Pieter Rombouts

Professor of Analog Electronics - Ghent University

Bio

Pieter Rombouts was born in Leuven, Belgium, in 1971. He obtained the Ir. degree in applied physics and the Dr. degree in electronics from Ghent University, Belgium, in 1994 and 2000, respectively. Since 1994 he has been with the Electronics and Information Systems Department of Ghent University, where he is currently Professor. In 2002 he was a visiting professor at the University Carlos III, Madrid, Spain.

He currently serves as an Associate Editor for IEEE Transactions on Circuits and Systems—Part II: Express Briefs. His technical interests are signal processing, circuits and systems theory, and analog circuit design.

Abstract

Extended Counting: a very efficient improved incremental A/D conversion  technique.

Incremental A/D conversion is an A/D conversion technique that has several similarities to Sigma delta modulation. One of these similarities is that it requires that the internal circuits operate at a much higher clock frequency than the effective sample rate of the converter. This is especially the case when the required resolution is high and when the order of the incremental converter is low. 
However, there is one major difference between Sigma Delta modulation and incremental A/D conversion: i.e. sigma delta modulators are oversampled whereas incremental A/D converters operate at Nyquist-rate.

Due to their Nyquist-rate operation, incremental converters are well suited for sensor signals that are multiplexed, as is inherently the case in column level ADC's for matrix-based imagers. However, due to the narrow column spacing, in such applications, area efficiency is of utmost importance. Hence, it would be desirable to use a low order incremental converter, preferrably first order. Unfortunately a first-order incremental converter can not achieve a good resolution (of e.g. 12 bits) in a reasonable number of clock cycles. To overcome this, extended counting has been presented as an improvement over conventional first-order incremental A/D conversion. 

In this talk the properties and design trade-offs of such extended counting A/D converters will be explained and illustrated based on several actually measured CMOS circuits.