Low-power ovenization of fused silica resonators for temperature-stable oscillators

Abstract

In this paper, we report on tem operation of silica MEMS oscillators on an silica platform.Temperature servo-contro implemented using an on-chip RTD-based temp and a resistive heater. A wide-range linear an has been implemented to reduce the effective TC silica resonator by an order of magnitude. Dig method is used to mitigate offset errors cause temperature sensing. By effectively removing th the frequency drift of an oscillator u micromechanical resonator is reduced to less tha 105 °C of external temperature change. consumption to ovenize the entire platform con resonators is lower than 15.8 mW.

A temperature-stable mems oscillator on an ovenized micro-platform using a PLL-based heater control system

“…The heater driver is designed using a square-root generator to linearize the transfer characteristic from the control voltage (V CTRL ) to the heater power (P heat ). Using such a design, the PLL can be treated as a linear control system, and the loop gain is near constant regardless of the operating point [2]. The analog square-root generator circuit is designed using CMOS translinear circuits [6].…”

“…For tight control of the frequency, this method requires accurate monitoring of the resonator temperature. Techniques utilizing a resistive temperature detector on chip are inaccurate in estimating the true local temperature of the resonator [2]. Among other sensing methods, frequency-based temperature sensing has been used in quartz crystal references with excellent accuracy [3].…”

A Temperature-Stable Piezoelectric MEMS Oscillator Using a CMOS PLL Circuit for Temperature Sensing and Oven Control

“…However, a low phase noise oscillator typically induces a large driving power on the resonator. The resonators in oscillator circuits can experience significant self-heating [2], which induces temperature gradient in the system. If the thermal resistances of the resonators (R th,RES1 and R th,RES2 ) could be made very small, the temperature offset between T RES1 and T RES2 could still be minimized.…”

“…For tight control of frequency stability, this method requires accurate monitoring of the resonator temperature. Although micro-fabrication technology allows integrating a resistive temperature detector (RTD) on-chip with MEMS devices, a previous study has revealed that temperature sensing using an on-chip RTD is non-ideal due the significantly different thermal characteristics of resonant devices and the RTD [2]. An improved method based on frequency-based temperature sensing has gained success in conventional quartz crystal references [3].…”

“…Similar method has been adopted in realizing ovenized MEMS using phase-lock loops (PLLs), including capacitively transduced MEMS resonators [4] and piezoelectric MEMS resonators [5]. A distinct feature of our previous work [2], [5] compared to other ovenized MEMS devices [4], [6]- [9] is the stabilization of multiple devices in a general-purpose micro-platform without adding constraints to individual device designs. Such a micro-platform potentially paves the way for ovenized device-fusion applications.…”