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:
Jun. 25, 1991
Filed:
Oct. 31, 1989
Steven P Cok, Seattle, WA (US);
John Fluke Mfg. Co., Inc., Everett, WA (US);
Abstract
A digital phase/frequency detector circuit in a phase locked loop comprises multiple bistable devices which are clocked up and down respectively by input and references digital signals to generate square waves. The duty ratio corresponds to the phase/frequency difference and sweeps repetitively between minimum and maximum values as the phase/frequency difference changes monotonically. The square waves are combined logically and additively in the output. The output is integrated to obtain an every increasing output over many cycles of the phase/frequency difference until the maximum is reached depending on the number of bistable devices which are used. Added circuitry is used to avoid coincidence problems in the clocking input and reference digital signals, to minimize resultant irregularities, and hold the bistable devices at maximum or minimum, as appropriate, until the direction of phase/frequency difference reverses. At either maximum or minimum a sawtooth waveform exists of one magnitude of value out of many magnitudes of value between maximum and minimum. The many magnitudes depend on the number of bistable devices.