1/f noise in graded-channel MOSFETs for low-power low-cost RFICs

Low frequency noise has been characterized and identified for the first time in a graded-channel MOS (GCMOS) technology designed for low-power low-cost RFICs. The noise was found to be composed of bias dependent generation-recombination (G/R) and random-telegraph-signal (RTS) noise and a bias independent 1/f noise component. G/R and RTS noise has been attributed to single trapping centers in the gate oxide of small area devices. As the gate area increases, the assemblage of large numbers of trapping event distributed uniformly in either energy or spatial location leads to the "pure" 1/f noise observed in large area devices. The results presented in this paper on the area dependence and bias dependence of the low frequency noise gives strong support for the McWhorter's surface number fluctuations model governing the noise characteristics in these devices and thus the 1/f noise can be predicted and modeled for circuit applications using the GCMOS technology.