8 Detailed Description

8.1 Overview

The OPA814 is a high-voltage, unity-gain-stable, 250-MHz gain bandwidth product (GBWP), voltage-feedback

operational amplifier (op amp) featuring a 5.3

‑nV/√Hz, low-noise JFET input stage. The low offset voltage

(250 μV, maximum), offset voltage drift (3.5 μV/°C, maximum), and unity gain bandwidth of 600 MHz makes this

device an excellent choice for high input impedance, high-speed data acquisition front-ends. The high-voltage

capability combined with the 750

‑V/µs slew rate enables applications needing wide output swings (9 VPP at

VS = 12 V) for high-frequency signals such as those often found in medical instrumentation, optical front-ends,

test, and measurement applications. The low-noise JFET input with picoamperes of bias current makes this

device attractive in high-gain TIA applications, and in test and measurement front-ends.

The OPA814 is built using TI's proprietary high-voltage, high-speed, complementary bipolar SiGe process.

8.2 Functional Block Diagram

The OPA814 is a conventional voltage-feedback op amp with two high-impedance inputs and a low-impedance

output. Figure 8-1 and Figure 8-2 show two standard amplifier configuration examples that are supported for this

device. The reference voltage (VREF) level shifts the dc operating point for each configuration, which is typically

set to mid-supply in single-supply operation. VREF is typically set to ground in split-supply applications.

+

±

VIN

RG

VREF

VREF

RF

VSIG

VREF

(1 + RF / RG) × VSIG

VOUT

VS+

VS±

Figure 8-1. Noninverting Amplifier

+

±

VIN

RG

VREF

VREF

RF

VSIG

VREF

±(RF / RG) × VSIG

VOUT

VS+

VS±

Figure 8-2. Inverting Amplifier

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OPA814

SBOSA14 – APRIL 2023

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