Full-scale non-linear analysis of IV-IV compound semiconductor based IMPATTs in high-power operation mode at MM-wave window frequency

Full-scale, non-linear large-signal model of IV-IV SiC Double-Drift IMPATT diode with general doping profile is derived. This model, for the first time, has been used to analyze large-signal characteristics of SiC-IMPATTs at 94 GHz of MM-wave window frequency. Under small-voltage modulation (~ 2%, i.e. small-signal condition) results are in good agreement with calculations done using a linearised small-signal model. The large-signal values of the diode´s negative conductance (5 × 10⁶ Sm^-2), susceptance (104.0 × 10⁶ Sm^-2), breakdown voltage (207.6 V), and power generating efficiency (15%, RF power: 25.0 W at 94.0 GHz) are obtained at modulation amplitude ~ 50% of DC breakdown voltage, for a fixed average current density. The large-signal calculations exhibit power and efficiency saturation for large-signal (>; 50%) voltage modulation and thereafter decrease gradually with further increasing voltage-modulation. This generalized large-signal formulation is applicable to all type of IMPATT structures with distributed and narrow avalanche zones. The simulator is made more realistic by incorporating the space-chare effects, realistic field and temperature dependent material parameters in SiC. The electric field snap-shots and the large-signal impedance and admittance of the diode with current excitation are expressed in closed loop form.