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:
Oct. 26, 2010
Filed:
Jul. 22, 2008
Yasuo Kitayama, Chitose, JP;
Hiroki Kimura, Chitose, JP;
Naoki Onishi, Chitose, JP;
Nobuo Tsukamoto, Akishima, JP;
Yasuo Kitayama, Chitose, JP;
Hiroki Kimura, Chitose, JP;
Naoki Onishi, Chitose, JP;
Nobuo Tsukamoto, Akishima, JP;
Nihon Dempa Kogyo Co., Ltd, Tokyo, JP;
Abstract
A VCO driving circuit and a frequency synthesizer wherein the impedance viewed from a VCO control terminal is reduced to prevent the VCO phase noise characteristic from degrading. A VCO driving circuit and a frequency synthesizer having the VCO driving circuit, which comprises a coarse adjustment DAC that receives a digital data, which has a coarse adjustment frequency, to output an analog signal; a fine adjustment DAC that receives a digital data, which has a fine adjustment frequency, to output an analog signal; a low response speed LPFthat removes noise from the output signal from the coarse adjustment DAC and then provides the resultant signal as an input to a VCO control terminal; a high response speed LPFthat converts the output signal from the fine adjustment DAC to a voltage, thereby smoothing the signal; a resistor that connects an input stage of the LPFto that of the LPF; and a capacitor used for providing a capacitive coupling such that the output of the LPFis added to that of the LPF