Active electronic tag and signal modulation method thereof

摘要

An active electronic tag and a signal modulation method are provided herein. The active electronic tag includes an antenna, a first amplifier, an automatic gain control circuit, a phase synchronization locking circuit, a control unit, a tag unit and a second amplifier. The antenna receives a detecting signal transmitted from a reader, in which the detecting signal is carried on a first carrier. The phase synchronization locking circuit generates a second carrier. The control unit generates a response signal, in which the response signal is carried on the second carrier. By utilizing a phase difference of the first carrier and the second carrier, the response signal cancels the first carrier on the reader so as to transmit the information stored in the active electronic tag.

主权项

1. An active electronic tag, comprising:
an antenna for receiving a detecting signal transmitted from a reader, wherein the detecting signal is carried by a first carrier; a first amplifier connected to the antenna, for amplifying the detecting signal; an automatic gain control circuit connected to the first amplifier, for stabilizing the amplified detecting signal in a feedback loop; a phase synchronization locking circuit connected to the first amplifier, for receiving the amplified detecting signal and a TX enable signal, and generating a second carrier and a phase-locked clock; a control unit connected to the first amplifier and the phase synchronization locking circuit, for receiving the amplified detecting signal, the second carrier and the phase-locked clock, and detecting a change of a load resistance, wherein when the change of the load resistance is detected, the control unit generates the TX enable signal and a response signal, and the response signal is carried by the second carrier; a tag unit connected to the control unit, for storing tag information, wherein the control unit transmits the detecting signal to the tag unit and selects either the first carrier or the phase-locked clock as a driving clock for the tag unit, and the tag unit varies its load resistance according to the tag information, and the control unit switches the driving clock for the tag unit according to the change of the load resistance; and a second amplifier connected to the control unit and the antenna, for amplifying and outputting the response signal to the antenna, wherein the antenna transmits the amplified response signal to the reader, and the response signal utilizes a phase difference between the first carrier and the second carrier to cancel the amplitude of the first carrier on the reader, so as to transmit the tag information.