Homodyne RFID receiver and method

• US 7,535,360 B2
• Filed: 04/24/2007
• Issued: 05/19/2009
• Est. Priority Date: 11/19/2004
• Status: Active Grant

• Current Assignee: Neology Incorporated (OEP Technologie BV)
• Original Assignee: Sirit Technologies, Inc.
• Inventors: d'Hont, Loek J., Barink, Bernard
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US11/739,584
• Publication Number:
  US 20070247314A1
• Time in Patent Office: 756 Days
• Field of Search: 340/572.2, 340/10.1, 340/10.3, 340/10.4, 342/42, 342/44
• US Class Current: 340/572.2
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: H03D 1/2245 using two quadrature channels H03D1/2209 takes precedence

Abstract

An RFID circuit comprises an RF carrier signal source, a hybrid coupled to the RF carrier signal source operable to generate an in-phase and a quadrature phase component of the RF carrier signal, a switch coupled to the hybrid operable to pass one of the in-phase and quadrature phase components of the RF carrier signal to its output, and a mixer coupled to the output of the switch operable to multiply one of the in-phase and quadrature phase component of the carrier signal and a received modulated carrier signal and generate a baseband signal.

Claims

1. An Radio Frequency (RF) device, comprising:

an RF antenna operable to receive a backscattered signal;

a signal source operable to generate an in-phase and a quadrature-phase component of an RF carrier signal;

a first mixer coupled to the signal source and operable to multiply the in-phase component of the RF carrier signal and the received backscattered signal to generate a first baseband signal;

a second mixer coupled to the signal source and operable to multiply the quadrature-phase component with the received backscattered signal to generate a second baseband signal; and

a multiplexer operable to pass one of the first baseband signal or the second baseband signal as a demodulated RF output signal based, at least in part, on an amplitude of the first baseband signal or an amplitude of the second baseband signal.

2. The RF device of claim 1, further comprising a polarity switch operable to update a polarity of the demodulated RF output signal based, at least in part, on a polarity of the first baseband signal or a polarity of the second baseband signal.

3. The RF device of claim 2, further comprising logic coupled to the first and second mixers and operable to determine whether the first and second baseband signals have the same polarity, wherein the polarity switch updates the polarity of the demodulated RF output signal based, at least in part, on this determination.

4. The RF device of claim 3, wherein the logic comprises an XOR gate coupled to a delay line and a majority decision block.

5. The RF device of claim 1, further comprising:

first 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

second logic coupled to the first logic operable to determine when the larger amplitude switches between the first and second baseband signals, wherein the multiplexer passes the one of the first baseband signal or the second baseband signal based, at least in part, on the larger amplitude.

6. The RF device of claim 5, wherein the first logic comprises a comparator operable to compare the amplitudes of the first and second baseband signals.

7. The RF device of claim 5, wherein the second logic comprises a delay line and an XOR gate.

8. The RF device of claim 1, further comprising first and second amplifiers respectively coupled to the first and second mixers and operable to amplify the first and second baseband signals.

9. The RF device of claim 1, further comprising first and second data slicers respectively coupled to the first and second mixers and operable to generate first and second digital baseband signals corresponding to the first and second baseband signals.

10. The RF device of claim 1, further comprising:

an information signal source;

a transmitter receiving the RF carrier signal and the information signal and operable to modulate the RF carrier signal according to the information signal, wherein the antenna transmits the modulated RF carrier signal.

11. The RF device of claim 10, further comprising a splitter coupled to the RF carrier signal source and operable to pass the RF carrier signal to a hybrid and the transmitter, wherein the signal sources includes the hybrid.

18. The method of claim 9, further comprising amplifying first baseband signal and the second baseband signal.

12. A method comprising:

generating an in-phase component of a RF carrier signal and a quadrature-phase component of the RF carrier signal;

receiving a backscattered signal;

splitting the backscattered signal into a first backscattered component and a second backscattered component;

multiplying the first backscatter component and the in-phase component of the RF carrier signal to generate a first baseband signal;

multiplying the second backscatter component and the quadrature-phase component of the RF carrier signal to generate a second baseband signal; and

passing the first baseband signal or the second baseband signal as a demodulated RF output signal based, at least in part, on an amplitude of the first baseband signal or the second baseband signal.

13. The method of claim 12, further comprising:

determining whether the first baseband signal and the second baseband signal have a same polarity; and

updating a polarity of the demodulated RF output signal based, at least in part, on the determination.

14. The method of claim 13, wherein determining whether the first baseband signal and the second baseband signal have the same polarity comprises:

obtaining an XOR output of the first and second baseband signals;

inserting a plurality of delays in the XOR output;

generating a plurality of variably delayed XOR outputs; and

generating a majority decision output in response to the plurality of variably delayed XOR outputs.

15. The method of claim 12, further comprising:

determining whether of the first baseband signal or the second baseband signal has a larger amplitude; and

determining when the larger amplitude switches between the first baseband signal and the second baseband signal, wherein the first baseband signal or the second baseband signal is passed as the demodulated RF output signal based, at least in part, on the larger amplitude.

16. The method of claim 15, wherein determining which of the first and second baseband signals have a larger amplitude comprises:

determining an amplitude level of the first baseband signal and the second baseband signal; and

comparing the amplitude level of the first baseband signal and the amplitude level of the second baseband signal.

17. The method of claim 15, wherein determining when the larger amplitude switches between the first baseband signal and the second baseband signal comprises:

receiving a determination of which of the first baseband signal or the second baseband signal has a larger amplitude;

inserting variable delays; and

generating an XOR output of at least two variably delayed determination of signal with the larger amplitude.