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:
May. 15, 2012
Filed:
Mar. 25, 2010
Applicant:
Qicheng Yu, Lexington, MA (US);
Inventor:
Qicheng Yu, Lexington, MA (US);
Assignee:
Silicon Laboratories Inc., Austin, TX (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03D 13/00 (2006.01); G01R 25/00 (2006.01);
U.S. Cl.
CPC ...
Abstract
Efficient techniques improve the linearity of a charge pump in fractional-N PLLs. A feedback clock pulse several VCO clock periods wide is formed and supplied to a phase frequency detector (PFD). The down pulse generated by the PFD is fixed to eliminate the nonlinearity associated with up and down current source mismatch. The up pulse is made to fall when the down pulse falls, that is, when the feedback clock pulse falls.