High-Frequency Noise Modeling of MOSFETs for Ultra Low-Voltage RF Applications

In this paper, analytical models for high-frequency drain-current noise, gate-current noise, and their cross-correlation of MOSFETs are presented with an emphasis on the weak- and moderate-inversion regions. Unified expressions offering excellent continuity and smoothness from weak- to moderate- and strong-inversion regimes were developed. It is demonstrated that the continuity and the accuracy of the calculated four noise parameters, such as minimum noise figure, normalized noise resistance, and optimum source conductance and susceptance, are significantly improved in the weak- and moderate-inversion regions by using the proposed unified noise model, which includes the junction-induced drain-current noise. A figure-of-merit is introduced to determine the optimum gate biasing point of MOSFETs, where high gain can be achieved at low driving power and low operating noise. The results obtained from the proposed model manifest good agreement with the on-wafer measurement results.