Fluctuation Noise in a Microwave Superregenerative Amplifier

A brief review of superregenerative (sr) operation is followed by the substitution of Rice´s Fourier series representation for noise current into the expression for the output of an SR amplifier. Expressions are derived for the noise figure. It is then shown how a reflex klystron can be used as the active element. Expressions for the noise figure in terms of the klystron parameters are derived. Calculation for a hypothetical, but realistic, case shows that low noise figures are obtainable if certain conditions are met. In particular, it is shown that deliberate introduction of beam current, with its consequent shot noise, during the quliescent interval provides a smaller over-all noise figure.