Texas Instruments THS4151 User manual

THS4151
EVM User's Guide for HighĆSpeed
Full ĆDifferential Amplifier
February 2001 Mixed-Signal Products
User’s Guide
SLOU109

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Copyright 2001, Texas Instruments Incorporated

iii
Read This First
Preface
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.
The design of the high-speed amplifier PCB is an elegant and sensitive
process. Therefore, the user must approach the PCB design with care and
awareness. It is recommend that the user initially review the datasheet of the
device under test. It is also helpful to review the schematic and layout of the
THS4151 EVM to determine the design techniques used in the evaluation
board.In addition, itis recommended thatthe user reviewthe 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 THS4151 EVM
- Chapter 3—General High-Speed Amplifier Design Considerations

Related Documentation From Texas Instruments
iv
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
- THS4151 data sheet (literature number SLOS321)
- THS4151 application report (literature number SLOA054A),
Fully-Differential Amplifiers
FCC Warning
This equipment is intended for use in a laboratory test environment only. It
generates, uses, and can radiate radio frequency energy and has not been
testedforcompliance withthelimits ofcomputingdevices pursuant tosubpart
Jofpart15ofFCCrules,whicharedesignedtoprovidereasonableprotection
against radio frequency interference. Operation of this equipment in other
environments may cause interference with radio communications, in which
case 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
v
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 THS4151 EVM Specifications 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Schematic of the Populated Circuit (Default Configuration) 1-3. . . . . . . . . . . . . . . . . . . . . . .
1.5 THS4151 EVM Schematic 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 Additional Sample Schematics 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7 THS4151 EVM Layout 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Using the THS4151 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 THS4151 EVM Bill of Materials 2-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 General High-Speed Amplifier Design Considerations 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Running Title—Attribute Reference
vi
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) (+ VCC 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 THS4151 EVM Bill of Materials 2-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
Introduction and Description
Introduction and Description
The Texas Instruments THS4151 evaluation module (EVM) helps designers
evaluate the performance of the THS4151 operational amplifier. Also, this
EVM is a good example of high-speed PCB design.
This document details the Texas Instruments THS4151 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.
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 THS4151 EVM.
Topic Page
1.1 Description 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Evaluation Module Features 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 THS4151 EVM Specification 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Schematic of the Populated Circuit (Default Configuration) 1-3. . . . . . .
1.5 THS4151 EVM Schematic 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 Additional Sample Schematics 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7 THS4151 EVM Layout 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1

Description
1-2
Introduction and Description
1.1 Description
The THS4151 EVM is a good example of PCB design and layout for
high-speed operational amplifier applications. It is a complete circuit for the
high-speed operational amplifier. The EVM is made of the THS4151
high-speed operational amplifier, a number of passive components, and
various features and footprints that enable the user to experiment, test, and
verify various operational amplifier circuit implementations. The board
measures 4.5 inches in length by 2.5 inches in width. Initially, this board is
populated for a single-ended input amplifier (see Figure 1-2 for populated
circuits). The outputs (VO+ and VO–) can be tested differentially or single
ended. Gain is set to one and can be changed by changing the ratios of the
feedback and gain resistors (see the device datasheet for recommended
resistor values). The user may populate various footprints on the evaluation
moduleboard to verifyfilter designsor perform other experiments. Eachinput
isterminatedwitha50-Ωresistorto provide correctline-impedancematching.
1.2 Evaluation Module Features
THS4151 high-speed operational amplifier EVM features include:
J Voltage supply operation range: 5-V to ±15-V operation (see the
device data sheet)
J Single and differential input and output capability
J Nominal 50-Ωinput and output termination resistors. They can be
configured according to the application requirement.
J VOCM direct input control (see schematic and the device data sheet)
J VOCM pin can be controlled via transformer center-tap (see
schematic)
J Shutdown pin control, JU1 (if applicable to the device, see the device
data sheet)
J Input and output transformer footprints for changing single-ended
signals to differential signals
J Footprint for high-precision, balanced feedback and gain resistors
(0.01% or better)
J Footprints for low-pass filter implementation (see application note
SLOA054A)
J Footprints for antialiasing filter implementation (see application note
SLOA054A)
J Differential probe terminals on input and output nodes for differential
probe insertion
J Various GND and signal test points on the PCB
J Circuit schematic printed on the back of the EVM
J A good example of high-speed amplifier PCB design and layout

THS4151 EVM Specifications
1-3
Introduction and Description
1.3 THS4151 EVM Specifications
Supply voltage range, ±VCC 5 V to ±15 V (see the device data sheet). . . .
Supply current, ICC (see the device data sheet). . . . . . . . . . . . . . . . . . . . . . . .
Output drive, IO, VCC = ±15 (see the device data sheet). . . . . . . . . . . . . . . . .
For complete THS4151 amplifier IC specifications, parameter measurement
information, and additional application information, see the THS4151 data
sheet, TI literature number SLOS321.
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)
374 Ω
+
–
THS4151
–
+
VCC
VCC–
402 Ω
0 Ω
0 Ω
VIN
AC 0 Ω
0 Ω
RX1
0 Ω
R1b
R1a 374 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
402 Ω
R6B
RX3
49.9 Ω
JU4
JU3
Rx0
24.9 Ω
Note: Default populated footprints on the EVM from the input nodes to the output terminals Gain = 1

THS4151 EVM Schematic
1-4
Introduction and Description
1.5 THS4151 EVM Schematic
Figure 1–2.Schematic