Wafer-level vacuum-encapsulated ultra-low voltage tuning fork MEMS resonator

We present the design of a wafer-level vacuum-encapsulated silicon tuning fork resonator operating at 32 kHz, along with a low power Complementary Metal-Oxide Semiconductor (CMOS) sustaining amplifier towards an oscillator. The resonator is designed using MEMS Integrated Design for Inertial Sensors (MIDIS) process developed by Teledyne DALSA Semiconductor Inc. (TDSI). The MicroElectroMechanical Systems (MEMS) resonator is designed to operate with an ultra-low DC polarization voltage, as low as 1V, and low motional resistance. This is achieved by using a transduction gap reduction technique based on electrostatic deflection of movable electrode and subsequent localized melting of welding pads. A transimpedance operational amplifier is used as sustaining amplifier to help with continuous oscillation. The oscillator operates with an average power consumption of 1.86 mW that is suitable for mobile electronics.