An efficient method for determining threshold voltage, series resistance and effective geometry of MOS transistors

An accurate and robust method of extracting the threshold voltage, the series resistance and the effective geometry of MOS transistors is presented. The method is based on efficient nonlinear optimization using an iterative linear regression procedure which usually converges in less than four rounds. Thereby extracted parameters are obtained from analytical expressions for the solutions to a linear system of equations whereby time consuming numerical differentiations are avoided. MOSFET parameters are explicitly identified as parameters of an underlying widely used device model that is a good approximation for operation in the linear region. The method is particularly suitable for process characterization and can be used on as few as twelve data points (three data points from each of four different size transistors). By connecting external resistors in series with the transistors, we show that the extracted values of the parameters are independent of the series resistance.