Space-charge effect on large-signal behavior of transit-time-effect devices

A unified view of the latge-signal behavior of transit-time-effect diodes under cartier injection in-phase with the cathode field is given by modeling the injection characteristic as an exponential dependence on cathode field. The concept consists of an extension of a unified view of small-signal behavior by introducing another parameter which expresses the nonlinearity of injection in addition to small-signal injection conductance, and by assuming velocity saturation. Phase advance and suppression of injection current due to space-charge effect are influential factors which dominate the large-signal behavior and which impose a limitation on output power. The present treatment gives a way for optimizing the device and circuit as well as for estimation of the ultimate available power for a given carrier-injection characteristic.