An interactive approach to the design of adaptive impedance matching circuits

This paper illustrates a simple interactive method to determine the values of the components of an adaptive Π matching network; the network consists of a series inductor and two shunt capacitors. The network architecture can either be based on tunable or switchable components. Based on a specified range of load variation at a certain frequency, the required minima and maxima of such components are determined; consequently, the impedance boundary of the adaptive matching circuit, encircling the required matching domain, is plotted on an inherently created Smith chart. An interactive design procedure, based on a set of explicit equations, is proposed to study the impact of varying each component upon the matching domain. A case study is presented, where the load impedance is varied in a specified domain, and the most appropriate values for the Π network are evaluated using the proposed technique. Evaluated values for the network components are compared to the closest standard values. Then, the most suitable standard values are selected using a proposed selection strategy to obtain the minimum matching error. Although the proposed method is applied to a Π matching network, it can be easily extended to other matching networks.