Lumped and Distributed Matching Networks

Abstract

Lumped and distributed passive networks are often used in RF power amplifier design as matching networks and filters. It is often required that an impedance at the frequency of operation be transformed to another impedance level, and this is typically accomplished using passive networks. In many RF applications, interconnect transmission lines have a characteristic impedance of 50 Ω, and the input and output ports of circuits often need to be matched to 50 Ω. Thus, these passive networks are commonly referred to as matching networks, transforming one impedance level to another to match a specific impedance level. In RF applications where a relatively narrow band of frequency carries the signals of interest, these networks can also serve as frequency-selective filters. This chapter provides a brief overview of both lumped-element matching networks, which consist of passive elements such as capacitors and inductors, and distributed matching networks that employ transmission lines.