Seminars

A Low Noise Temperature-to-Digital Converter for a High Stability MEMS-Based Oscillator

Thursday, October 11, 2012

Dr. Michael Perrott

Abstract

This talk presents a MEMS-based programmable oscillator which achieves better than +/-0.5ppm frequency stability from -40 degrees C to 85 degrees C and less than 1ps (rms) integrated phase noise (12kHz to 20MHz). We focus on the key component of this system, which is a thermistor-based temperature-to-digital converter (TDC) that enables accurate and low noise compensation of temperature-induced variation of the MEMS resonant frequency. The TDC utilizes several circuit techniques including a high resolution, tunable reference resistor based on a switched capacitor network and fractional-N frequency division, a switched resistor measurement approach which allows a pulsed bias technique for reduced noise, and a VCO-based quantizer for digitization of the temperature signal. To verify the effectiveness of these techniques, measured performance of a 180nm CMOS IC with co-packaged MEMS die is presented which demonstrates 0.1mK (rms) resolution for the TDC within a 5Hz bandwidth and power consumption of 3.97mA with 3.3V supply.

Speaker Biography

Michael H. Perrott received the B.S. degree in Electrical Engineering from New Mexico State University, Las Cruces, NM in 1988, and the M.S. and Ph.D. degrees in Electrical Engineering and Computer Science from Massachusetts Institute of Technology in 1992 and 1997, respectively. From 1997 to 1998, he worked at Hewlett-Packard Laboratories in Palo Alto, CA, on high speed circuit techniques for Sigma-Delta synthesizers. In 1999, he was a visiting Assistant Professor at the Hong Kong University of Science and Technology. From 1999 to 2001, he worked at Silicon Laboratories in Austin, TX, and developed circuit and signal processing techniques to achieve high performance clock and data recovery circuits. He was an Assistant and then Associate Professor in Electrical Engineering and Computer Science at the Massachusetts Institute of Technology from 2001 to 2008. He was with SiTime Corporation from 2008 to 2010, where he developed key technology for MEMS-based oscillators. He is currently a professor at Masdar Institute in Abu Dhabi, where he is focusing on low power, mixed-signal circuits for health and fitness and other applications.