The reference signal for the PWM control circuit can be an audio signal, and the
full-bridge circuit could be used as a PWM audio amplifier. APWM audio amplifier
is referred to as a class D amplifier. The triangular wave carrier signal for this
application is typically 250 kHz to provide adequate sampling, and the PWM
waveform is low-pass filtered to recover the audio signal and deliver power to a
speaker. The spectrum of the PWM output signal is dynamic in this case.
Class D amplifiers are much more efficient than other types of audio power
amplifiers. The class AB amplifier, the traditional circuit for audio applications,
has a maximum theoretical efficiency of 78.5 percent for a sine wave of maximum
undistorted output. In practice, with real audio signals, class AB efficiency is
much lower, on the order of 20 percent. The theoretical efficiency of the class D
amplifier is 100 percent because the transistors are used as switches. Because
transistor switching and filtering are imperfect, practical class D amplifiers are
about 75 percent efficient.
Class D audio amplifiers are becoming more prevalent in consumer electronics
applications where greater efficiency results in reduced size and increased
The reference signal for the PWM control circuit can be an audio signal, and thefull-bridge circuit could be used as a PWM audio amplifier. APWM audio amplifieris referred to as a class D amplifier. The triangular wave carrier signal for thisapplication is typically 250 kHz to provide adequate sampling, and the PWMwaveform is low-pass filtered to recover the audio signal and deliver power to aspeaker. The spectrum of the PWM output signal is dynamic in this case.Class D amplifiers are much more efficient than other types of audio poweramplifiers. The class AB amplifier, the traditional circuit for audio applications,has a maximum theoretical efficiency of 78.5 percent for a sine wave of maximumundistorted output. In practice, with real audio signals, class AB efficiency ismuch lower, on the order of 20 percent. The theoretical efficiency of the class Damplifier is 100 percent because the transistors are used as switches. Becausetransistor switching and filtering are imperfect, practical class D amplifiers areabout 75 percent efficient.Class D audio amplifiers are becoming more prevalent in consumer electronicsapplications where greater efficiency results in reduced size and increased
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