Patent ID: 6640090
Filing Date: 2003-10-28
Classification: G07C,H04B

Abstract:
A signal transmitter utilizing an ASK modulation wave, the signal transmitter comprising:a modulator circuit for outputting a first modulated signal through an ASK modulation of a data signal using an ASK modulation signal under a condition that the ASK modulation signal and data signal are synchronized with each other; a first push-pull circuit for executing a push-pull operation based on the first modulated signal; a first resonance circuit including a first coil antenna and a first capacitor, the first resonance circuit for transmitting a transmission signal in a radio wave through a resonance of the first coil antenna and the first capacitor under a condition that the first push-pull circuit is executing the push-pull operation; and a switching device connected between the first resonance circuit and a ground for switching to disconnect or connect the first resonance circuit and the ground, wherein the modulator circuit controls the switching device to cut off a connection between the first resonance circuit and the ground in synchronization with the first modulated signal.