International Business Machines Corporation

David Bruce White

Jerry D Hayes

Amol Anil Joshi

William John Wright

Bijan Salimi

Nilesh C Date

Methods and systems for determining timing constraint analysis of an integrated circuit (IC) may include defining a sequence of sample points for timing constraint analysis of an n&#xd7;n matrix, each sample point corresponding to a timing arc of the IC that includes data and reference slews; initially simulating extreme sample points of the matrix, according to the sequence, by substituting timing constraints from liberty files of the IC type for time values of the data slews and conducting a binary search for optimized timing constraints; and interpolating other sample points, according to the sequence, each of the other sample points having a starting bisection point that results from linear interpolation of the timing constraint analysis from adjoining sample points, which were simulated.

Methods and systems to reduce a number of simulations in a timing analysis

A method and system for predicting the sensitivity of the integrated circuit logic cell timing performance to variations in voltage and temperature. Rather than using the prior art approach of multiplicative derating factors to model voltage and temperature effects on timing performance, adders are used to model the change in performance due to variations in operating conditions (i.e., voltage and temperature). The adders are treated as functions of input transition time (Tx) and output load capacitance (Cload). The change in performance as measured in time forms a plane over the Tx-Cload operating range for variations in either voltage or temperature. The adders, using a plane equation as a function of Tx and Cload, greatly improve the absolute accuracy in predicting the effects of variations in voltage and temperature, as compared to using the prior art methods involving multiplicative derating factors.

Method and system for using voltage and temperature adders to account

Modeling of propagation delay and output transition time by use of fitting functions comprised of standard Taylor series and inverse powers is disclosed. These components are used as a basis for generating an equation that predicts circuit performance over a wide range of input transition and output capacitive loads. The present invention includes a computer implemented method for adding functions to the fitting functions or removing functions from the fitting functions until an acceptable error limit has been reached.

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Essex Junction, VT, United States of America

David Bruce White