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:
Dec. 02, 1997
Filed:
Jan. 29, 1996
Frank D Ferraiolo, Essex Junction, VT (US);
John E Gersbach, Burlington, VT (US);
Masayuki Hayashi, Williston, VT (US);
Ilya I Novof, Essex Junction, VT (US);
Charles J Masenas, Jr, Essex Junction, VT (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A protective circuit for a phase lock loop ensures that the VCO does not initiate a runaway condition when outputting a signal having a frequency higher than the feedback divider can respond to. During normal phase lock operation, a counter keeps track of the PLL input signal and is reset by the feedback divider. In the runaway condition the counter is not reset and triggers a control signal to the VCO. A second counter can be used to keep track of the feedback divider output and to reset the first counter. When the first counter far outruns the second counter the control signal is triggered.