Near Field Communications, NFC, Communicators and NFC Communications Enabled Devices

• US 20110189953A1
• Filed: 01/31/2011
• Published: 08/04/2011
• Est. Priority Date: 03/11/2005
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.), Innovision Research & Technology PLC (Broadcom, Inc.)
• Inventors: Symons, Peter
• Granted Patent: US 8,233,842 B2
• Time in Patent Office: Days
• US Class Current: 455/41.1
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0715 the arrangement including means to regulate power transfer to the integrated circuit
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/10237 the reader and the record carrier being capable of selectively switching between reader and record carrier appearance, e.g. in near field communication [NFC] devices where the NFC device may function as an RFID reader or as an RFID tag
• CPC Class Codes: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems
• CPC Class Codes: H04B 5/0075 using inductive coupling transformers or inductances adapted for inductive coupling H01F38/14
• CPC Class Codes: H04B 5/0081 with antenna coils loop aerials H01Q7/00
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A NFC communicator or NFC communications enabled device has a data store to store data, an inductive coupler to couple inductively with the magnetic field of a radio frequency signal and a signal supplier to supply a radio frequency signal to the inductive coupler. A modulator is provided to modulate a radio frequency signal in accordance with data and a demodulator is provided to extract data from a modulated radio frequency signal inductively coupled to the coupler A controller enables the NFC communicator or NFC communications enabled device both to initiate near field radio frequency communication with another near field RF communicator and to respond to near field radio frequency communication initiated by another near field RF communicator. The inductive coupler has an antenna and a variable impedance element and the controller is operable to control the variable impedance element to control a magnetic field strength associated with a radio frequency signal supplied by the signal supplier.

Claims

1-23. -23. (canceled)

24. A near field communications (NFC) communicator, comprising:

an inductive coupler, having a gain-controlled impedance element, configured to couple inductively with a magnetic field of a first radio frequency signal and a second magnetic field;

a modulator, coupled to the inductive coupler, configured to modulate first data to provide the first radio frequency signal;

a demodulator, coupled to the inductive coupler, configured to extract second data from the second radio frequency signal; and

a controller configured to control the gain-controlled impedance element to control a magnetic field strength of the magnetic field.

25. The NFC communicator of claim 24, wherein the inductive coupler comprises:

an antenna coil configured and arranged in series with the gain-controlled impedance element.

26. The NFC communicator of claim 24, wherein the gain-controlled impedance element comprises:

an amplifier having an input coupled to a first connection of the gain-controlled impedance element and an output coupled to a second connection of the gain-controlled impedance element; and

a variable feedback element coupled between the input of the amplifier and the output of the amplifier.

27. The NFC communicator of claim 26, wherein the gain-controlled impedance element further comprises:

a first capacitor coupled between the output of the amplifier and the second connection of the gain-controlled impedance element; and

a second capacitor coupled between the second connection of the gain-controlled and a ground.

28. The NFC communicator of claim 27, wherein an impedance of the gain-controlled impedance element is denoted as:

Z₁=C₁−

(K−

1)C₂,

where Z₁ represents the impedance of the gain-controlled impedance element, C₁ represents a capacitance of the second capacitor, C₂ represents a capacitance of the first capacitor, and K represents a gain of the amplifier.

29. The NFC communicator of claim 26, wherein the variable feedback element comprises:

a plurality of resistors coupled to a corresponding switch from among a plurality of switches, each of the plurality of switches being controlled by the controller.

30. The NFC communicator of claim 29, wherein the controller is configured to adjust a gain of the gain-controlled impedance element by controlling the plurality of switches to control the magnetic field strength of the magnetic field.

31. The NFC communicator of claim 24, further comprising:

a magnetic field strength controller configured to sense at least some of the magnetic field to provide a correction signal input,

wherein the controller is further configured to adjust the gain-controlled impedance element to control the magnetic field strength of the magnetic field according to the correction signal input.

32. The NFC communicator of claim 31, wherein the magnetic field strength controller comprises:

a sense coil configured to sense at least some of the magnetic field to provide a sensed magnetic field;

an error amplifier configured to compare the sensed magnetic field and a reference signal to provide an error signal, the reference signal indicating a required magnetic field strength; and

a control loop stabilizer configured operate upon the error signal to provide the correction input signal.

33. The NFC communicator of claim 32, wherein the controller is further configured to adjust the gain-controlled impedance element until the required magnetic field strength has been achieved.

34. The NFC communicator of claim 32, wherein the control loop stabilizer is further configured to provide a proportional signal, an integrated signal, and a differentiated signal based upon the error signal and to combine the proportional signal, the integrated signal, and the differentiated signal to provide the correction input signal.

35. A near field communications (NFC) communicator, comprising:

means for coupling inductively with a magnetic field of a first radio frequency signal and a second magnetic field, the means for coupling having a gain-controlled impedance element;

means for modulating first data to provide the first radio frequency signal;

means for demodulating second data from the second radio frequency signal; and

means for controlling the gain-controlled impedance element to control a magnetic field strength of the magnetic field.

36. The NFC communicator of claim 35, further comprising:

means for sensing at least some of the magnetic field to provide a correction signal input,

wherein the means for controlling is configured adjust the gain-controlled impedance element to control the magnetic field strength of the magnetic field according to the correction signal input.

37. The NFC communicator of claim 36, wherein the means for sensing comprises:

second means for sensing at least some of the magnetic field to provide a sensed magnetic field;

means for comparing the sensed magnetic field and a reference signal to provide an error signal, the reference signal indicating a required magnetic field strength; and

means for operating upon the error signal to provide the correction input signal.

38. The NFC communicator of claim 37, wherein the means for controlling is further configured to adjust the gain-controlled impedance element until the required magnetic field strength has been achieved.

39. The NFC communicator of claim 37, wherein the means for operating is further configured to provide a proportional signal, an integrated signal, and a differentiated signal based upon the error signal and to combine the proportional signal, the integrated signal, and the differentiated signal to provide the correction input signal.