A/D converter with direct drive capacitive input composed of INA331/INA332

As shown in the figure, this is an A/D converter that directly drives capacitive inputs, which is composed of INA331/332. Since the output of INA331/332 is low impedance, it can directly drive capacitive loads when working at high frequencies. The input voltage is amplified and output by INA331 and directly sent to the 12-bit high-speed, low-power sampling A/D converter ADS7818 or ADS7822. The internal input of ADS7818 or ADS7822 is a capacitor array (CDAC) digital-to-analog converter, that is, a capacitive input. The A/D converter converts the input analog signal into a 12-bit digital signal output.