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:
Jan. 02, 2007
Filed:
Mar. 24, 2005
Daniel Gudmunson, Dripping Springs, TX (US);
John Melanson, Austin, TX (US);
Rahul Singh, Austin, TX (US);
Ahsan Chowdhury, Austin, TX (US);
Daniel Gudmunson, Dripping Springs, TX (US);
John Melanson, Austin, TX (US);
Rahul Singh, Austin, TX (US);
Ahsan Chowdhury, Austin, TX (US);
Cirrus Logic, Inc., Austin, TX (US);
Abstract
A method and apparatus for maintaining an ideal frequency ratio between numerically-controlled frequency sources provides a mechanism for maintaining coherence between multiple synchronization references where a known ideal rational relationship between the sources is known. Multiple numerically controlled oscillators (NCOs) generate the multiple synchronization references, which may be clock signals or numeric phase representations and the outputs of the NCOs are compared with a ratiometric frequency comparator that determines whether there is an error in the ratio between the NCO outputs. The frequency of one of the NCOs is then adjusted with a frequency correction factor provided by the ratiometric frequency comparator. The NCO inputs can represent ratios of the synchronization reference frequencies to a fixed reference clock and the NCOs clocked by the fixed reference clock.