Loop filter for class D amplifiers
US7002406B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 14, 2004 |
| Grant date | Feb 21, 2006 |
| Priority date | — |
| Expiry date | Jun 8, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F2200/78
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A class-D amplifier circuit (30; 30′) providing improved open-loop error for base-band frequencies, such as the audio band, is disclosed. The amplifier circuit (30; 30′) includes a comparator (35) for generating a pulse-width-modulated output signal that is applied to an output power stage (37). An LC filter (32) is at the output of the power stage (37). The amplifier circuit (30; 30′) includes a loop filter having multiple feedback loop paths, with at least one feedback loop path coupled to the output of the power stage (37), and optionally, at least one feedback loop path coupled to the output of the LC filter (32). The transfer function (Hmae(s)) of the loop filter has a real part that has a much steeper slope (on the order of 80 dB/decade) at frequencies above the pulse-width-modulation switching frequency than the slope of its magnitude characteristic at frequencies below this switching frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.