NEW CONCEPTS FOR SOLID STATE MICROWAVE GENERATORS

The basic theory of transit-time delay diodes is presented, and their maximum power output calculated. This output is about 13 of that calculated for conventional transistors on a similar basis, but the maximum operating frequency should be much higher. It is shown how the maximum voltage decreases with frequency, leading to a lower impedance level. Experimental devices designed to make use of delay in the collector depletion layer did not show negative resistance because of difficulty in operating at the required voltage. The reverse recovery of a PIN diode is calculated and shown to be useful for harmonic generator applications. The transition time from on to off is determined by the transit time for carriers across the I region in space charge limited flow, and by the diode capacitance. Experimental epitaxial diodes showed the expected performance of less than 1 ns turn-off time in a diode with 15 pf capacitance.