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:
Nov. 06, 2001
Filed:
May. 15, 1998
Achim Vowe, München, DE;
Infineon Technologies AG, Munich, DE;
Abstract
The lock detector circuit for a phase-locked loop has two counters and a comparator, to which the counter readings of the two counters are fed. The lock detector circuit is symmetric and has two comparators in which the counter readings of the counters are checked separately in each case. If the difference between the counter readings exceeds a predetermined threshold value in one of the comparators, then the phase-locked loop is immediately set to the non-locked state and the counter readings are reset to zero. Frequency differences are detected immediately in the novel lock detector circuit, without a time delay and independently of the relative position of the reference edges of the signals to be compared. The phase-locked loop is thus quickly and reliably set to a locked or non-locked state. Furthermore, the functioning of the lock detector circuit is preserved when one of the two clock signals fails to appear, for example in the event of a crystal fault.