ABSTRACT
Power amplifiers are usually distinguished by their operating class-A, AB or B, and so on. The most elementary level, there are five classes of device operation. More sophisticated amplifier types such as Class-G, Glass-S, are combinations of the basic classes. The five basic classes are Class-A, Class-AB, Class-B, Class-C, Class-D. In parallel, that is, shunt, connection, output currents are summed, the intention being either to increase power capability, which does not affect basic operation, or to improve linearity. For a parallel connection the two class letters are separated by a dot, that is '•'. In a series connection the voltage drop between supply rail and output is split up between two or more devices, or voltages are otherwise summed to produce the output signal. Series connection is denoted by a plus sign between the two Class letters. The first letter denotes the class of that section of the amplifier that actually controls the output voltage.
