Design of Ultra-Low Power Pulse-Driven MEMS Oscillator

Abstract

This paper presents an energy efficient pulse-driven on-chip MEMS oscillator which consists of MEMS resonator and sustaining CMOS circuit. Conventional oscillators are driven by means of an inverter-based amplifier low-pass filtered through a series resistor. However, this architecture suffers from multiple energy losses. Firstly, the inverter amplifier is driven by a sinusoidal input, thus consuming significant static power. Additional power is also consumed by the series resistance. The proposed pulsed driver provides a 180° degree shift, effectively replacing the amplifier. The driver injects energy in the oscillator by periodically switching one oscillator end to V DD when the other end reaches the bottom voltage, and to V SS when the other end reaches the peak voltage. The proposed configuration reduces the static power consumption, as the switch is driven by two rectangular voltages and reduces leakage by activating only one of the two switches at a time. This pulse-driven oscillator, running at 33.14kHz, is simulated to consume 835pW when driven at 0.8V, leading to more than ×15 power saving with respect to the traditional configuration, which consumes 13.2nW.