| 摘要 |
A device includes a coil (11) coupled to a magnetic field having power energy by electromagnetic induction, a rectifier (12) for subjecting the power energy fetched by the coil to full-wave rectification, a smoothing circuit (13) for smoothing a rectified output from the rectifier and forming a fixed internal power source, an MOS transistor (14) having a source and a drain connected in parallel across the coil, and a constant-voltage control circuit (15) adapted to be actuated to control the gate voltage of the MOS transistor in response to the output of the smoothing circuit, thereby limiting voltage (power) applied to the rectifier. The device further includes a data reception unit (21) for detecting a modulated component of the power energy fetched by means of the coil and receiving an information signal represented by the modulated, component and a data transmission unit (24) for controlling the gate voltage of the MOS transistor in response to transmission information, changing the extent of electromagnetic-induction coupling to the magnetic field of the coil, and transmitting the transmission information. |
