Support Transducer Enabled Single Resonator Channel Select Filter

In this work, we report a piezoelectric channel select filter design using a single resonator which utilizes Thin Piezo on Substrate (TPoS) transducer uniquely positioned so as to drive the central bulk Single Crystal Silicon (SCS) into resonance. Here, the support transducers operate in a combined length extension and an in-plane shear mode. A short connector between transducers and central SCS is used to create a frequency split to realize the filter. The device is fabricated using MEMSCAP Inc. AlN-on-silicon platform. A differential drive and single port sense method was employed to realize the narrow bandwidth (NBW) filter with a reduced feedthrough level. As a result, we demonstrate a 20.62 MHz TPoS MEMS filter with an extremely flat passband and a tiny bandwidth of 18 kHz (0.087% BW), a 4dB Insertion Loss with a 39dB Stop Band Rejection and less than 0.1dB passband ripple.