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FBgservice manual download site
2. Brief introduction of working principleFBgservice manual download site
Class-d power amplifier, the input signal into a PWM signal, pulse-width modulated signal. Class-d audio amplifier circuits in General, does not use a/d converters (a/d) converter circuit the PWM signal, but with a range of sine wave signal amplification similar to the triangle wave, as the converter input, as shown in Figure 9, the transformation corresponds to phase comparator. When a sine wave is larger than the triangle wave when Converter output "1"; when the sine-wave amplitude is less than the triangle-wave amplitude, converter outputs "0"; so that you can enter the width of the sinusoidal signal into a sine-wave PWM wave amplitude variation.FBgservice manual download site
FBgservice manual download site
When input analog audio signal, PWM modulator, an analog audio signal into its amplitude corresponds to the high frequency PWM pulse width pulse, pulsed propeller-driven power amplifier, and then low-pass filter push the speaker sound.FBgservice manual download site
It is worth mentioning that, audio PWM code can also be obtained through the following two ways: one is the analog audio signal to the a/d converter, PWM digital audio signals directly; the second is the encoded digital audio, such as the CD PCM digital signal, PCM-PWM of the digital signal converter into PWM pulse signal, then sent back level.FBgservice manual download site
Class-d amplifier power MOSFET switches used in, namely high power field-effect transistor, and in order to ensure sufficient excitation, also has drive circuit, MOSFET can fully open and shut.FBgservice manual download site
Note: class-d audio power amplifier based on PWM mode to be compared with sampling frequency audio signals, after natural samples, audio signal amplitude and pulse width of PWM wave is proportional to the change, and after the driver, added to the power grid of MOs tubes, control power on/off the device to achieve amplification. After amplifying the PWM signal is low-pass filter, and revert to the audio signal.FBgservice manual download site
Four, class-d amplifier circuit analysis
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