NEAR FIELD COMMUNICATIONS (NFC) DEVICE HAVING ADJUSTABLE GAIN

• US 20130237150A1
• Filed: 03/12/2012
• Published: 09/12/2013
• Est. Priority Date: 03/12/2012
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Royston, Philip Stewart
• Granted Patent: US 9,184,798 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: H03D 2200/0082 Quadrature arrangements
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H03G 3/3052 in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver H03G3/32, H03G3/34 take precedence
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 17/26 using historical data, averaging values or statistics
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/70 specially adapted for specific purposes
• 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
• CPC Class Codes: H04W 52/04 TPC

Abstract

A near field communications (NFC) device is disclosed that is capable of optimizing a gain for received signals. Measurements are made of signals received from an NFC environment and are compared to one or more threshold hold values. Based on the comparison, it is determined whether the measurements indicate underamplification or overamplification. Depending on the results of the analysis, one or more components within the NFC device is adjusted to increase or decrease the gain, respectively. The measurements may be taken during an unloaded baseline state or during loading, and may be compared to previous measurements to estimate their accuracy.

Claims

1. A near-field communication (NFC) device that operates within an NFC environment, the NFC device comprising:

a transmitter module configured to transmit a transmission signal to the NFC environment, the transmitter module including an amplifier configured to amplify the transmission signal;

a receiver module configured to receive a received signal from the NFC environment, the receiver module including;

a signal detection module configured to detect the received signal; and

a decoder module configured to decode the received signal; and

a gain adjustment module configured to measure the received signal, to analyze the measurement, and to adjust a component of the amplifier, the signal detection module, or the decoder module based on the analysis.

2. The NFC device of claim 1, wherein the receiver module comprises:

an analog-to-digital converter, and

wherein the gain adjustment module is configured to measure the received signal output from the analog-to-digital converter.

3. The NFC device of claim 2, wherein the signal detection module is configured to output the received signal to the decoder module as a quadrature signal having an in-phase component and a quadrature component,

wherein the analog-to-digital converter includes a first analog-to-digital converter configured to convert and to output the in-phase component of the received signal and a second analog-to-digital converter configured to convert and to output the quadrature component of the received signal, and

wherein the gain adjustment module is configured to individually measure and analyze the in-phase component output from the first analog-to-digital converter and the quadrature component output from the second analog-to-digital converter.

4. The NFC device of claim 3, wherein the gain adjustment module is configured to perform the measurement by squaring the in-phase component of the received signal and squaring the quadrature component of the received signal.

5. The NFC device of claim 4, wherein the gain adjustment module is configured to perform the analysis by comparing each of the measurements to at least one predetermined threshold.

6. The NFC device of claim 5, wherein the at least one predetermined threshold includes a first threshold and a second threshold,

wherein the gain adjustment module is configured to, if either measurement is below the first threshold, control the component so as to increase a gain, and

wherein the gain adjustment module is configured to, if either measurement is above the second threshold, control the component so as to decrease the gain.

7. The NFC device of claim 6, wherein the first threshold and the second threshold are set based on a maximum output level of the analog-to-digital converter.

8. A method for adjusting gain within a near-field communication (NFC) device that communicates within an NFC environment, the method comprising:

turning on a communication field;

receiving a signal from the NFC environment;

measuring the received signal;

analyzing the measurement; and

controlling a component within the NFC device depending on the analysis of the measurement.

9. The method of claim 8, wherein the received signal is measured sufficiently close in time to the turning on of the communication field so as to be substantially unloaded.

10. The method of claim 9, further comprising:

determining that a present gain of the NFC device is acceptable;

determining if there exists a previously-stored gain in memory; and

if there is no previously-stored gain in the memory, storing the present gain in the memory.

11. The method of claim 10, further comprising:

if there is the previously-stored gain in the memory;

comparing the present gain to the previously stored gain; and

if the present gain is larger than the previously-stored gain, controlling the component so as to implement the stored gain.

12. The method of claim 8, wherein the received signal is measured at a timing following the turning on of the communication field so as be loaded by a signal from the NFC environment.

13. The method of claim 12, further comprising:

measuring the received signal at regular intervals during a time period following the turning on of the communication field to acquire a plurality of measurements;

determining a maximum measurement from among the plurality of measurements; and

performing the analysis on the maximum measurement.

14. The method of claim 12, further comprising:

first polling the NFC environment to determine an amount of response delay time necessary for an external NFC device to load the received signal;

second polling the NFC environment;

during the second polling, tracking an amount of elapsed time; and

performing the measurement of the received signal when the elapsed time is approximately equal to the response delay time.

15. A near-field communication (NFC) device that communicates within an NFC environment, comprising:

a transmitter module being characterized by a transmission gain;

a receiver module being characterized by a reception gain, and configured to receive a signal from the NFC environment; and

a gain adjustment module configured to adjust at least one of the transmission gain and the reception gain such that a measurement of the received signal is within a measurement window.

16. The NFC device of claim 15, wherein the gain adjustment module includes:

a measurement module configured to measure the received signal; and

an analysis module configured to analyze the measurement to determine whether the measurement of the received signal is within the measurement window.

17. The NFC device of claim 16, wherein the measurement window includes a lower threshold and an upper threshold, wherein the analysis module is configured to analyze the measurement by comparing the measurement to the lower threshold and the upper threshold, the lower threshold and the upper threshold each being set based on performance capabilities of at least one component from among the transmitter module or the receiver module.

18. The NFC device of claim 17, further comprising:

a gain module configured to adjust at least one of the transmission gain and the reception gain so as to set a new gain for the NFC device,

wherein, if the measurement is below the lower threshold, the gain module is configured to adjust the at least one of the transmission gain and the reception gain so as to set the new gain for the NFC device to be larger than a previous gain, and

wherein, if the measurement is above the upper threshold, the gain module is configured to adjust at least one of the transmission gain and the reception gain so as to set the new gain for the NFC device to be less than the previous gain.

19. The NFC device of claim 16, wherein the gain adjustment module further includes a memory module configured to store a previous gain setting of the NFC device,

wherein, if the analysis module determines the gain of the NFC device to be within the measurement window, the analysis module, is configured to compare at least ore of the transmission gain and the reception gain to at least one previous transmission gain and reception gain stored in the memory module.

20. The NFC device of claim 19, wherein if the analysis module determines the at least one of the transmission gain and the reception gain to be smaller than the at least one previous transmission gain and reception stored in the memory module, the analysis module is configured to store the at least one of the transmission gain and the reception gain in the memory module so as to overwrite the previous gain setting.