RF Power Amplifiers
Chapter One
Introduction
1.1 Block Diagram of RF Power Amplifiers
A power amplifier is a key element to build a wireless communication system
successfully. To minimize interference and spectral re-growth, transmitters must be linear.
A block diagram of an RF power amplifier is shown in Figure 1.1. It consists of a transistor
(MOSFET, MESFET, or BJT), output network, input network, and RF choke. In RF power
amplifiers, a transistor can be operated
as a dependent-current source;
as a switch;
in overdriven mode (partially as a dependent source and partially as a switch).
Figure 1.2(a) shows a model of an RF power amplifier in which the transistor is operated
as a voltage- or current-dependent current source. When a MOSFET is operated as a dependent
current source, the drain current waveform is determined by the gate-to-source voltage
waveform and the transistor operating point. The drain voltage waveform is determined
by the dependent current source and the load network impedance. When a MOSFET is
operated as a switch, the switch vol ... read full excerpt from RF Power Amplifiers ebook
