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:
May. 26, 2009
Filed:
Feb. 27, 2007
Michael David Cesky, Rochester, MN (US);
James David Strom, Rochester, MN (US);
Michael David Cesky, Rochester, MN (US);
James David Strom, Rochester, MN (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and enhanced phase-locked loop (PLL) circuit enable effective testing of the PLL. A phase frequency detector generates a differential signal, receiving a reference signal and a feedback signal of an output signal of the PLL circuit. A charge pump is coupled to the phase frequency detector receiving the differential signal. The charge pump applies either negative or positive charge pulses to a low-pass filter, which generates a tuning voltage input applied to a voltage controlled oscillator. A first divider is coupled to the voltage controlled oscillator receives and divides down the VCO output signal, providing the output signal of the PLL circuit. A second divider receives the output signal of the PLL circuit and provides the feedback signal to the phase frequency detector. The output signal of PLL circuit is applied to a clock distribution.