Tag device, reader device, and RFID system
Embodiments relate to a tag device, a reader device, and a radio frequency identification (RFID) system. The Q embodiment provides a tag device comprising: a reception module converting a received high frequency signal into a scale level, and Q converting the converted scale level into a digital signal to output the same; a transmission module modulating a transmission signal M to output the same; and a controller controlling the reception module and the transmission module. The tag device communicates with the reader device through wireless short distance communication.
1. A tag device comprising:
a reception module converting a received high frequency signal into a scale level, and converting the converted scale level into a digital signal to output the same;
a transmission module modulating a transmission signal to output the same; and
a controller controlling the reception module and the transmission module;
wherein the reception module comprises a first signal processor converting the received high frequency signal into a log scale by using a log amplifier that receives a received signal through its positive terminal and converts the received signal into the scale level to output a DC level analog signal;
a second signal processor amplifying a gain of the signal converted into the log scale by the first signal processor;
a third signal processor controlling a signal level and a gain of the second signal processor under control of the controller; and
a fourth signal processor changing an output signal of the second signal processor according to an output signal of the third signal processor to output the signal as a digital signal.
2. The tag device according to claim 1 , wherein the first signal processor further comprises:
a gain control circuit connected between an output terminal and a negative terminal of the log amplifier, and controlling an amplification gain of the log amplifier using resistance varied by the controller.
3. The tag device according to claim 1 , wherein the second signal processor comprises:
a first operation amplifier amplifying an output signal of the first signal processor and outputting the same; and
a first feedback circuit connected between an output terminal and a negative terminal of the first operation amplifier, and
the third signal processor comprises:
a second operation amplifier amplifying a reference voltage of the controller and outputting the same;
a second feedback circuit connected between an output terminal and a negative terminal of the second operation amplifier; and
a feedback circuit feeding back a signal of the second feedback circuit to the first feedback circuit.
4. The tag device according to claim 1 , wherein the fourth signal processor comprises a comparator comparing an output signal of the second signal processor with an output signal of the third signal processor to output a digital signal to the controller.
5. The tag device according to claim 1 , comprising a voltage generator receiving an output of the log amplifier to generate a voltage, and supplying the voltage to each element through the controller.
6. The tag device according to claim 1 , comprising a first filter removing a noise of the signal converted into the log scale by the first signal processor.
7. The tag device according to claim 1 , wherein the first signal processor further comprises a second filter passing signals in a predetermined band from received signals.
8. The tag device according to claim 1 , wherein the transmission module comprises:
a first modulator modulating the transmission signal;
a first amplifier amplifying the signal modulated by the first modulator;
a second modulator modulating the transmission signal;
a second amplifier amplifying the signal modulated by the second modulator; and
a coupler outputting at least one of signals amplified by the first amplifier and the second amplifier to an antenna.
9. The tag device according to claim 8 , wherein the first modulator comprises an amplitude shift keying modulation method, and the second modulator comprises one of a frequency shift keying modulation method and a quadrature phase shift keying modulation method.
10. The tag device according to claim 1 , wherein the controller controls an operation in one of a passive mode and an active mode depending on whether battery power is supplied, and selects a different modulation method depending on each mode.
11. A reader device comprising:
a reception module converting a received high frequency signal into a scale level, and outputting the converted scale level reception signal as a digital signal;
a transmission module modulating an information request signal to output the same; and
a controller controlling the reception module and the transmission module;
wherein the reception module comprises:
a first signal processor converting the received high frequency signal into a log scale by using a log amplifier that receives a received signal through its positive terminal and converts the received signal into the scale level to output a DC level analog signal;
a second signal processor amplifying a gain of the signal converted into the log scale by the first signal processor;
a third signal processor controlling a signal level and a gain of the second signal processor under control of the controller; and
a fourth signal processor changing an output signal of the second signal processor according to an output signal of the third signal processor to output the signal as a digital signal.
12. The reader device according to claim 11 , wherein the first signal processor further comprises:
a gain control circuit connected between an output terminal and a negative terminal of the log amplifier, and controlling an amplification gain of the log amplifier using resistance varied by the controller.
13. The reader device according to claim 11 , wherein the transmission module comprises:
a first modulator modulating the information request signal;
a second modulator modulating the information request signal;
a coupler outputting at least one of signals amplified by the first modulator and the second modulator; and
a signal separator separating output signals of the coupler into a signal of the same phase and an orthogonal signal, and transmitting the signal through an antenna.
14. The reader device according to claim 13 , wherein the signal of the same phase separated by the signal separator of the transmission module is transmitted through a first transmission antenna, and the orthogonal signal is transmitted through a second transmission antenna, and the first and second transmission antennas comprise a circular polarized antenna.
15. The reader device according to claim 13 , wherein the first modulator comprises an amplitude shift keying modulation method, and the second modulator comprises one of a frequency shift keying modulation method and a quadrature phase shift keying modulation method.
16. A radio frequency identification system comprising:
a tag device comprising:
a first reception module converting a received high frequency signal into a scale level, and outputting the converted scale level reception signal as a digital signal;
a first transmission module modulating an information request signal to output the same; and
a first controller controlling the first reception module and the first transmission module, and
a reader device comprising:
a second reception module converting a high frequency signal received from the tag device into a scale level, and outputting the converted scale level reception signal as a digital signal;
a second transmission module modulating an information request signal, and transmitting the signal to the tag device; and
a second controller controlling the second reception module and the second transmission module,
wherein the first reception module or second reception module comprises:
a first signal processor converting the received high frequency signal into a log scale by using a log amplifier that receives a received signal through its positive terminal and converts the received signal into the scale level to output a DC level analog signal;
a second signal processor amplifying a gain of the signal converted into the log scale by the first signal processor;
a third signal processor controlling a signal level and a gain of the second signal processor under control of the controller; and
a fourth signal processor changing an output signal of the second signal processor according to an output signal of the third signal processor to output the signal as a digital signal.
17. The radio frequency identification system according to claim 16 , wherein the first transmission module comprises:
a first modulator modulating the transmission signal;
a first amplifier amplifying the signal modulated by the first modulator;
a second modulator modulating the transmission signal;
a second amplifier amplifying the signal modulated by the second modulator; and
a first coupler outputting at least one of signals amplified by the first amplifier and the second amplifier to an antenna.
18. The radio frequency identification system according to claim 16 , wherein the second transmission module comprises:
a first modulator modulating the information request signal;
a first amplifier amplifying the signal modulated by the first modulator;
a second modulator modulating the information request signal;
a second amplifier amplifying the signal modulated by the second modulator;
a second coupler outputting at least one of signals amplified by the first amplifier and the second amplifier; and
a signal separator separating output signals of the coupler into a signal of the same phase and an orthogonal signal, and transmitting the signal through each polarization antenna.