High frequency noise modeling of SiGe HBTs using a direct parameter extraction technique

This work describes the complete process to model the high frequency noise characteristics of a SiGe HBT based on a direct parameter extraction technique. The parameters of the equivalent circuit have been extracted from S parameter and DC measurement data in a simple and accurate way. The elements of the model have been determined gradually starting from the outer shell by operating the transistor at various bias conditions. A direct extraction method to obtain the substrate network elements and the extrinsic capacitances is also presented which enables the determination of the base resistance from the Z parameters. Noise parameter measurements have been carried out and a good agreement has been achieved both in S parameter and noise parameter data which is a proof of the physical validity of the parameter extraction and the modeling method.