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:
Apr. 11, 2006
Filed:
Sep. 24, 2001
Kee Eng Soo, Kamunting, MY;
Ashok Ramakant Patil, Duluth, GA (US);
Michael D. Geren, Suwanee, GA (US);
Macwien Krishnamurthi Annamalai, Petaling Jaya, MY;
Kee Eng Soo, Kamunting, MY;
Ashok Ramakant Patil, Duluth, GA (US);
Michael D. Geren, Suwanee, GA (US);
Macwien Krishnamurthi Annamalai, Petaling Jaya, MY;
Motorola, Inc., Schaumburg, IL (US);
Abstract
This invention includes a circuit for the prevention of acoustic feedback between an electronic device and an audio accessory. In a preferred embodiment, the circuit prevents audio feedback between a cellular telephone and a speakerphone accessory. The circuit includes a current limiting device coupled serially in the receive (Rx) line. The current limiting device is actuated via a delay circuit coupled between the current limiting device and the transmit (Tx) line. When a bias current is presented to the Tx line, the bias propagates through the delay circuit, thereby actuating the current limiting device a predetermined time after the presentation of the bias. The circuit keeps the Rx line open long enough for the phone to deactivate its internal microphone.