Multiprotocol RFID reader
First Claim
Patent Images
1. An RFID reader accessible through a computer system for interrogating at least one RFID tag, comprising:
- a frequency synthesizer configured to generate a continuous wave signal;
a controller coupled to the computer system through a PC card interface and configured to generate a plurality of control signals, the controller and the PC card interface both operate based on a clock signal generated by a crystal oscillator that is referenced by the frequency synthesizer in generating the continuous wave signal, and wherein a frequency of the clock signal is about 14.75 MHz or an integer multiple of 14.75 MHz;
a transmit chain configured to form a transmit signal from a first portion of the continuous wave signal according to at least one of the control signals;
a frequency divider coupled between the crystal oscillator and the controller; and
a receive chain configured to form a plurality of signals for extracting information associated with the RFID tag based on a received signal from the RFID tag and a second portion of the continuous wave signal;
wherein the frequency synthesizer, the controller, the transmit chain, and the receive chain are inter-coupled within a housing suitable for plugging in a PCMCIA slot of the computer system.
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Abstract
An RFID reader accessible thorough a personal computer and includes a PC card interface and a controller both operating according to clock signals from a crystal oscillator. The RFID reader further includes a linearized power amplifier modulator in a transmit path, a receive chain capable of demodulating EPCglobal Class_1 and Class_0 signals from RFID tags, and an integrated switching device for selecting one of a plurality of antenna for transmitting or receiving RF signals.
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Citations
28 Claims
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1. An RFID reader accessible through a computer system for interrogating at least one RFID tag, comprising:
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a frequency synthesizer configured to generate a continuous wave signal; a controller coupled to the computer system through a PC card interface and configured to generate a plurality of control signals, the controller and the PC card interface both operate based on a clock signal generated by a crystal oscillator that is referenced by the frequency synthesizer in generating the continuous wave signal, and wherein a frequency of the clock signal is about 14.75 MHz or an integer multiple of 14.75 MHz; a transmit chain configured to form a transmit signal from a first portion of the continuous wave signal according to at least one of the control signals; a frequency divider coupled between the crystal oscillator and the controller; and a receive chain configured to form a plurality of signals for extracting information associated with the RFID tag based on a received signal from the RFID tag and a second portion of the continuous wave signal; wherein the frequency synthesizer, the controller, the transmit chain, and the receive chain are inter-coupled within a housing suitable for plugging in a PCMCIA slot of the computer system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An RFID reader capable of interrogating EPCglobal class—
- 0 and class—
1 RFID tags, comprising;a frequency synthesizer configured to generate a local oscillator signal; an RF receiver configured to receive the local oscillator signal from the frequency synthesizer and an RF signal from an RFID tag and to generate at least one in-phase signal, at least one quadrature signal, and at least one frequency-shift-keying (FSK) signal based on the RF signal and the local oscillator signal; wherein the RF receiver further comprises; an in-phase demodulator configured to generate the at least one in-phase signal; a quadrature demodulator configured to generate the at least one quadrature signal; an image reject mixer (IRM) coupled to the in-phase and quadrature demodulators; a frequency shift keying (FSK) receiver coupled to the IRM and configured to generate the at least one FSK signal; and an adjustable phase shifter coupled between the frequency synthesizer and in-phase and quadrature demodulators and configured to cause an adjustable phase shift in the local oscillator signal so as to minimize conversion of phase noise in the local oscillator signal into amplitude noise in the in-phase and quadrature signals. - View Dependent Claims (17, 18, 19, 20, 21)
- 0 and class—
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22. An image reject mixer (IRM) for use with an RF receiver configured to receive a local oscillator signal from a local frequency synthesizer and an RF signal from a remote object, comprising:
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a first mixer configured to generate a first intermediate frequency (IF) signal by mixing a first portion of the RF signal with a first portion of the local oscillator signal, a second mixer configured to generate a second IF signal by mixing a second portion of the RF signal and a phase-shifted second portion of the local oscillator signal; a first all-pass filter coupled to the first mixer and configured to cause a first phase shift in the first IF signal from the in-phase demodulator; a second all-pass filter coupled to the second mixer and configured to cause a second phase shift in the second IF signal from the quadrature demodulator; and a summer coupled to first and second all-pass filter networks and configured to generate an output that is a sum of the first IF signal from the first all-pass filter and the second IF signal from the second all-pass filter; blocking capacitors placed at specified locations in the IRM, wherein the capacitance values of the blocking capacitors are selected so that the IRM has a high-pass function to filter out frequencies below a predetermined frequency band; and wherein each of the first and second all-pass filters comprises an op-amp with associated components, and wherein component values in the first and second all-pass filters are selected such that a total relative phase shift between the first IF signal and the second IF signal is 90°
or nearly 90°
. - View Dependent Claims (23, 24, 25)
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26. A method for interrogating an RFID tag, comprising:
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generating a clock signal; generating a continuous wave signal referencing the clock signal; generating a plurality of control signals; controlling the generation of the control signals via a PC card interface operating based on the clock signal; modulating the continuous wave signal according to one of the plurality of control signals; receiving an RF signal from the RFID tag; demodulating the RF signal by mixing it with a portion of the continuous wave signal to generate at least one in-phase signal, at least one quadrature signal, and at least one FSK signal; selecting the at least one in-phase signal, the at least one quadrature signal, or the at least one FSK signal to draw information included in the RF signal from the RFID tag; and causing an adjustable phase shift in the portion of the continuous wave signal to minimize conversion of phase noise in the continuous wave signal into amplitude noise in the at least one in-phase signal, at least one quadrature signal, and at least one FSK signal. - View Dependent Claims (27, 28)
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Specification