A MEMS variable capacitor with piezoresistive position sensing fabricated in a standard 0.35 µm CMOS process

A variable MEMS capacitor with piezoresistive feedback is presented. The capacitor is fabricated in a commercial 0.35 µm CMOS process with MEMS post-processing. The work presented demonstrates a piezoresistive sensing scheme capable of controlling hysteresis effects in a CMOS-MEMS variable capacitor. Potential applications of the sensing scheme include closed-loop control of variable capacitors and detection of dielectic charging.