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:
Jan. 13, 2004
Filed:
Sep. 27, 2002
Hirokazu Miyagawa, Takasaki, JP;
Katsumi Yamamoto, Kokubunji, JP;
Tatsuji Matsuura, Tokyo, JP;
Katsumi Osaki, Takasaki, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
The present invention is directed to reduce fluctuations in modulation frequency of a VCO caused by a temperature change in a semiconductor integrated circuit for use in a radio communication system of a frequency hopping method performing modulation by controlling the VCO of an LC oscillation type in accordance with transmission data in an open loop by using the VCO. In a semiconductor integrated circuit of a frequency hopping method performing modulation by directly controlling an LC oscillation type VCO on the basis of transmission data and transmitting data while switching a carrier frequency, a temperature characteristic correcting circuit is provided which give a negative temperature characteristic to a reference current value of a circuit (such as a DA converter) for generating a control voltage of the VCO so that a modulation-side control input voltage having a positive temperature characteristic and controlling the VCO comes to have a negative temperature characteristic.