X-band IMPATT microstrip power sources

Silicon avalanche transit-time diodes have been integrated with microstrip oscillator circuits to produce miniaturized X-band power sources. The oscillator circuits are fabricated using thin-film gold or copper on 1 inch by 1 inch, 25-mil thick alumina substrates. Circuits using both capacitive and inductive output coupling have been used with success. CW X-band powers greater than 500 mW at approximately 3 percent efficiency are obtained with these circuits. A method of heat sinking the diodes, which allows input powers up to 25 watts in a 6-mil junction diameter, is discussed. Some of the features of the power sources considered for applications were measured at various power levels and are presented. These include FM and AM noise, injection- locking characteristics, and power accumulation from more than a single diode.