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:
Feb. 02, 1999
Filed:
Aug. 10, 1995
Eisaku Saiki, Yokohama, JP;
Shintaro Suzumura, Yokohama, JP;
Kazutoshi Ashikawa, Maebashi, JP;
Tsuguyoshi Hirooka, Fujisawa, JP;
Seiichi Mita, Kanagawa-ken, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A magnetic recording and reproducing apparatus such as a disk drive has a phase locked loop circuit which is less susceptible to an effect of noise of a power supply and ground and reduces a clock jitter. The magnetic recording and reproducing apparatus is compatible to a constant density recording system without increasing a circuit scale and a power consumption and with a small number of IC pins. The phase locked loop circuit of the magnetic recording and reproducing apparatus is provided with two D/A converter circuits to drive a loop filter. It is also provided with a circuit for distributing a reference potential of a voltage controlled oscillator (VCO) and a center frequency of the VCO, a gain of the VCO and a current gain of the D/A converter circuit are changed in linked relation. A reference voltage source is provided such that a center point or one end of the loop filter is connected to the reference voltage eliminating the ground connection.