Particle Swarm Optimization of a Cascaded Multisection Line Impedance Matching Circuit

Metaheuristic optimization methods enable to design circuits with a high degree of freedom. Advances in computer performance have made it possible to search for good solutions in a huge number of parameter spaces. In this paper, we propose a design of an impedance matching circuit consisting of a large number of cascaded line-sections using the particle swarm optimization. By making each section a line sufficiently shorter than a quarter wavelength transmission line, it is expected that the variety of circuit patterns will increase and the desired characteristics will be realized with a high degree of freedom. We provide a design example of a 20-section transmission line transformer implemented in a microstrip line configuration and describe the trade-off between the overall length of the transformer and the impedance matching performance.