On 1/f trapping noise in MOSTs

New calculations are given for the 1/f noise in metal-oxide-semiconductor transistors (MOSTs) based on the McWhorter model (number fluctuations). Particular attention is paid to two regions of the drain current-voltage characteristic: weak inversion and near saturation. The results are at variance with previous theories, where some errors have been made. The gravest error was the violation of the physical law whereby the variance of the number of carriers N in the channel is ≤N. The calculations do not give a divergent noise power at current saturation, as found by other authors. In the ohmic region, the relation between the spectral density of the drain current fluctuations and the number of carriers is determined. The Langevin method and the Klaassen-Prins method for calculating the 1/f noise in MOSTs are discussed and shown to have been used incorrectly when the mobility and the Hooge 1/f noise parameter depend on position in the channel.