Motorola Corporation

Bull S.a.

Sleiman N Chamoun

Daniel Snyder

Jean-Marie Boudry

Alberto J Reyes

Dana Mark Rigg

Karen S Ramondetta

Mark Chase

James H Tolar, Ii

Supamas Sirichotiyakul

A cell library (21) is optimized for specific operating characteristics. A stimulus file (23) is divided into a number of simulation run files. The simulation run files (27) are distributed to more than one computer work station so that the simulation of the cell occurs in parallel. The netlist (24) of each cell is parameterized to allow the cell to be changed and resimulated to better meet the specific operating characteristics. A cost function (32) is provided which uses the results of a transistor level simulation to calculate the quality of the cell design relative to the specific operating characteristics. Simulated annealing (34) is used to generate new simulation parameter values from a cost generated from the cost function (32). The cell is resimulated a number of times to optimize for the specific operating characteristics and the best design is retained for a new cell library (39). The process is repeated for each cell of the cell library (21).

Method for generating an optimized integrated circuit cell library

A method of selecting device (14-16, 18-24, 28-30) threshold voltages for high speed and low overall power involves identifying (42) the critical paths by predetermined timing criteria. All transistors have an initial, typically high, threshold voltage (40). Transistors outside the critical paths keep the initial high threshold voltages to minimize static power drain. The transistors in the critical path are selected (43) according to a predetermined sorting function to have a low threshold voltage and thereby switch faster. Although the lower threshold voltage devices consume more static power in standby mode, the power drain is accepted as a trade-off in favor of increased speed through the critical path. The supply voltage is reduced to minimize dynamic power. The integrated circuit is thus optimized to run at a higher frequency with lower overall power consumption.

Method of selecting device threshold voltages for high speed and low

The integrated circuit includes at least one conductance (6) which is adjustable by a digital control signal (17) which encodes steps in value for quantizing an exact value to within a fixed relative accuracy .DELTA.p. The conductance (6) includes elementary conductances which each define a step in value such that each elementary conductance is dimensioned so that a single level in value of the conductance (6) corresponds to two successive levels of the value of the digital control signal (17). If the result from the first of the two levels of value of the digital control signal (17) is a value which is lower, or respectively higher, than the exact value, the corresponding elementary conductance is enabled, or respectively disabled. Accordingly, the adjusted total value of the conductance (6) is equal to the exact value to within the same relative accuracy .DELTA.p, without oscillating between two values straddling this exact value. It is possible to use this type of conductance in high frequency communication integrated circuits.

Integrated curcuit with conductance adjustable by digital control signal

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Sleiman N Chamoun