Dual Low Bias Current
Precision Operational Amplifier
OP297
Rev. G
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FEATURES
Low offset voltage: 50 μV maximum
Low offset voltage drift: 0.6 μV/°C maximum
Very low bias current: 100 pA maximum
Very high open-loop gain: 2000 V/mV minimum
Low supply current (per amplifier): 625 μA maximum
Operates from ±2 V to ±20 V supplies
High common-mode rejection: 120 dB minimum
APPLICATIONS
Strain gage and bridge amplifiers
High stability thermocouple amplifiers
Instrumentation amplifiers
Photocurrent monitors
High gain linearity amplifiers
Long-term integrators/filters
Sample-and-hold amplifiers
Peak detectors
Logarithmic amplifiers
Battery-powered systems
GENERAL DESCRIPTION
The OP297 is the first dual op amp to pack precision perform-
ance into the space saving, industry-standard 8-lead SOIC
package. The combination of precision with low power and
extremely low input bias current makes the dual OP297 useful
in a wide variety of applications.
Precision performance of the OP297 includes very low offset
(less than 50 V) and low drift (less than 0.6 V/°C). Open-
loop gain exceeds 2000 V/mV, ensuring high linearity in every
application.
Errors due to common-mode signals are eliminated by the
common-mode rejection of over 120 dB, which minimizes
offset voltage changes experienced in battery-powered systems.
The supply current of the OP297 is under 625 A.
The OP297 uses a super-beta input stage with bias current
cancellation to maintain picoamp bias currents at all tempera-
tures. 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
per amplifier. This part can operate with supply voltages as low
as ±2 V.
PIN CONFIGURATION
8
7
6
5
1
2
3
4
OUTA
–INA
+INA
V+
OUTB
–INB
+INBV–
B
A
00300-001
Figure 1.
TEMPERATURE (°C)
INPUT CURRENT (pA)
60
–60
40
20
0
–20
–40
–75 –50 –25 0 25 50 75 100 125
I
OS
I
B
+
I
B
–
V
S
= ±15V
V
CM
= 0V
00300-002
Figure 2. Low Bias Current over Temperature
INPUT OFFSET VOLTAGE (µV)
NUMBER OF UNITS
400
0
300
200
100
1200 UNITS
–100 –80 –60 –40 –20 0 20 40 60 80 100
T
A
= 25°C
V
S
= ±15V
V
CM
= 0V
00300-003
Figure 3. Very Low Offset
Combining precision, low power, and low bias current, the
OP297 is ideal for a number of applications, including instru-
mentation amplifiers, log amplifiers, photodiode preamplifiers,
and long term integrators. For a single device, see the OP97; for
a quad device, see the OP497.
