Effect of Joule heating on the performance of micromechanical piezoresistive oscillator

Joule heating is more widely existed in micromechanical resonators, and is also an innovative approach for the implementation of mechanical resonator in a broad range of fields such as timing applications, filters and sensors. However, the physical mechanism by which Joule heating affects the performance of resonator has not been thoroughly studied, and the ability to accurately control heat and suppress thermal noise in micro-and nanomechanical resonators remains a key challenge limiting practical applications as well. In this paper, we established the theoretical model based on temperature variation to explain the physical mechanism of the Joule heating effect on the performance of resonator. In the experiment, when the drain current increased from 3.35 mA to 11.62 mA, the dynamic range enhanced by 20.3 dB, which verified that the drain current can be conducive to enhance the signal-to-noise ratio (SNR) of resonator. Intuitively, adding Joule heating will make more thermal noise for the system, which will deteriorate the frequency stability of oscillator. However, there was a counterintuitive phenomenon in piezoresistive oscillator. Contrary to the capacitive oscillator, for a self-sustained mechanical oscillator based on piezoresistive detection method, the frequency stability of oscillator will be improved as the drain current increases. The experimental result showed that the Allan deviation have improved with a slope of −11.22ppb/mA. Our finding revealed the potential of joule heating for applications in high dynamic range sensors and time reference oscillators, as well as the fundamental study of the temperature variation and energy dissipation in micro and nano systems.