A New Optimisation-Based Methodology for Determination of Small-Signal Equivalent Circuit Model Parameters for a Si / SiGe HBT Process

An accurate and simple method for determining the small-signal equivalent circuit model parameters of Si/SiGe heterojunction bipolar transistors is presented. This method differs from the previous ones in that it overcomes the often less accurate parasitic elements’ extraction by finding out the proper equivalent circuits for the dummy structures, used to assess the access interconnects’ contribution, and incorporate those in the complete circuit of the model. The method is based on optimization and requires the S-parameter measurements of the dummy structure and the active device. It is shown that it can be easily implemented in commercial software. To validate our methodology, we determined the model elements of a Si/SiGe HBT in the active region. Excellent results were obtained up to 20 GHz.