Systems and methods for self-calibration for wireless communication

Patent metadata

Field	Value
Publication number	US-9515750-B2
Application number	US-201514863131-A
Country	US
Kind code	B2
Filing date	Sep 23, 2015
Priority date	Nov 7, 2014
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A method for inductively coupled communication is described. The method includes applying a carrier signal at a carrier frequency to an antenna circuit. The antenna circuit includes an antenna and a matching network that resonate at a resonant frequency. The method also includes measuring a looped-back signal over a range of impedance values. The looped-back signal includes the carrier signal received by a receiver coupled to the antenna circuit. The method further includes setting a calibrated impedance as an impedance configuration that produces a resonance peak in the looped-back signal.

First claim

What is claimed is:

1. A method for inductively coupled communication, comprising:
applying a carrier signal at a carrier frequency to an antenna circuit, the antenna circuit comprising an antenna and a matching network that resonate at a resonant frequency;
measuring a looped-back signal over a range of impedance values, the looped-back signal comprising the carrier signal received by a receiver coupled to the antenna circuit;
setting a calibrated impedance as an impedance configuration that produces a resonance peak in the looped-back signal;
determining an impedance offset based on a difference between a default impedance and the calibrated impedance, wherein the default impedance comprises a preconfigured matching network impedance associated with the carrier frequency; and
applying the impedance offset to the matching network for an operation that uses a second carrier frequency that differs from the carrier frequency used to set the calibrated impedance.

2. The method of claim 1 , wherein measuring the looped-back signal over a range of impedance values comprises:
applying a first impedance configuration to the antenna circuit;
measuring a resonance of the looped-back signal based on the first impedance configuration;
determining whether there is a subsequent impedance configuration to apply;
applying the subsequent impedance configuration to the antenna circuit; and
measuring resonance of the looped-back signal based on the subsequent impedance configuration.

3. The method of claim 1 , wherein measuring the looped-back signal over the range of impedance values comprises measuring a DC level that is proportional to the looped-back signal, the DC level being measured over the range of impedance values.

4. The method of claim 1 , wherein an impedance configuration comprises a set of capacitance values applied to one or more capacitors in the matching network that produces a given impedance in the antenna circuit.

5. The method of claim 1 , wherein the carrier signal is generated by a near-field communication (NFC) initiator transmitter coupled to the antenna circuit and the carrier signal is received by an NFC initiator receiver coupled to the antenna circuit.

6. An electronic device for inductively coupled communication, comprising:
a processor;
a memory in communication with the processor; and
instructions stored in the memory, the instructions executable by the processor to:
apply a carrier signal at a carrier frequency to an antenna circuit, the antenna circuit comprising an antenna and a matching network that resonate at a resonant frequency;
measure a looped-back signal over a range of impedance values, the looped-back signal comprising the carrier signal received by a receiver coupled to the antenna circuit;
set a calibrated impedance as an impedance configuration that produces a resonance peak in the looped-back signal;
determine an impedance offset based on a difference between a default impedance and the calibrated impedance, wherein the default impedance comprises a preconfigured matching network impedance associated with the carrier frequency; and
apply the impedance offset to the matching network for an operation that uses a second carrier frequency that differs from the carrier frequency used to set the calibrated impedance.

7. The electronic device of claim 6 , wherein the instructions executable to measure the looped-back signal over a range of impedance values comprise instructions executable to:
apply a first impedance configuration to the antenna circuit;
measure a resonance of the looped-back signal based on the first impedance configuration;
determine whether there is a subsequent impedance configuration to apply;
apply the subsequent impedance configuration to the antenna circuit; and
measure resonance of the looped-back signal based on the subsequent impedance configuration.

8. The electronic device of claim 6 , wherein the instructions executable to measure the looped-back signal over the range of impedance values comprise instructions executable to measure a DC level that is proportional to the looped-back signal, the DC level being measured over the range of impedance values.

9. The electronic device of claim 6 , wherein an impedance configuration comprises a set of capacitance values applied to one or more capacitors in the matching network that produces a given impedance in the antenna circuit.

10. The electronic device of claim 6 , wherein the carrier signal is generated by a near-field communication (NFC) initiator transmitter coupled to the antenna circuit and the carrier signal is received by an NFC initiator receiver coupled to the antenna circuit.

11. An apparatus for inductively coupled communication, comprising:
means for applying a carrier signal at a carrier frequency to an antenna circuit, the antenna circuit comprising an antenna and a matching network that resonate at a resonant frequency;
means for measuring a looped-back signal over a range of impedance values, the looped-back signal comprising the carrier signal received by a receiver coupled to the antenna circuit;
means for setting a calibrated impedance as an impedance configuration that produces a resonance peak in the looped-back signal;
means for determining an impedance offset based on a difference between a default impedance and the calibrated impedance, wherein the default impedance comprises a preconfigured matching network impedance associated with the carrier frequency; and
means for applying the impedance offset to the matching network for an operation that uses a second carrier frequency that differs from the carrier frequency used to set the calibrated impedance.

12. The apparatus of claim 11 , wherein the means for measuring the looped-back signal over a range of impedance values comprise:
means for applying a first impedance configuration to the antenna circuit;
means for measuring a resonance of the looped-back signal based on the first impedance configuration;
means for determining whether there is a subsequent impedance configuration to apply;
means for applying the subsequent impedance configuration to the antenna circuit; and
means for measuring resonance of the looped-back signal based on the subsequent impedance configuration.

13. A computer-program product, the computer-program product comprising a non-transitory computer-readable medium having instructions thereon, the instructions comprising:
code for causing an electronic device to apply a carrier signal at a carrier frequency to an antenna circuit, the antenna circuit comprising an antenna and a matching network that resonate at a resonant frequency;
code for causing the electronic device to measure a looped-back signal over a range of impedance values, the looped-back signal comprising the carrier signal received by a receiver coupled to the antenna circuit;
code for causing the electronic device to set a calibrated impedance as an impedance configuration that produces a resonance peak in the looped-back signal;
code for causing the electronic device to determine an impedance offset based on a difference between a default impedance and the calibrated impedance, wherein the default impedance comprises a preconfigured matching network impedance associated with the carrier frequency; and
code for causing the electronic device to apply the impedance offset to the matching network for an operation that uses a second carrier frequency that differs from the carrier frequency used to set the calibrated impedance.

14. The computer-program product of claim 13 , wherein the code for causing the electronic device to measure

Assignees

• Qualcomm Inc

Inventors

• Mofidi Mahbod
• Yudhish Kritarth
• Neymanov Bakhtiyar
• Saad Jr John
• Frankland Stephen

Classifications

• G06K7/10336

  the antenna being of the near field type, inductive coil · CPC title

• H04B17/14

  of the whole transmission and reception path, e.g. self-test loop-back · CPC title

• H04B17/221 Primary

  of receiver antennas, e.g. as to amplitude or phase · CPC title

• H04B5/45

  Transponders · CPC title

• H04B5/266

  One coil at each side, e.g. with primary and secondary coils · CPC title