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:
Oct. 26, 2010
Filed:
Oct. 25, 2007
Hwang Soo Son, Cupertino, CA (US);
Hwang Soo Son, Cupertino, CA (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A circuit for TDMA noise reduction is provided, which may be used in a mobile phone. The circuit includes a first audio amplifier, a second audio amplifier, and a switch. The circuit is attachable to a stereo headphone with two speakers, each speaker having two inputs. The first speaker has one input that is coupled to one input of the second speaker. The other input of each speaker is coupled to a corresponding audio amplifier. During a talk mode for the mobile phone, the common input of the two speakers is left floating. In this mode, the TDMA noise is substantially cancelled, and the sound is differential monophonic. When the mobile phone is not in a talk mode, the common input of the speakers is driven to Vdd/2 or ground, so that the sound is stereophonic.