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:
Apr. 23, 1996
Filed:
Dec. 13, 1993
James R Lundberg, Austin, TX (US);
Charles E Nuckolls, Austin, TX (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A method and apparatus for performing frequency detection in an all digital phase lock loop (10). Frequency detection is accomplished using a frequency detector (11), coupled to an digitally controlled oscillator (DCO 16). The frequency detector (11) forces phase alignment of a reference clock signal to the DCO (16) output and then counts the number the DCO (16) output pulses occurring during a reference clock period. The reference clock signal enables the DCO (16) on one signal transition and detects the presence of an oscillator counter (52) output on the same reference clock signal transition, but one reference clock period later. A synchronizer (49) is used to pass the counter (52) output to ensure no metastability. The DCO (16) is then disabled to allow frequency adjustments to occur via other circuitry.