Texas ths6022 User manual

THS6022 250ĆmA
Dual Differential Drivers
Evaluation Module
November 1998 Mixed-Signal Products
User’s Guide
SLOU035

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Copyright 1998, Texas Instruments Incorporated

iii
Chapter Title—Attribute Reference
Preface
Related Documentation From Texas Instruments
J THS6022 250-mA DUAL DIFFERENTIAL DRIVERS (literature
numberSLOS225). This isthedatasheet for theTHS6022 amplifier
integrated circuit used on the EVM
J THS4001 HIGH-SPEED LOW-POWER OPERATIONAL
AMPLIFIER
(literature number SLOS206) This is the data sheet
for the THS4001 amplifier integrated circuit used on the EVM.
J PowerPAD  Thermally Enhanced Package (literature number
SLMA002) This is the technical brief for the special PowerPAD
package in which the THS6022 amplifier IC is supplied.
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
testedforcompliancewiththelimitsofcomputing devices pursuant to subpart
Jofpart 15ofFCCrules,which aredesignedtoprovidereasonableprotection
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
TI is a trademark of Texas Instruments Incorporated.

iv

Running Title—Attribute Reference
v
Chapter Title—Attribute Reference
Contents
1 General Information 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 Features 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Description 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Input Configuration 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 THS6022 EVM Specifications 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Using The THS6022 EVM 1-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 THS6022 EVM Performance 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7 General High-Speed Amplifier Design Considerations 1-8. . . . . . . . . . . . . . . . . . . . . . . . . . .
1.8 General PowerPAD Design Considerations 1-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Reference 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 THS6022 Dual Differential Line Drivers EVM Parts List 2-2. . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 THS6022 EVM Board Layouts 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Running Title—Attribute Reference
vi
Figures
1–1 THS6022 Evaluation Module 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–2 THS6022 Evaluation Module Schematic 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–3 THS6022 Evaluation Module Block Diagram 1-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–4 THS6022 EVM Driver Frequency Response With a 50-W Load 1-7. . . . . . . . . . . . . . . . . . . . .
1–5 THS6022 EVM Driver Frequency Response Test Circuit 1-7. . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–6 PowerPAD PCB Etch and Via Pattern – Minimum Requirements 1-9. . . . . . . . . . . . . . . . . . . .
1–7 Maximum Power Dissipation vs. Free-Air Temperature 1-10. . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–1 THS6022 EVM Component Placement Silkscreen and Layout 2-3. . . . . . . . . . . . . . . . . . . . . .
2–2 THS6022 EVM PC Board: Layer 1 — Top Side Layout 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–3 THS6022 EVM PC Board: Layer 2 — Back Side Ground Plane Layer 2-4. . . . . . . . . . . . . . . .
2–4 THS6022 EVM PC Board: Solder Mask — Back Side 2-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
General Information
General Information
This chapter details the Texas Instruments (TI) THS6022 250-mA Dual
Differential Line Driver Evaluation Module (EVM), SLOP133. It includes a list
ofEVMfeatures,abriefdescriptionofthemoduleillustratedwithapictorialand
schematic diagrams, EVM specifications, details on configuring, connecting,
and using the EVM, and a discussion on high-speed amplifier and PowerPAD
package design considerations.
Topic Page
1.1 Features 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Description 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Input Configuration 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 THS6022 EVM Specifications 1–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Using The THS6022 EVM 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 THS6022 EVM Performance 1–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7 General High-Speed Amplifier Design Considerations 1–9. . . . . . . . . . .
1.8 General PowerPADDesign Considerations 1–10. . . . . . . . . . . . . . . . . .
Chapter 1

Features
1-2
General Information
1.1 Features
THS6022 250-mA Dual Differential Driver EVM features include:
J A Complete Client Side ADSL Differential Line Driver
J Multiple Input Configurations Set Via On Board Jumpers
J Includes a THS4001 High-Speed Amplifier as an Inverter
J Standard BNC Connectors Inputs and Outputs
J ±5-V to ±15-V Operation
J Nominal 50-ΩImpedance Inputs
J Pad Area On Board For User Component Placement and Testing
J Good Example of PowerPAD Package and High-Speed Amplifier
Design and Layout
1.2 Description
The TI THS6022 250-mA Dual Differential Line Driver Evaluation Module
(EVM) is a complete client side ADSL high-speed driver circuit. It consists of
the TI THS6022 Dual Differential Line Driver IC, a TI THS4001 High-Speed
Low-Power Operational Amplifier IC, and a number of passive parts, all
mounted on a multilayer circuit board (Figure 1–1). The EVM uses standard
BNC connectors for inputs and outputs and also includes a pad area for user
component connection and testing. It is completely assembled, fully tested,
and ready to use — just connect it to power, a signal source, and a load
(if desired).
Figure 1–1.THS6022 Evaluation Module
J2
+VCC GND
J1
+
C8
U1
+Driver 1 Output
L2 Texas Instruments
THS6022 EVM
SLOP133
Rev. B
–VCC
J3
Driver 1
Input J4
R5
R6
L1 C1
R1
R2
J5
U2
R3
JP2
C10
R12
Driver 2 Output
Pad1
GND
Pad2
C3
R4
C7
Driver 2
Input J6
JP1
R9
R10
J7
C5
R8
C2
C13 C14
C9
R13
R15

Description
1-3
General Information
Inputpowerisappliedto the EVM through banana jacks J1,J2,andJ3.AnLC
filteroneachpowerbusisolatestheEVMcircuitsfromtheexternalsupply.The
schematic for the EVM appears in Figure 1–2.
Figure 1–2.THS6022 Evaluation Module Schematic
1
–
+
U2:A
THS6022
2
1
3
5
4
R4
1 KΩ
R2
49.9 Ω
R3
1 KΩ
R1
49.9 Ω
R8
49.9 Ω
R7
TBD
15 V
–15 V
R5
1 KΩ
15 V
–
+6
4
7
–15 V
2
3
JP1
JP2
R9
49.9 Ω
–
+13
14
12
10
11
R11
TBD
U2:B
THS6022
–15 V
R15
49.9 Ω
R14
TBD
R12
1 KΩ
R13
1 KΩ
C4
TBD
C13
0.1 µF
C3
0.1 µF
C2
0.1 µF
C6
TBD
R6
1 KΩ
U1
THS4001
C7
0.1 µF
C5
0.1 µF
C12
TBD
C10
0.1 µF
C9
0.1 µF
C14
0.1 µF
C11
TBD
J4
Driver 1
Input
1
J6
Driver 2
Input
R10
49.9 Ω
15 V
J5
Driver 1
Output
Driver 2
Output
J7
GND
2 OUT
1 OUTPad1
Pad2
L2
0.22 µH
C8
6.8 µF
J3
C1
6.8 µF
L1
0.22 µH
–15 V
J1
15 V
J2

Description
1-4
General Information
The THS6022 EVM is equipped with a separate BNC connector for the Driver
1 input and the Driver 2 input. Each input is terminated with a 50-Ωresistor to
provide correct line impedance matching (Figure 1–2). Note that using a
source with a 50-Ωoutput impedance will create a voltage divider at the EVM
inputs. Thus, accurate knowledge of the source output characteristics is
required to determine proper input signal amplitudes.
Driver outputs are routed through client side ADSL-standard 49.9-Ωresistors
to provide correct transmission line impedance matching when run through a
1:1 transformer with a 100-Ωline termination. These resistors also allow
separatereceiverstoviewadifferentialinputsignalfromthetransmissionline.
All of the amplifiers on the EVM (THS6022 and THS4001) follow the classic
operational amplifier gain equations:
Inverting Gain +
–RF
RG(1)
Non-Inverting Gain + 1 )
RF
RG(2)
The gain of the amplifiers can be easily changed to support different
applications by changing resistor ratios. Any of the components on the EVM
boardcanbe replacedwithdifferentvalues.Also,componentpadshave been
placed in convenient locations on the PCB (shown as components with the
valueTBDintheschematic)toallownumerousmodificationstothebasicEVM
configuration. However, care must be taken because the surface-mount
solder pads on the board are somewhat fragile and will not survive a large
number of soldering/desoldering operations.
The THS6022 IC is a current-feedback amplifier (CFB) and because of this,
extracaremustbe taken to ensure thatafeedbackresistoris always included
in the design. In addition, there must never be a capacitor directly in the
feedback path between the noninverting input and the amplifier output.
Disregarding this guideline will likely result in a part that oscillates. The
THS4001 IC amplifier used on the EVM, however, is a classic
voltage-feedback amplifier (VFB) and has no restrictions on resistors or
capacitors in the feedback path. But, to maximize bandwidth, high value
resistors and capacitors should be used with discretion.
Andfinally,theEVMcircuitboardisagood example of proper boardlayoutfor
high-speed amplifier and PowerPAD designs. It can be used as a guide for
user application layouts.