Design Factors in Low-Noise Figure Input Circuits

The use of double-tuned circuits in the inputs of high-frequency amplifiers often results in achieving better noise figures than if the simpler single-tuned network were used. This paper describes a method for calculating the minimum noise figure attainable with double-tuned circuits and provides simple data for designing the network. The results of the analysis, including both active and passive tube input loading, are presented in the form of a nomogram. The constants of a double-tuned input circuit that will provide minimum noise figure may be determined rapidly.