7 Detailed Description

7.1 Overview

The PGA848 is a monolithic, high-voltage, precision programmable-gain instrumentation amplifier. The PGA848

combines a high-speed current-feedback input stage with an internally matched gain resistor network, followed

by a four-resistor, difference amplifier output stage. Eight preprogrammed decade gains are selectable using

gain-select pins A0, A1, and A2. Gains range from 0.5V/V to 100V/V, discussed in greater detail in Section 7.3.1.

A functional block diagram for the PGA848 is shown in the next section. The differential input voltage is fed

into a pair of matched, high-impedance input, current-feedback amplifiers. An integrated precision-matched

gain resistor network amplifies the differential input voltage. An output difference amplifier, A3, rejects the input

common-mode component and refers the output signal to the voltage level set by the REF pin.

The PGA848 output amplifier bandwidth is optimized to drive high-performance analog-to-digital converters

(ADCs) with sampling rates up to 1MSPS, without additional ADC drivers. The output amplifier uses a separate

power supply that is independent of the input-stage power supply. When driving an ADC, use a low-impedance

connection from LVDD and LVSS to the ADC power supplies. This configuration protects the ADC inputs from

damage resulting from inadvertent overvoltage conditions.

7.2 Functional Block Diagram

+

–

+

–

6.67k

3.33k

3.33k

6.67k

A<2:0>

DGND

IN–

IN+

DGND

VS+

A1

A2

A3

OUT

LVSS

LVDD

LVSS

LVDD

REF

DA_IN–

DA_IN+

VS+

VS−

LVDD

LVSS

VS+

VS−

VS+

VS−

VS+

VS−

VS+

VS−

VS+

VS−

+

–

VS+

VS−

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PGA848

SBOSAN4 – AUGUST 2025

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Product Folder Links: PGA848