Auto-calibration method for inertial MEMS sensors

A method, comprising:

• applying a frequency sweep self-test signal to a test electrode of an inertial sensor and to a first demodulator of the inertial sensor;
• generating a first digital signal with the inertial sensor based on the frequency sweep self-test signal;
• generating a demodulated signal by demodulating the first digital signal and the frequency sweep self-test signal;
• generating a baseband signal by passing the demodulated signal through a digital low-pass filter;
• and
• identifying a resonant frequency of the inertial sensor by analyzing the baseband signal with a calibration circuit.

A device comprising:

• a pattern generator configured to generate a variable frequency self-test signal;
• an inertial sensor including a self-test electrode configured to receive the variable frequency self-test signal, the inertial sensor configured to generate an analog sensor signal based on the variable frequency self-test signal;
• an analog to digital converter configured to generate a digital sensor signal based on the analog sensor signal;
• a demodulator including a first input configured to receive the digital sensor signal, a second input configured to receive the self-test signal, and an output configured to output a demodulated signal;
• a first low pass filter coupled to the output of the demodulator and configured to generate a baseband signal;
• and
• a calibration circuit configured to identify a resonant frequency of the inertial sensor by analyzing the baseband signal.