Low power pulse generator as a capacitive interface for MEMS applications

This paper presents an ultra low power pulse generator based on special design of a voltage controlled ring oscillator (VCRO). This pulse generator can be used as a capacitive sensor interface for MEMS applications with the advantage of using short pulse width to achieve lower power consumption and high sensitivity for low capacitance. The pulse frequency can be controlled by voltage bias. The design is made using 2 mu m MEMS compatible silicon-on-insulator CMOS technology. The power consumption is estimated to be in the range of 2 mu W when the pulse frequency is set to 300 kHz.