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. 05, 2013
Filed:
Mar. 28, 2012
Timothy M. Johnson, San Jose, CA (US);
Lawrence F. Heyl, Colchester, VT (US);
Wendell B. Sander, Los Gatos, CA (US);
Douglas M. Farrar, Los Altos, CA (US);
Timothy M. Johnson, San Jose, CA (US);
Lawrence F. Heyl, Colchester, VT (US);
Wendell B. Sander, Los Gatos, CA (US);
Douglas M. Farrar, Los Altos, CA (US);
Apple Inc., Cupertino, CA (US);
Abstract
An audio host device has an electrical interface having a speaker contact, a microphone contact, and a reference contact. The reference contact is shared by a microphone and a speaker. The reference contact is also directly coupled to a power return plane of the audio host device. A difference amplifier is provided, having a cold input and a hot input. The hot input is coupled to the microphone contact. A switched attenuator circuit is also provided that has first and second states. In the first state, the attenuator circuit couples a sense point of the reference contact to the cold input, while in the second state the cold input is isolated from the reference sense point. Other embodiments are also described and claimed.