Dual Lo

w Bias Current

Precision Operational Amplifier

OP297

Rev. F

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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,

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

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.

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

+INB

V–

B

A

Figure 1.

TEMPERATURE (°C)

60

–60

40

20

0

–20

–40

–75

–50

–25

0

25

50

75

100

125

Figure 2. Low Bias Current over Temperature

INPUT OFFSET VOLTAGE (µV)

400

0

300

200

100

1200 UNITS

–100 –80

–60

–40

–20

0

20

40

60

80

100

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.