CMOS-embedded high-power handling RF-MEMS tunable capacitor using quadruple series capacitor and slit with dielectric bridges structure

Abstract

In this paper, we report on a high-power handling RF-MEMS tunable capacitor that has a quadruple series capacitor (QSC) and a movable electrode using a slit with dielectric bridges (SDB) structure. The QSC structure consists of two fixed metal–insulator–metal (MIM) capacitors and two MEMS capacitor elements connected in series, and enables reduction of the RF voltage to the MEMS capacitors. The SDB structure is able to increase the release voltage without increasing the pull-in voltage. The combination of these structures enables improving power handling capabilities. A capacitor bank using QSC and SDB structures was fabricated by a micromachining process above CMOS control circuits. Measurement results demonstrate the excellent power handling capability up to +44 dBm for cold switching, and up to +35 dBm under hot switching. Moreover, the Q-factor of the capacitor bank is very high that is above 150 at 1 GHz, and the capacitance can be changed from 1.1 to 5.3 pF at a resolution of 4 bits by the internal control circuits thanks to monolithic integration.