Dual Low Bias Current
Precision Operational Amplifier
OP297
FEATURES
Low Offset Voltage: 50 V Max
Low Offset Voltage Drift: 0.6 V/ C Max
Very Low Bias Current: 100 pA Max
Very High Open-Loop Gain: 2000 V/mV Min
Low Supply Current (Per Amplifier): 625 A Max
Operates From 2 V to 20 V Supplies
High Common-Mode Rejection: 120 dB Min
Pin Compatible to LT1013, AD706, AD708, OP221,
LM158, and MC1458/1558 with Improved Performance
APPLICATIONS
Strain Gage and Bridge Amplifiers
High Stability Thermocouple Amplifiers
Instrumentation Amplifiers
Photo-Current Monitors
High Gain Linearity Amplifiers
Long-Term Integrators/Filters
Sample-and-Hold Amplifiers
Peak Detectors
Logarithmic Amplifiers
Battery-Powered Systems
PIN CONNECTIONS
OUTA
1
–INA
2
+INA
3
V–
4
A
B
8
V+
7
OUTB
6
–INB
5
+INB
Precision performance of the OP297 includes very low offset,
under 50
µV,
and low drift, below 0.6
µV/°C.
Open-loop gain
exceeds 2000 V/mV, ensuring high linearity in every application.
Errors due to common-mode signals are eliminated by the
OP297’s common-mode rejection of over 120 dB, which mini-
mizes offset voltage changes experienced in battery-powered
systems. Supply current of the OP297 is under 625
µA
per
amplifier, and the part can operate with supply voltages as low
as
±
2 V.
The OP297 uses a super-beta input stage with bias current
cancellation to maintain picoamp bias currents at all temperatures.
This is in contrast to FET input op amps whose bias currents
start in the picoamp range at 25°C, but double for every 10°C
rise in temperature, to reach the nanoamp range above 85°C.
Input bias current of the OP297 is under 100 pA at 25°C and is
under 450 pA over the military temperature range.
Combining precision, low power, and low bias current, the OP297
is ideal for a number of applications, including instrumentation
amplifiers, log amplifiers, photodiode preamplifiers, and long-
term integrators. For a single device, see the OP97; for a quad,
see the OP497.
400
1200 UNITS
T
A
= 25 C
V
S
= 15V
V
CM
= 0V
GENERAL DESCRIPTION
The OP297 is the first dual op amp to pack precision performance
into the space-saving, industry-standard, 8-lead SOIC package.
Its combination of precision with low power and extremely low
input bias current makes the dual OP297 useful in a wide variety
of applications.
60
V
S
= 15V
V
CM
= 0V
40
INPUT CURRENT (pA)
20
I
B
–
0
I
B
+
–20
I
OS
–40
NUMBER OF UNITS
300
200
100
–60
–75
–50
–25
0
25
50
TEMPERATURE ( C)
75
100
125
0
–100 –80
–60
–40
–20
0
20
40
60
INPUT OFFSET VOLTAGE ( V)
80
100
Figure 1. Low Bias Current over Temperature
Figure 2. Very Low Offset
REV. E
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
© 2003 Analog Devices, Inc. All rights reserved.
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