| 摘要 |
A class AD audio amplifier system ( 10 ) with improved recovery from clipping events is disclosed. The amplifier system ( 10 ) includes multiple audio channels ( 20 ), each of which can be constructed to include a pulse-width-modulator (PWM) ( 24 ). The PWM modulator ( 24 ) includes a pair of comparators ( 39 A, 39 B; 52+, 52 -) that generate complementary PWM output signals based upon the comparison between a filtered difference signal and a reference waveform. Clip detection logic ( 26 ) is provided to detect clipping at the output of the channel ( 20 ), preferably by detecting successive edges of the reference waveform without an intervening edge of a PWM output signal. In response to detecting clipping, a first integrator ( 30; 45 ) is reset to remove residuals and to eliminate the first integrator ( 30; 45 ) from the loop filter of the modulator ( 24 ). A saturation level circuit ( 35 ) applies a clamping voltage, preferably in both clipping and non-clipping situations, to a second integrator ( 36; 47 ). As a result, the loop filter is prevented from entering extreme conditions during clipping, which greatly reduces the clipping recovery time.
|
