Motorola Corporation

Markus G Wloka

Sean C Tyler

Binay J George

Steven D Millman

A plurality of serially coupled circuit cells ( ) are modeled as a distributed serial load. The distributed serial load provides an accurate load model in situations where one cell is effected by loading on subsequent circuit cells, i.e. downstream loading is conveyed back to the first cell. The capacitance ( ) and resistance ( , of each cell has a loading effect on each previous cell. The effective resistance and capacitive values of each cell is identified and maintained as one element of the distributed serial load model. The distributed serial load accurately models the loading of unbuffered cells ( ). The distributed serial load is also applicable to portions of circuit cells ( ) that are not be buffered and where the downstream loading has an effect on previous circuit drivers ( ).

Method of modeling circuit cells with distributed serial loads

A computer implemented method provides for simulation standard cells from an integrated circuit design in parallel on a distributed simulation system. The integrated circuit design (10) is divided into a plurality of standard cells (12-18). Characterization parameters such as temperature, process, supply voltage, edge rate and capacitive load are individually assigned (34) to each one of the standard cells. A first one (12) of the standard cells is scheduled (36) and dispatched (38) for simulation in a first computer workstation (22) on the distributed simulation system (20). A second one (14) of the standard cells is scheduled and dispatch for execution in a second computer workstation (24) on the distributed simulation system during the simulation of the first standard cell. The results of the first and second simulations are stored (40) upon completion of the respective simulation tasks.

Method of parallel simulation of standard cells on a distributed

A method executed by a computer program performs cell characterization in a distributed simulation system by partitioning characterization tasks into individual simulations. A simulation job is generated based on the individual simulations and placed into a simulation job queue. The simulation job queue is copied into a database. The simulation job is accessed and processed in a remote simulator. The remote simulator returns a simulation status and simulation results which are placed into an acknowledge queue. The simulation process is repeated upon detecting an error condition from the simulation status. The simulation status is read from the acknowledge queue and the acknowledge queue is copied into the database.

Method of cell characterization in a distributed simulation system

A method executed by a computer simulator measures energy dissipation in a cell having one or more outputs. A first series of simulations is performed with given cell parameters over a simulation period while varying capacitance on a first output of the cell for providing a first range of currents sunk by the cell. A second series of simulations provides a second range of currents by varying capacitance on a second output. The first and second ranges of currents are converted to first and second ranges of energy dissipations. The energy dissipation due to the charging rates is subtracted from energy dissipation due to the switching for providing a model of energy dissipation by the cell itself. A nominal point of the first range of energy dissipation may be subtracted from each point of the second range of energy dissipation for providing an offset range of energy dissipations.

Method of cell characterization for energy dissipation

A method for deriving a piecewise-linear model which comprises measuring the behavior of a desired characteristic of an object. Recording the observations in a computer memory. Creating a piece-wise linear model of the observations based on the highest and lowest valued observations. Computing an error value for the dependent variable of each observation based on the piece-wise linear model. Determining a new piece-wise linear model based on two segments by interpolation. Recursively repeating the steps of computing error values and determining an improved piece-wise linear model until a predetermined acceptance condition is achieved. Performing a computer simulation of the desired characteristic of the object using the improved piecewise-linear model.

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Chandler, AZ, United States of America

Markus G Wloka