GB2496459A - An NFC reader with means for varying the antenna Q-factor - Google Patents
An NFC reader with means for varying the antenna Q-factor Download PDFInfo
- Publication number
- GB2496459A GB2496459A GB1120192.8A GB201120192A GB2496459A GB 2496459 A GB2496459 A GB 2496459A GB 201120192 A GB201120192 A GB 201120192A GB 2496459 A GB2496459 A GB 2496459A
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- antenna
- text
- near field
- field communications
- reader
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- 230000005540 biological transmission Effects 0.000 claims description 10
- 239000003990 capacitor Substances 0.000 abstract description 15
- 230000000694 effects Effects 0.000 abstract description 4
- 230000000295 complement effect Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
- H01Q1/2208—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems
- H01Q1/2216—Supports; Mounting means by structural association with other equipment or articles associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems used in interrogator/reader equipment
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
- G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
- G06K7/10158—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/189—High frequency amplifiers, e.g. radio frequency amplifiers
- H03F3/19—High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only
- H03F3/195—High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only in integrated circuits
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
- H03F3/245—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages with semiconductor devices only
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/02—Transmitters
- H04B1/04—Circuits
- H04B1/0458—Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages
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- H04B5/24—
-
- H04B5/77—
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45631—Indexing scheme relating to differential amplifiers the LC comprising one or more capacitors, e.g. coupling capacitors
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45641—Indexing scheme relating to differential amplifiers the LC being controlled, e.g. by a signal derived from a non specified place in the dif amp circuit
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45686—Indexing scheme relating to differential amplifiers the LC comprising one or more potentiometers, which are not shunting potentiometers
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45702—Indexing scheme relating to differential amplifiers the LC comprising two resistors
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45726—Indexing scheme relating to differential amplifiers the LC comprising more than one switch, which are not cross coupled
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Power Engineering (AREA)
- Toxicology (AREA)
- Health & Medical Sciences (AREA)
- Electromagnetism (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Artificial Intelligence (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Health & Medical Sciences (AREA)
- Signal Processing (AREA)
- Near-Field Transmission Systems (AREA)
- Transmitters (AREA)
Abstract
The present application relates to a near field communications (NFC) reader 42 including a power amplifier 44 with an output which connects to an input terminal of an antenna 46 by means of an antenna filter. The antenna filter includes one or more resistors (48a, 48b) connected in series to one or more capacitors (50a, 50b). The NFC reader 42 includes means (52a, 52b) for adjusting the Q factor of the antenna so as to increase the available transmit bandwidth and/or improve the efficiency of the reader. The means for adjusting the Q factor of the antenna may include a variable resistive component (52a, 52b) connected in series between the output of the amplifier 44 and the input of the antenna 66, which has the effect of varying the output impedance of the amplifier. The means for adjusting the Q factor of the antenna may comprise switches (72a, 72b, Fig. 4) that can be activated to bypass the capacitors (70a, 70b, Fig. 4) of the antenna filter.
Description
A NEAR FIELD COMMUNICATIONS READER
Technical Field
The present application relates to a near field communications (NFC) reader.
Background to the Invention
Near field communication (NFC) readers, used for transmission of data to compatible NFC devices such as NFC tags and the like, typically include an antenna having at its input an antenna filter for filtering out unwanted frequencies in a signal to be transmitted.
The reader may be required to transmit data at rates up to 848kbps. However, the bandwidth of the antenna filter may be as low as 300kHz, which for higher-rate data contravenes the Nyquist-Shannon criteria, and can lead to significant levels of intersymbol interference (151) in the transmitted signal.
Most known NFC readers are designed to support a transmit data rate of 424kbps whilst also being able to generate a strong magnetic field at the reader's transmit antenna.
These dual requirements are achieved by using an antenna filter with a Q factor that is high enough to achieve a minimum field strength but not too high to prevent data reception.
Part of a typical hown NFC system is shown schematically at 10 in Figure 1. In the system of Figure 1 an NFC reader 12 comprises a power amplifier 14 whose output is connected to input terminals of an antenna 16 by means of an amplifier filter made up of resistors 18a, 18b and capacitors 20a, 20b which are connected in series between differential outputs of the power amplifier 16 and the input terminals of the antenna 14.
An NFC tag 22 communicates with the reader 12 by means of an antenna 24, with the other components of the tag 22 being represented by a capacitor 26 and a resistor 28 connected in parallel with the antenna 24. /3
The resistors 1 Sa, I Sb and the capacitors 20a, 20b are of fixed value, and the loaded Q factor of the antenna 16 (i.e. the Q factor of the antenna when it is coupled to the tag antenna) of the reader 12 is determined by the total series resistance of the resistors iSa, I Sb (as well as the series resistance of connecting components). As the resistors ISa, 1 Sb arc of fixed value, the loaded Q thctor of the antenna is a fixed value, although during operation of the reader 12 the Q factor ofthe reader is affected by the value of the load on the tag 22. The loaded Q factor of the antenna 16 has a value zrfL Q = , whcrej is the frequency of the transmitted signal, L is the inductance of + Rb the antenna 16, R is the resistance of the series resistor ISa, and R1, is the resistance of the series resistor 1 Sb.
Summary of Invention
The present application relates to a near field communications (NFC) reader having a power amplifier having an output which connects to an input terminal of an antenna by means of an antenna filter made up of one or more series resistors and one or more series capacitors. The NFC reader includes means for adjusting the Q factor of the antenna so as to increase the available transmit bandwidth and/or improve the efficiency of the reader. In an embodiment, the means for adjusting the Q factor of the antenna is a variable resistive component connected in series between the output of the amplifier and the input of the antenna, which has the effect of varying the output impedance of the amplifier. Additionally or alternatively, the means for adjusting the Q factor of the antenna may comprise switches that can be activated to bypass the one or more series capacitors ofthe antenna filter.
According to a first aspect of the present invention there is provided a near field communications (NFC) reader comprising an amplifier for driving an antenna of the reader and an antenna filter, the reader further comprising means for varying the Q factor of the antenna.
Varying the Q factor of the antenna permits data with a \vide range of data rates to be transmitted by the reader without intersymbol interference. Additionally, varying the Q factor can help to increase the efficiency of the reader in eases where high transmit power is not required.
The means for varying the Q factor of the antenna may comprise means for adjusting the output impedance of the amplifier.
For example, the means for varying the Q factor of the antenna may comprise an adjustable resistance connected between an output of the amplifier and the antenna.
The adjustable resistance may be provided by a plurality of selectable resistors.
Alternatively, the adjustable resistance may be provided by a plurality of clccically operable s\vitches, each of which has an on-resistance.
As a further alternative, the adjustable resistance may be provided by a digital potentiometer or resistive digital to analogue converter.
Additionally or alternatively, the variable resistive component could be produced by means of suitable shunt or series feedback around the power amplifier without using additional components.
Alternatively, the means for varying the Q factor of the antenna may comprise a variable transconductance (g111) cascodc stage in the power amplifier.
The near field communications reader may further comprise a controller configured to receive an indication of the data rate of data to be transmitted and to control the means for adjusting the output impedance of the amplifier to accommodate transmission of the data at the indicated data rate.
The antenna filter may comprise a capacitance connected in series between an output of the amplifier and an input of the antenna, and die near field communications reader may further comprise means for bypassing the capacitance.
According to a second aspect of the invention there is provided a near field communications reader comprising an amplifier for driving an antenna of the reader and an antenna filter comprising a capacitance connected in series between an output of the amplifier and ai input of the antenna, the near field communications reader further comprising means for bypassing the capacitance.
Bypassing the capacitance has the effect of flattening the frequency response of the antenna filter, thereby permitting transmission of data at higher data rates than can usually be transmitted by an NFC reader without intcrsymbol interference.
The means for bypassing the capacitance may comprise a switch connected in parallel with the capacitance such that when activated the switch short circuits the capacitance.
The near flcld communications reader may further comprise a controller for controlling the operation of the switch according to the data rate of data to be transmitted by the near
field communications reader.
Brief Description of the Drawings
Embodiments of the invention will now be described, strictly by way of example only, with reference to the accompanying drawings, of which Figure 1 is a schematic representation of a known NFC reader and tag;
S
Figure 2 is a schematic representation of an NFC reader according to one embodiment of the prcsent invention; Figure 3 is a schematic representation of a bank of switchable resistors which may be used as a variable resistive component in the NFC reader illustrated in Figure 2; and Figure 4 is a schematic representation of an NFC reader according to an alternative embodiment of the present invention.
Descrintion of the Embodiments Referring first to Figure 2, an NEC system incorporating an NEC reader according to one embodiment is shown generally at 40. As in the embodiment illustrated in Figure 1, the NFC reader 42 comprises a power amplifier 44 whose output is connected to input terminals of an antenna 46 by means of an antenna filter made up of resistors 48a, 48b and capacitors 50a, SOb which are connected in series between differential outputs of the power amplifier 44 and the input terminals of the antenna 46. The NEC reader 42 is able to transmit a data signal to a compatible NEC device such as the lag 22 illustrated in Figure 1, which is reproduced in Figure 2.
The power amplifier 44 in the embodiment illustrated in Figure 2 is implemented as part of an integrated circuit (i.e. is an "on-chip" component), whilst the resistors 48a, 48b and capacitors 50a, SOb which make up the antenna filter, and the antenna 46, are off-chip components (i.e. they are external to the integrated circuit containing the power amplifier 42). The dashed line in Figure 2 represents the border between on-chip and off-chip components.
The NEC reader 42 of Figure 2 includes on-chip variable resistive components 52a, 52b connected to the differential outputs of the power amplifier 44, which effectively enable the output impedance of the power amplifier 44 to be adjusted to vary the Q factor of the antenna 46 to accommodate different data rates, as will be described below.
In Figure 2 these on-chip variable resistive components 52a, 52b are shown as variable resistors, but it is to be appreciated that these components may be implemented in a variety of ways. For example, the variable resistive components could be implemented as one or more resistive digital to analogue converters (RDACs, also referred to a digital potentiometers). Alternatively, the on-chip resistive components 52a, 52b could be implemented as banks of resistors 54 that can be selectively connected to the outputs of the amplifier 44 by means of switches 56 such as fransistors, as is illustrated schematically in Figure 3. As a further alternative, the resistors 54 could be omitted, with the resistance being provided only by the series resistance of the switch (e.g. the collector-emitter resistance in the case where the switch is a bipolarjunetion transistor, or the drain-source resistance in the case where the switch is a field effect transistor).
Since the variable resistive components 52a, 52b are in series with the resistors 48a, 48b of the antenna filter, they can be used to adjust the Q factor of the antenna 46. For example, where a higher transmission bandwidth is required, the Q ifictor can be reduced by increasing the resistance of the variable resistive components 52a, 52b. Similarly, if a lower transmission bandwidth is required, the Q factor can be increased by reducing the resistance of the variable resistive components 52a, 52b. This also has the effect of increasing the efficiency of the reader 42, since at a high Q factor more of the power of the signal output by the amplifier 44 is transmitted by the antenna 46, and so for a given transmitted signal power a lower power input is required at the amplifier 44.
To achieve this adjustment of the Q factor of the antenna 44, the reader 42 includes a controller 58 which receives an indication of the data rate of the data to be transmitted, and controls the resistance of the variable resistive components 52a, 52b, e.g. by switching on selected ones ofthe switches 56, to adjust the loaded Q factor of the antenna 46 to enable the transmission of the data at the desired data rate. In this way the loaded Q factor of the antenna 46 can be adjusted to provide sufficient transmit bandwidth to transmit the data at the required data rate without contravening the Nyquist-Shannon criteria, thus reducing or negating the problem of high levels of intersymbol interference in the transmitted signal.
In sonic embodiments the power amplifier 44 may be provided with shunt or series feedback as will be familiar to those skilled in the art. The shunt and/or series feedback may be adjustable, thus providing a variable resistive component without requiring any additional resistive components. The adjustable shunt or series feedback thus provides an additional or alternative means for adjusting the Q factor of the antenna 46.
Additionally or alternatively, the power amplifier 44 may include a variable transconductance (gui) cascode stage, such that adjustment of the variable transconductance provides an additional or alternative means for adjusting the Q factor of the antenna 46.
Referring now to Figure 4, an NFC reader according to a further embodiment is shown generally at 60. In the embodiment illustrated in Figure 4 an NFC reader 62 comprises a power amplifier 64 whose output is connected to input terminals of an antenna 66 by means of an antenna filter made up of resistors 68a, 68b and capacitors 70a, 70b which are connected in series between differential outputs of the power amplifier 64 and the input terminals of the antenna 66. The NFC reader 62 is able to transmit a data signal to a compatible NFC device such as the tag 22 illustrated in Figure 1, which is reproduced in Figure 4.
As in the previous embodiment, the power amplifier 64 in the embodiment illustrated in Figure 4 is implemented as part of an integrated circuit (i.e. is an "on-chip" component), \vhilst the resistors 6Sa, 6ft and capacitors 70a, 70b which make up the antenna filter, and the antenna 66, are off-chip components (i.e. they are external to the integrated circuit containing the power amplifier 62). The dashed line in Figure 4 represents the border between on-chip and off-chip components.
The NEC reader 62 of Figure 4 includes off-chip switches 72a, 72b connected in parallel with the capacitors 70a, 70b between the resistors 68a, 68b and the terminals of the antenna 66. The switches 72a, 72b can be activated to connect the resistors 68a, 68b directly to the terminals of the antenna 66, i.e. when activated the switches 72a, 72b short circuit the capacitors 70a, 70b. Bypassing the capacitors 70a, 70b in tins way effectively flattens the frequency response of the antenna filter, which increases the bandwidth available for data transmission, at the expense of reducing the Q factor of the antenna 66 by a large amount. This arrangement is particularly usethl where data is to be transmifted between two powered devices such as mobile telephones, where higher transmission data rates are more important than high Q factor, as the transmitted data signal need not be high power, since the receiving device is powered.
As in the embodiment illustrated in Figure 2, the reader 62 of the embodiment illustrated in Figure 4 includes a controller 74 which receives an indication ofthe data rate of date to be transmitted. If this data rate meets a predetermined condition, e.g. if the data rate exceeds a particular threshold, the controller 74 causes the switches 72a, 72b to close, causing the capacitors 70a, 70b to be bypassed (short-circuited), thereby increasing the transmit bandwidth of the antenna 66.
It will be appreciated that the features illustrated in Figures 2 and 4 are complementary.
In other words, the reader 42 of Figure 2 may be provided with the switches 72a, 72b illustrated in Figure 4, in which ease the controller 58 controls not only the variable resistive components 58a, 58b, but also the switches 72a, 72b.
Claims (3)
- <claim-text>CLAIMSA near field communications (NFC) reader comprising an amplifier for driving an antenna of the reader and an antenna filter, the reader further comprising means for varying the Q factor of the antenna.</claim-text> <claim-text>2. A near field communications reader according to claim 1 wherein the means for varying the Q factor of the antenna comprises means for adjusting the output impedance of the amplifier.</claim-text> <claim-text>3. A near field communications reader according to claim 1 wherein the means for varying the Q factor of the antenna comprises an adjustable resistance connected between an output of the amplifier and the antenna.</claim-text> <claim-text>4. A near field communications reader according to claim 3 wherein the adjustable resistance is provided by a plurality of selectable resistors.</claim-text> <claim-text>5. A near field communications reader according to claim 3 wherein the adjustable resistance is provided by a plurality of electrically operable switches, each of which has an on-resistance.</claim-text> <claim-text>6. A near field communications reader according to claim 3, wherein the adjustable resistance is provided by a digital potentiometer or resistive digital to analogue converter.</claim-text> <claim-text>7. A near field communications reader according to claim 3, wherein the adjustable resistance is provided by shunt or series feedback around the power amplifier.</claim-text> <claim-text>8. A near field communications reader according to claim 1 wherein the means for varying the Q factor of the antenna comprises a variable transconductance (g0 cascode stage in the power amplifier. I0</claim-text> <claim-text>9. A near field communications reader according to claim 2 further comprising a controller configured to rcccivc an indication of thc data rate of data to be transmitted and to control the means for adjusting the output impcdance of the amplificr to acconimodate transmission of the data at the indicated data ratc.</claim-text> <claim-text>10. A near field communications reader according to claim 2 wherein the antenna filter comprises a capacitance connected in series between an output of the amplifier and an input of the antenna, the near field communications reader further comprising means for bypassing the capacitance.</claim-text> <claim-text>11. A near field communications reader comprising an amplifier for driving an antenna of the reader and an antenna filter comprising a capacitance connected in series between an output of the amplifier and an input of the antenna, the near field communications reader further comprising means for bypassing the capacitance.</claim-text> <claim-text>12. A near field communications reader according to claim 11 wherein the means for bypassing the capacitance comprises a switch connected in parallel with the capacitance such that when activated the switch short circuits the capacitance.</claim-text> <claim-text>13. A near field communications reader according to claim 11 further comprising a controller for controlling the operation of the switch according to the data rate of data to be transmitted by the near field communications reader.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWSCLAIMS1. A near field communications (NEt) reader comprising an amplifier for driving an antenna of the reader and an antenna filter, the reader further comprising means for varying the Q factor of the antenna, comprising an adjustable resistance connected between an output of the amplifier and the antenna, wherein the adjustable resistance is provided by a plurality of electrically operable switches, each of which has an on-resistance.
- 2. A near field communications reader according to claim 1, wherein adjustable resistance is additionally provided by shunt or series feedback around the power amplifier.
- 3. A near field communications reader according to claim 1 further comprising a C?) controller configured to receive an indication of the data rate of data to be transmitted and to control the adjustable resistance to accommodate transmission of the data at the C'J indicated data rate.N-4. A near field communications reader according to claim 1 wherein the antenna filter further comprises a capacitance connected in series between an output of the amplifier and an input of the antenna, the near field communications reader further comprising means for bypassing the capacitance.</claim-text>
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US13/292,756 US9397385B2 (en) | 2011-11-09 | 2011-11-09 | Near field communications reader |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB201120192D0 GB201120192D0 (en) | 2012-01-04 |
| GB2496459A true GB2496459A (en) | 2013-05-15 |
| GB2496459B GB2496459B (en) | 2014-06-04 |
Family
ID=45475581
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1120192.8A Expired - Fee Related GB2496459B (en) | 2011-11-09 | 2011-11-23 | A near field communications reader |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US9397385B2 (en) |
| DE (1) | DE102011055810B4 (en) |
| GB (1) | GB2496459B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2501578A (en) * | 2012-04-23 | 2013-10-30 | Cambridge Silicon Radio Ltd | NFC interrogator with parallel resonant circuit comprising a variable resistance to permit adjustment of quality factor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2490343B1 (en) * | 2011-02-16 | 2016-06-22 | Nxp B.V. | Near field communication device |
| US9397385B2 (en) * | 2011-11-09 | 2016-07-19 | Qualcomm Technologies International, Ltd. | Near field communications reader |
| US9819394B2 (en) * | 2013-04-29 | 2017-11-14 | MEDIATEX Singapore Pte. Ltd. | Method for controlling an antenna network quality factor of a near field communication device without changing matching network, and associated apparatus |
| JP2015154512A (en) * | 2014-02-10 | 2015-08-24 | キヤノン株式会社 | Electronic equipment and power transmission device |
| US9847804B2 (en) * | 2014-04-30 | 2017-12-19 | Skyworks Solutions, Inc. | Bypass path loss reduction |
| KR102232725B1 (en) | 2014-08-04 | 2021-03-26 | 삼성전자주식회사 | Method of operating NFC device and NFC device |
| US9882610B1 (en) | 2016-11-08 | 2018-01-30 | Welch Allyn, Inc. | Near field communication sensor system |
| KR102544939B1 (en) | 2016-11-14 | 2023-06-21 | 삼성전자주식회사 | Near field communication device |
| DE102018123248A1 (en) * | 2018-09-21 | 2020-03-26 | Ifm Electronic Gmbh | Near-field initiator with at least one controllable tuning element |
| KR20210077180A (en) * | 2019-12-17 | 2021-06-25 | 삼성전자주식회사 | Near field communication reader, operation method of near field communication reader, and operation method of electronic device including near field communication reader |
| WO2021151229A1 (en) * | 2020-01-29 | 2021-08-05 | Stmicroelectronics (China) Investment Co., Ltd | Devices and methods for near-field communication detection |
| US10812148B1 (en) * | 2020-03-06 | 2020-10-20 | Avid Indentification Systems, Inc. | Variable-Q antenna coil circuit for RFID applications |
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| Publication number | Priority date | Publication date | Assignee | Title |
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Cited By (3)
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| GB2501578A (en) * | 2012-04-23 | 2013-10-30 | Cambridge Silicon Radio Ltd | NFC interrogator with parallel resonant circuit comprising a variable resistance to permit adjustment of quality factor |
| US9071289B2 (en) | 2012-04-23 | 2015-06-30 | Cambridge Silicon Radio Limited | Transceiver supporting multiple modulation schemes |
| GB2501578B (en) * | 2012-04-23 | 2020-01-15 | Qualcomm Technologies Int Ltd | A Transceiver |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2496459B (en) | 2014-06-04 |
| DE102011055810A1 (en) | 2013-05-16 |
| US20130115876A1 (en) | 2013-05-09 |
| US9397385B2 (en) | 2016-07-19 |
| DE102011055810B4 (en) | 2017-02-23 |
| GB201120192D0 (en) | 2012-01-04 |
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| Date | Code | Title | Description |
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| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20161123 |