Worst case voltage drops in power and ground buses of CMOS VLSI circuits

Currents flowing in the power and ground (P&G) buses of CMOS digital circuits affect both circuit reliability and performance by causing excessive voltage drops. Excessive voltage drops manifest themselves as glitches on the P&G buses and cause erroneous logic signals and degradation in switching speeds. Maximum current estimates are needed at every contact point in the P&G buses to study the severity of the voltage drop problems and to redesign the supply buses accordingly. These currents, however, depend on the specific input patterns that are applied to the circuit. Since it is prohibitively expensive to enumerate all possible input patterns, this problem has, for a long time, remained largely unsolved. In this thesis, we propose a pattern-independent, linear time algorithm (iMax) that estimates at every contact point, an upper bound envelope of all possible current waveforms that result from the application of different input patterns to the circuit. The algorithm is extremely efficient and produces good results for most circuits as is demonstrated by experimental results on several benchmark circuits. The accuracy of the algorithm can be further improved by resolving the signal correlations that exist inside a circuit. We also present a novel partial input enumeration (PIE) technique to resolve signal correlations and significantly improve the upper bounds for circuits where the bounds produced by iMax are not tight. We establish with extensive experimental results that these algorithms represent a good time-accuracy trade-off and are applicable to VLSI circuits.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Kriplani, Harish

Contributors dc:contributor

• Hajj, Ibrahim N.

• Engineering, Electronics and Electrical
• Computer Science

Statement dc:rights

• Copyright 1994 Kriplani, Harish

Language dc:language

eng

Identifier

AAI9416387
(UMI)AAI9416387

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/20706