Application of a simplified real-frequency synthesis method to distributed-element amplifier design

Abstract

The simplified real-frequency method is probably the best microwave circuit synthesis method available for the design of broadband amplifiers for electronic countermeasure (ECM) or communications applications. When applied to the design of interstage equalizers for microwave amplifiers, the procedure, contrary to classical synthesis techniques, utilizes only the measured scattering parameters of the 2-port active device. The method thus directly includes device feedback effects, and neither an a priori choice of matching network topology nor an analytical form of the system transfer function is necessary. In the version described in this article, the optimization process is applied simultaneously to transducer power gain, input match (VSWR), and noise figure of a multistage amplifier. A procedure for directly extracting distributed transmission line elements for matching networks is briefly described. The program FREEL is then applied to the design of 3-stage 2-8-GHz and 1.15-1.5-GHz MESFET amplifiers in which three topologies are compared: lumped element, cascaded transmission line, and transmission line and open circuited stubs.