Dominant Loss Mechanisms of Whispering Gallery Mode RF-MEMS Resonators with Wide Frequency Coverage.

Zeji Chen,Quan Yuan,Qianqian Jia,Wenli Liu,Fuhua Yang,Jinling Yang,Yinfang Zhu

doi:10.3390/s20247017

Abstract

This work investigates the dominant energy dissipations of the multi-frequency whispering gallery mode (WGM) resonators to provide an insight into the loss mechanisms of the devices. An extensive theory for each loss source was established and experimentally testified. The squeezed film damping (SFD) is a major loss for all the WGMs at atmosphere, which is distinguished from traditional bulk acoustic wave (BAW) resonators where the high-order modes suffer less from the air damping. In vacuum, the SFD is negligible, and the frequency-dependent Akhiezer damping (AKE) has significant effects on different order modes. For low-order WGMs, the AKE is limited, and the anchor loss behaves as the dominant loss. For high-order modes with an extended nodal region, the anchor loss is reduced, and the AKE determines the Q values. Substantial Q enhancements over four times and an excellent f × Q product up to 6.36 × 1013 at 7 K were achieved.

Highlights

Micro-electro-mechanical system (MEMS) resonators with small occupation, IC compatibility, and lower power consumption have emerged as a key enabling solution to constitute advanced RF-front transceivers for future wireless communications [1,2,3,4,5]
bulk acoustic wave (BAW) resonators with promising f × Q products [7,8,9,10], many outperforming RF components have been demonstrated, such as MEMS oscillators with low phase noise [11,12,13] and RF channel-select filters with ultra-narrow passband [14,15]
For some widely-used BAW resonators, it is hard to maintain high f × Q products in high-order modes as the Q values degrade sharply due to the severer anchor loss

Summary

Introduction

Micro-electro-mechanical system (MEMS) resonators with small occupation, IC compatibility, and lower power consumption have emerged as a key enabling solution to constitute advanced RF-front transceivers for future wireless communications [1,2,3,4,5]. The bulk acoustic wave (BAW) resonators are extremely attractive for their high stiffness and low energy dissipation [6]. BAW resonators with promising f × Q products [7,8,9,10], many outperforming RF components have been demonstrated, such as MEMS oscillators with low phase noise [11,12,13] and RF channel-select filters with ultra-narrow passband [14,15]. For some widely-used BAW resonators, it is hard to maintain high f × Q products in high-order modes as the Q values degrade sharply due to the severer anchor loss. In width extensional mode resonators, the Q values in even modes suffer from severe energy loss at the tether attachment point [10]. Like Lamé mode resonators [18], and composite thin-film piezoelectric-on-substrate (TPoS) resonators vibrating in Sensors 2020, 20, 7017; doi:10.3390/s20247017 www.mdpi.com/journal/sensors

Methods

Results

Conclusion