OP297_06 Datasheet, PDF (1/16 Pages) Analog Devices – Dual Low Bias Current Precision Operational Amplifier

Dual Low Bias Current
Precision Operational Amplifier
OP297
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
OUTA 1
–INA 2
+INA 3
V– 4
AB
8 V+
7 OUTB
6 –INB
5 +INB
Figure 1.
60
V_S = ±15V
V_CM = 0V
40
20
I_B–
0
I_B+
–20
I_OS
–40
–60
–75 –50
–25
0
25
50
75
TEMPERATURE (°C)
100 125
Figure 2. Low Bias Current over Temperature
400
1200 UNITS
300
T_A = 25°C
V_S = ±15V
V_CM = 0V
200
100
0
–100 –80 –60 –40 –20 0 20 40 60
INPUT OFFSET VOLTAGE (µV)
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.
Rev. F
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