An automatic tuning technique for background frequency calibration in gyroscope interfaces based on high order bandpass Delta-Sigma modulators

Achieving high quality measurements with continuous-time Delta-Sigma modulator based micromachined gyroscope systems requires matching the resonant frequencies of the drive and of the sense loops. This work presents a system that synchronizes and calibrates the frequency of the electrical filter to the resonance frequency of the sensor. It is employed in a fourth order continuous-time bandpass Delta-Sigma based gyroscope system. The synchronization process is done in the background without interrupting the normal operation of the gyroscope´s closed-loop interface. Simulations show that the proposed synchronization/calibration technique reduces the error in the electrical resonant frequency to less than 0.4% relative to the mechanical resonant frequency.