RF/Microwave Solid State Switches: Part 1

Solid state switches are ubiquitous in modern RF/microwave systems. They are utilized to control signal flows, select signal sources and for many other applications. These switches are implemented either with positive-intrinsicnegative (PIN) diodes or with field effect transistors (FETs) such as pseudomorphic high electron mobility transistors (pHEMTs), each of which offers relative advantages and disadvantages. Part 1 of this article includes an overview of RF/ microwave switches, theory of operation for PIN diodes and some representative PIN diode switch circuits. In Part 2 we will discuss more PIN diode switch configurations, the theory of operation for FETs, some representative RF/microwave FET switch topologies, the relative advantages of PIN and FET switches and some criteria by which one of these technologies may be selected over the other for switch applications.