Monte Carloanalysis of dynamic and noise performance of submicron MOSFETs at RF and microwave frequencies

Abstract

In this paper, an ensemble 2D bipolar Monte Carlosimulator is employed for the study of static characteristics,high-frequency response and noise behaviour in a 0.3 µmgate-length n-MOSFET in common source configuration.Short-channel effects, such as velocity overshoot in the pinch-off region, together with the appearance of hot electrons at thedrain end of the channel are observed in the staticcharacteristics. Admittance parameters and the small-signalequivalent circuit have been calculated in order tocharacterize the dynamic response of the device. The use of abipolar simulator allows one to study the dynamics of both types ofcarriers simultaneously. While the static results are dominatedby the electron transport, the contribution of holes mainly affects the drain-substrate capacitive coupling. The noisebehaviour of the simulated MOSFET is also studied (up to40 GHz) by means of different parameters, such as the spectral densities of the current fluctuations at the drain and gateterminals (and their cross-correlation), normalized α,β and C parameters and NFmin . In the saturationregime, due to the presence of hot carriers, an increase indrain and gate noise with respect to the long-channelprediction has been found. Moreover, a stronger correlationbetween drain and gate noise is observed, especially at lowdrain current. Induced gate noise is found to play a crucialrole in the determination of NFmin at high draincurrents.