Compact K-band distributed RF MEMS phase shifter based on high-speed switched capacitors

Abstract

A high-speed switched capacitor based distributed MEMS phase shifter has been presented. Miniaturization of the conventional MEMS capacitor dimensions has been done to achieve sub-microsecond switching, lower actuation voltage and a compact structure. Conventional design approach of such high-speed MEMS capacitor based phase shifter employs cascading the capacitors on a linear coplanar transmission line. Compactness of the device is achieved by employing space filling curves like i) Meander line CPW and ii) Modified Hilbert curve CPW. Simulations conducted reveal that the modified Hilbert Curve based phase shifter provides the most compact structure and yields a phase shift of ∼180° at 22GHz (K-band). The modified Hilbert Curve occupies an area of (820×820) µm2 only. Electromechanical simulations indicate that the switched capacitors require an actuation voltage of 14V and a switching time of 220ns.