Behavioural modelling of MEMS oscillators and phase noise simulation
MEMS frequency references and MEMS vibrating sensors, based on a resonator vibrating at its resonance frequency, offer interesting prospects in terms of miniaturization, cost and precision but their design optimization is difficult because multiple physical domains must be taken into account, as well as the associated nonlinearities that limit the carrier power. Once the model is set up, the simulation of the accurate phase noise that limits the sensor's precision is also a difficult matter. In this work, a behavioural model in Verilog-A is presented, that allows multi-physic simulations : mechanical, piezoelectric, electrostatic and electrical analytic descriptions including the associated nonlinear behaviours are derived. Transient and phase noise analysis are then performed with this model through the dedicated CADENCE PSS (Periodic Steady State) and Pnoise (Periodic Noise) analysis and compared to the analytical expression of the nonlinear critical amplitude, and to the standard Leeson analytical expression for phase noise. This work is the first step to improve the performances of such MEMS oscillators.
mems oscillator phase noise resonator nonlinearities verilog-a model