This module describes some commonly encountered classes of power output circuits and techniques used to improve performance. This class of common emitter amplifier has a plenty of gain but very low efficiency. It has smaller heat dissipation, so small heatsink is needed. Designing audio power amplifiers bob cordell new york chicago san francisco lisbon london madrid mexico city milan new delhi san juan seoul singapore sydney toronto. Many power amplifiers are affected by noise and distortion.
Most audio power amplifiers use class a circuitry except in the drive and output stages, where they use class b or. The limitations due to the efficiency of class a power amplifiers. An alternative approach to the design of a transistor power amplifier combining good performance with simple construction is to use the output transistors in a class. Class a power amplifier is a type of power amplifier where the output transistor is on full time and the output current flows for the entire cycle of the input wave form. In other words, a power amplifier amplifies the power of the input signal which is why these types of amplifier circuits are used in audio amplifier output stages to drive loudspeakers. Class a amplifier design introduction to amplifier design basic design process. Electronics tutorial about the class a amplifier and single stage class a power amplifier using transformer coupled outputs from a common emitter design. Power amplifiers purpose of a power amplifier generate high output power efficient conversion of dc power to rf power linear amplification generally pas will be common source cascode inductor is a choke to provide d apacitor is a ac coupling path to output james buckwalter 2.
Classesa, ab, b, and c amplifiers can be defined in terms of the conduction angle y as follows. Part ii to appear later will cover the switching amplifier modes of operation. A simple class ab power amplifiers with feedbackpair complimentary was designed to overcome the mentioned problems. This module shows how to simply calculate the values needed to make a working amplifier that has correct class a bias as described in amplifier. A tuned circuit or filter is a necessary part of the classc amplifier. Class a in this video we take a brief look at the class a transistor amplifier. The designed circuit was the simulated using protues software. The classification of an amplifier as either a voltage or a power amplifier is made by comparing the characteristics of the input and output.