OPA211_15 Datasheet, PDF (18/45 Pages) Texas Instruments – Low Power, Precision Operational Amplifier

OPA211, OPA2211
SBOS377H – OCTOBER 2006 – REVISED NOVEMBER 2015
8 Detailed Description
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8.1 Overview
The OPAx211 family of operational amplifiers are available in single-channel versions (OPA211) and dual-
channel versions (OPA2211). Single-channel versions are available with and without shutdown. The OPAx211
family of operational amplifiers features ultra-low noise of 1.1-nV/√Hz, low total harmonic distortion + noise of
0.000015% and wide, rail-to-rail output swing. These unique features makes the OPAx211 family suitable for
wide dynamic range applications and driving high-speed analog-to-digital converters. The OPAx211 family is
protected against excessive differentially applied input voltages and is fully characterized for electromagnetic
interference rejection ratio (EMIRR). The OPAx211 operates with as little as 4.5-V (±2.25-V) power supply
voltage and with power supply voltages up to 36 V (±18 V). The OPAx211 family is specified to operate from
–40°C to +125°C with little change in parametric behavior over the full temperature range.
8.2 Functional Block Diagram
V+
Pre-Output Driver
IN-
IN+
OUT
V-
8.3 Feature Description
8.3.1 Total Harmonic Distortion Measurements
OPA211 series operational amplifiers have excellent distortion characteristics. THD + Noise is below 0.0001% (G
= +1, V_O = 3 V_RMS) throughout the audio frequency range, 20 Hz to 20 kHz, with a 600-Ω load.
The distortion produced by OPA211 series operational amplifiers is below the measurement limit of many
commercially available distortion analyzers. However, a special test circuit shown in Figure 43 can be used to
extend the measurement capabilities.
Operational amplifier distortion can be considered an internal error source that can be referred to the input.
Figure 43 shows a circuit that causes the operational amplifier distortion to be 101 times greater than that
normally produced by the operational amplifier. The addition of R₃ to the otherwise standard noninverting
amplifier configuration alters the feedback factor or noise gain of the circuit. The closed-loop gain is unchanged,
but the feedback available for error correction is reduced by a factor of 101, thus extending the resolution by 101.
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