Abstract: 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.

Abstract: An active electronic tag for a memory card is disclosed herein. The active electronic tag includes an antenna, a first amplifier, an automatic gain control circuit, a phase synchronization locking circuit, a decoding and TX/RX control unit and a second amplifier. The antenna receives a detecting signal transmitted from a card reader, in which the detecting signal is carried on a first carrier. The phase synchronization locking circuit generates a positive carrier and a negative carrier with a phase difference of 180 degree. The decoding and TX/RX control unit generates a response signal, which is carried on the negative carrier. By utilizing the phase difference of the first carrier and the negative carrier, the response signal cancels the first carrier on the card reader, so as to transmit the information saved inside the active electronic tag.

Abstract: An active electronic tag for a memory card is disclosed herein. The active electronic tag includes an antenna, a first amplifier, an automatic gain control circuit, a phase synchronization locking circuit, a decoding and TX/RX control unit and a second amplifier. The antenna receives a detecting signal transmitted from a card reader, in which the detecting signal is carried on a first carrier. The phase synchronization locking circuit generates a positive carrier and a negative carrier with a phase difference of 180 degree. The decoding and TX/RX control unit generates a response signal, which is carried on the negative carrier. By utilizing the phase difference of the first carrier and the negative carrier, the response signal cancels the first carrier on the card reader, so as to transmit the information saved inside the active electronic tag.

Abstract: 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.