Stmicroelectronics Gmbh

Chao-Ming Tsai

Yamu Hu

Deyou Fang

David C McClure

Milad Alwardi

A microelectromechanical system (MEMS) gyroscope includes a driving mass and a driving circuit that operates to drive the driving mass in a mechanical oscillation at a resonant drive frequency. An oscillator generates a system clock that is independent of and asynchronous to the resonant drive frequency. A clock generator circuit outputs a first clock and a second clock that are derived from the system clock. The drive loop of the driving circuit including an analog-to-digital converter (ADC) circuit that is clocked by the first clock and a digital signal processing (DSP) circuit that is clocked by the second clock.

MEMS gyroscope control circuit

A drive signal is applied to a MEMS gyroscope having several intrinsic resonant modes. Frequency and amplitude of mechanical oscillation in response to the drive signal is sensed. At startup, the drive signal frequency is set to a kicking frequency offset from a resonant frequency corresponding to a desired one of the intrinsic resonant modes. In response to sufficient sensed amplitude of mechanical oscillation at the kicking frequency, a frequency tracking process is engaged to control the frequency for the drive signal to sustain mechanical oscillation at the frequency of the desired one of the plurality of intrinsic resonant modes as the oscillation amplitude increases. When the increasing amplitude of the mechanical oscillation exceeds a threshold, a gain control process is used to exercise gain control over the applied drive signal so as to cause the amplitude of mechanical oscillation to match a further threshold. At that point start-up terminates.

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Southlake, TX, United States of America

Chao-Ming Tsai