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Gallium arsenide p-n junction avalanche transit time oscillators were characterized with respect to noise performance. The results of these measurements were compared to other p-n junction oscillators, Read diodes, and Gunn diodes. Measurements include: receiver noise, using these devices as local oscillators for both balanced and single-ended mixer configurations; AM noise sideband-to-carrier ratios; FM noise sideband-to-carrier ratios, and AM and FM noise sideband-to-carrier ratios with cavity locking; thermal noise as a function of reverse bias current and amplifier noise figure. In general, the GaAs devices were superior in all respects to the Si- p-n and Si-Read structures. It also exhibited better FM noise than the Gunn oscillator and only slightly worse AM noise. (Author)

The report describes a unique theoretical design which has advanced the performance of avalanche transit time diodes for the direct generation of coherent microwave energy. A rigorous computer aided analysis is presented which solves the continuity equations and Poisson's equation for an avalanching electron hole plasma. The theoretical characterization of these devices with respect to AC impedance and noise performance is obtained and has led to internally designed and fabricated gallium arsenide avalanche transit time oscillators and amplifiers. The microwave performance characteristics of these devices have set the state-of-the-art in terms of DC to rf efficiency and amplifier noise figure and has resulted in component application for military systems. Gallium arsenide devices are presently being tested and evaluated in several Army systems. These systems include a Ku-band local oscillator for a portable battlefield radar; an X-band transmitter for a digital communications system; a Ku-band velocity sensor for air cushion vehicles; a pump for a traveling wave tube in a classified coherent doppler system. Details of the results of these tests are discussed along with several other proposed Army applications. (Author)

The theoretical analysis of gallium arsenide avalanche transit time devices has been presented. This analysis has established the criteria for optimum design of oscillators and amplifiers and has led to the application of these devices in Army communications and radar systems. (Author)

The basic equations for the determination of semiconductor net impurity doping profiles are derived. A computer technique is introduced which aids the accurate solution of the basic equations. The described method is mathematically rigorous and represents a vast improvement over previously used techniques. (Author)

P-N junction diodes, both silicon and gallium arsenide, oscillate at microwave frequencies when reverse biased into avalanche. Principal mechanism of oscillation is the creation of a dynamic ac negative resistance through avalanche transit time effects. This report presents details on the performance characteristics of p-n junction evalanche oscillators including description of a signal substitution measurement technique. This technique permits accurate measurement of closely spaced by distinct oscillations without the use of filters and is used to detect, observe, and characterize avalanche oscillation in the frequency range 6 - 50 GHz. Details of experimental results on CW and pulsed oscillations, including rf outputs, dc to rf efficiency, tunability, stability, and parametric effects are given for GaAs oscillators. Comparative oscillation performance of some silicon avalanche oscillators is also given. In addition, details of recent avalanche amplifier investigations are presented. Principal highlights of these avalanche devices are oscillation outputs of over 25 mW at 13 GHz with 5.7% efficiency, 1000 MHz tunable bandwidths for 2:1 power changes; amplifiers are 44 db gain at -60 dbm, and 12 db gain at 0 dbm in the 12 - 15 GHz frequency range. (Author)

The report presents preliminary results on the generation of microwave energy from epitaxial gallium arsenide varactor diodes biased into avalanche. These diodes were originally designed to be used in a low-noise parametric amplifier or high-efficiency harmonic generators. An experimental measurement technique using a signal substitution method is fully described. The measurement technique allows one to fully isolate and examine characteristics of the frequency of oscillation without use of filters and to examine any frequency of oscillation between 6.0 and 50 GHz. Details of experimental results on both CW abd pulsed oscillators are given. Pulsed oscillations were observed between 7.89 and 31.2 GHz with specific data tabulated. CW oscillation output of over 20 mW in K sub u band, 13.4 GHz with efficiencies of 4/5 per cent was observed. Specific data such as CW output variation with bias current, efficiency variation with bias current, etc., are presented. In addition, parametrically related oscillation and diode tunability are discussed. (Author)