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. 15, 2002
Filed:
May. 04, 2000
Shigemi Chimura, Kyoto, JP;
Rohm Co., Ltd., Kyoto, JP;
Abstract
An IC card produces electric power by rectifying a high-frequency signal received from a reader/writer. A MOS transistor is connected to an antenna and the received signal is rectified by the parasitic diode of the MOS transistor. The capacitance accompanying the transistor is added to the capacitance of an input tuning capacitor. Switching the on/off state of the transistor causes the capacitance added to that of the tuning capacitor to change; accordingly, the input tuning frequency changes and the relation between the input tuning frequency and the frequency of the received high-frequency signal changes. As a result, the amplitude of the received high-frequency signal changes and thus the obtained power also changes.