Analysis of the Effect of Interdigital Transducer Electrode Number in Lamb Wave Piezoelectric MEMS

This work investigates the influence of the number N of electrode pairs of the interdigital transducers (IDTs) over the frequency response of a flexural plate wave (FPW) piezoelectric MEMS transducer. The number of electrode pairs N located over the diaphragm of a FPW MEMS directly affects the bandwidth and the frequency response of the transducer. Specifically, this paper addresses the case of a one-port piezoelectric MEMS transducer having the IDT positioned near the diaphragm edge. The electrical conductance G(f) of the IDT is analysed using FEM and LTspice simulations. The developed analysis was experimentally validated on a fabricated AlN-based piezoelectric MEMS transducer. The number of multiple waves was correctly detected within the expected bandwidth, in good agreement with theoretical predictions.