A sandwich structure type RF-MEMS variable capacitor is proposed, that consists of a movable middle plate, and fixed top and bottom plates having different areas. Simulation results show that the proposed capacitor can operate at a control voltage of less than 3.2 V; it achieves a tuning range of 4.8:1 (capacitance:630-130 fF) in the range of 0 to 3.2 V and at a frequency of 7.5 GHz.

A low-noise, low-power 10-GHz CMOS VCO was developed using cost-effective 0.18-µm CMOS technology. A complementary cross-coupled topology was employed to decrease the power dissipation and phase noise. The fabricated VCO demonstrates a low phase noise of -106 dBc/Hz at an offset frequency of 1 MHz and a low power dissipation of 4.4 mW.