A CMOS-MEMS arrayed resonant-gate field effect transistor (RGFET) oscillator

作者：Chin Chi Hang^*; Li Ming Huang; Chen Chao Yu; Wang Yu Lin; Li Sheng Shian

来源：Journal of Micromechanics and Microengineering, 2015, 25(11): 115025.

DOI：10.1088/0960-1317/25/11/115025

• CMOS-MEMS
• RGFET
• array
• transconductance
• power handling
• Pierce oscillator
• phase noise

A high-frequency CMOS-MEMS arrayed resonant-gate field effect transistor (RGFET) fabricated by a standard 0.35 mu m 2-poly-4-metal CMOS-MEMS platform is implemented to enable a Pierce-type oscillator. The proposed arrayed RGFET exhibits low motional impedance of only 5 k Omega under a purely capacitive transduction and decent power handling capability. With such features, the implemented oscillator shows impressive phase noise of -117 dBc Hz(-1) at the far-from-carrier offset (1 MHz). In this work, we design a clamped-clamped beam (CCB) arrayed resonator utilizing a high-velocity mechanical coupling scheme to serve as the resonant-gate array. To achieve a functional arrayed RGFET, a corresponding FET array is directly placed underneath the resonant gate array to convert the motional current on the resonant-gate array into a voltage output with a tunable transconductance gain. To understand the behavior of the proposed device, an equivalent circuit model consisting of the resonant unit and FET is also provided. To verify the effects of the post-CMOS process on device performance, a conventional MOS I-D current measurement is carried out. Finally, a CMOS-MEMS arrayed RGFET oscillator is realized by utilizing a Pierce oscillator architecture, showing decent phase noise performance that benefits from the array design to alleviate the nonlinear effect of the resonant gate.

• 出版日期2015-11
• 单位清华大学