Improved nonlinear electrothermal simulation of bipolar transistors: Application to InP/InGaAs DHBTs

In this paper, an innovative approach for circuit-based electrothermal simulations of bipolar transistors is applied, which allows accurately accounting for the impact of nonlinear thermal effects. In a previous investigation, it was demonstrated that the thermal resistance formulations embedded in advanced compact models (AgilentHBT, HICUM) are inadequate to properly describe such effects, and an improved formulation was proposed to solve this issue. Here, this formulation is implemented in the HICUM/L2 model using various approaches. Circuit-based electrothermal simulations are run in Keysight ADS to test convergence likelihood and to verify the accuracy of the improved HICUM/L2 version. The analysis is performed by considering experimental data measured on a state-of-the-art high-frequency InP/InGaAs transistor as a reference.