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Calculation of AC Power in CMOS Circuits Using Simulation Data

IP.com Disclosure Number: IPCOM000062476D
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kahle, JA: AUTHOR [+3]

Abstract

A method is described for exactly computing AC power dissipation in CMOS very large-scale integration (VLSI) as a function of circuit activity. In a CMOS VLSI design power dissipation by net basis is computed as: (Image Omitted) The standard method for computing power dissipation had been by estimating N.S. based on experimentation and not explicitly computed as a function of circuit activity. This is a significant flaw since circuit activity is often a function of the software programs being executed. The method of power calculation, described here, eliminates this problem by automatically using circuit simulation data and net capacitance to compute the actual power used in running a particular piece of software code.

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Calculation of AC Power in CMOS Circuits Using Simulation Data

A method is described for exactly computing AC power dissipation in CMOS very large-scale integration (VLSI) as a function of circuit activity. In a CMOS VLSI design power dissipation by net basis is computed as:

(Image Omitted)

The standard method for computing power dissipation had been by estimating N.S. based on experimentation and not explicitly computed as a function of circuit activity. This is a significant flaw since circuit activity is often a function of the software programs being executed. The method of power calculation, described here, eliminates this problem by automatically using circuit simulation data and net capacitance to compute the actual power used in running a particular piece of software code. The simulator has the capability of generating an ALL EVENTS TRACE (AET), which is a record of all switching activity for every net during the simulation. By keeping a running total of the switching activity for each net during the simulation, the net switching variable in Equation
(1) will have been accurately calculated. The capacitance for each net is procured from other measurements. Using Equation (1) to calculate the power for each net and then summing the result for all nets in the CMOS VLSI design, the exact power associated with running a particular set of software can be calculated. The benefits from being able to accurately calculate power dissipation on a CMOS design are the...