The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Nov. 21, 2017

Filed:

Oct. 30, 2014
Applicant:

Realtek Semiconductor Corp., Hsinchu, TW;

Inventors:

Ming-Cheng Chiang, Hsinchu, TW;

Chia-Chi Tsai, Hsinchu, TW;

Assignee:
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04R 29/00 (2006.01); H04R 5/04 (2006.01); H04R 3/00 (2006.01); H03F 3/217 (2006.01);
U.S. Cl.
CPC ...
H04R 5/04 (2013.01); H03F 3/217 (2013.01); H04R 3/00 (2013.01); H04R 29/001 (2013.01);
Abstract

A circuit for driving a loudspeaker is disclosed. The circuit includes: a signal generator connected to the loudspeaker, generating a first signal comprising a first pulse with positive value and a second pulse with negative value; a detection circuit connected to the loudspeaker, detecting a second signal produced by the loudspeaker in response to the first signal; and a processing circuit connected to the signal generator and the detection circuit, calculating the impedance of the loudspeaker according to the second signal; wherein each pulse width of the first and second pulses is between 100 ns and 900 ns.


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