Abstract
This work reports the design and characterization of a PLL (phase-locked loop)-based control scheme implemented in a CMOS (complementary metal oxide semiconductor) process for resonance matching between capacitive micro-resonators. The system-on-chip implementation can be utilized for calibrating individual resonance in a large sensor array or matching the drive and sense modes for micromachined vibratory gyroscopes. The target micro-resonator acts as a voltage-controlled oscillator in the control loop with the resonance being adjusted by the electrostatic spring-softening effect. Sinusoidal test inputs applied to the control loop are shown to provide better resonance matching than square-wave inputs. This work successfully demonstrates automated matching by pulling the resonance of a target micro-resonator within 2.4×10-2% of the reference resonance under atmospheric pressure.