JAJSPR4B April 2023 – September 2023 PGA855
PRODUCTION DATA
The PGA855 is a monolithic, high-voltage, precision programmable-gain instrumentation amplifier. The PGA855 combines a high-speed current-feedback input stage with an internally matched gain resistor network, followed by a four-resistor, fully differential amplifier output stage. Eight preprogrammed binary gains, ranging from 0.125 V/V to 16 V/V are selectable using gain-select pins A0, A1, and A2.
A functional block diagram for PGA855 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 is used to amplify the differential input voltage. A fully differential output difference amplifier, A3, rejects the input common-mode component and refers the output signal to the voltage level set by the VOCM pin.
The PGA855 output amplifier bandwidth is optimized to drive high-performance analog-to-digital converters (ADCs) with sampling rates up to 1 MSPS without the need for an additional ADC driver. 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 due to inadvertent overvoltage conditions.