Design of reflection amplifiers. B - Practical realisation

The present investigation is concerned with the realization of microwave negative resistance amplifiers using Gunn or IMPATT diodes. The problem to be resolved in designing such amplifiers is the achievement of a suitable transformation between input and output impedances and device impedance allowing the desired gain, center frequency, and bandwidth to be obtained while avoiding spurious outputs at other frequencies. A procedure for solving this problem is illustrated with the aid of a practical example. Most of the considered approaches are applicable to both Gunn and IMPATT diodes. However, there are also some differences regarding the methods to be employed for both devices. Generally speaking, the Gunn diode exhibits a larger value of negative resistance over a broader bandwidth than the IMPATT. Attention is given to device measurement, circuit configuration, waveguide amplifiers, multiple diode circuits, and multistage amplifiers.