Small-signal equivalent circuit for IMPATT transistors

A lumped-distributed small-signal equivalent circuit of an IMPATT transistor, a 3-terminal transistor-like device having a base-collector junction operated as an IMPATT diode, is presented. The equivalent circuit is composed of RLC elements, two controlled sources and one transmission line. Characterisation of the device based on this model gives clear insight into the small-signal and noise behaviour of the IMPATT transistors.