Mathematical foundation for constructing accurate dynamic bipolar transistor compact models

For present and future mm- and sub-mm-wave applications, compact models need to capture the large-signal dynamic transistor behavior up to several harmonics, which are often far beyond the transistor cut-off frequencies. Since such such frequencies exceed the existing or usually affordable measurement capability, a physically and mathematically sound approach for developing compact models is required that guarantees a desired level of accuracy. This paper demonstrates the construction of physics-based equivalent circuits for the intrinsic transistor operation based on a closed-form solution of the DD transport and continuity equation. The solutions are verified based on device simulation.