiple Feedback.
+
–
–
+
VDD
VSS
–1 dBm
AC
RX1
RX2
R1B
R1A
R2A
R10
RX7
R2B
RX3
R7 R3A
C2
R3B
C1B
C1A
Note: Butterworth filter implemented with multiple feedback architecture

THS4121 EVM Layout
1-7
Introduction and Description
1.7 THS4121 EVM Layout
Figure 1–7.Top Layer (Silkscreen)
TEXAS INSTRUMENTS
THS4121 EVM
REV A
VDD
VSS
Figure 1–8.Top (Layer 1) (Signals)
TEXAS INSTRUMENTS
THS4121 EVM
REV A
VDD
VSS

THS4121 EVM Layout
1-8 Introduction and Description
Figure 1–9.Internal Plane (Layer 2) (Ground Plane)
Figure 1–10. Internal Plane (Layer 3) (±Power Plane)

THS4121 EVM Layout
1-9
Introduction and Description
Figure 1–11. Bottom (Layer 4) (Ground and Signal)

1-10 Introduction and Description

2-1
Using the THS4121 EVM
Using the THS4121 EVM
It is recommended that the user perform the following exercises to learn the
usage of the EVM. This practice helps the user learn about the various EVM
terminals and their functions. In addition, it suggests the components and
equipment needed to operate the EVM.
Topic Page
2.1 Required Equipment 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Power Supply Setup 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Input and Output Setup 2–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 Testing the EVM Setup 2–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5 Power Down Verification 2–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6 Measuring the Frequency Response 2–5. . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.7 Butterworth Filter 2–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.8 THS4121 EVM Bill of Materials 2–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 2

2-2 Using the THS4121 EVM
2.1 Required Equipment
-One double-output dc power supply (±5 V, 100 mA output minimum)
-Two dc current meters with resolution to 1 mA and capable of the
maximum current the dc power supply can supply. If available, set the
current limit on the dc power supply to 100 mA.
Note: Some power supplies incorporate current meters which may be
applicable to this test.
-50-Ωsource impedance function generator (1 MHz, 10 VPP sine wave)
-Oscilloscope (50-MHz bandwidth minimum, 50-Ωinput impedance).
2.2 Power Supply Setup
1) Set the dc power supply to ±1.65 V.
2) Makesure the dc power supply is turned offbeforeproceeding to the next
step.
3) Connect the positive (+) terminal of the power supply to the positive (+)
terminal of the current meter number 1.
4) Connectthenegative(–)terminalofthecurrentmeternumber1totheVDD
of the EVM (J7).
5) Connect the common ground terminal of the power supply to the ground
GND on the EVM (J9).
6) Connect the negative (–) terminal of the power supply to the negative (–)
terminal of the second current meter.
7) Connectthepositive(+)terminalofthecurrent meternumber2totheVSS
of the EVM (J8).
Figure 2–1.Power Supply Connection
POWER SUPPLY
GND–1.65V +1.65 V
+–+–
CURRENT
METER 2 CURRENT METER 1
J8 VSS J9 GND
J7 VDD J6 VOCM
EVM
THS4121
Figures are not drawn to scale.