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:
Mar. 13, 2012
Filed:
Nov. 20, 2009
Takashi Kawamoto, Kodaira, JP;
Takashi Kawamoto, Kodaira, JP;
Renesas Electronics Corporation, Kanagawa, JP;
Abstract
A phase locked loop (PLL) which has a desired frequency characteristic even though a manufacturing process of a semiconductor integrated circuit has fluctuations. The semiconductor integrated circuit includes the PLL and a control unit. The PLL has a phase frequency detector, a loop filter, a voltage controlled oscillator (VCO) and a divider. The VCO comprises a voltage-current converter (VIC) and a ring oscillator. In response to a control voltage, the VIC generates a control current for setting each operating current of the ring oscillator. The control unit switches the PLL to a calibration operating period of its open loop and a normal operating period of its closed loop.