Mosfet Modeling for Rf Ic Design

High-frequency (HF) modeling of MOSFETs for radio-frequency (RF) integrated circuit (IC) design is discussed. Modeling of the intrinsic device and the extrinsic components is discussed by accounting for important physical effects at both dc and HF. The concepts of equivalent circuits representing both intrinsic and extrinsic components in a MOSFET are analyzed to obtain a physics-based RF model. The procedures of the HF model parameter extraction are also developed. A subcircuit RF model based on the discussed approaches can be developed with good model accuracy. Further, noise modeling is discussed by analyzing the theoretical and experimental results in HF noise modeling. Analytical calculation of the noise sources has been discussed to understand the noise characteristics, including induced gate noise. The distortion behavior of MOSFET and modeling are also discussed. The fact that a MOSFET has much higher “low-frequency limit” is useful for designers and modelers to validate the distortion of a MOSFET model for RF application. An RF model could well predict the distortion behavior of MOSFETs if it can accurately describe both dc and ac small-signal characteristics with proper parameter extraction.