A High Tuning-Ratio Silicon-Micromachined Variable Capacitor with Low Driving Voltage

Abstract

A bulk-micromachined variable capacitor, in which the gap distance between parallel plates is adjusted by comb-drive actuators, has been developed. This capacitor possesses the merits of parallel-plate capacitors and comb-drive actuation without their demerits. Therefore, this device has high tuning range and low tuning voltages with a small footprint and stiff springs, resulting in lower mechanical noise sensitivity and high tuning speed. The initial fabricated devices demonstrate a 5:1 tuning ratio at 20V with 8.46pF maximum capacitance.