Patent ID: 6532438
Filing Date: 2003-03-11
Classification: G01R,G06F

Abstract:
A method for improving simulation of a bipolar transistor by improving an expression of base charge, where the expression of the base charge, which describes the variation of Early voltage, for the bipolar transistor varies and the Early voltage is dependent on at least one variable, said method comprising the steps of:measuring the Early voltage as a function of said variable; fitting a mathematical function to the measured Early voltage such that the deviation between measured and simulated characteristics of the bipolar transistor decreases; inputting the mathematical function for the Early voltage into a differential equation to obtain an improved expression for the base charge, wherein the differential equation is expressed as: dLc/dx=IC/[x+VEarly(x)]where IC is the bipolar transistors collector current and x is a variable dependent on a collector/emitter voltage and VEarly is the Early voltage; dividing collector output characteristics of the measured Early voltage, with respect to the variable, into a plurality of arbitrary regions; and fitting a mathematical function within each of the regions.