Influence of silicon on quality factor, motional impedance and tuning range of pzt-transduced resonators

Abstract

This paper provides a quantitative comparison and explores the design space of PZT-only (Lead Zirconium Titanate) and PZT-on-Silicon length-extensional mode resonators for incorporation into RF MEMS filters and oscillators. We experimentally measured the correlation of motional impedance (RX) and quality factor (Q) with the resonators’ silicon layer thickness (tSi). For identical lateral dimensions and PZT-layer thickness (tPZT), the PZT-on-Silicon resonator has higher resonant frequency (dominated by silicon), higher Q (5,100 vs. 140) and lower motional impedance (51 Ω vs. 205 Ω). However, PZT-only resonator demonstrated much wider frequency tuning range (5.1% vs. 0.2%).