4.3 S-Parameter Simulation

In the previous section two-dimensional simulations of one-finger power HBTs on GaAs are presented. A good agreement of simulations of four different types of devices with measured data in a wide temperature range is demonstrated. In addition, it is possible by accounting properly for self-heating to simulate correctly the output device characteristics. Considering the ability to reproduce correctly the DC-device behavior including thermal aspects the work is extended with transient simulation of small-signal parameters to connect DC- and RF- device operation. In the following subsections a comparison of simulated and measured S-parameters and the dependence of $f_{\mathrm{T}}$ on some device parameters are presented.

Figure 4.23: T-like eight-element small-signal HBT equivalent circuit used for S-parameter calculation