RF and Microwave Circuit and Component Design for Wireless Systems

CHAPTER ELEVEN

Power Amplifiers

11.1 INTRODUCTION

RF/Microwave power amplifiers are important circuit components used in every system including cordless and cellular telephone, base station equipment, space borne, airborne, and ground-based (fixed/mobile) satellite communications, wireless local area networks, terrestrial broadcast and telecommunications, point-to-point radio, wideband satellite communications, phased array radar (PAR), electronic warfare (EW), and smart weapons. Most of these systems require low-cost (high volume) and more reliable solid-state power amplifiers [1–12]. The cordless and cellular telephone require low-bias voltage operation (2–5 V), single power supply, very high efficiency (analog versions) or high linearity (digital versions). The cellular telephone may require dual- or triple-mode operation including multiple frequencies in both digital and analog versions. The power output requirements are in the range of 0.2–3 W.

For wireless base stations high linearity is of paramount importance in power amplifiers. For example, for PCS (1.8–2.0 GHz) requirements for power levels are in the range of 5–200 W. Modern active-aperture antenna subsystems for phased-array applications require hundreds or even thousands of transmit/receive (T/R) modules, each delivering tens of watts of output power. These phased-array antenna subsystems will be employed in airborne communication and radar systems, ground-based and ship-based tactical radars, as well as space-based ...