An improved 1/f noise model of an MOS transistor

An improved 1/f noise model of an MOS transistor is developed which verifies previously observed dependencies on geometry and the density of surface states (NSS) but predicts an explicit bias dependence in addition to the dependence brought out by the change of NSSwith bias. The model is an extension of the tunneling mechanism proposed by McWhorter in which carriers in the channel tunnel into and out of traps distributed in the oxide. The essential difference between this work and previous work is in the assumed transformation between the fluctuation in the number of trapped carriers and the resulting fluctuation in the drain current. The improved noise model results in the experimentally verified prediction that noise gradually decreases as the drain bias increases until saturation is reached. In addition, the improved noise model predicts a definite gate bias dependence of 1/f noise, increasing as the gate voltage decreases to threshold and below and increasing as the gate voltage increases well above threshold.