Search

Presents a biographical entry for each author and co-author included in this issue of the publication.

A theory is formulated which describes quantitatively the noise and transfer properties of IMPATT diode reflection-type negative resistance amplifiers. This theory is based on the method used in the large-signal theory of noise in IMPATT diode oscillators by the present authors. The theory takes into account the signal dependence of the noise generation in the diode, the noise and/or modulation present in the input signal, and also the intermodulation effects occurring between the various frequency bands. The equations are conveniently arranged in matrix form; such a formulation makes it easier to obtain quantitative results in terms of measurable noise and modulation parameters. Agreement between measured and theoretically predicted AM and FM noise of injection-locked oscillators is good. The usefulness of the theory is illustrated by results of calculations on minimum attainable noise of a given amplifier, maximum noise allowable on the input signal, AM-FM conversion, phase distortion, bias modulation, and the correlation between various types of noise.

A silicon n+–p–π–p+ reach-through avalanche photodiode is described, where the p region has a high-low-high doping profile formed by a combination of ion implantation and epitaxy. Effective noise factors as low as 0.008–0.014 have been realised reproducibly for operation in the near-infrared. The influence of the primary photocurrent in the determination of the excess noise is discussed.

Using a simplified theory of parasitic oscillations in IMPATT-diode oscillators, a locus chart is constructed that facilitates the study of parasitic oscillations of the degenerate type. Results of experiments on a high-Q factor coaxial/waveguide circuit (Kurokawa circuit) are explained by this locus chart.

It is shown theoretically, and verified experimentally, that a photodiode, illuminated by monochromatic light of varying wavelength, may show interference ripples in its responsivity, owing to multiple reflections between the diode front and back contact. The amplitude of the ripples is found to increase linearly with the avalanche multiplication factor.

Two definitions of the intrinsic response time of a semi-conductor avalanche are in use which have not yet been very well distingusihed. It is shown that these response times and related quantities, such as the ‘average’ or ‘effective’ ionisation rate α¯, and its field derivative α¯, occur in well defined families. Among other things, it is shown that an accepted expression for α¯ is not consistent with either of these two response times.

An analytical relationship for the output-spectrum width of a low-level-operating IMPATT-diode oscillator is verified experimentally by measuring relevant diode and circuit quantities as well as the oscillator noise. Good agreement between theory and experiment is found if the spectrum width is assumed to be predominantly due to f.m. noise.