OPA830 datasheet(19/56 Pages) TI

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7 Detailed Description

7.1 Overview

The OPA838 is a power-efficient, decompensated, voltage-feedback amplifier (VFA). Combining a negative-rail

input stage and a rail-to-rail output (RRO) stage, the device provides a flexible option where higher gain or

transimpedance designs are required. This 300-MHz gain-bandwidth product (GBP) amplifier requires less than

1 mA of supply current over a 2.7

‑V to 5.4-V total supply operating range. A shutdown feature on the 6-pin

package versions provides power savings where the system requires less than 1 µA when shut down. A

decompensated amplifier operating at low gains (less than 6 V/V) can experience a low phase margin that risks

oscillation. The TINA model for the OPA838 predicts those conditions.

7.2 Functional Block Diagram

The OPA838 is a standard voltage-feedback op amp with two high-impedance inputs and a low-impedance

output. Standard applications circuits are supported; see Figure 7-1 and Figure 7-2. These application circuits

are shown with a dc VREF on the inputs that set the dc operating points for single-supply designs. The VREF is

often ground, especially for split-supply applications.

OPA838

SIG

REF

S+

S-

OUT

REF

SIG

Figure 7-1. Noninverting Amplifier

V IN

OPA838

SIG

REF

S+

S-

OUT

SIG

REF

Figure 7-2. Inverting Amplifier

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OPA838

SBOS867D – AUGUST 2017 – REVISED SEPTEMBER 2024

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OPA830 Datasheet(PDF) 19 Page - Texas Instruments