Patent ID: 10873295

Abstract:
This application relates to amplifier circuitry for amplifying an input signal from a MEMS capacitive sensor. The amplifier circuitry includes a first amplifier for receiving the input signal (VINP) and outputting a first output signal (VOUTP) based on the input signal. A second amplifier is configured to output a second output signal (VOUTN) which varies inversely with the first output signal. The first and second amplifier outputs are connected via first and second impedances so that a voltage at a common-mode node is equal to a common-mode voltage of the first and second output signals. The second amplifier has an input stage having an input terminal connected to a first reference voltage (VR1) and a feedback terminal connected to the common-mode node. The second amplifier also has an output stage connected between an output terminal of the input stage and the second amplifier output.