Texas Instruments Stereo Amplifier THS4503EVM User Manual

THS4503EVM  
User’s Guide  
June 2002  
HPL  
SLOU132  
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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 be fit for commercial use. As such, the goods being provided  
may not be complete in terms 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.  
The user assumes all responsibility and liability for proper and safe handling of the goods. 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.  
TI currently deals with a variety of customers for products, and therefore our arrangement 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.  
Please read the EVM User’s Guide and, specifically, the EVM Warnings and 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.  
Persons handling the product must have electronics training and observe good laboratory 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 2002, Texas Instruments Incorporated  
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EVM WARNINGS AND RESTRICTIONS  
It is important to operate this EVM within the input voltage range of 5 V and the output  
voltage range of +5 V and –5 V.  
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.  
Applying loads outside of the specified output range may result in unintended operation and/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.  
During normal operation, some circuit components may have case temperatures greater than  
50°C. The EVM is designed to operate properly with certain components above 50°C as long  
as the input and output ranges are maintained. These components include but are not limited  
to linear regulators, switching transistors, pass transistors, and current sense resistors. These  
types of devices can be identified using the EVM schematic located in the EVM User’s Guide.  
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 2002, Texas Instruments Incorporated  
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Preface  
Read This First  
About This Manual  
This manual provides information about using the THS4503 fully differential  
amplifier on evaluation module PCB marked with Edge # 6439396.  
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 a sensitive process.  
- 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 helpful to review the schematic and layout of the THS4503EVM to  
determine the design techniques used in the evaluation board.  
- It is recommended that the user review the application note Fully  
Differential Amplifiers (literature number SLOA054) to learn more about  
differential amplifiers. This application note reviews fully differential amps  
and presents calculations for various filters.  
How to Use This Manual  
This document contains the following chapters:  
- Chapter 1—Introduction and Description  
- Chapter 2—Using the THS4503EVM  
- Chapter 3—THS4503EVM Applications  
- Chapter 4—High-Speed Amplifier PCB Layout Tips  
- Chapter 5—EVM Hardware Description  
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.  
iii  
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Related Documentation From Texas Instruments  
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.  
FCC Warning  
This equipment is intended for use in a laboratory test environment only. It gen-  
erates, uses, and can radiate radio frequency energy and has not been tested  
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-  
vironments 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.  
Electrostatic Sensitive Components  
This EVM contains components that can potentially be damaged by  
electrostatic discharge. Always transport and store the EVM in its  
supplied ESD bag when not in use. Handle using an antistatic  
wristband. Operate on an antistatic work surface. For more  
information on proper handling, refer to SSYA008.  
Related Documentation From Texas Instruments  
The URLs below are correct as of the date of publication of this manual. Texas  
Instruments applications apologizes if they change over time.  
- THS4503 data sheet (literature number SLOS350)  
- Application report (literature number SLOA054), Fully Differential  
Amplifiers  
- Application report (literature number SLOA069), How (Not) to Decouple  
High Speed Op Amp Circuits,  
- Application report (literature number SLOA072), Single Supply Differen-  
tial Op Amp Techniques,  
iv  
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Trademarks  
- Application report (literature number SLMA002), Power Pad Thermally  
Enhanced Package,  
- Application report (literature number SLMA004), Power Pad Made Easy,  
- Application report (literature number SSYA008), Electrostatic Discharge  
Trademarks  
PowerPAD is a trademark of Texas Instruments.  
v
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vi  
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Contents  
1
2
3
Introduction and Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1  
1.1  
1.2  
1.3  
1.4  
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2  
Evaluation Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2  
THS4503EVM Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2  
EVM Default Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3  
Using the THS4503EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1  
2.1  
2.2  
2.3  
2.4  
Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2  
Power Supply Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2  
Function Generator Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3  
Signal Connection V  
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3  
IN−  
THS4503EVM Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1  
3.1  
3.2  
Single-Ended In/Single-Ended Out, Utilizing Transformer . . . . . . . . . . . . . . . . . . . . . . . . 3-2  
Single-Ended to Fully Differential Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2  
4
5
High-Speed Amplifier PCB Layout Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1  
EVM Hardware Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1  
vii  
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Figures  
1−1.  
2−1.  
2−2.  
3−1.  
3−2.  
3−3.  
5−1.  
5−2.  
5−3.  
Schematic of the Populated Circuit on the EVM (Default Configuration) . . . . . . . . . . . . . . 1-3  
Power Supply Connection for 5 Vdc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2  
Signal Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3  
Single-Ended In/Single-Ended Out, Utilizing Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2  
Sinlge Supply Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3  
Output of an AC-Coupled, Single-Supply Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4  
Top Layer 1 (Signals for THS4503EVM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2  
Bottom Layer 2 (Ground and Signal) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3  
Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4  
Tables  
5−1  
THS4503EVM Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1  
viii  
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Chapter 1  
Introduction and Description  
The Texas Instruments THS4503 evaluation module (EVM) helps designers  
evaluate the performance of the THS4503 fully differential operational  
amplifier (FDA). Also, this EVM is a good example of high-speed PCB design.  
This document details the THS4503EVM. It includes a list of EVM features, a  
brief description of the module illustrated with a series of schematic diagrams,  
EVM specifications, details on connecting and using the EVM, and a  
discussion of high-speed amplifier design considerations.  
This EVM enables the user to implement various circuits to clarify the available  
configurations presented by the schematic of the EVM. The user is not limited  
to the circuit configurations presented here. The EVM provides enough  
hardware hooks that the only limitation should be the creativity of the user.  
Topic  
Page  
1.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2  
1.2 Evaluation Module Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2  
1.3 THS4503EVM Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2  
1.4 EVM Default Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3  
1-1  
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Description  
1.1 Description  
The THS4503EVM provides a platform for developing high-speed FDA  
application circuits. It contains the THS4503 high-speed FDA, 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 PC board measures 3.08 by 2.42 inches.  
1.2 Evaluation Module Features  
THS4503 high-speed operational amplifier EVM features include:  
- Wide operating supply voltage range: single supply 5 Vdc to dual supply  
5 Vdc operation (see the device data sheet). Single supply operation is  
obtained by placing a jumper from GND (J7) to –V (J5).  
S
- Single-ended and fully differential input capability  
- Single-ended and fully differential output capability  
- Nominal 50-input termination (R1||R2). Termination can be configured  
according to the application requirement.  
- V  
OCM  
direct input through TP1  
- Output transformer T1  
- Footprints for antialiasing filter implementation using locations R6, R7, C5,  
and C6  
- Footprints for low pass filter implementation using locations C3, C4  
- 800-load provided through R8, R10, R9, and R11 reflected through T1  
- Three convenient GND test points on the PCB  
- Power supply ripple rejection capacitors (C8 and C11)  
- Decoupling capacitors (C9, C12) populated with 0.1 µF capacitors—  
design final decoupling in accordance with SLOA069.  
- PowerPADheatsinking capability  
- A good example of high-speed amplifier PCB design and layout  
1.3 THS4503EVM Operating Conditions  
- Supply voltage range, V  
5 V to 5 V (see the device data sheet)  
(see the device data sheet)  
S
- Supply current, I  
S
For complete THS4503 amplifier IC specifications, parameter measurement  
information, and additional application information, see the THS4503 data  
sheet, TI literature number SLOS350.  
1-2  
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EVM Default Configuration  
1.4 EVM Default Configuration  
As delivered, the EVM has a fully functional example circuit, just add power  
supplies, a signal source, and monitoring instrument. See Figure 1−1 for the  
default schematic diagram. The user can change the gain by changing the  
ratios of the feedback and gain resistors (see the device data sheet for  
recommended resistor values). Chapter 5 has a complete EVM schematic  
diagram showing all component locations.  
The default configuration assumes a 50-signal source and contains a  
termination resistor R1 for the source.  
Some components such as C8, C9, C11, C12, TP1, TP2, R10, T1, and J4 are  
omitted on the application schematics of Chapter 3 for clarity.  
Figure 1−1. Schematic of the Populated Circuit on the EVM (Default Configuration)  
TP3 TP4 TP5  
TP2  
PD−  
TP1  
Vocm  
J7  
GND  
R4  
392  
J2  
Vout+  
C13  
µ
1 F  
+VS  
T1  
3
R2  
R6 0  
R7 0  
R8  
C1 0  
J1  
4
6
3
1
J4  
U1  
Vin−  
Vout  
340  
374  
1
2
8
4
R1  
5
R10  
280  
Vocm  
+
56.2  
5
C2 0  
R3  
R9  
J6  
Vin+  
THS4503  
340  
402  
6
ADP41WT  
R17  
0
VS  
R5  
J3  
Vout−  
392  
J5  
VS  
J8  
+VS  
+VS  
VS  
+
C8  
C11  
C12  
C9  
µ
µ
µ
6.8 F  
6.8 F  
0.1 F  
µ
0.1 F  
+
Introduction and Description  
1-3  
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1-4  
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Chapter 2  
Using the THS4503EVM  
This section describes how to connect the THS4503EVM to test equipment.  
It is recommended that the user connect the EVM as described in this section  
to avoid damage to the EVM or the THS4503 installed on the board.  
Topic  
Page  
2.1 Required Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2  
2.2 Power Supply Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2  
2.3 Function Generator Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3  
2.4 Signal Connection V  
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3  
IN−  
2-1  
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Required Equipment  
2.1 Required Equipment  
- One dual-output dc power supply ( 5 V, 1 A output minimum)  
- Two dc current meters with resolution to 1 mA and capable of the  
maximum current the dc power supply can supply.  
- 50-source impedance function generator (1 MHz, 10 V sine wave)  
PP  
- Oscilloscope (50-MHz bandwidth minimum, 50-input impedance)  
- 3 BNC-to-SMA cables  
- BNC-to-BNC cable  
- 5 Banana-to-Banana wires; 4 red, 1 black  
2.2 Power Supply Connection (Refer to Figure 2−1)  
1) Set the dual dc power supply to 5 V. If available, set the current limit on  
the dc power supply to 100 mA.  
2) Make sure the dual dc power supply is turned off before proceeding to the  
next step.  
3) Connect the positive (+) terminal of the power supply to the positive (+)  
terminal of the current meter number 1.  
4) Connect the negative (–) terminal of the current meter number 1 to +VS  
(J8).  
5) Connect the common ground terminal of the power supply to GND (J7).  
6) Connect the negative (–) terminal of the power supply to the negative (–)  
terminal of the second current meter.  
7) Connect the positive (+) terminal of the current meter number 2 to –VS  
(J5).  
Figure 2−1. Power Supply Connection for 5 Vdc  
2-2  
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Function Generator Setup  
2.3 Function Generator Setup  
Note:  
The oscilloscope inputs 1 and 2 must be set to 50-input impedance for  
proper results.  
1) Connect the function generator to oscilloscope channel 1.  
2) Set vertical channels 1 and 2 of the oscilloscope to 0.2 V/division and the  
time-base to 0.1 µs/division.  
3) Set the function generator to generate a 1-MHz, 0.5 V (1 V ) sine wave  
PP  
with no dc offset.  
4) Verify that the output is 1 MHz, 0.5 V (1 V ).  
PP  
5) Disable the function generator output before proceeding to the next step.  
6) Disconnect the cable from the oscilloscope, retaining the setting of the  
function generator.  
2.4 Signal Connection V  
(Refer to Figure 2−2)  
IN−  
1) Using a BNC-to-SMA cable, connect the function generator to J1 (VIN−).  
2) Using a BNC-to-SMA cable, connect the oscilloscope channel 1 to J2  
(VOUT+).  
3) Using a BNC-to-SMA cable, connect the oscilloscope channel 2 to J3  
(VOUT−).  
Figure 2−2. Signal Connections  
Using the THS4503EVM  
2-3  
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2-4  
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Chapter 3  
THS4503EVM Applications  
Example applications are presented in this chapter. These applications dem-  
onstrate the most popular circuits, but many other circuits can be constructed.  
The user is encouraged to experiment with different circuits, exploring new and  
creative design techniques. After all, that is the function of an evaluation board.  
Topic  
Page  
3.1 Single-Ended In/Single-Ended Out, Utilizing Transformer . . . . . . . . . 3-2  
3.2 Single-Ended to Fully Differential Application . . . . . . . . . . . . . . . . . . . 3-2  
3-1  
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Single-Ended In/Single-Ended Out, Utilizing Transformer  
3.1 Single-Ended In/Single-Ended Out, Utilizing Transformer  
The fully differential amp output can be monitored by a single-ended  
instrument at J4. The THS4503EVM utilizes Mini-Circuits CD542 footprint  
transformers to make the fully differential to single-ended conversion. An  
ADP4−1WT transformer is installed on the board.  
R8, R9, and R10 are chosen such that the load on the fully differential amp is  
800 when combined with the load impedance transformed by the turn ratio  
T1. This load is chosen because it is a common input impedance value for  
ADCs, and is the impedance at which many fully differential amp parameters  
are measured. The 800-load occurs when one of two conditions is met:  
- R11 is installed and the measuring instrument is set to 1-Minput  
impedance  
or  
- R11 is not installed and the measuring instrument has an input impedance  
of 50 .  
Figure 3−1. Single-Ended In/Single-Ended Out, Utilizing Transformer  
TP1  
Vocm  
R4  
C13  
392Ω  
µ
1 F  
+VS  
3
T1  
R2  
R6 0  
R7 0  
R8  
C1 0  
J1  
Vin−  
4
6
3
1
J4  
Vout  
U1  
374  
402  
340  
1
2
8
4
5
R1  
R10  
5
R11  
49.9Ω  
Vocm  
+
56.2  
280  
C2 0  
R3  
R9  
THS4503  
340  
6
ADP41WT  
R17  
0
VS  
R5  
392Ω  
3.2 Single-Ended to Fully Differential Application  
The schematic of Figure 3−2 shows the proper technique for ac-coupling. The  
voltage present on the V pin determines the dc operating point of the  
OCM  
circuit. When no voltage is connected to TP1, the V  
voltage level is  
OCM  
determined by a voltage divider internal to the op amp, and is approximately  
equal to half of +VS. This dc voltage is present on both outputs, and also  
present on both inputs—being connected through R2 and R3.  
3-2  
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Single-Ended to Fully Differential Application  
Figure 3−2. Single Supply Operation  
TP1  
Vocm  
R4  
W
392  
C13  
m
1
F
+VS  
3
C1  
R2  
R6  
0
J1  
Vin−  
J2  
U1  
Vout+  
W
374  
1
2
8
4
5
R1  
56.2  
W
Vocm  
+
C2  
R3  
R7 0  
J3  
Vout−  
THS4503  
W
402  
6
R17  
0
R5  
W
392  
Note:  
For this and some of the following circuits, it is necessary to install capacitors  
into locations designated as resistors, and vice versa. Because the  
capacitors and resistors come in the same case size, this should be easily  
accomplished.  
The designer should note that the ground connection of the schematic at C2  
through R17 is a second input—to avoid confusion about whether a coupling  
capacitor is actually needed. In fact, there is no difference between  
single-ended and fully differential inputs to the board, except that the  
single-ended circuits utilize ground as signal return, while fully differential  
inputs utilize the other input as signal return. Any fully differential input to the  
board can be converted to a single-ended input merely by connecting one of  
the inputs to ground.  
This circuit allows the input voltage to swing below the negative power supply  
rail of the op-amp, as shown in Figure 3−3.  
THS4503EVM Applications  
3-3  
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Single-Ended to Fully Differential Application  
Figure 3−3. Output of an AC-Coupled, Single-Supply Application  
3
2
1
0
−1  
0
500 n  
1 Ω  
t − Time − s  
The designer should realize that the coupling capacitors, acting with the  
gain resistors, produce a high pass characteristic into the circuit.  
This application circuit has interaction between R  
, R  
, and R .  
source termination  
g
Texas Instruments has provided an engineer design utility to facilitate the  
design of these circuits. Engineer design utilities are available on the Am-  
plifiers and Comparators section of the Analog and Mixed Signal portion of  
the TI web page.  
Designers should be aware that each individual feedback path is an invert-  
ing path. There is no noninverting gain circuit for fully differential amps.  
The designer should also be aware that the gain is affected by the open  
loop characteristic of the FDA, the same as single−ended op amps. If there  
is sufficient safety margin between the closed loop response and open loop  
response of the FDA (40 dB or more), the error contribution from the open  
loop response of the FDA is negligible and can be ignored.  
3-4  
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Chapter 4  
HighĆSpeed Amplifier PCB Layout Tips  
The THS4503EVM layout has been designed for use with high-speed signals  
and can be used as an example when designing PCBs incorporating the  
THS4503. Careful attention has been given to component selection,  
grounding, power supply bypassing, and signal path layout. Disregarding  
these basic design considerations could result in less than optimum  
performance of the THS4503 high-speed operational amplifier. Surface-  
mount components were selected because of the extremely low lead  
inductance associated with this technology. This helps minimize both stray  
inductance and capacitance. Also, because surface-mount components are  
physically small, the layout can be very compact.  
Tantalum power supply bypass capacitors at the power input pads help filter  
switching transients from the laboratory power supply. Power supply bypass  
capacitors are placed as close as possible to the IC power input pins in order  
to minimize the return path impedance. This improves high frequency  
bypassing and reduces harmonic distortion. The GND side of these capacitors  
should be located close to each other, minimizing the differential current loops  
associated with differential output currents. If poor high frequency  
performance is observed, replace the 0.1-µF capacitors with microwave  
capacitors with a self-resonance at the frequency that produces trouble. A  
proper ground plane on both sides of the PCB should be used with high-speed  
circuit design. This provides low-inductive ground connections for return  
current paths.  
In the area of the amplifier input pins, however, the ground plane has been  
removed to minimize stray capacitance and reduce ground plane noise  
coupling into these pins. This is especially important for the inverting input pin.  
As low as 1 pF capacitance at the inverting input can significantly affect the  
response of the amplifier or even oscillation.  
In general, it is best to keep signal lines as short and as straight as possible.  
Incorporation of microstrip or stripline techniques is also recommended when  
signal lines are greater than 1 inch in length. These traces must be designed  
with a characteristic impedance of either 50 or 75 , as required by the  
application. Such a signal line must also be properly terminated with an  
appropriate resistor.  
4-1  
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Circuit pathways should be made as symmetrical as possible for both  
feedback pathways to minimize second and other even-harmonic content.  
The printed-circuit board used with PowerPAD packages must have features  
included in the design to remove the heat from the package efficiently. As a  
minimum, there must be an area of solder-tinned-copper underneath the  
PowerPAD package. This area is called the thermal land. The thermal land  
varies in size depending on the PowerPAD package being used, the PCB  
construction and the amount of heat that needs to be removed. In addition, this  
thermal land may or may not contain thermal vias depending on PCB  
construction. The requirements for thermal lands and thermal vias are detailed  
Finally, all inputs and outputs must be properly terminated, either in the layout  
or in the load instrumentation. Unterminated lines, such as coaxial cable, can  
appear to be a reactive load to the amplifier. By terminating a transmission line  
with its characteristic impedance, the amplifier’s load then appears to be  
purely resistive, and reflections are absorbed at each end of the line. Another  
advantage of using an output termination resistor is that capacitive loads are  
isolated from the amplifier output. This isolation helps minimize the reduction  
in the amplifier’s phase-margin and improves the amplifier stability resulting  
in reduced peaking and settling times.  
4-2  
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Chapter 5  
EVM Hardware Description  
This chapter describes the EVM hardware. It includes the EVM parts list, and  
printed circuit board layout.  
Table 5−1.THS4503EVM Bill of Materials  
SMD  
Size  
Reference  
Designator  
PCB Manufacturer’s  
Qty. Part Number  
Distributor’s  
Part Number  
Item Description  
1
2
3
CAP, 6.8 µF, tanatalum,  
35 V, 10%  
D
C8, C11  
2
2
6
(AVX)  
TAJD685K035R  
(Garrett)  
TAJD685K035R  
CAP, 0.1 µF, ceramic,  
X7R, 16 V  
0508  
0805  
C9, C12  
(AVX)  
0508YC104KAT2A  
(Garrett)  
0508YC104KAT2A  
Open  
C3, C4, C5, C6,  
C7, C10  
4
5
Open  
Open  
1206  
0805  
C13, C14  
2
6
R11, R12, R13,  
R14, R15, R16  
6
Resistor, 0 , 1/8 W  
0805  
0805  
0805  
0805  
0805  
0805  
1206  
1206  
C1, C2, R6, R7  
4
1
2
1
2
1
1
1
1
3
2
(Phycomp)  
(Garrett)  
9C08052A0R00JLHFT 9C08052A0R00JLHFT  
(Phycomp) (Garrett)  
9C08052A2800FKHFT 9C08052A2800FKHFT  
(Phycomp) (Garrett)  
9C08052A3400FKHFT 9C08052A3400FKHFT  
(Phycomp) (Garrett)  
9C08052A3740FKHFT 9C08052A3740FKHFT  
(Phycomp) (Garrett)  
9C08052A3920FKHFT 9C08052A3920FKHFT  
(Phycomp) (Garrett)  
9C08052A4020FKHFT 9C08052A4020FKHFT  
(Phycomp) (Garrett)  
9C12063A0R00JLHFT 9C12063A0R00JLHFT  
(Phycomp) (Garrett)  
9C12063A56R2FKRFT 9C12063A56R2FKRFT  
7
Resistor, 280 , 1/8 W,  
1%  
R10  
R8, R9  
R2  
8
Resistor, 340 , 1/8 W,  
1%  
9
Resistor, 374 , 1/8 W,  
1%  
10  
11  
12  
13  
14  
15  
16  
Resistor, 392 , 1/8 W,  
1%  
R4, R5  
R3  
Resistor, 402 , 1/8 W,  
1%  
Resistor, 0 , 1/4 W  
R17  
R1  
Resistor, 56.2 , 1/4 W,  
1%  
Transformer, 4:1  
Test points (black)  
Test points (red)  
CD542 T1  
(Mini-Circuits)  
ADT4−1WT  
(Mini-Circuits)  
ADT4−1WT  
TP3, TP4, TP5  
(Keystone)  
5001  
(Allied)  
839−3601  
TP1, TP2  
(Keystone)  
5000  
(Allied)  
839−3600  
5-1  
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SMD  
Size  
Reference  
Designator  
PCB Manufacturer’s  
Qty. Part Number  
Distributor’s  
Part Number  
Item Description  
17  
18  
19  
20  
Jack, banana receptacle,  
0.25” diameter hole  
J5, J7, J8  
3
5
4
4
(HH Smith)  
101  
(Newark)  
35F865  
Connector, SMA PCB  
Jack  
J1, J2, J3, J4,  
J6  
(Amphenol)  
901−144−8RFX  
(Newark)  
01F2208  
Standoff, 4−40 Hex,  
0.625” Length  
(Keystone)  
1804  
(Allied)  
839−2089  
Screw, Phillips, 4−40,  
.250”  
SHR−0440−016−SN  
21  
22  
IC, THS4503  
U1  
1
1
(TI) THS4503DGN  
Board, printed circuit  
(TI) EDGE # 6439396  
Figure 5−1. Top Layer 1 (Signals for THS4503EVM)  
5-2  
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Figure 5−2. Bottom Layer 2 (Ground and Signal)  
EVM Hardware Description  
5-3  
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Figure 5−3. Schematic Diagram  
TP2  
PD−  
TP1  
TP3 TP4 TP5  
VCC+  
R15  
VCC+  
Vocm  
J7  
GND  
R13  
*
*
C4  
*
C13  
R14  
R16  
*
C14  
*
1 F  
R4  
392  
µ
*
J2  
+VS  
Vout+  
T1  
3
R2  
374  
R6 0  
R8  
340  
C1 0  
J1  
4
3
1
J4  
U1  
Vin−  
Vout  
1
2
8
4
C5  
*
R1  
56.2  
5
C7  
R10  
280  
R11  
*
Vocm  
+
*
5
C2 0  
R3  
402  
R7 0  
R9  
340  
6
J6  
Vin+  
THS4503  
ADP41WT  
C6  
*
6
R17  
0
J3  
VS  
R5  
392  
Vout−  
C3  
*
J5  
VS  
J8  
+VS  
VS  
+VS  
+
C8  
6.8 F  
C11  
6.8 F  
C12  
0.1 F  
C10  
*
C9  
0.1 F  
R12  
*
+
µ
µ
µ
µ
Note: Devices designated with an * are not installed on the EVM. The user must supply these components.  
5-4  
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