Dual Low Bias Current
Precision Operational Amplifier
OP297
PIN CONFIGURATION
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
–INB
5
+INB
A
B
Figure 1.
60
VS = ±15V
VCM = 0V
INPUT CURRENT (pA)
40
20
I B–
0
I B+
–20
IOS
–60
–75
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
125
00300-002
–40
Figure 2. Low Bias Current over Temperature
400
1200 UNITS
TA = 25°C
VS = ±15V
VCM = 0V
NUMBER OF UNITS
300
200
100
0
–100 –80
–60
–40
–20
0
20
40
INPUT OFFSET VOLTAGE (µV)
60
80
100
00300-003
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
per amplifier. This part can operate with supply voltages as low
as ±2 V.
6
V– 4
The OP297 is the first dual op amp to pack precision performance 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.
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 μA.
OUTB
+INA 3
GENERAL DESCRIPTION
Precision performance of the OP297 includes very low offset
(less than 50 μV) and low drift (less than 0.6 μV/°C). Openloop gain exceeds 2000 V/mV, ensuring high linearity in every
application.
V+
7
–INA 2
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
8
OUTA 1
00300-001
FEATURES
Figure 3. Very Low Offset
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 device, see the OP497.
Rev. G
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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. Specifications subject to change without notice. No
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