Modeling of noise behavior of graded bandgap channel MOSFET at GHz frequencies

Abstract

A novel graded band gap channel Si-SiGe MOSFET structure has been suggested and its characteristics has been investigated. The investigations indicated that the suggested structure reduces the short-channel effects, increases the cutoff frequency, and hence makes it usage at high frequency and Low noise applications prefeable. To show the superior performance of the suggested structure at GHz frequencies, and as an example, the noise behavior of the structure is thoroughly investigated. First the device noise model parameters are calculated from D.C. and A.C. characteristics. The extracted noise model parameters are then used to determine the minimum noise figure and minimum noise temperature at GHz frequencies. The effects of the different device parameters on the noise performance are determined. Finally, the results are compared with those of conventional MOSFET structure to show the superior performance of graded band gap Si-SiGe MOSFETs at these frequency ranges.