“D”功放制作资料.pdf

Class D Audio Power Amplifier Jason Cookson, EE Janelle Tonti, EE May 10, 2002 The University of Maine ECE 403 Final Report ii Abstract There is always a push to create amplifiers that are more efficient. High efficiency translates to less power wasted, lower operating temperatures, and longer battery life in portable applications. For audio amplifiers, it is also imperative to have excellent sound quality by maintaining low distortion through the entire audio range. This class D audio power amplifier achieves high efficiency while retaining exceptional sound quality, making it an outstanding audio power amplifier. It achieves high efficiency by using a pulse width modulation (PWM) scheme to convert the analog input into a stream of “pulses.” These pulses control power transistors that allow current to flow through the load and turn the transistors either completely on or completely off keeping wasted energy to a minimum. There is very little audible distortion introduced by this class D audio power amplifier. Our class D audio power amplifier has an output power of 71.25 W for a 9 Ω load, far above the specified 10 W. We calculated an efficiency of 86.9% which exceeds the required 50% efficiency. The necessary frequencies of operation from 200 Hz - 10 kHz are easily amplified; this amplifier performs well over the entire audio band. iii Table of Contents A