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. 08, 1996
Filed:
Oct. 12, 1995
John E Gersbach, Burlington, VT (US);
Masayuki Hayashi, Williston, VT (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
Calibration systems and techniques for analog phase-lock loops (PLLs) providing the capability to dynamically maintain a constant damping factor. Damping factor is calibrated by automatically setting a reference bias current I.sub.r to the PLL's charge pump such that the charge current I.sub.c output therefrom maintains the desired PLL damping characteristic. The technique presented involves selecting a known first frequency F.sub.1 and allowing the PLL circuit to reach steady state, after which a known second frequency F.sub.2 is applied and the PLL circuit is monitored to determine whether steady state at this second frequency F.sub.2 is accomplished within a predetermined target time T.sub.x, which corresponds to the desired damping factor. The determination of whether lock occurs within the target time T.sub.x is then employed to automatically set the reference current I.sub.r.