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.
Patent No.:
Date of Patent:
Feb. 22, 2000
Filed:
Apr. 27, 1999
Applicant:
Inventor:
Koichiro Nagata, Ibaraki, JP;
Assignee:
Matsushita Electric Industrial Co., Ltd., Osaka-fu, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04R / ;
U.S. Cl.
CPC ...
381111 ; 381117 ; 330251 ; 3302 / ;
Abstract
Class D amplifiers are difficult to incorporate into audio amplifier systems because of the interference created by the amplifier and/or the surrounding circuits. The modulation frequencies f1 and f2 of two class D amplifiers in an audio amplifier system are adjusted so that the frequency f1-f2 of interference between the modulation frequencies is outside the reproducible frequency band B1 of speakers converting the class D amplifier output to audible sound. As a result, interference that may result from simultaneous use of two class D amplifiers for similar purposes is inaudible and not perceived as noise.