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. 05, 1995
Filed:
Dec. 13, 1993
Charles E Nuckolls, Austin, TX (US);
James R Lundberg, Austin, TX (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A method and apparatus for performing, after frequency acquisition, phase acquisition and phase maintenance in a digital phase-locked loop 10. A phase detector (12), determines the phase relation of an oscillator output to a reference clock signal, and provides a control signal to a controller (13), indicative thereof. When a subsequent logic state of the control signal provided by the phase detector is equal to an initial logic state of the control signal, the controller (13) increments or decrements a control value initially corresponding to a baseline frequency of the oscillator by the gain value, based upon the logic state of the control signal. When the control signal changes state, phase-lock has been acquired, and a gain value which determines the magnitude of change of the oscillator frequency is decreased. On every subsequent change in the logic state of the control signal, the gain value is decreased, unless at a minimum. If the control signal does not change for a predefined number of cycles, the gain value is increased.