OPA187_17 Datasheet, PDF (15/35 Pages) Texas Instruments – Drift, Low Power, Rail-to-Rail Output 36-V Operational Amplifiers Zero-Drift Series

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7 Detailed Description
OPA187, OPA2187, OPA4187
SBOS807 – DECEMBER 2016
7.1 Overview
The OPAx187 operational amplifier combines precision offset and drift with excellent overall performance,
making the device ideal for many precision applications. The precision offset drift of only 0.005 µV/°C provides
stability over the entire temperature range. In addition, this device offers excellent overall performance with high
CMRR, PSRR, and A_OL. As with all amplifiers, applications with noisy or high-impedance power supplies require
decoupling capacitors close to the device pins. In most cases, 0.1-µF capacitors are adequate.
The OPAx187 device is part of a family of zero-drift, low-power, rail-to-rail output operational amplifiers. These
devices operate from 4.5 V to 36 V, are unity-gain stable, and are suitable for a wide range of general-purpose
applications. The zero-drift architecture provides ultra-low input offset voltage and near-zero input offset voltage
drift over temperature and time. This choice of architecture also offers outstanding ac performance, such as ultra-
low broadband noise and zero flicker noise.
7.2 Functional Block Diagram
Figure 36 shows a representation of the proprietary OPAx187 architecture. Functional blocks CHOP1 and
CHOP2 operate such that the non-idealities of GM1 are cancelled while the input signal is left in-phase. The
integrated notch filter of the OPAx187 family suppresses most of the auto-zero amplifier carrier.
V+
C2
CHOP1
GM1
CHOP2
Notch
Filter
GM2
GM3
+IN
OUT
-IN
C1
GM_FF
V-
Copyright © 2016, Texas Instruments Incorporated
Figure 36. Functional Block Diagram
Copyright © 2016, Texas Instruments Incorporated
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Product Folder Links: OPA187 OPA2187 OPA4187