op497fy Analog Devices, Inc., op497fy Datasheet - Page 8

• Manufacturer Part Number: op497fy
• Description: Precision Picoampere Input Current Quad Operational Amplifier
• Manufacturer: Analog Devices, Inc.

OP497
OPEN-LOOP GAIN LINEARITY
The OP497 has both an extremely high gain of 2000 V/mv mini-
mum and constant gain linearity. This enhances the precision of
the OP497 and provides for very high accuracy in high closed-loop
gain applications. Figure 5 illustrates the typical open-loop gain
linearity of the OP 497 over the military temperature range.
APPLICATIONS
Precision Absolute Value Amplifier
The circuit of Figure 6 is a precision absolute value amplifier
with an input impedance of 30 MΩ. The high gain and low
TCV
input signals. In this circuit, the input always appears as a com-
mon-mode signal to the op amps. The CMR of the OP497
exceeds 120 dB, yielding an error of less than 2 ppm.
Teflon is a registered trademark of the Dupont Company.
V
OS
IN
of the OP497 ensure accurate operation with microvolt
2
3
–15
OP497
–15V
+15V
1/4
R
V
V
8
4
0.1 F
CM
L
S
–10
0.1 F
C2
= 10k
=
C3
= 0V
1
15V
C1
30pF
OUTPUT VOLTAGE – Volts
–5
1N4148
D1
1N4148
T
T
T
A
A
A
D2
= +125 C
1k
= +25C
= –55 C
R1
0
R2
2k
6
5
5
OP497
1k
1/4
R3
10
0V < V
7
OUT
15
< 10V
PRECISION CURRENT PUMP
Maximum output current of the precision current pump shown
in Figure 7 is ± 10 mA. Voltage compliance is ± 10 V with ± 15 V
supplies. Output impedance of the current transmitter exceeds
3 MΩ with linearity better than 16 bits.
PRECISION POSITIVE PEAK DETECTOR
In Figure 8, the CH must be of polystyrene, Teflon , or polyeth-
ylene to minimize dielectric absorption and leakage. The droop
rate is determined by the size of CH and the bias current of the
OP497.
SIMPLE BRIDGE CONDITIONING AMPLIFIER
Figure 9 shows a simple bridge conditioning amplifier using
the OP497. The transfer function is:
The REF43 provides an accurate and stable reference voltage
for the bridge. To maintain the highest circuit accuracy, R
should be 0.1% or better with a low temperature coefficient.
V
IN
1k
I
OUT
3
2
V IN
OP497
=
–
+
1/4
V
R5
IN
=
V
10k
10k
100
R1
R2
OUT
V
1
RESET
IN
= 10mA/ V
=
1N4148
1k
2
3
C
V
10k
R4
H
OP497
REF
2N930
10k
1/4
R3
1k



7
R
1
∆
+
OP497
+15V
–15V
1k
R
1/4
∆
8
4
R
10k
6
5
R5



6
5
OP497
R
R
1/4
F
+15V
–15V
4
8
0.1 F
0.1 F
I
OUT
10mA
7
F
V
OUT