High-frequency dependence of channel noise in short-channel RF MOSFETs

Using a two-dimensional (2-D) Green's function technique, similar to Shockley's impedance field technique, simulation results of the drain i/sub d/ and gate induced i/sub g/ channel noise are presented for an nMOS transistor as a function of frequency. The simulation results show that for frequencies much lower than the cutoff frequency of the transistor f/sub t/ the correlation factor (i.e., i~/sub g~/i~*/sub d~///spl radic/i/sub g//sup -2/i/sub g//sup -2/) between the drain and gate channel noise is equal to approximately 0.4j. For frequencies near the f/sub t/ of the device the correlation factor approximately equals 0.3j. For f/f/sub t//spl sim/0.3, the contribution of the gate induced noise compared to the drain noise was found to be on the order of 1% (i.e., i/sub g//sup -2//i/sub d//sup -2/(f/sub t//f)/sup 2/).