Dual frequency MEMS resonator through mixed electrical and mechanical coupling scheme

Abstract

Miniaturised transceivers are essential in multiband wireless communication systems for higher data rates and low power consumption. Microelectromechanical system (MEMS) resonator filters are actively considered for deployment in transceivers for radio frequency and intermediate frequency (IF) signal filter and oscillator applications. In this study, the authors propose dual frequency capacitive transduced MEMS resonator with two-port electrical configuration. Clamped-clamped beam resonator was selected to serve as a basic resonant tank for the filter concept validation. Five design strategies low loss structural material, array design, mixed electrical and mechanical coupling scheme, sub-micro meter transduction gap and large transduction area were explored. With these strategies, the device achieves dual band filter characteristics, narrow pass band, desired bandwidth, low insertion loss and better stop band rejection. Dual frequency response of the proposed resonator is demonstrated at centre frequencies 400 kHz and 2.57 MHz with a narrow pass band of 3 and 20 kHz, respectively. Low insertion loss of 19.8 and 25.6 dB for frequencies centred at 400 kHz and 2.57 MHz, respectively and stop band rejection >35 dB was achieved. The proposed MEMS resonator may be incorporated in the implementation of dual band pass filter for IF signal filter and dual frequency oscillator applications.