Switching thermal piezoresistive oscillators from damped to self-sustained regime using tunable resistors

Over the last few years, Thermal Piezoresistive Back Action (TPBA) in biased silicon nanobeams has demonstrated its interest to control the quality factor of resonators and its ability to reach self-sustained oscillations regime. This paper reports a new technique to move from damped to self-sustained regime by switching the sign of the TPBA viscous force during device operation by means of tunable resistors embedded in the biasing circuit. For a specific value of the resistor, the damping rate becomes independent of the biasing voltage, thus cancelling TPBA effect in the device. TPBA decoupling between electrical and thermal domains is here investigated to account for this notable point. Such a configuration can be appropriate for cases where MEMS response needs to be independent of motion readout.