MEMS sensor

An amplifier apparatus for amplifying an input signal from a MEMS capacitive sensor comprising:

• an amplifier arrangement having first and second inputs;
• wherein the first input is configured to receive the input signal and the second input is configured to receive a second signal which is in antiphase with the input signal;
• a signal generator for generating the second signal at said second input;
• and
• a bias source for biasing the MEMS capacitive sensor with a bias voltage;
• wherein the bias voltage is modulated based on the second signal,
• wherein the signal generator generates the second signal based on a common-mode voltage of first and second output signals of the amplifier arrangement.

An amplifier arrangement for amplifying an input signal from a MEMS capacitive sensor comprising:

• a first single-ended input amplifier configured to receive and amplify the input signal as a first output signal;
• a second single-ended input amplifier configured to receive and amplify a second signal as a second output signal;
• wherein the second signal is generated by the amplifier arrangement to be in antiphase to the first signal;
• and
• a modulator for modulating a bias voltage applied to the MEMS capacitive sensor based on said second signal,
• wherein the second signal is generated by the amplifier arrangement based on a common-mode voltage of the first and second output signals.

An amplifier apparatus for amplifying an input signal from a MEMS capacitive sensor comprising:

• a sense node for receiving the input signal;
• an antiphase signal generator for generating a second signal which is in antiphase with the input signal;
• and
• an amplifier arrangement configured to receive the input signal at a first input and the second signal at a second input and to output corresponding first and second output signals,
• wherein the antiphase signal generator comprises a feedback amplifier configured to receive a common-mode signal indicative of a common mode voltage of the first and second output signals and a common-mode reference voltage and to drive the second signal at the second input of the amplifier arrangement to keep the common mode voltage of the first and second output signals to be equal to the common-mode reference voltage.

An amplifier apparatus for amplifying an input signal from a MEMS capacitive sensor comprising:

• an amplifier arrangement having first and second inputs;
• wherein the first input is configured to receive the input signal and the second input is configured to receive a second signal which is in antiphase with the input signal;
• a signal generator for generating the second signal at said second input;
• and
• a bias source for biasing the MEMS capacitive sensor with a bias voltage;
• wherein the bias voltage is modulated based on the second signal,
• wherein the signal generator comprises a feedback amplifier configured to receive a common-mode signal indicative of a common mode voltage of first and second output signals of the amplifier arrangement and a common-mode reference voltage and to drive the second signal at the second input of the amplifier arrangement to keep the common mode voltage of the first and second output signals to be equal to the common-mode reference voltage.

An amplifier arrangement for amplifying an input signal from a MEMS capacitive sensor comprising:

• a first single-ended input amplifier configured to receive and amplify the input signal as a first output signal;
• a second single-ended input amplifier configured to receive and amplify a second signal as a second output signal;
• wherein the second signal is generated by the amplifier arrangement to be in antiphase to the first signal;
• and
• a modulator for modulating a bias voltage applied to the MEMS capacitive sensor based on said second signal,
• wherein the second single-ended input amplifier comprises a feedback amplifier configured to receive a common-mode signal indicative of a common mode voltage of the first and second output signals and a common-mode reference voltage and to drive the second signal at the second input of the amplifier arrangement to keep the common mode voltage of the first and second output signals to be equal to the common-mode reference voltage.