Small signal lumped model for IMPATT diodes

A small signal lumped model of a general IMPATT diode is presented. By applying state space analysis techniques the model is used to predict the small signal impedance of both pn and pin IMPATT diodes as a function of frequency and d.c. bias current. A lumped element equivalent circuit for the microwave cavity in a Read diode coaxial oscillator is derived. Using a state space description of the diode-cavity configuration, the variation of small signal oscillation frequency with d.c. bias current is evaluated.