Recovery from clipping events in a class D amplifier
US7425864B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 3, 2006 |
| Grant date | Sep 16, 2008 |
| Priority date | — |
| Expiry date | Mar 16, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2200/78
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
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 (39A, 39B; 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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.