Seminars

VCO-based Quantizers: Has Their Time Arrived?

Thursday, October 11, 2012

Dr. Michael Perrott

Abstract

VCO-based quantizers take advantage of the steadily increasing speed of modern CMOS processes by quantizing time rather than amplitude. Their implementation leads to highly digital architectures that benefit directly from Moore's law, and offer intriguing benefits such as inherent shaping of their quantization noise. In this talk, we examine their potential for achieving high resolution analog-to-digital conversion (ADC), and identify key shortcomings such as nonlinearity of the voltage-to-frequency characteristic and its impact on SNDR. Circuit techniques are then presented to overcome such shortcomings, along with recent results verifying their effectiveness. In particular, we show that using phase rather than frequency within a continuous-time Sigma-Delta ADC topology enables 78dB SNDR performance within 20MHz bandwidth with a power efficiency of 330 fJ/conversion step. Finally, we conclude by generalizing the VCO-based quantizer as an efficient combination of a voltage-to-time converter and a time-to-digital converter, and discuss its advantages compared to other recent approaches which combine these components.

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.