AD8021 evaluation board

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AN-646
APPLICATION NOTE
One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106 • Tel: 781/329-4700 • Fax: 781/326-8703 • www.analog.com
Universal Evaluation Board for High Speed Op Amps
By John Ardizzoni
Analog Devices’ high speed universal evaluation board
(EVAL-ADOPAMP-1R) is designed to help customers
quickly prototype new op amp circuits and reduce design
time. The evaluation board can be used with almost any
Analog Devices’ op amp in various configurations and
applications. Figure 1 shows the universal evaluation
board schematic.
There are two options for supply bypassing. The first
is connecting additional shunt capacitors (C2, C5) in
parallel with the electrolytic capacitors (C1, C4) from
each supply to ground. This technique of power supply
bypassing provides wideband rejection of unwanted
noise on the supply lines. It is implemented by placing a
0  resistor in the C6 position and shunt capacitors in the
C1, C2, C4, and C5 positions.
The evaluation board is a 2-layer PCB that accepts SMA
connectors on the input and output for efficient connection to test equipment. The evaluation board can also
accommodate an SMA connector for the disable pin,
a feature found on Analog Devices’ op amps, such as
the AD8063AR and AD8027AR.
The second approach connects one capacitor between
the supply rails. This method uses fewer components
and can improve the PSRR at higher frequencies. It is
implemented by inserting a 0  resistor in the C2 position, inserting the bypass capacitor in the C5 position,
and omitting C6. Optimal bypassing is circuit dependent
and therefore must be evaluated by the designer.
The ground plane, component placement, and supply
bypassing have been laid out to minimize parasitic
inductances and capacitances. The evaluation board’s
components are primarily SMT 1206 case size, with the
exception of the electrolytic bypass capacitors (C1, C4),
which are 3528 case size. The board can also be used
with op amps that utilize external frequency compensation capacitors, such as the AD8021AR.
Figure 2 shows the evaluation board assembly drawing.
The recommended layout pattern for making connections
to the op amp and supporting circuitry is shown in
Figure 3.
R6
GND1 GND2 GND3 GND4
*
+VS
C2
TP1
*
C1
10F
R2
IN –
+VS
*
*
1
R1
*
R3
NC
DIS
2 –IN
*
8
+VS 7
3
VOUT 6
+IN
4
R4
IN +
*
R9
*
–VS
CC
R5
5
C3
*
*
C5
*
–VS
C4
10F
*USER DEFINED VALUE
+
–VS
Figure 1. Universal Evaluation Board Schematic
REV. A
DIS
C6
+
R7
*
R8
*
OUT
AN-646
UNIVERSAL HIGH SPEED
OP AMP EVALUATION BOARD
GND4
+VS
IN–
TP1
GND3
IN–
R6
DUT
R8
C3
IN+
C2
R7
OUT
*
R4
A00336C
R5
–VS
R9
C6
C4
GND2
R1
R2
OUT
*
R3
DIS
C5
*
C1
E03686–0–6/03(A)
ANALOG
DEVICES
IN+
GND1
EVAL-ADOPAMP-1R
SO SINGLE
COMPONENT SIDE
CIRCUIT SIDE
* SMA EDGE CONNECTOR JOHNSON COMPONENTS, INC. P/N 142-0701-831
Figure 2. Board Assembly Drawings
Figure 3. Board Layout Patterns
© 2003 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective companies.
–2–
REV. A
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