A Micro-Oven-Controlled Dual-Mode Piezoelectric MEMS Resonator With ±400 PPB Stability Over −40 to 80 °C Temperature Range

Abstract

In this article, the design, implementation, and characterization of a micro-oven-controlled dual-mode piezoelectric microelectromechanical system (MEMS) resonator are presented. The designed MEMS resonator simultaneously operates in the width extensional (WE) mode and length shear (LS) mode. Both modes show high quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> ). The measured <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> is 15672 for the WE mode and 17781 for the LS mode. Taking advantage of the significant difference in frequency–temperature characteristics between the two modes, accurate temperature sensing and precisely closed-loop micro-oven control are implemented by phase locking the MEMS resonator at an oven-set temperature. In-plane micro-oven is composed of four folded beams and an isolation frame, which maintains an extremely uniform temperature distribution on the resonating element. The micro-oven structure requires less than 7.8 mW to maintain the resonator’s temperature at the preset temperature over variations in the external temperature range of −40 °C to 80 °C. Measured real-time frequency stability of the reported micro-oven-controlled MEMS resonator is less than ±400 ppb over a wide temperature range from −40 °C to 80 °C.