Validation of thermal resistance extracted from measurements on stripe geometry SiGe HBTs

In this article, we present a straightforward methodology to validate the consistency of thermal resistance (RTH) measurements for a set of stripe geometry silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs). The proposed approach is based on the behavior of frequency-dependent thermal impedance (ZTH) of HBTs. The key advantage of this method is its simplicity and ease of applicability because it requires no additional measurements than the conventional approaches to extract the electrothermal parameters. First, we provide a physics-based formulation to extract ZTH as a function of RTH. As a next step, we propose different normalization methods for ZTH in stripe emitter SiGe HBTs to validate the RTH used in our ZTH formulation. Finally, we substantiate our validation technique across stripe emitter SiGe HBTs having different emitter dimensions corresponding to STMicroelectronics B55 technology.