140 GHz Pulsed Impatt Combiner High Power Source.

Abstract : The objective of this program was to develop silicon IMPATT diode and power combiner circuit technology in order to demonstrate improved pulse power generating capability at 140 GHz. The program efforts have led to significant advances in the state-of-the-art for pulsed solid state power generation in D-band. The diodes fabricated for this program were double drift IMPATTs with active regions formed by a combination of n-type epitaxial growth and multiple dose/energy p-type ion implants. Copper heat sinks were used. The most successful diode package configuration was a double quartz standoff configuration. The three types of power combining structures investigated were: 1) A resonant rectangular waveguide structure with center-mounted diodes. 2) A variation of (1), employing the coplanar biasing configuration. 3) A rectangular waveguide combiner with sidewall-mounted diodes (Kurakowa circuit). The rectangular cavity with sidewall mounted diodes was by far the most successful. In this circuit, power from two pulsed diodes was combined with approximately 90% combining efficiency. High peak power output at 140 GHz was achieved for both single and multiple diode oscillators. Single diode peak power levels of 3.0 watts at 3% efficiency were obtained for a 100 ns pulse length and a 50 KHz pulse repetition frequency. A two-diode power combiner based on an oversize version of Kurakowa circuit was constructed which produced 3.0 watts of peak output power. Two high power pulsed sources complete with modulators were delivered to the Army. One of these sources is a single diode oscillator, the other a two diode power combiner oscillator.