1.05 GHz MEMS Oscillator Based On Lateral-Field-Excited Piezoelectric AlN Resonators

Chengjie Zuo, University of Pennsylvania
Jan Van der Spiegel, University of Pennsylvania
Gianluca Piazza, University of Pennsylvania

Abstract

This paper reports on the first demonstration of a 1.05 GHz microelectromechanical (MEMS) oscillator based on lateral-field-excited (LFE) piezoelectric Aluminum Nitride (AlN) contour-mode resonators. The oscillator shows a phase noise level of –81 dBc/Hz at 1 kHz offset frequency and a phase noise floor of –146 dBc/Hz, which satisfies the GSM requirements of Ultra High Frequency (UHF) local oscillators (LO). The circuit was fabricated in the AMIS 0.5 μm CMOS process, with the oscillator core consuming only 3.5 mW static power. A simple two-mask process was used to fabricate the LFE AlN resonators from 843 MHz to 1.64 GHz with high Q (up to 2,200) and kt2 (up to 1.2%). This process further relaxes manufacturing tolerances and improves yield. All these advantages make it suitable for post-CMOS integrated on-chip direct GHz frequency synthesis in reconfigurable multi-band wireless communications.