Homodyne RFID receiver and method
First Claim
Patent Images
1. An RFID circuit comprising:
- an RF carrier signal source;
a hybrid coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals;
first and second mixers coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively; and
first logic coupled to the first and second mixers operable to select one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal, further includes;
second logic coupled to the first and second mixers and operable to determine whether the first and second baseband signals have the same polarity;
third logic coupled to the first and second mixers and operable to determine which of the first and second baseband signals have a larger amplitude; and
fourth logic coupled to the third logic operable to determine when signal having larger amplitude is switching from the first baseband signal to the second, and vice versa.
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Abstract
An RFID circuit comprising an RF carrier signal source, a hybrid coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals, first and second mixers coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively, and first logic coupled to the first and second mixers operable to select one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal.
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Citations
22 Claims
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1. An RFID circuit comprising:
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an RF carrier signal source; a hybrid coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals; first and second mixers coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively; and first logic coupled to the first and second mixers operable to select one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal, further includes; second logic coupled to the first and second mixers and operable to determine whether the first and second baseband signals have the same polarity; third logic coupled to the first and second mixers and operable to determine which of the first and second baseband signals have a larger amplitude; and fourth logic coupled to the third logic operable to determine when signal having larger amplitude is switching from the first baseband signal to the second, and vice versa. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method comprising:
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generating a carrier signal; receiving a modulated carrier signal; multiplying the received modulated carrier signal and first and second phase-shifted carrier signals and generating first and second baseband signals, respectively; and selecting one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal, further includes; determining whether the first and second baseband signals have the same polarity; determining which of the first and second baseband signals has a larger amplitude; and determining when the signal having larger amplitude is switching from the first baseband signal to the second, and vice versa. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. An RFID device comprising:
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an RF carrier signal source; means coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals; mixer means coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively; multiplexer means operable to select one of the first and second baseband signals as the demodulated RFID output signal, the multiplexer makes the selection in response to a determination of which one of the first and second baseband signals has a larger amplitude; and polarity switching means operable to flip the polarity of the demodulated RFID output signal in response to a determination of whether the first and second baseband signals have the same polarity and a determination of when the signal having the larger amplitude switches to the other signal substantially simultaneously as switching selection from one of the first and second baseband signals to the other as the demodulated RFID output signal. - View Dependent Claims (20)
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21. An RFID circuit, comprising:
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an RF carrier signal source; a hybrid coupled to the RF carrier signal source operable to generate first and second phase-shifted RF carrier signals; a first and a second mixer coupled to the hybrid each operable to multiply a respective one of the first and second carrier signals and a received backscattered modulated carrier signal and generate first and second baseband signals, respectively; and a first logic coupled to the first and second mixers, wherein the first logic is configured to; include a second logic coupled to the first and second mixers operable to determine whether the first and second baseband signals have the same polarity; and select one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal.
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22. A method comprising:
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generating a carrier signal; receiving a modulated carrier signal; multiplying the received modulated carrier signal and first and second phase-shifted carrier signals and generating first and second baseband signals, respectively; and selecting one of the first and second baseband signals having a larger amplitude as a demodulated RFID output signal, wherein selecting includes determining whether the first and second baseband signals have the same polarity.
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Specification