Trim circuit and method of oscillator drive circuit phase calibration

A device comprising:

• a movable mass;
• an oscillator drive circuit configured to provide an oscillating drive signal at a resonant frequency to drive the movable mass, the oscillator drive circuit including a phase shift circuit having an input configured to receive a first signal indicative of an oscillation of the movable mass and having an output, the phase shift circuit being configured to add a phase shift component to the first signal and produce a second signal shifted in phase by the phase shift component;
• and
• a trim circuit comprising:
• a first comparator connected with the input of the phase shift circuit and configured to receive the first signal;
• a second comparator in communication with the output of the phase shift circuit and configured to receive the second signal;
• and
• a processing element in communication with the first and second comparators, the processing element being configured to determine a phase lag between the first and second signals and produce a trim code in response to the phase lag for use by the phase shift circuit, wherein the oscillator drive circuit and the trim circuit are implemented inside an integrated circuit of the device, wherein the trim code is configured to minimize a difference between the phase lag and a target phase lag.

A device comprising:

• a movable mass;
• an oscillator drive circuit configured to provide an oscillating drive signal at a resonant frequency to drive the movable mass, the oscillator drive circuit including a phase shift circuit having an input configured to receive a first signal indicative of an oscillation of the movable mass and having an output, the phase shift circuit being configured to add a phase shift component to the first signal and produce a second signal shifted in phase by the phase shift component;
• a trim circuit comprising:
• a first comparator connected with the input of the phase shift circuit and configured to receive the first signal;
• a second comparator in communication with the output of the phase shift circuit and configured to receive the second signal;
• and
• a processing element in communication with the first and second comparators, the processing element being configured to determine a phase lag between the first and second signals and produce a trim code in response to the phase lag for use by the phase shift circuit, wherein the oscillator drive circuit and the trim circuit are implemented inside an integrated circuit of the device;
• and
• an oscillator for producing a digital clock signal having a clock frequency that is greater than the resonant frequency, wherein the processing element is configured to:
• determine a first quantity of clock pulses of the digital clock signal during a period of the first signal;
• define a target phase lag in response to the first quantity of clock pulses:
• determine a second quantity of clock pulses of the digital clock signal between a first edge of the first signal and a second edge of the second signal;
• determine the phase lag from the second quantity of clock pulses;
• and produce the trim code that minimizes a difference between the phase lag and the target phase lag.