Patent ID: 8085130

Claim:
A radio frequency identification (RFID) tag, comprising: a signal port, having a first port and a second port; an antenna, coupled to the signal port for receiving a first radio frequency (RF) signal and transmitting the first RF signal to the signal port; a battery-assisted circuit, coupled to the signal port, and generating a second RF signal to the signal port, wherein a frequency of the second RF signal is different to that of the first RF signal; a modulator, coupled between a controller and the signal port; a power harvester, coupled between the signal port and the controller for converting a synthesized signal received by the signal port, so as to generate an operating power to the controller, wherein the synthesized signal comprises the first RF signal and the second RF signal; and a filter, coupled between the signal port and a demodulator for filtering the second RF signal in the synthesized signal and transmitting the filtered synthesized signal to the demodulator, wherein the demodulator down-converts the filtered synthesized signal to generate a base band signal, and transmits the base band signal to the controller.