MEMS resonator

Over the past decade, a great deal of research effort has been devoted to development of low-power and high-Q micromechanical resonators with a high quality factor (Q) suitable for bring the frequency reference and signal processing functionalities, such as oscillators, mixers and frond-end filters at higher frequency bands (e.g., UHF and beyond), on to a single chip. Currently, devices based on mechanical vibration such as quartz crystals and surface acoustic wave (SAW) are widely used to implement high-Q oscillators and band-pass filters in communications transceivers. Unfortunately, despite of the beneficial high Q offered by quartz crystal and SAW devices, they are off-chip components that must be integrated with electronics at the board level, thus hindering the ultimate miniaturization and portability of wireless transceivers. Very promising alternatives to overcome the issue with the off-chip devices have been demonstrated by on-chip micromechanical resonators with electrostatic and piezoelectric transduction mechanisms along with small form factor, high quality factor (Qs >10,000) and low insertion loss.

The objective for the present project is design and fabricate piezoelectrically transduced mechanical filters in the frequency range from 1 GHz to 12 GHz (L, S, C, and X band) with 5% bandwidth with low insertion and small motional resistance in order to interface directly these devices with 50-Ω electronics. The microfabrication and testing of the piezoelectrically-transduced resonators and filters has been completed. A new novel design consisted of SOI-based devices with silicon as the structural layer and ZnO as the piezoelectric transducer layer has been implemented. Preliminary on-wafer probing test in the open air (atmospheric environment) has been done. MEMS resonators and filters with frequencies in the range of 100 MHz to 4.8 GHz have been successfully demonstrated. Devices with frequencies of 1.8GHz, 2.4 GHz and 4.8 GHz have shown promising preliminary results comparable with the performance of the current state of commercial filter technologies such as FBAR and SAW filter.