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:
Mar. 18, 2014
Filed:
May. 09, 2008
Charles W. T. Nicholls, Nepean, CA;
Philippe Wu, Kanata, CA;
Charles W. T. Nicholls, Nepean, CA;
Philippe Wu, Kanata, CA;
Apple Inc., Cupertino, CA (US);
Abstract
A method and apparatus for correcting oscillator frequency drift due to crystal aging. Correction signals that reflect a difference between an oscillator timing signal and a reference timing signal over a reference timing signal interval are modeled so that auxiliary correction signals can be generated in the event of loss of the reference timing signal. A temperature curve is generated to model how temperature variation impacts oscillator frequency drift. A rate of frequency drift due to crystal aging is also determined. During loss of a reference timing signal, auxiliary correction signals can be generated to maintain the oscillator at a desired frequency until the reference timing signal becomes available again.