Variable-impedance reference circuit and varying method
AssigneeWacom Co., Ltd.
InventorYasuo Oda
Life of this patent
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Abstract
A reference circuit having a variable-impedance function for reducing current consumption is provided. By switching an output impedance of the reference circuit so that the output impedance is large when transmitting a high-frequency signal to a sensor coil, and the output impedance is small when receiving a response signal from the sensor coil, current consumption is reduced. The reference circuit includes a loop gain adjusting circuit having a switch for switching a gain. The magnitude of the output impedance of the reference circuit is switched by opening and closing the switch to switch the gain.
Claims12
A variable-impedance reference circuit comprising a reference circuit for supplying a reference electric potential to a sensor coil, wherein the variable-impedance reference circuit switches an output impedance of the reference circuit so that the output impedance is large during transmitting a high-frequency signal to the sensor coil and the output impedance is small during receiving a response signal from the sensor coil.
A method for varying an output impedance of a reference circuit for supplying a reference electric potential to a sensor coil, the method comprising the steps of:
- increasing the output impedance of the reference circuit during transmitting a high-frequency signal to the sensor coil;
- and
- reducing the output impedance of the reference circuit during receiving a response signal from the sensor coil, wherein current consumption is thereby reduced.
Dependencies are inferred from the claim text.