Temperature-stable piezoelectric MEMS resonators using integrated ovens and simple resistive feedback circuits

This paper reports on the design and demonstration of a miniaturized and integrated heater that enables low power ovenization and temperature stability for piezoelectric MEMS resonators. The low power ovenization is implemented by an integrated symmetric oven platform and high thermal-resistance supporting structures. The temperature compensation circuit is formed by a modified Wheatstone bridge with an on-chip dummy resistor and a constant resistance feedback loop is used to stabilize the resonator center frequency over temperature. Through the use of the integrated heater and the simple feedback circuit, we were able to reduce the resonator's intrinsic frequency instability to 100 ppm (from over 2700 ppm) over a temperature range of -35 °C to + 85 °C. Compared with the state of the art, this paper constitutes a fundamental step forward in the demonstration of temperature stable oscillators with a focus on improving resonator temperature stability with very low power consumption.