Invention Grant
- Patent Title: Plop-free amplifier
- Patent Title (中): 无波动放大器
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Application No.: US12945505Application Date: 2010-11-12
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Publication No.: US08687821B2Publication Date: 2014-04-01
- Inventor: Han Martijn Schuurmans
- Applicant: Han Martijn Schuurmans
- Applicant Address: NL Eindhoven
- Assignee: NXP B.V.
- Current Assignee: NXP B.V.
- Current Assignee Address: NL Eindhoven
- Priority: EP09176061 20091116
- Main IPC: H04B15/00
- IPC: H04B15/00

Abstract:
An amplifier is disclosed, wherein the output stage is split between a primary output stage and a secondary stage. To minimize or eliminate any audible plop when the amplifier is switched on, the primary stage is connected, and the second stage is gradually connected using a switch. The gradual connection can be by means of varying the pulse-density of a pulse wave modulation on the switch, from fully open (0% pulse-density) to fully closed (100%). The inverse process can minimize or eliminate plop during switch-off. Separate feedback loops are switchable, from the primary and secondary stages; in a DC-coupled embodiment, the feedback loop from the secondary stage may include DC-offset cancelling circuitry, to both reduce or eliminate the plop and avoid and DC-offset current through the speaker.
Public/Granted literature
- US20110116653A1 PLOP-FREE AMPLIFIER Public/Granted day:2011-05-19
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