ADAPTIVE MATCHING WITH ANTENNA DETUNING DETECTION

• US 20190098435A1
• Filed: 09/27/2017
• Published: 03/28/2019
• Est. Priority Date: 09/27/2017
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Zeng, Xinping, Agboh, Peter M., Reddy, Vusthla Sunil
• Granted Patent: US 10,455,392 B2
• Time in Patent Office: Days
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

An electronic device includes a transmitter configured to generate a signal. The electronic device also includes tuning circuitry coupled to the transmitter, wherein the tuning circuitry comprises a variable capacitance element and at least one fixed capacitance element having a fixed capacitance, wherein the variable capacitance element is configured to provide a dynamic capacitance based upon a voltage value related to a determined phase difference between the signal and a second signal, wherein the tuning circuitry is configured to adjust a frequency of the first signal to generate a tuned signal based upon a total capacitance comprising the fixed capacitance and the dynamic capacitance. The electronic device further includes an antenna coupled to the tuning circuitry and configured to generate an electromagnetic field based on the tuned signal.

Claims

1. An electronic device comprising:

a transmitter configured to generate a first signal;

a clock control circuit configured to generate a second signal;

tuning circuitry coupled to the transmitter, wherein the tuning circuitry comprises a variable capacitance element and at least one fixed capacitance element having a fixed capacitance, wherein the variable capacitance element is configured to provide a dynamic capacitance based upon a voltage value related to a determined phase difference between the first signal and the second signal, wherein the tuning circuitry is configured to adjust a frequency of the first signal to generate a tuned signal based upon a total capacitance comprising the fixed capacitance and the dynamic capacitance; and

an antenna coupled to the tuning circuitry and configured to generate an electromagnetic field based on the tuned signal.

3. The electronic device of claim 1, comprising a receiver coupled to the tuning circuitry, wherein the receiver comprises a phase comparator configured to generate an indication of a difference in phase between the second signal and the first signal as a phase compared signal.

4. The electronic device of claim 3, wherein the receiver comprises a filter coupled to the phase comparator and configured to filter the phase compared signal to generate the voltage value.

5. The electronic device of claim 4, wherein the receiver comprises an output coupled to the variable capacitance element and configured to transmit the voltage value to the variable capacitance element.

6. The electronic device of claim 1, comprising a receiver coupled to the clock control circuit and the tuning circuitry, wherein the receiver comprises the phase compensation element configured to receive the clock signal prior to a phase comparator and adjust a phase of the clock signal to generate a phase-adjusted second signal.

7. The electronic device of claim 1, wherein the tuning circuitry is configured to adjust the frequency of the first signal to generate the tuned signal corresponding to the electromagnetic field having a frequency of 13.56 MHz.

8. The electronic device of claim 1, wherein the tuning circuitry is configured to adjust the frequency of the first signal to generate the tuned signal corresponding to the electromagnetic field having a predetermined frequency.

2. (canceled)

9. A method comprising:

receiving an input signal having a first phase from a transmitter;

receiving a second signal having a second phase from a clock control circuit configured to transmit a clock signal to the transmitter;

comparing the input signal having the first phase with the second signal having the second phase;

generating a phase comparison signal based upon a difference in phase between the input signal having the first phase and the second signal having a second phase; and

outputting a control signal having a voltage based upon the phase comparison signal to control an amount of capacitance of a variable capacitance element of an antenna tuning circuit of a communication interface.

10. The method of claim 9, wherein outputting the control signal causes tuning circuitry to adjust a frequency of the input signal to generate a tuned signal based at least in part upon the amount of capacitance of the variable capacitance element.

11. The method of claim 9, wherein receiving the second signal comprises receiving the second signal as a phase shifted clock signal.

12. The method of claim 9, comprising filtering the phase comparison signal to generate the control signal.

13. The method of claim 9, wherein outputting the control signal causes tuning circuitry to adjust a frequency of the input signal to generate a tuned signal based upon a total amount of capacitance, wherein the total amount of capacitance comprises the amount of capacitance of the variable capacitance element and an amount of capacitance of a fixed capacitance element.

14. A device, comprising:

a transmitter configured to generate a first signal having a first phase;

a clock control circuit configured to generate a second signal having a second phase; and

a receiver comprising;

an input configured to receive the first signal having the first phase;

a phase comparator configured to;

compare the first signal having the first phase with the second signal having the second phase; and

generate a phase comparison signal based upon a difference in phase between the first signal having the first phase and the second signal having the second phase; and

an output configured to transmit a control signal having a voltage based upon the phase comparison signal to control an amount of capacitance of a variable capacitance element of an antenna tuning circuit of a communication interface.

15. The device of claim 14, wherein:

the clock control circuit is coupled to the transmitter and the receiver; and

the clock control circuit is configured to transmit the second signal having the second phase to the phase comparator.

16. The device of claim 14, wherein the clock control circuit is configured to transmit a clock signal to the receiver, wherein the transmitter comprises a phase compensation circuit configured to receive the clock signal and adjust a phase of the clock signal based upon an operational characteristic of the transmitter to generate the second signal.

17. The device of claim 16, comprising a Near-Field Communication (NFC) chip comprising the clock control circuit, the transmitter, and the receiver.

18. The device of claim 14, comprising the antenna tuning circuit, wherein the antenna tuning circuit is coupled to the transmitter and the receiver and comprises tuning circuitry coupled to the transmitter, wherein the tuning circuitry comprises the variable capacitance element and at least one fixed capacitance element having a fixed capacitance.

19. The device of claim 18, wherein the variable capacitance element is configured to provide an adjusted capacitance based upon the control signal to adjust a frequency of the first signal to generate a tuned signal based upon a total capacitance comprising the fixed capacitance and the adjusted capacitance.

20. The device of claim 19, comprising an antenna coupled to the antenna tuning circuit and configured to generate an electromagnetic field having a predetermined frequency based upon the tuned signal.