High-frequency thin-film piezoelectric transformers

Abstract

A voltage step-up/impedance transformer is presented which operates by modifying the electrode configuration of lateral-extensional mode thin-film piezoelectric-on-substrate (TPoS) resonators. The individual electrode pairs that cover the stress concentration areas of a 10 th order harmonic 30MHz resonator are connected in series at the output port to effectively unbalance the input and output impedances. After inductive cancelation of the electrode/pad capacitances at the output port, a voltage gain of +10.4 dB is achieved in such transformers. Additionally, an impedance transformation ratio of 19:1 is obtained.

Thin-film piezoelectric transformers operating in harmonics of out-of-plane flexure modes

“…Although there have been significant prior art detailing thin-film piezoelectric resonators for RF filters, there has been limited work on thin-film MEMS piezoelectric transformers (piezo-transformers) [1], [11][12][13][14][15]. While this work builds upon prior electrode shaping methods used for thin-film PZT resonators [16], it does contrast prior thinfilm PZT piezoelectric transformer work relying on the use of the typical extensional modes presented in the MEMS literature [1] and utilized with bulk-scale piezo-transformers [17].…”

PZT-on-silicon RF-MEMS lamb wave resonators and filters

“…High-frequency acoustic micro-electro-mechanical system (MEMS) or RF-MEMS resonators are showing promising performance for next generation of miniaturized and integrated systems. Various applications such as radio frequency (RF) oscillators [14] and filters [50,51,64], optomechanical systems [65], electrical transformers [66,67,68] are shaping up using these systems. Lamb-wave RF-MEMS resonators have demonstrated promising performance, such as high quality-factor (Q-factor) due to the released structures, higher phase velocity and smaller size compared to the traditional acoustic resonators means SAW resonators.…”