Compact Modelling of Noise in Nonuniform Channel MOSFET

Compact MOSFET noise models are mostly based on the Klaassen-Prins (KP) approach. However, the noise properties of lateral nonuniform MOSFETs are considerably different from the prediction obtained with the conventional KP-based methods which, at low gate voltages, can overestimate the thermal noise by 2-3 orders of magnitude. The presence of lateral nonuniformity makes the vector impedance field (IF) (the quantity responsible for noise propagation) position and bias dependent. This insight clearly explains the observed discrepancy and shows that the bias dependence of the important noise parameters cannot be predicted by conventional KP-based methods. Interestingly, this bias dependence of the noise parameters in the presence of lateral nonuniformity can be effectively used in the channel engineering of MOSFET to optimize the RF noise performance.