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:
Jan. 10, 1995
Filed:
Dec. 13, 1993
Charles E Nuckolls, Austin, TX (US);
James R Lundberg, Austin, TX (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
An all digital phase lock loop (ADPLL), (10) includes a variable digital oscillator (DCO 16), a phase detector (12), a controller (13) including an incrementor (19) and decrementor (21), and a set of oscillator control registers (22). A frequency tracking circuit (20) is separated from the phase acquisition/maintenance logic circuitry. The frequency tracking circuitry (20) uses an anchor value to maintain and update a DCO control value corresponding to a target frequency of operation of the DCO (16). Updates to the anchor value are facilitated by monitoring recent history of an output control signal (ahead or behind) provided by the phase detector (12). The anchor value is changed to maintain the target frequency of operation of the DCO (16), even in the presence of variations in operating environments.