Wideband analytical extraction technique of πequivalent circuit model for Si/SiGe heterojunction bipolar transistor in BICMOS process

A developed analytical extraction technique of small-signal -topology equivalent circuit model for Si/SiGe heterojunction bipolar transistor is presented. The intrinsic model parameters, including base resistance (Rb) which are difficult to extract in the previous works, are analytically extracted by utilising a novel set of exact equations that do not need any numerical fitting, special polarisation of the device or any kind of post processing. Moreover, the substrate effect and the distributed base-collector junction are accurately modelled and extracted. To the authors knowledge, the extracted values using the presented methodology exhibit flattest and widest frequency independent behaviour among all those extracted with earlier published analytical techniques, especially for base resistance. Excellent agreement is noted between the S-parameters measurements and their simulated counterpart using the extracted model in the frequency range from 40 MHz-40 GHz at different bias conditions.