Improved computer-aided design of amplifiers using feedback concepts

Novel applications of feedback concepts to the reflection and transmission properties of amplifiers lead to improved design techniques. The theoretical basis rests on the work of Bode, and is applied to 2-port descriptions of transistors, matching circuits and embedding networks. One result is an accurate method for determining the value of local feedback resistor or other elements needed to achieve a prescribed VSWR. Another is a means of accounting properly for feedback which is invariably present, leading to simpler transducer power gain expressions for use in design. The treatment is in terms of easily understood nodal analysis of simple 2-ports. Several numerical examples are given to enable readers to appreciate the potential of the new approach. These examples use extensive data banks of error corrected and smoothed measured S-parameters for transistor type NE72084, as no comparable data on chip versions of this or other types were available. Applications of the method using such data are likely to lead to better understanding and higher amplifier performance at microwave frequencies.