Temperature compensated silicon resonators for space applications

Abstract

This paper presents piezoelectric transduction and frequency trimming of silicon-based resonators with a center frequency in the low megahertz regime. The temperature coefficient of frequency (TCF) of the resonators is reduced using both passive and active compensation schemes. Specifically, a novel technique utilizing oxide-refilled trenches is implemented to achieve efficient temperature compensation while maintaining compatibility with wet release processes. Using this method, we demonstrate high-Q resonators having a first-order TCF as low as 3 ppm/°C and a turnover temperature of around 90 °C, ideally suited for use in ovenized platforms. Using active tuning, the temperature sensitivity of the resonator is further compensated around the turnover temperature, demonstrating frequency instability of less than 400 ppb. Such devices are ideally suited as timing units in space applications where size, power consumption, and temperature stability are of critical importance.

Mechanical properties of MEMS materials: reliability investigations by mechanical- and HRXRD-characterization related to environmental testing

“…Such resonators are especially suited for oven-controlled systems as the turnover temperature can be adjusted by the geometry of the structure. At the turnover point a frequency stability of ±0.1 ppm was demonstrated over a period of more than one hour [47].…”

Electrostatic stabilization of thermal variation in quality factor using anchor loss modulation

“…Typically, either a temperature-stable environment or a thermal-compensation scheme must be created. While most studies of thermal compensation address the stability of resonance frequency over temperature by reducing the Temperature Coefficient of Frequency (TCF), designing temperature-insensitive structure, or implementing a compensation algorithm [1], herein, we focus on the stabilization of Q-factor, a fundamental parameter of resonance devices. For ultra-high Q-factor resonators, Q-factor strongly depends on temperature [2].…”

A Temperature-Compensated Single-Crystal Silicon-on-Insulator (SOI) MEMS Oscillator with a CMOS Amplifier Chip

“…However, the elastic properties of Si are strongly temperature-dependent, so temperature fluctuations degrade the long-term frequency stability of Si-based oscillators. A number of compensation methods have been reported for improving temperature stability [ 2 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. For example, in [ 12 ], the authors implement a passive compensation method by utilizing silicon dioxide (SiO 2 ), which has an opposite TC f compared to the structural material of the main resonator (Si); this compensation technique results in a parabolic (second-order) frequency dependence versus temperature.…”