Fast and waveform independent characterization of current source models

Abstract

A fast characterization method for current source models (CSM) is proposed. It analyses the given transistor netlist of CMOS logic cells to determine both static and dynamic CSM parameters in the same DC simulation. To account for the influence of parasitic elements in large logic cells, an additional low pass filter is inserted to the CSMs. AC analysis is employed to efficiently define its parameters. The characterization is therefore independent of user specified input waveforms. CSMs of industrial gates have been integrated into a standard SPICE simulator, showing high accuracy also for noisy input waveforms. Used in path based timing analysis of ISCAS85 circuits, average errors of 3% have been observed while simulation times could be reduced by a factor of 100.