Department of Computer Science and Electrical Engineering
Abstract:
The theory of Class D amplifiers states that by utilising a switching method of operation it is possible to achieve amplification with zero power dissipation. Furthermore, if these switches are driven by a signal with duty ratio proportional to the instantaneous input voltage then the output will posses zero levels of distortion. However, practical Class D amplifiers cannot meet these characteristics due to unavoidable imperfections within the circuit elements used and the design realisation.
The focus of this work is to investigate methods of improving the performance of practical Class D amplifiers. Such methods include the reduction of shoot-through when implementing half-bridge switching circuitry, the selective filtering of the switching frequency from the output spectrum and the concept of closed loop control to compensate for inherent non-linearities within the amplifier.
Each of these methods are discussed and followed through to realisation,
where upon the effectiveness of each of the improvements is evaluated.
These evaluations lead to the conclusion that the theories of shoot-through
reduction, frequency selective filtering and closed loop control are all
able to improve the performance of Class D amplifiers. Yet the implementation
of these methods can be quite difficult.
Conference Paper :
Complete thesis: