Events Calendar

Integrated Systems Seminar Series

Speaker: Prof. John A. McNeill, Worcester Polytechnic Institute

Talk Title: Fundamental Limits on Noise Performance of VCO-Based ADCs

Series: Integrated Systems Seminar

Abstract: Low-cost energy-efficient analog-to-digital converters (ADCs) are needed in many rapidly growing mixed-signal application areas such as wireless communication, autonomously powered sensing and monitoring nodes, and implanted biomedical devices for assistive technology. In systems constrained by battery power or scavenged energy limits, ADC energy efficiency as expressed by the fJ/step figure-of-merit is a critical design driver. Scaling of CMOS to nanometer dimensions has enabled dramatic improvement in digital power efficiency; however, most traditionally dominant ADC architectures are not well suited to the lower supply voltage environment. The improvement in time resolution enabled by increased digital speeds naturally drives design toward time-domain ADC architectures such as voltage-controlled-oscillator (VCO) based ADCs. Despite much recent work on techniques to improve SNR performance, the overhead of additional circuitry to mitigate VCO nonlinearity imposes a power penalty that has until now kept efficiency performance far above the minimum capability of the VCO-based approach. This talk will begin with a brief overview of the VCO-based approach and previous techniques to improve linearity in VCO-based ADCs. Next, the talk covers application of the "split ADC" architecture to enable lookup-table (LUT) based digital background calibration for a family of reconfigurable VCO-based ADCs in 28nm CMOS, targeting sample rates from 1 to 300 MSps and resolutions of 8 to 14 bits. Finally, work on fundamental sources of VCO jitter will be applied to determine the ultimate limit on performance for techniques such as VCO-based ADCs which perform the ADC function in the time domain.

Biography: John McNeill received his bachelor's degree from Dartmouth College in 1983, M.S. from the University of Rochester in 1991, and Ph.D. from Boston University in 1994. From 1983 to 1990 he worked in industry in the design of high speed, high resolution analog-to-digital converters and low noise interface electronics used in wide dynamic range imaging systems. In 1994, he joined Worcester Polytechnic Institute, in Worcester, Massachusetts, where he now is a Professor and Associate Head in the Electrical and Computer Engineering department. In 1999 he received WPI's Award for Outstanding Teaching. In 2006, with co-authors Michael Coln and Brian Larrivee of Analog Devices, he received the Lewis Winner award for Best Paper at the 2005 ISSCC. His research interests are in the areas of low-jitter VCO design and self-calibrating analog-to-digital converters.

Host: Hosted by Prof. Hossein Hashemi, Prof. Mike Chen, and Prof. Mahta Moghaddam. Organized and hosted by SungWon Chung.

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 132

Audiences: Everyone Is Invited

Contact: Elise Herrera-Green