Analytical Modeling of SiGe HBT Intermodulation Linearity

Abstract

Linearity is a key concern in RF systems, particularly an amplifier. Volterra series allow us to easily identify the contribution of various individual nonlinearities, as well as to identify the interaction between individual nonlinearities.

Nonlinear current source of Volterra series and direct derivation of Volterra series are two methods that analyze nonlinear distortion effectively. This thesis applied Volterra series to circuit linearity analysis and performed with the help of a matrix solver in Matlab. ADS used is to verify the validity of analytical expressions.

Supported by Volterra series approach, requirement of IM3 cancellation can be found at both low frequency and high frequency. ADS simulation is used to investigate conditions required for IM3 cancellation.