GB2484104A - Combined regulator and rectifier for a near field RF communicator - Google Patents

Combined regulator and rectifier for a near field RF communicator Download PDF

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Publication number
GB2484104A
GB2484104A GB1016368.1A GB201016368A GB2484104A GB 2484104 A GB2484104 A GB 2484104A GB 201016368 A GB201016368 A GB 201016368A GB 2484104 A GB2484104 A GB 2484104A
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GB
United Kingdom
Prior art keywords
voltage
regulator
near field
communicator
controlled impedance
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB1016368.1A
Other versions
GB2484104B (en
GB201016368D0 (en
GB2484104A9 (en
Inventor
Robin Wilson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Broadcom Innovision Ltd
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Innovision Research and Technology PLC
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Priority to GB1016368.1A priority Critical patent/GB2484104B/en
Publication of GB201016368D0 publication Critical patent/GB201016368D0/en
Publication of GB2484104A publication Critical patent/GB2484104A/en
Publication of GB2484104A9 publication Critical patent/GB2484104A9/en
Application granted granted Critical
Publication of GB2484104B publication Critical patent/GB2484104B/en
Expired - Fee Related legal-status Critical Current
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Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
    • H04B5/40—Near-field transmission systems, e.g. inductive or capacitive transmission systems characterised by components specially adapted for near-field transmission
    • H04B5/48—Transceivers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Near-Field Transmission Systems (AREA)

Abstract

A near field RF communicator comprises an inductive coupler 200 that couples with an RF H-field to provide an RF voltage signal; and a regulator having a voltage controlled impedance 703 coupled to the inductive coupler to attenuate the RF voltage signal to provide an output voltage; and a controller 702 to control the voltage controlled impedance such that the output voltage does not exceed a reference voltage and switches it into a non-conducting state in the event that the received RF voltage is less than the output voltage. The voltage controlled impedance can be connected between the input and output of a series regulator of a received voltage and its operation modified if the input voltage is less than the output voltage to provide a rectified output voltage. The regulator can be a series regulator such as a low dropout regulator. The communicator can comprise a switchable impedance 722 in parallel with the inductive coupler that the controller switched into a conducting state when the regulator voltage controlled impedance is switched to a non-conducting state. The voltage controlled impedance can be an IGFET such as a MOS transistor and the controller comprise a class AB amplifier. The near field communicator can be a NFC communicator and comprise a long range communication interface.

Description

Near Field RF Communicators
This invention relates to near field RF communicators and near field communications enabled devices and their methods of operation.
Near field RF (radio frequency) communication is becoming more and more commonplace as is the use of such technology to transfer data. Near field RF communicators communicate through the modulation of the magnetic field (H field) generated by a radio frequency antenna. Near field RF communication thus requires an antenna of one near field RF communicator to be present within the alternating magnetic field (H field) generated by the antenna of another near field RF communicator by transmission of an RF signal (for example a 13.56 Mega Hertz signal) to enable the magnetic field (H field) of the RF signal to be inductively coupled between the communicators. The RF signal may be modulated to enable communication of control and/or other data. Ranges of up to several centimetres (generally a maximum of 1 metre) are common for near field RF communicators.
NFC communicators are a type of near field RF communicator that is capable in an initiator mode of initiating a near field RF communication (through transmission or generation of an alternating magnetic field) with another near field RF communicator and is capable in a target mode of responding to initiation of a near field RF communication by another near field RF communicator. The term "near field RF communicator" includes not only NFC communicators but also initiator near field RF communicators such as RFID transceivers or readers that are capable of initiating a near field RF communication but not responding to initiation of a near field RF communication by another near field RF communicator and target or responding near field RF communicators such as RFID transponders or tags that are capable of responding to initiation of a near field RF communication by another near field RF communicator but not of initiating a near field RF communication with another near field RF communicator. Hence NFC communicators can act as both RFID transceivers and RFID transponders and are able to communicate with other NFC communicators, RFID transceivers and RFID transponders.
I
In addition NFC communicators may be associated with or comprised within or attached to certain peripheral devices, for example SIM cards (e.g. UICC), Secure Elements, memory devices (for example MCU, RAM, ROM and non-volatile memory), display driver or other drivers. During operation the NFC communicator must also be able to communicate with and transfer data to and from such peripheral device.
There are several standards in existence which set out certain communication protocols and functional requirements for RFID and near field RF communications.
Examples are ISO/IEC 14443, ISO 15693, ISO/IEC 18092 and ISO/lEG 21481.
NFC and Near field RF communicators may be comprised within a larger device, such as a mobile telephone, FDA or computer which may comprise a high frequency (e.g. VHF, "FM" or UHF) receiver and transmitter for long range communications for example using GSM or wi-fi frequencies. When a near field RF communicator is comprised within such host devices it is advantageous to reduce emissions from the NFC communicator in frequency bands employed by the host device To protect circuitry of near field RF communicators from over voltage conditions due to high amplitude RF H-fields it has been proposed to use shunt regulators to regulate the induced voltages.
To enable a near field RF communicator to harvest a DC power supply from a radio frequency H-field it has been proposed to provide rectification circuitry coupled to the antenna to provide a rectified supply voltage. It has been proposed to use actively switched rectifiers to reduce energy losses which arise in passive rectifiers due to diode bias voltages. An example of an active switched rectifier is described in international patent application number W02009/093076.
When using rectification circuitry in combination with shunt regulators to protect circuitry of near field RF communicators from over voltage conditions the shunt regulator can be arranged to regulate voltages on the "AC side" of the rectifier. In other words the regulator regulates the antenna voltages directly based on a rectified voltage supply voltage provided by the rectifier. In such arrangements the shunt element is coupled directly across the antenna of the near field RF communicator.
The inventors in the present case have appreciated that rapid switching of rectification and regulation circuitry can generate high frequency (out of band) switching noise. Accordingly the inventors have recognised a need in the art for a near field RF communicator able to harvest energy efficiently from an RF H-field without increasing high frequency (out of band) emissions.
Aspects and examples of the invention are set out in the claims and address at least a part of the above described technical problem.
In an aspect there is provided a near field RF communicator comprising an inductive coupler adapted to couple with an RF H-field to receive an RF voltage signal; and a series regulator comprising a voltage controlled impedance coupled to the inductive coupler in series to attenuate the received RF voltage signal to provide an output voltage; and, a controller configured to control the voltage controlled impedance such that the output voltage is not greater than a reference voltage and to switch the voltage controlled impedance into a non-conducting state in the event that the received RF voltage is less than the output voltage.
This has the advantage of merging the two, currently separate, functions of a rectifier and a series supply line regulator and enables the regulator input to be fed directly
by the AC power harvested from the RF H-field.
This and other examples of the invention have the advantage of providing reduced circuit area, and reduced out of band electromagnetic emissions.
In some possibilities the near field RF communicator comprises a switchable impedance, coupled in parallel with the inductive coupler wherein the controller is configured to switch the switchable impedance into a conducting state when the voltage controlled impedance of the series regulator is switched into a non-conducting state. This has the advantage of drawing current from the inductive coupler during periods when the line regulator is switched off to further reduce out of band emissions.
In one possibility the regulator comprises a series line regulator such as a series low drop out regulator. This has the advantage of providing rectification which requires low voltage headroom without the need to provide a full active switched bridge rectifier.
In an aspect there is provided a near field RF communicator comprising a series regulator arranged to regulate a received voltage, the regulator having an input and an output coupled by a voltage controlled impedance, wherein the regulator is configured to switch off the voltage controlled impedance in the event that the input voltage is less than the output voltage to provide a rectified voltage at the regulator output. Preferably, when the voltage controlled impedance is switched off it behaves as open circuit or is substantially non conducting.
In an aspect there is provided a near field RF communicator comprising a series regulator arranged to regulate a received voltage, a voltage controlled impedance being coupled between an input and an output of the regulator, wherein the regulator is configured to modify the operation of the voltage controlled impedance in the event that the input voltage is less than the output voltage to provide a rectified output signal from the regulator.
Aspects of the invention include a near field RF communicator substantially as described herein and/or as shown in the accompanying drawings.
In an embodiment a near field RF communicator comprises an NFC communicator.
In an embodiment there is provided an electronic device comprising a near field RF communicator substantially as described herein and/or as shown in the accompanying drawings. In one possibility an electronic device comprises a telecommunications interface or a VHF or UHF or FM radio transmitter or receiver. In a preferred embodiment a telecommunications interface comprises a cellular mobile telecommunications interface, or a GSM module, or a cellular modem. These embodiments have the advantage that near field communicators according to the invention produce less powerful emissions in high frequency RF bands and therefore VHF/UHF/FM/cellular/GSM transmitters and receivers with which they are used are not adversely affected by these emissions.
As will be apparent to the skilled practitioner in the context of the present disclosure one or more features of one or more aspect or embodiment of the invention may be combined advantageously with any of the other aspect or embodiment of the invention.
A specific embodiment of the invention will now be described, by way of example only with reference to the accompanying drawings, in which: Figure 1 shows a very schematic drawing of components of a near field RF communicator; Figure 2 shows a very schematic drawing of components of another near field RF communicator; and Figure 3 shows a very schematic drawing of components of another near field RF communicator.
Figure 1 shows a near field RF communicator comprising an antenna 200 having first and second antenna connections 202 and 204. Antenna 200 is arranged in a single ended configuration so antenna connection 204 is connected to a ground or reference voltage. Antenna connection 202 is connected to a drain terminal of an insulated gate field effect transistor (IGFET) 703. The gate connection of IGFET 703 is connected to a control connection of regulator controller 702. Antenna connection 202 is also connected to a first input terminal 712 of regulator controller 702. The source connection of IGFET 703 is connected to a second input connection 710 of regulator controller 702. Capacitance 720 is connected between the source connection of IGFET 703 and a ground or reference voltage. Regulator controller 702 is coupled to receive a control or reference voltage VREF. The reference voltage may be provided by any appropriate reference such as, for example, a band gap reference. The controller may provide a modulation signal 733 to the other NFC functionality based on the control voltage applied to the regulator.
Other NFC functionality 750 such as modulation and demodulation circuitry and other functionality is coupled to the source connection of IGFET 703.
In operation regulator controller 702 provide a control voltage to IGFET 703 to attenuate the voltage ACI so that the voltage at the regulator output VDD does not exceed a reference voltage VREF so that the regulator 703, 702 operates as a series low drop out regulator. The regulator controller is arranged to compare the voltage VDD at its output with the AC voltage at its input ACI and to switch off the IGFET 703 if ACI is lower than VDD. In the example of Figure 1 controller 702 comprises a first amplifier configured to compare VDD with a reference voltage and to apply a voltage to control the impedance of the IGFET based on this comparison.
A second amplifier is configured to compare the output voltage VDD with the input voltage ACI and to drive the IGFET into a non-conducting state, for example to switch off the conduction channel in the IGFET if ACI is less than VDD. Preferably the first and second amplifiers are arranged in a class-AB amplifier configuration.
Other arrangements may be used to provide the functionality of controller 702 such as, for example, a suitable configuration of logic gates.
Another possibility for the regulator/rectifier of Figure 1 is shown in Figure 2, where components are common to Figures 1 and 2 like reference numerals are used to indicate like elements. The regulator controller 702 of Figure 2 comprises a second control output 727 which is coupled to the control connection of IGFET 722. The source connection of IGFET 722 is connected in series with resistor 724 to antenna connection 202. The drain connection of IGFET 722 is connected to a ground or reference voltage so that resistor 724 and IGFET 722 provide a switchable load coupled in parallel with the antenna.
In operation the controller 702 of Figure 2 operates in the same manner as controller 702 in Figure 1. However, the controller is arranged such that, when ACI is less than VDD and the IGFET 703 is driven into a non-conducting state, to switch off the conduction channel in the IGFET 703 the controller applies a control voltage to switch on IGFET 722. This means that, when the IGFET 703 is switched off the IGFET 722 and resistance 724 provide a load which continues to draw current from the antenna. This has the advantage of reducing high frequency (out of band) emissions due to the rectification switching.
As will be appreciated, although Figures 1 and 2 show single ended configurations, but differential mode arrangements may be provided by making appropriate modifications to the circuits of Figures 1 and 2, for example by the addition of additional series line regulators such as those shown in Figure 3 in which like reference numerals indicate like elements.
Although the diagrams show MOS transistors, as will be appreciated by the skilled practitioner in the context of the present disclosure, by making appropriate modifications to the circuitry any appropriate IGFET or other appropriate voltage controlled impedance such as a BJT or JFET may be used to provide the same function.
Any feature of the near field RF communicators described herein may be used advantageously in combination with one or more features set out in one or more of the claims set out below. In addition particular features described as relating to a method extend to apparatus adapted to perform that method so that method features may be applied in apparatus aspects and apparatus features may be employed in method aspects of the invention.

Claims (7)

  1. Claims 1. A near field RF communicator comprising an inductive coupler adapted to couple with an RF H-field to provide an RF voltage signal; and a regulator comprising a voltage controlled impedance coupled to the inductive coupler to attenuate the RF voltage signal to provide an output voltage and a controller configured to control the voltage controlled impedance such that the output voltage does not exceed a reference voltage and to switch the voltage controlled impedance into a non-conducting state in the event that the received RF voltage is less than the output voltage.
  2. 2. The near field RF communicator of claim I in which the regulator comprises a series line regulator such as a series low drop out regulator.
  3. 3. The near field RF communicator of any preceding claim further comprising a switchable impedance, coupled in parallel with the inductive coupler wherein the controller is further configured to switch the switchable impedance into a conducting state when the voltage controlled impedance of the series regulator is switched into a non-conducting state.
  4. 4. The near field RF communicator of claim 1,2 or 3 in which the controller comprises a class AB-amplifier.
  5. 5. The near field RF communicator of any preceding claim in which the voltage controlled impedance comprises an IGFET
  6. 6. The near field RF communicator of claim 5 in which the IGFET is a MOS transistor.
  7. 7. A near field RF communicator comprising a series regulator arranged to regulate a received voltage, and a voltage controlled impedance being coupled between an input and an output of the regulator, wherein the regulator is configured
GB1016368.1A 2010-09-29 2010-09-29 Near field RF communicators Expired - Fee Related GB2484104B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1016368.1A GB2484104B (en) 2010-09-29 2010-09-29 Near field RF communicators

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Application Number Priority Date Filing Date Title
GB1016368.1A GB2484104B (en) 2010-09-29 2010-09-29 Near field RF communicators

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GB201016368D0 GB201016368D0 (en) 2010-11-10
GB2484104A true GB2484104A (en) 2012-04-04
GB2484104A9 GB2484104A9 (en) 2016-11-02
GB2484104B GB2484104B (en) 2017-11-08

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2530358A (en) * 2014-09-22 2016-03-23 Cambridge Silicon Radio Ltd Receiver circuit

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1139280A2 (en) * 2000-03-28 2001-10-04 Hitachi, Ltd. Semiconductor integrated circuit device and contactless electronic device
US20070249398A1 (en) * 2006-04-21 2007-10-25 Renesas Technology Corp. Semiconductor integrated circuit and non-contact electronic device using the same
US20090141518A1 (en) * 2007-11-30 2009-06-04 Infineon Technologies Ag Circuit and method for rectifying and regulating voltages

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1139280A2 (en) * 2000-03-28 2001-10-04 Hitachi, Ltd. Semiconductor integrated circuit device and contactless electronic device
US20070249398A1 (en) * 2006-04-21 2007-10-25 Renesas Technology Corp. Semiconductor integrated circuit and non-contact electronic device using the same
US20090141518A1 (en) * 2007-11-30 2009-06-04 Infineon Technologies Ag Circuit and method for rectifying and regulating voltages

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2530358A (en) * 2014-09-22 2016-03-23 Cambridge Silicon Radio Ltd Receiver circuit
WO2016048844A1 (en) * 2014-09-22 2016-03-31 Cambridge Silicon Radio Limited Receiver circuit
US9906064B2 (en) 2014-09-22 2018-02-27 Qualcomm Technologies International, Ltd. Receiver circuit
GB2530358B (en) * 2014-09-22 2020-09-16 Qualcomm Technologies Int Ltd Receiver circuit
DE102015107886B4 (en) * 2014-09-22 2020-10-22 Qualcomm Technologies International, Ltd. Receiver circuit

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Publication number Publication date
GB2484104B (en) 2017-11-08
GB201016368D0 (en) 2010-11-10
GB2484104A9 (en) 2016-11-02

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20180929