Granted Patent B2

US 8,730,016 · App. 13/082,999 · Granted May 20, 2014

Inventors: Rachid El Waffaoui (Eindhoven, NL); Giuliano Manzi (Graz, AT)

Assignee: NXP B.V.

Abstract

Claims (44)

1. A non-contact communication device comprising:

an antenna having an antenna impedance and being configured to receive an AC signal having an input voltage and an input current,

a main unit comprising a power-extraction unit having a charge pump and a communication unit including a main unit impedance,

a tuning circuit, and

a matching network for matching the antenna impedance to the main unit impedance and comprising a capacitor bank for providing a selectable capacitance,

wherein the tuning circuit includes a passive phase detector for detecting a phase difference between the input voltage and the input current, and the passive phase detector being configured to respond to the input voltage and the input current by generating a quadrature phase error signal, the tuning circuit being configured to respond to the quadrature phase error signal by adjusting the impedance of the matching network in dependence on the phase difference so as to minimize quadrature phase error, by selecting the capacitance of the matching network.

2. A non-contact communication device as claimed in claim 1 , wherein:

the passive phase detector is configured to detect a phase difference between the input voltage and the input current by detecting the phase difference between the input voltage and a coil voltage across a matching coil, which matching coil forms part of the antenna, and

the passive phase detector includes a plurality of mixers for providing the quadrature phase error signal based on the input voltage and the input current.

3. A non-contact communication device as claimed in claim 1 , wherein the power-extraction unit comprises a first output for providing power to the tuning circuit and a second output for providing power to the communication unit.

4. A non-contact communication device as claimed in claim 3 wherein the first power output has at least one or more stages and a smaller time constant than the second power output.

5. A non-contact communication device as claimed in claim 1 , wherein the tuning circuit further comprises a quantiser for quantising an output of the passive phase detector and for providing an input to a counter, which counter is configured to select the capacitance of the matching network.

6. A method of operating a non-contact communication device, the method comprising:

receiving an AC signal at an antenna;

extracting power from the AC signal using a power-extraction unit having a charge pump; and

using at least a part of the extracted power to tune the device by:

detecting a phase difference between a voltage and a current of the AC signal in a passive phase detector, and

responding to the AC signal by generating a quadrature phase error signal and responding to the quadrature phase error signal by adjusting a matching network, so as to minimise quadrature phase error, in dependence on the phase by selecting a capacitance of the matching network.

7. The method of claim 6 wherein adjusting the matching network in dependence on the phase comprises

quantising an output of the passive phase detector,

adjusting a counter in response to the quantisation, and

selecting the capacitance of a capacitor bank in dependence on the counter.

8. The method of claim 6 , further comprising, subsequent to tuning the device, using a further part of the extracted power to power a communication unit.

9. The method of claim 6 , further including comparing the quadrature phase error signal to a reference signal and, in response, providing a correction signal.

10. The method of claim 7 , further including comparing the quadrature phase error signal to a reference signal and, in response, providing a correction signal, and wherein selecting the capacitance of the matching network is performed in response to the correction signal by sending an increment signal or decrement signal for selecting the capacitance.

11. A non-contact communication device as claimed in claim 1 , further including a comparison circuit configured and arranged to respond to the passive phase detector by comparing the quadrature phase error signal to a reference signal and, in response, providing a correction signal.

12. A non-contact communication device as claimed in claim 1 , further including a comparison circuit and logic circuitry, the comparison circuit being configured and arranged to respond to the passive phase detector by comparing the quadrature phase error signal to a reference signal and, in response, providing a correction signal, and the logic circuitry being configured and arranged to respond to the correction signal.

13. A non-contact communication device as claimed in claim 12 , further including a counter circuit which responds to the correction signal by sending an increment signal or decrement signal for selecting the capacitance.

14. A non-contact communication device as claimed in claim 13 , wherein the increment signal or decrement signal is received and processed by the capacitor bank by changing the capacitance.

15. A non-contact communication device as claimed in claim 1 , further including a comparison circuit and logic circuitry, the comparison circuit being configured and arranged to respond to the passive phase detector by comparing the quadrature phase error signal to a reference signal and, in response, providing a correction signal, and the logic circuitry being configured and arranged to select the capacitance in response to the correction signal.

16. A non-contact communication device as claimed in claim 15 , further including a counter circuit which responds to the correction signal by sending an increment signal or decrement signal for selecting the capacitance.

17. A non-contact communication device as claimed in claim 16 , wherein the increment signal or decrement signal is received and processed by the capacitor bank by changing the capacitance.

18. A non-contact communication device as claimed in claim 1 , wherein the tuning circuit further includes

a counter circuit,

a digital control circuit,

a comparator circuit configured and arranged to receive the quadrature phase error signal, compare the quadrature phase error signal to a reference value, and output the comparison to a counter circuit,

the digital control circuit being configured and arranged to set the capacitance of the matching network based on the output of the comparison.

19. A non-contact communication device as claimed in claim 1 , wherein the tuning circuit further includes

a capacitor bank, including a plurality of capacitors, configured and arranged to provide an adjustable range of capacitance, and

a digital control block configured and arranged to

receive an analog signal indicative of the quadrature phase error signal,

select the capacitance of the capacitor bank based on the received analog signal, and

transmit data indicative of the selected capacitance to the capacitor bank,

the capacitor bank being responsive to the data by controlling the coupling of the plurality of capacitors based on the selected capacitance value.

Assignments (10)

Priority Claims (1)

Continuity (1)