| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a vehicular wireless device capable of constantly maintaining a resonance frequency even if a current fed to an LC resonance circuit is changed. <P>SOLUTION: When a magnetic field generating region is widened, a gain of a gain amplifier part 12 is set large and the current fed to the LC resonance circuit composed of an inductor 17 and a capacitor is increased. When the magnetic field generating region is narrowed, the gain of the gain amplifier part 12 is set small and the current fed to the LC resonance circuit is reduced. When the current fed to the LC resonance circuit is increased, a first FET 20 is driven into a conductive state and a first capacitor 18 is used. When the current fed to the LC resonance circuit is reduced, a second FET 21 is driven into a conductive state and a second capacitor 19 is used. The resonance frequency can be constantly maintained by switching a capacitance value of the capacitor though inductance of the inductor 17 is changed by the current to be fed. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
