Small-signal impedance of bulk semiconductor amplifier having a nonuniform doping profile

A convenient method for studying the small-signal impedance of a bulk semiconductor amplifier having a nonuniform doping profile is presented. The small-signal impedance is represented as a two-dimensional sum of the interaction impedance which represents the electrical interaction between various sections in the amplifier due to the transport effect. When the diffusion current is negligible, the two-dimensional plot of the magnitude of the interaction impedance shows which part of it is important. The two-dimensional representation may provide a convenient method of synthesizing the doping profile of a bulk semiconductor amplifier which gives a desired impedance characteristic.