Designing a new high gain CMOS amplifier towards a 17.22 MHz MEMS based Si oscillator for a cost effective clock generator IC

Abstract

A novel sustaining amplifier is designed and characterized for a Si-based MEMS resonator, in implementing a reference oscillator in 180 nm CMOS process. A two port electrical model of the MEMS resonator is used to compute the insertion loss (−76 dB) and phase shift (95°). Total open loop transimpedance gain is achieved as 122 dBΩ with −70°phase shift, at the resonant frequency of 17.22 MHz. This amount of gain is investigated as capable to sustain MEMS resonator's oscillation, in the realization of a cost effective, miniaturized and low power CMOS reference oscillator which oversees on application in clock generation.

Micromachined Resonators: A Review

“…When used in timing circuits as precision clocks [ 200 ] or as RF carriers [ 10 ], MEMS resonators are used as the frequency reference element. Whether MEMS resonators are used in sensing or in timing applications, the sustaining amplifier needs to carefully be designed to consider the particularities of MEMS resonators in order to enable high quality oscillation [ 213 , 214 , 215 , 216 ].…”

A high-performance oscillator based on RF MEMS resonator and low-noise sustaining circuit for timing applications

“…The reference oscillators based on radio frequency micro-electromechanical system (RF MEMS) resonators are considered as potential substitutes for quartz crystal and SAW oscillators due to their small size, low cost, high performance, and complementary-metal-oxide-semiconductor (CMOS) compatible fabrication process, which provide ideal approaches to achieve low-power and high-precision timing references [1]. However, several issues, such as high noise of the feedback circuits, poor phase noise performance, and frequency stability problems, prevent their use in high precision applications [2].…”