MEMS device automatic-gain control loop for mechanical amplitude drive

摘要

This document discusses, among other things, apparatus and methods for digital automatic gain control for driving a MEMS device, such as a proof mass. In an example, an apparatus can include a driver configured to oscillate a proof mass of a MEMS device, a charge-to-voltage (C2V) converter configured to provide oscillation information of the proof mass, an analog-to-digital converter (ADC) configured to provide a digital representation of the oscillation information, and a digital, automatic gain control circuit to provide oscillation amplitude error information using a comparison of the oscillation information to target amplitude information, and to provide a digital drive command signal using an amplified representation of the oscillation amplitude error information.

主权项

1. An apparatus comprising:
a driver configured to oscillate a proof mass of a MEMS gyroscope; a charge-to-voltage (C2V) converter configured to receive a sense signal from a MEMS gyroscope and to provide oscillation information of the proof mass; an analog-to-digital converter (ADC) configured to receive the oscillation information of the proof mass and to provide a digital representation of the oscillation information; and a digital, automatic gain control circuit configured to receive the digital representation of the oscillation information, to provide oscillation amplitude error information using a comparison of the oscillation information to target amplitude information, and to provide a digital drive command signal using an amplified representation of the oscillation amplitude error information, the digital, automatic gain control circuit includes an output stage, the output stage including:
a fine gain register configured to provide a basic unit of change of the digital drive command signal;a low pass filter; anda coarse gain counter configured to increment on overshoot of the fine gain register, to decrement on undershoot of the fine gain register, and to provide a correction to the amplified representation of the oscillation amplitude error information.