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Experimental Characterization and Analysis of an Asynchronous Approach for Reduction of Substrate Noise in Digital Circuitry

TitleExperimental Characterization and Analysis of an Asynchronous Approach for Reduction of Substrate Noise in Digital Circuitry
Publication TypeJournal Article
Year of Publication2012
AuthorsLe, J., C. Hanken, M. Held, M. S. Hagedorn, K. Mayaram, and T. S. Fiez
JournalIEEE Transactions on Very Large Scale Integration (VLSI) Systems
Volume20
Issue2
Pagination344 - 356
Date Published02/2012
ISSN1557-9999
Keywordsasynchronous circuit, delta-sigma modulator (DSM), NULL convention logic (NCL), substrate noise, synchronous circuit
Abstract

Delay insensitive asynchronous circuitry provides significant advantages with respect to substrate noise due to localized switching. The differences between the substrate noise from NULL convention logic (NCL) and traditional clocked Boolean logic (CBL) are described and analyzed based on measured results. A test chip fabricated in the TSMC 0.25 μm process shows that a pseudo-random number generator implemented with NCL generates 23 dB less substrate noise compared to the equivalent synchronous design. In a larger scale digital circuit, the substrate noise improvement offered by an asynchronous 8051 processor over its synchronous counterpart was nearly 10 dB. The effect of this substrate noise on an analog circuit was explored with a delta-sigma modulator (DSM) example. The signal-to-noise ratio performance of a second order DSM was not affected by the substrate noise from the NCL 8051 processor while it experiences up to 15 dB degradation when the CBL 8051 processor is clocked near integer multiples of the DSM sampling frequency.

DOI10.1109/TVLSI.2010.2100835
Short TitleIEEE Trans. VLSI Syst.