Startup and shutdown click noise elimination for class D amplifier
US7417504B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 3, 2007 |
| Grant date | Aug 26, 2008 |
| Priority date | — |
| Expiry date | Aug 3, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F1/305
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method of minimizing an audible click noise from a speaker in a Class D audio power amplifier upon shutdown or startup of a switching stage having two switches series connected at a node, the speaker being connected to the node via an output filter comprising an inductor and a capacitor, the switches being controlled by a controller. The method including the steps of determining a timing interval at the node to transition a peak voltage of the capacitor, the capacitor voltage being a speaker voltage; and eliminating the audible transient voltage excursion across the speaker that causes a click noise during the timing interval, wherein at startup ON and OFF times of the switches are incrementally increased from zero to a normal mode and at shutdown the ON OFF times of the switches are incrementally decreased from the normal mode to zero.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.