Generator of a MM-range series operation of GaAs Gunn-diodes

We experimentally investigated the operation of two Gunn-diodes in series; they are designed for operation in the 8 mm wavelength band. Experimental samples of diodes made in the semiconductor engineering problem laboratory of of the Kharkov National University were investigated. The experimental samples of GaAs Gunn-diodes operate in continuous mode and have the following parameters: threshold voltage of 2 V, threshold currents of 1.2-1.25 A, output microwave power of 60-80 mW. For each diode volt-ampere and volt-watt characteristics were run. The diodes were compared and selected under the optimum characteristics. The characteristics are presented for single diodes and for two series connected diodes. If the parameters of diodes are equal (threshold currents within 1-2% of each other), the included diodes consistently work simultaneously. The frequency of generation is synchronized by the higher frequency diode (in our experiment it made 37.54 GHz), and the total output microwave power with two diodes consistently made 120 mW (factor of addition of output power of single diodes about 0.9).