Intermodulation distortion analysis in finfet transistors

This thesis investigates intermodulation distortion (IMD) in FinFET (Fin Field Effect Transistor) devices, which are fundamental components of modern nanoscale semiconductor technology. IMD arises when multiple frequency components interact within a nonlinear system, generating unwanted spectral products that degrade signal integrity in analog and RF applications. Such distortion can significantly limit the performance of high-frequency electronic systems. A detailed small-signal equivalent circuit model of the FinFET was developed to examine second- and third-order intermodulation mechanisms. The model includes intrinsic device parameters such as transconductance (gm), parasitic capacitances (Cgs, Cgd), and channel resistance (Rds), enabling accurate representation of nonlinear device behavior. To analytically characterize these nonlinearities, the Volterra series expansion method was applied. Using Maple 2018, first-, second-, and third-order transfer functions (H₁, H₂, H₃) were derived symbolically, allowing explicit extraction of higher-order nonlinear kernels including gm1, gm2, gm3, Cgs2, and Cgs3. These expressions establish a rigorous mathematical basis for identifying the dominant contributors to IMD in FinFET devices. Simulation studies conducted in Multisim and MATLAB/Simulink were used to validate the analytical findings over various frequency and amplitude levels. The results show that IMD becomes increasingly significant at higher frequencies, emphasizing the need to account for nonlinear distortion effects in the design of FinFET-based analog and RF circuits. Overall, this thesis advances the understanding of nonlinear behavior in FinFETs and provides modeling insights that support the optimization of next-generation high-frequency circuit designs.