Design of an Electronic Oscillator Based on an On-Chip MEMS Resonator Aimed at Sensing Applications

We present the design of an integrated electronic oscillator aimed at the detection of the response of an integrated MEMS resonant mass sensor. The resonator and oscillator are designed to be fabricated on a CMOS-compatible bulk micromachining technology which allows the coexistence of MEMS components and integrated circuits on the same chip. The resonator is targeted at the development of low-cost integrated smart biosensors for the detection of diagnostic markers in a POCT (point-of-care testing) context. The oscillator is based on a standard positive feedback topology, using the MEMS resonator as a two-port, frequency selective element. The main design issues are the low input impedance of the resonator and its significant attenuation. ELDO simulations of the designed circuit, based on an equivalent model of the resonator extracted from experimental data, were performed, and the results are presented and commented.