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:
Nov. 02, 1999
Filed:
Apr. 24, 1997
Hitachi Ltd., Tokyo, JP;
Abstract
The present invention designs and implements a high-speed PLL circuit and a high-speed synthesizer using the high-speed PLL circuit which has an increased switching speed, a reduced number of jitters and a reduced magnitude of spurious response. In order to achieve the above, the present invention provides a PLL circuit forming a closed loop wherein: one of the inputs of a phase comparator 1 serves as the input of the PLL circuit and the output of phase comparator 1 is connected to the input of a loop filter 2; the output of loop filter 2 is connected to the input of a voltage-controlled oscillator (VCO) 3; the output of the VCO 3 serves as the output of the PLL circuit; and the output of the VCO 3 is supplied to the other input of phase comparator 1 through a frequency divider 4. The circuit form and circuit constants of loop filter 2 are determined so that the transfer function of the closed loop becomes a Gaussian function.