Noise Optimization Techniques for Linear Transistor Amplifiers

Citation

DiLoreto, Aldo Gene (1962) Noise Optimization Techniques for Linear Transistor Amplifiers. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/5JV3-EZ18. https://resolver.caltech.edu/CaltechTHESIS:08192011-090320424

Abstract

Methods of minimizing the effects of internally generated noise in transistor amplifiers are described. The study is both theoretical and experimental in nature, the greater part of the theoretical portion being based on van der Ziel’s transistor noise model. From this model, analytical expressions are formulated giving (in terms of easily measurable transistor parameters) the operating point and source resistance that will optimize the noise performance of the amplifier. The derived equations are substantiated by an experimental study. Both audio and radio frequency amplifiers are considered. At audio frequencies, the work is primarily experimental in nature. Here, attention is focused on developing a simplified optimization procedure. For the radio frequency amplifier, formulas are also derived that describe the effect of source reactance on the amplifier’s noise performance. Formulas giving the noise figures of the transformer- coupled transistor amplifier are included. From these equations, analytical expressions are formulated that describe the emitter current and transformer turns ratio which will minimize the effects of internally generated noise. An experimental investigation verified the results. A portion of the work is devoted to a theoretical and experimental study of temperature and its effect on the noise performance of transistor amplifiers. This study, which considers temperatures from 77 to 320° K, differs from those previously conducted in that a wide range of source resistances are used. Equations describing the degradation in noise performance produced by resistive stabilizing components are given. Also included is an analytical description of the methods used to obtain noise-factor measurements.

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