A Study on Nonreciprocal Parametric Amplifiers

Abstract

Two or three methods are described to obtain a nonreciprocal parametric amplifier by use of two parametric elements in the frequency inverting case without using nonreciprocal elements such as a uniguide or a circulator. This kind of amplifier can be matched at the input terminal and/or at the output terminal. In a certain case the backward insertion loss can be made infinite. It was proved, however, in regard to the stability criterion that the two properties (matching and infinite backward insertion loss) can not be realized simultaneously. The other characteristics are almost the same as the usual negative resistance parametric amplifier. Some experimental results are presented with respect to one of the amplifiers. Though it has an electrical difficulty of construction, if once built, it may be convenient for low noise pre-amplifier.