A 500 watt l-band electron bombarded semiconductor amplifier

This paper describes the design, fabrication and test results of a developmental Electron Bombarded Semiconductor (EBS)microwave amplifier. The EBS amplifier utilizes an electrostatically focused, 20 kV electron beam to produce an amplified current in a pair of silicon diodes by impact ionization. The input signal is applied to a broadband meander-line structure which deflects the electron beam, producing a linear modulation of the electron beam current striking the diodes. The diodes are mounted in radial-line resonators which present an optimized impedance to the amplified RF current produced in the diodes and which also provide RF matching to the diode capacitance. A novel interconnection of the resonators permits operating the diodes in dc parallel and RF series. The maximum output power obtained to date is 520 watts at 0.1 percent duty at 1.5 GHz and 250 watts at 1 percent duty. At the 500 watt level the saturated gain is 23 dB and small signal gain is 29 dB. The 3 dB bandwidth is 106 MHz or 6.8 percent.