I'm using SwCAD and trying to determine the parameters of the high-frequency pi-model for the BJT. For convenience, I've combined the circuit with the BJT and the model in one circuit so I can combine the graphs as well:
First I used small dc signals to determine the values for rpi, gm, ro and then I tried to use small ac signals to determine the values for the capacitors (the values in the model are just placeholders.) I wasn't able to do so. When I write the nodal equation for the collector of the BJT and solve for cu using the small-signal values obtained from the simulation, the value will always have an imaginary part which is obviously unacceptable.
Is it some limitation of the way SwCAD models the BJT? I don't think it is a limitation of the model because it is cited in many books in electronics as a reliable model up to ~100 MHz.