Simulation of a two-diode microwave limiter

The power-limiting characteristics for a single-diode limiter and a two-diode module have been investigated using the numerical modeling software ISTOC based on the fundamental semiconductor equation system. A PIN-diode having a 5 /spl mu/m basewidth is shown to operate successfully as a passive limiter at frequencies up to 2 GHz providing an isolation of about 20 dB. At higher frequencies its operation is severely degraded because of the transit-time effect. A new version of a two-diode quasi-active limiter module is shown to be an attractive alternative to conventional solid-state limiter devices. The optimal value for the Schottky-barrier diode capacitance is found. An isolation of 11.5 dB has been demonstrated for the 1.5 cm range. The utilized modeling technique enables analyzing multi-element microwave devices with a complicated interaction between the components in stationary and dynamic regimes. It provides also an effective means for the optimization of device properties.