Mems filter with voltage tunable center frequency and bandwidth

Abstract

This paper reports on the design of a reconfigurable ladder filter using RF MEMS resonators with voltage-tunable series and parallel resonance frequencies. The ladder filter consists of one shunt and two series resonators operating in the half-wave thickness shear vibration mode. It demonstrates a center frequency tuning range of 8 MHz at 817 MHz and an adjustable bandwidth from 600 kHz to 2.8 MHz, while maintaining an insertion loss < 4 dB, stop-band rejection > 30 dB and pass-band ripple < 2 dB. This voltage tunable design enables channel agility and reconfigurability, substantially reducing the filter count in channel-select radio receiver architectures. Finally, a simple algorithm is provided to facilitate dynamic tuning of filter center frequency and bandwidth.