In this paper, based on a precise and efficient analytical function of relatively realistic dopant fluctuations, a new method is proposed to simulate the threshold voltage variation of MOSFET's with non-uniform channel doping due to random dopant fluctuations. Both the number and position fluctuations of dopants are taken into account. Using this method, 2500 microscopically different devices under certain process conditions that cover the range of channel length L from 35 nm to 90 nm, oxide thickness T-ox from 1 nm to 4 nm and channel surface doping concentration N-A from 1 x 10(18) to 5 x 10(18) cm(-3) are simulated to show how our method works. (c) 2006 Elsevier Ltd. All rights reserved.