|
QwEservice manual download site
QwEservice manual download site
Modulator in the first part, the easiest just to use an op amp constitute comparators can be completed. The original audio signal plus a DC bias and sent to the positive input terminal of the amplifier and the other by self-excited oscillation generates a triangular wave added to the negative input of the op amp, as shown in Figure 8. When a potential higher than the negative end on positive triangle-wave potential, comparator output is high, otherwise the output low. If the audio input signal is zero, the DC bias voltage of triangular Crest 1/2, compare the output of high and low level as last, the output is a square wave duty cycle for 1:1. Dang has audio signal entered Shi, in are half week during, compared device output high level of time than low level long, square of accounted for empty than is greater than 1:1; in negative half week during, due to also has DC partial reset, so compared device are entered end of level also is is greater than zero, but audio signal range above triangle wave range of time is was reduced, square accounted for empty than is less than 1:1. So, the comparator output waveform is a range of audio signal pulse width is modulated waveform, called the PWM (pulse width modulated Pulse Width Modulation) or PDM (Pulse Duration Modulation of pulse duration modulation) waveforms.QwEservice manual download site
QwEservice manual download site
Class-d audio amplifier is the second part, which is a pulsed high current switch amplifier control, PWM signal output into a high-voltage comparator; high current power PWM signal. Maximum power output by the load and supply voltage and current of the transistor allowed to flow through to decide.QwEservice manual download site
Part III is a low-pass filter, whose role is to restore power PWM waveform of the sound. Because the current is large, using the structure of RC low-pass filter, resistance will consume large amounts of electricity, which is obviously not allowed, so LC low-pass filter is used here. When the pulse duty ratio is greater than the 1:1 arrives, c the charge time is greater than the discharge time, output levels rise when narrow pulse arrives, discharge time, decline in output levels, consistent with the original audio signal's amplitude fluctuation, so the original audio signal is restored.
8 Home Previous 3 4 5 6 7 8 Next Last |