Vlsi Technology, Inc.

Bruce S Seiler

Michael N Misheloff

Daniel R Brasen

Harish K Sarin

Michael R Grossman

Andrew J McNelly

A power usage simulator generates, for all the logic cells in a circuit cell library, a power model that characterizes a cell's power consumption behavior as a two-part, piecewise-linear function based on signal slew rates and output load. A logic simulator is modified so that for each signal transition in a specified logic circuit, the logic simulator performs a power usage computation utilizing the power usage model for all cells affected by each signal transition. The power usage value for each signal transition is posted to a power usage output data structure, with each posted power usage value having an associated time value. The posted power usage values are then analyzed by (A) accumulating the posted power usage values to provide a total power usage value, and (B) clocking the accumulation of power usage values with an end user set clock rate so as to produce a power usage profile indicating the time varying rate of power consumption during the simulation time period. The clocked accumulation of power usage enables easy detection of whether the peak rate of power consumption during the simulation time exceeds a specified threshold (e.g., a threshold associated with a particular power bus design). Thus, data generated by the power usage simulation may be used, either directly or indirectly to determine that the simulated logic circuit requires a larger power bus design, or that the logic circuit should be modified so as to reduce its peak power usage rate.

Slew rate based power usage simulation and method

Segments within a power network of an integrated circuit are calculated utilizing information generated during design and placement. The performance of logic blocks within the integrated circuit is simulated to obtain an estimated maximum current requirement for each logic block. After obtaining an estimated maximum current requirement for each logic block, the estimated maximum current flow through each power net segment is obtained by summing the estimated current requirements for each logic block which draws current through the power net segment. Based on this estimated maximum current flow through each power segment, a width for each power net segment is calculated. After widths have been calculated, a check may be made to assure that a predetermined electromigration limit is not exceeded. When projected current flow through a power net segment will result in an exceeding of the predetermined electromigration limit, the width of the power net segment is increased.

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Fremont, CA, United States of America

Bruce S Seiler