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:
Oct. 22, 2013
Filed:
Dec. 01, 2010
Gan Wen, Beijing, CN;
Gan Wen, Beijing, CN;
Telefonaktiebolaget L M Ericsson (publ), Stockholm, SE;
Abstract
A method and circuit is provided for determining a control voltage of a voltage controlled oscillator with fast frequency lock of a phase-locked loop and which is advantageous to the situation when an ultra-low frequency reference is used. The method and circuit determines a current error between a reference clock signal and a feedback clock signal, and checks if the error is larger than the threshold value which checks if an error sign indicator is set, i.e. the error has switched sign since startup of feedback loop; if the error sign indicator is not set, the circuit determines a divisor, k, using the current error, e, current control voltage, u, previous error e, and previous control voltage, u; however, if the error sign indicator is set the circuit determines a divisor, k, using stored values for the latest control voltage and error when the error was negative and stored values for the latest control voltage and error when the error was positive; furthermore, the method and circuit determines a control voltage step using the determined error divided by the divisor, k, and determines a new control voltage using the current control voltage, u, and the determined control voltage step.