WO2013002737A1 - Method and circuit intended for high-frequency communication between an interrogator and a smart tag - Google Patents

Method and circuit intended for high-frequency communication between an interrogator and a smart tag Download PDF

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Publication number
WO2013002737A1
WO2013002737A1 PCT/SI2012/000026 SI2012000026W WO2013002737A1 WO 2013002737 A1 WO2013002737 A1 WO 2013002737A1 SI 2012000026 W SI2012000026 W SI 2012000026W WO 2013002737 A1 WO2013002737 A1 WO 2013002737A1
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WO
WIPO (PCT)
Prior art keywords
amplitude
tag
antenna
interrogator
voltage
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Application number
PCT/SI2012/000026
Other languages
French (fr)
Other versions
WO2013002737A8 (en
Inventor
Vinko KUNCH
Maksimilijan ŠTIGLIC
Andrej Vodopivec
Original Assignee
Ids D.O.O.
Austriamicrosystems Ag
Priority date (The priority date 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 date listed.)
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Publication date
Application filed by Ids D.O.O., Austriamicrosystems Ag filed Critical Ids D.O.O.
Publication of WO2013002737A1 publication Critical patent/WO2013002737A1/en
Publication of WO2013002737A8 publication Critical patent/WO2013002737A8/en

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/0701—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management
    • G06K19/0702—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management the arrangement including a battery
    • G06K19/0705—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management the arrangement including a battery the battery being connected to a power saving arrangement
    • 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
    • H04B1/59—Responders; Transponders

Definitions

  • the invention relates to a method intended for high-frequency communication between a traditional interrogator of a passive smart tag and a smart tag of the invention, the circuit of which is galvanically coupled with a voltage source, the subject matter of the invention being related to automatically setting an amplitude of a tag's responding signal with respect to the latest till then observed weakening of the high-frequency signal in a path between the interrogator and said smart tag.
  • Active smart tags comprising various sensors and a data logger are known. Such active smart tags must function in the absence of an interrogator's field as well. They are therefore equipped with a battery.
  • Said interrogator can be any of simple traditional interrogators of high-frequency passive smart tags. ⁇
  • Said interrogator can be any of simple traditional interrogators of high-frequency passive smart tags.
  • ⁇ There are also known active smart tags for ultrahigh frequency at 900 MHz. Such active smart tags are still able to respond strongly enough to the interrogator only by passive load-modulation (backscatter) even when the interrogator's electromagnetic field in their place is so weak that they cannot extract enough power for their operation therefrom.
  • Smart tags for ultrahigh frequency are therefore provided with a battery in order to ensure their operation also in conditions of still satisfactory communication which actually increases their range.
  • the range of high-frequency smart tags e.g. at 13.56 MHz, cannot be increased in this way. Namely, a distance from the interrogator, at which such smart tags can no longer respond by changing the impedance of their antennas, approximately equals the distance, at which they cannot extract enough power for their operation from this weak interrogator's electromagnetic field in their place any more.
  • High-frequency smart tags at 13.56 MHz which are not equipped with sensors or a data logger, do not need an own voltage source for supplying their circuit.
  • Such high- frequency smart tags are only passive. When they need to communicate with a moderately distant interrogator, they are energized by the interrogator's high- frequency electromagnetic field in their place. They communicate with the interrogator by passively varying the impedance of their antennas in time intervals of their responding, which causes an interference rise in voltage amplitude at the interrogator's antenna in those time intervals.
  • a coupling between the interrogator's antenna and the antenna of the miniature smart tag having dimensions of 10 mm times 10 mm is very low. Therefore the miniature smart tag extracts too low power for energizing itself from the interrogator's electromagnetic field even at practically usable distances from the interrogator, what's more the signal being load-modulated by the miniature smart tag too weakly influences the voltage accross the interrogator's antenna by interfering with said voltage in order for the interrogator to be able to detect said load-modulated signal.
  • the interrogator's electromagnetic field in the place of the miniature smart tag gets additionally weaker when the tag is inserted into another device, for example into a mobile telephone.
  • a micro SD card is known (US 2010/0044444 Al), which is provided with an improved antenna and a circuit amplifying the interrogator's signal received by the tag's antenna prior to decoding.
  • the tag's circuit is galvanically connected to a voltage source. But there is no suggestion how such micro SD card should form a signal to respond to the interrogator.
  • Patent EP 1 801 741 B l discloses a technical solution to the technical problem of how to increase a data transmission range of a 13.56 MHz load-modulation system comprising a reading device and a transponder, however, no amplitude setting of a transponder's responding signal with regard to a weakening of a high-frequency signals along a path between the reading device and the transponder is considered.
  • the technical problem to be solved by the present invention is how to set an amplitude of a responding signal from a high-frequency smart tag, whose circuit is galvanically coupled with a voltage source, to an interrogator of passive smart tags that a weakening of the high-frequency signal in a path between the interrogator and said smart tag will be concerned.
  • the technical problem of the invention is solved by the method of the invention intended for a high-frequency communication between an interrogator and a smart tag as characterized by the features of claim 1, dependent claims 2 - 4 characterizing the variants of its embodiments, and by the circuit of the invention for carrying out said method as characterized by the features of claim 5, dependent claim 6 characterizing a variant of its embodiments.
  • the high-frequency smart tag of the invention advantageously sets an amplitude of its responding signals as low as possible by considering the latest till then observed weakening of the high-frequency signal in a path between the interrogator and said smart tag, hereby advantageously eliminating a too strong electromagnetic emission and saving battery's energy.
  • Fig. 1 a block diagram of a circuit of the invention in a high-frequency smart tag intended for high-frequency communication with an interrogator
  • Fig. 2 a graph of time developments of a rectified and smoothed voltage across an
  • interrogator's antenna for two responding signals of the smart tag without setting an amplitude of tag's responding signals for coupling factors 0.100, 0.020 and 0.005 between an interrogator's antenna and a tag's antenna and
  • Fig. 3 a graph of time developments as in Fig. 2, yet with an automatic setting
  • a method of the invention is intended for high-frequency communication between an interrogator and a smart tag.
  • a circuit of the smart tag is galvanically connected to a voltage source, e.g. a battery.
  • Said interrogator is one of traditional simple interrogators for high-frequency passive smart tags.
  • the interrogator operating in a constant wave mode transmits high-frequency radio waves with a constant amplitude. Said radio waves convey no information.
  • a resonance frequency fi of a high-frequency interrogator's antenna circuit equals 13.56 MHz, for instance.
  • the smart tag conducts such signal to its antenna A (Fig. 1) that the transmitted high-frequency signals, while influencing the interrogator's antenna, will exert the desired interference effect on the time development of the voltage across said antenna by interfering with the interrogator's high-frequency carrier signal present there.
  • the signal conducted to the tag's antenna A should have a suitable amplitude.
  • the smart tag first observes the first amplitude Ai, which is an amplitude of the voltage induced in the tag's antenna A by the interrogator's high- frequency carrier signal. This observation takes place in time intervals, in which according to the communication protocol the smart tag does not transmit said high- frequency signals.
  • the smart tag transmits high-frequency signals in that it excites its own antenna A with a voltage having an amplitude, which is essentilally constant within the duration of the responding signal.
  • said amplitude of the voltage across the antenna A as a second amplitude At is set with respect to the first amplitude Ai observed so far in a way that, roughly speaking, the second amplitude At is inversely proportional to the first amplitude Ai. Anyhow the second amplitude At advantageously increases in a monotonous way as the first amplitude Ai decreases.
  • the interrogator's signal got considerably weakened along the path from the interrogator to the smart tag.
  • the second amplitude At should be high, as equal weakening of the signal is also expected along the path from the smart tag to the interrogator.
  • the tag's antenna A is excited with the voltage, whose second amplitude At is automatically set to a highest value Atmax, when the first amplitude Ai is below the reference value Airef of the first amplitude Ai and the tag's antenna A is excited with a voltage, whose second amplitude At is set to a value determined by the expression Atmax . Airef / Ai when the first amplitude Ai is above its reference value Airef.
  • Airef of the first amplitude Ai is determined as a twofold to fivefold of minimum value Aimin of the first amplitude Ai, which the interrogator's magnetic field induces in the tag's antenna at a lowest value, as required by the standard, of the magnetic field density at a position of the tag's antenna.
  • the second amplitude At is set just high enough to enable communication and the electromagnetic emission is simultaneously reduced as much as possible and the battery's energy is saved.
  • FIG. 1 A circuit of a passive smart tag of the invention intended for high-frequency communication with a traditional interrogator is represented in Fig. 1.
  • the circuit of the smart tag of the invention is galvanically coupled with a voltage source in a known way.
  • An output signal ts' of a signal generator SG is conducted to tag's antenna A through an output amplifier OA, which in order to form said tag's responding signal sets the second amplitude At as an amplitude of the voltage of a signal ts across the tag's antenna.
  • the signal generator SG and the output amplifier OA are controlled by a transmit-on signal tos defining the start and end of the transmitting of the smart tag.
  • An amplitude measuring circuit AMC observes a first amplitude Ai, which is an amplitude of the voltage of a received signal rs, which the interrogator's high- frequency carrier signal induces at the tag's antenna A.
  • the circuit AMC measuring the amplitude Ai of the received interrogator's signal controls said output amplifier OA with its first output signal avs representing a measured amplitude value in a way that a second amplitude At, which is the amplitude of the voltage across the tag's antenna A to form a tag's responding signal, is set with respect to a value of the first amplitude Ai as observed so far. Roughly speaking, the second amplitude At is set inversely proportional to the first amplitude Ai.
  • the circuit AMC measuring the amplitude Ai with its second output signal ads representing a measured amplitude-decrease value controls said signal generator SG in a way that a phase-locked loop therein opens whenever the value of said first amplitude Ai drops below the predetermined value.
  • the amplitude measuring circuit AMC is connected to the tag's antenna A through an attenuator and a DC voltage defining circuit Att/DC.
  • the circuit Att/DC ensures for the signal rs to get attenuated while the smart tag transmits and sets up a DC voltage level in the circuit while the smart tag does not transmit.
  • the attenuator and DC voltage defining circuit Att/DC is controlled by means of said transmit-on signal tos, which notifies the start and end of the tag's transmission.
  • Figure 3 represents time developments as in Figure 2 but for the smart tag of the invention provided with an automatic setting of the amplitude of the tag's responding signal.
  • the amplitude measuring circuit AMC detects the very high first amplitude Ai and controls the output amplifier OA in a way that the second amplitude At is suitably lowered and the interrogator receives a signal with the expected amplitude.

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Near-Field Transmission Systems (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

A smart tag observes a first amplitude (Ai) being an amplitude of a voltage induced in a tag's antenna by an interrogator's carrier signal and transmits responding signals in that it excites its antenna with a voltage, whose amplitude as a second amplitude (At) is set with respect to said first amplitude (Ai), observed so far, in a way that the second amplitude (At) is inversely proportional to the first amplitude (Ai). The advantageous setting of the amplitude of the tag's responding signals eliminates a too strong electromagnetic emission and saves battery's energy.

Description

Method and circuit intended for high-frequency communication
between an interrogator and a smart tag
The invention relates to a method intended for high-frequency communication between a traditional interrogator of a passive smart tag and a smart tag of the invention, the circuit of which is galvanically coupled with a voltage source, the subject matter of the invention being related to automatically setting an amplitude of a tag's responding signal with respect to the latest till then observed weakening of the high-frequency signal in a path between the interrogator and said smart tag.
According to International Patent Classification the invention is classified to H 04B 01/59.
Active smart tags comprising various sensors and a data logger are known. Such active smart tags must function in the absence of an interrogator's field as well. They are therefore equipped with a battery.
Said interrogator can be any of simple traditional interrogators of high-frequency passive smart tags. <
are therefore equipped with a battery.
Said interrogator can be any of simple traditional interrogators of high-frequency passive smart tags. < There are also known active smart tags for ultrahigh frequency at 900 MHz. Such active smart tags are still able to respond strongly enough to the interrogator only by passive load-modulation (backscatter) even when the interrogator's electromagnetic field in their place is so weak that they cannot extract enough power for their operation therefrom. Smart tags for ultrahigh frequency are therefore provided with a battery in order to ensure their operation also in conditions of still satisfactory communication which actually increases their range.
However, the range of high-frequency smart tags, e.g. at 13.56 MHz, cannot be increased in this way. Namely, a distance from the interrogator, at which such smart tags can no longer respond by changing the impedance of their antennas, approximately equals the distance, at which they cannot extract enough power for their operation from this weak interrogator's electromagnetic field in their place any more.
High-frequency smart tags at 13.56 MHz, which are not equipped with sensors or a data logger, do not need an own voltage source for supplying their circuit. Such high- frequency smart tags are only passive. When they need to communicate with a moderately distant interrogator, they are energized by the interrogator's high- frequency electromagnetic field in their place. They communicate with the interrogator by passively varying the impedance of their antennas in time intervals of their responding, which causes an interference rise in voltage amplitude at the interrogator's antenna in those time intervals.
It would be useful to set an amplitude of a tag's responding signal with respect to conditions in a path between the smart tag and an interrogator in the smart tag for high-frequency at 13.56 MHz, which would be provided with a battery in order for this battery power to be acceptably used for transmitting signals by said smart tag. Yet a battery assisting a smart tag in transmitting responding signals would be absolutely indispensable especially under boundary circumstances when the smart tag is a miniature smart tag of very small linear dimensions or when the distance of the smart tag from the interrogator exceeds the normal communication range.
A coupling between the interrogator's antenna and the antenna of the miniature smart tag having dimensions of 10 mm times 10 mm is very low. Therefore the miniature smart tag extracts too low power for energizing itself from the interrogator's electromagnetic field even at practically usable distances from the interrogator, what's more the signal being load-modulated by the miniature smart tag too weakly influences the voltage accross the interrogator's antenna by interfering with said voltage in order for the interrogator to be able to detect said load-modulated signal. The interrogator's electromagnetic field in the place of the miniature smart tag gets additionally weaker when the tag is inserted into another device, for example into a mobile telephone.
A micro SD card is known (US 2010/0044444 Al), which is provided with an improved antenna and a circuit amplifying the interrogator's signal received by the tag's antenna prior to decoding. The tag's circuit is galvanically connected to a voltage source. But there is no suggestion how such micro SD card should form a signal to respond to the interrogator.
Patent EP 1 801 741 B l discloses a technical solution to the technical problem of how to increase a data transmission range of a 13.56 MHz load-modulation system comprising a reading device and a transponder, however, no amplitude setting of a transponder's responding signal with regard to a weakening of a high-frequency signals along a path between the reading device and the transponder is considered. The technical problem to be solved by the present invention is how to set an amplitude of a responding signal from a high-frequency smart tag, whose circuit is galvanically coupled with a voltage source, to an interrogator of passive smart tags that a weakening of the high-frequency signal in a path between the interrogator and said smart tag will be concerned.
The technical problem of the invention is solved by the method of the invention intended for a high-frequency communication between an interrogator and a smart tag as characterized by the features of claim 1, dependent claims 2 - 4 characterizing the variants of its embodiments, and by the circuit of the invention for carrying out said method as characterized by the features of claim 5, dependent claim 6 characterizing a variant of its embodiments.
The high-frequency smart tag of the invention advantageously sets an amplitude of its responding signals as low as possible by considering the latest till then observed weakening of the high-frequency signal in a path between the interrogator and said smart tag, hereby advantageously eliminating a too strong electromagnetic emission and saving battery's energy.
The invention will now be explained in more detail by way of a description of embodiments of a method as well as a circuit of a smart tag of the invention for a high-frequency communication between a traditional interrogator and said smart tag as well as by way of a corresponding block diagram and graphs of time developments and representing in
Fig. 1 a block diagram of a circuit of the invention in a high-frequency smart tag intended for high-frequency communication with an interrogator,
Fig. 2 a graph of time developments of a rectified and smoothed voltage across an
interrogator's antenna for two responding signals of the smart tag without setting an amplitude of tag's responding signals for coupling factors 0.100, 0.020 and 0.005 between an interrogator's antenna and a tag's antenna and
Fig. 3 a graph of time developments as in Fig. 2, yet with an automatic setting
according to the invention of the amplitude of the tag's responding signals.
A method of the invention is intended for high-frequency communication between an interrogator and a smart tag. A circuit of the smart tag is galvanically connected to a voltage source, e.g. a battery.
Said interrogator is one of traditional simple interrogators for high-frequency passive smart tags.
The interrogator operating in a constant wave mode transmits high-frequency radio waves with a constant amplitude. Said radio waves convey no information.
A resonance frequency fi of a high-frequency interrogator's antenna circuit equals 13.56 MHz, for instance.
According to the invention, the smart tag conducts such signal to its antenna A (Fig. 1) that the transmitted high-frequency signals, while influencing the interrogator's antenna, will exert the desired interference effect on the time development of the voltage across said antenna by interfering with the interrogator's high-frequency carrier signal present there. To this end the signal conducted to the tag's antenna A should have a suitable amplitude.
For this reason the smart tag first observes the first amplitude Ai, which is an amplitude of the voltage induced in the tag's antenna A by the interrogator's high- frequency carrier signal. This observation takes place in time intervals, in which according to the communication protocol the smart tag does not transmit said high- frequency signals.
Thereafter the smart tag transmits high-frequency signals in that it excites its own antenna A with a voltage having an amplitude, which is essentilally constant within the duration of the responding signal.
But said amplitude of the voltage across the antenna A as a second amplitude At is set with respect to the first amplitude Ai observed so far in a way that, roughly speaking, the second amplitude At is inversely proportional to the first amplitude Ai. Anyhow the second amplitude At advantageously increases in a monotonous way as the first amplitude Ai decreases.
When the first amplitude Ai is low, the interrogator's signal got considerably weakened along the path from the interrogator to the smart tag. In such case the second amplitude At should be high, as equal weakening of the signal is also expected along the path from the smart tag to the interrogator.
More precisely, the tag's antenna A is excited with the voltage, whose second amplitude At is automatically set to a highest value Atmax, when the first amplitude Ai is below the reference value Airef of the first amplitude Ai and the tag's antenna A is excited with a voltage, whose second amplitude At is set to a value determined by the expression Atmax . Airef / Ai when the first amplitude Ai is above its reference value Airef.
Said reference value Airef of the first amplitude Ai is determined as a twofold to fivefold of minimum value Aimin of the first amplitude Ai, which the interrogator's magnetic field induces in the tag's antenna at a lowest value, as required by the standard, of the magnetic field density at a position of the tag's antenna.
The second amplitude At is set just high enough to enable communication and the electromagnetic emission is simultaneously reduced as much as possible and the battery's energy is saved.
A circuit of a passive smart tag of the invention intended for high-frequency communication with a traditional interrogator is represented in Fig. 1.
The circuit of the smart tag of the invention is galvanically coupled with a voltage source in a known way.
An output signal ts' of a signal generator SG is conducted to tag's antenna A through an output amplifier OA, which in order to form said tag's responding signal sets the second amplitude At as an amplitude of the voltage of a signal ts across the tag's antenna.
According to the invention, the signal generator SG and the output amplifier OA are controlled by a transmit-on signal tos defining the start and end of the transmitting of the smart tag. An amplitude measuring circuit AMC observes a first amplitude Ai, which is an amplitude of the voltage of a received signal rs, which the interrogator's high- frequency carrier signal induces at the tag's antenna A.
The circuit AMC measuring the amplitude Ai of the received interrogator's signal controls said output amplifier OA with its first output signal avs representing a measured amplitude value in a way that a second amplitude At, which is the amplitude of the voltage across the tag's antenna A to form a tag's responding signal, is set with respect to a value of the first amplitude Ai as observed so far. Roughly speaking, the second amplitude At is set inversely proportional to the first amplitude Ai.
The circuit AMC measuring the amplitude Ai with its second output signal ads representing a measured amplitude-decrease value controls said signal generator SG in a way that a phase-locked loop therein opens whenever the value of said first amplitude Ai drops below the predetermined value.
The amplitude measuring circuit AMC is connected to the tag's antenna A through an attenuator and a DC voltage defining circuit Att/DC. The circuit Att/DC ensures for the signal rs to get attenuated while the smart tag transmits and sets up a DC voltage level in the circuit while the smart tag does not transmit.
The attenuator and DC voltage defining circuit Att/DC is controlled by means of said transmit-on signal tos, which notifies the start and end of the tag's transmission.
Time developments of a rectified and smoothed voltage Uirect across an interrogator's antenna during responding of the smart tag for two tag's responding signals are represented in Figure 2 for three different coupling factors between the interrogator's antenna and the tag's antenna: k = 0.100, 0.020 and 0.005. This smart tag is not provided with an automatic setting according to the invention of the amplitude of tag's responding signal. At the coupling factor k = 0.100 - the tag rests on the interrogator - the signal arriving at the interrogator's antenna exceeds the expected signal, which may cause both saturation in the interrogator's receiver and an unreliable operation.
Figure 3 represents time developments as in Figure 2 but for the smart tag of the invention provided with an automatic setting of the amplitude of the tag's responding signal. In case of the mentioned very good coupling between the interrogator's antenna and the tag's antenna - k = 0.100 - the amplitude measuring circuit AMC detects the very high first amplitude Ai and controls the output amplifier OA in a way that the second amplitude At is suitably lowered and the interrogator receives a signal with the expected amplitude.

Claims

Claims
1. A method intended for high-frequency communication
between an interrogator and a smart tag,
a circuit of said smart tag being galvanically coupled with a voltage source, characterized in
that in time intervals, in which, according to a communication protocol,
the smart tag does not respond to the interrogator
by transmitting high-frequency responding signals,
the smart tag observes a first amplitude (Ai),
which is an amplitude of a voltage
induced in a tag's antenna by an interrogator's high-frequency carrier signal,
and that the smart tag transmits said high-frequency signals,
in that it excites its own antenna with a voltage,
the amplitude of which voltage, being a second amplitude (At),
is essentially constant within an individual response and
is mainly set with respect to said first amplitude (Ai) observed so far
in that the second amplitude (At) is inversely proportional to the first amplitude (Ai).
2. The method as recited in claim 1 , characterized in
that the tag's antenna is excited by the voltage,
whose second amplitude (At) is automatically set to a highest value (Atmax) when the first amplitude (Ai) is below its reference value (Airef),
and that the tag's antenna is excited by the voltage,
whose second amplitude (At) is automatically set to a value,
which is determined by an expression Atmax . Airef / Ai
when the first amplitude (Ai) is above its reference value (Airef).
3. The method as recited in claim 2, characterized in
that the reference value (Airef) of the first amplitude (Ai) is determined as a twofold to fivefold of such minimum value (Aimin) of the first amplitude (Ai), which the interrogator's magnetic field induces in the tag's antenna
at a lowest value, as required by the standard,
of the magnetic field density at a position of the tag's antenna.
4. The method as recited in any of the preceding claims, characterized in that the resonance frequency (fi) of the interrogator's antenna circuit
equals 13.56 MHz.
5. A circuit intended for high-frequency communication
between an interrogator and a smart tag
a circuit of said smart tag being galvanically coupled with a voltage source, characterized in
that an amplitude measuring circuit (AMC) observes
an amplitude of the received signal (rs) as a first amplitude (Ai),
which is an amplitude of the voltage induced in the tag's antenna (A)
by the interrogator's high-frequency carrier signal, and
with its first output signal (avs) representing a measured amplitude value controls said output amplifier (OA) in a way
that said second amplitude (At),
which is the amplitude of the voltage across the tag's antenna (A)
to form a responding signal,
is set with respect to first amplitude (Ai) as observed by then
according to a chosen algorithm.
6. The circuit as recited in claim 6, characterized in
that the variable- gain amplifier (VGA) and the amplitude measuring circuit (AMC) are connected to the tag's antenna (A)
through an attenuator and a DC voltage defining circuit (Att/DC)
and that the signal generator (SG), the attenuator and DC voltage defining circuit
(Att/DC) and the output amplifier (OA) are controlled
by means of said transmit-on signal (tos)
defining the start and end of the tag's transmission
so that said circuit attenuates the signal from the tag's antenna (A)
while the smart tag transmits the responding signals
and sets up a DC voltage level
while the smart tag does not transmit the responding signals.
PCT/SI2012/000026 2011-06-28 2012-04-30 Method and circuit intended for high-frequency communication between an interrogator and a smart tag WO2013002737A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SI201100232A SI23785A (en) 2011-06-28 2011-06-28 Procedure and circuit for high-frequency communication between questioner and a smart label
SIP-201100232 2011-06-28

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WO2013002737A1 true WO2013002737A1 (en) 2013-01-03
WO2013002737A8 WO2013002737A8 (en) 2013-02-21

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080224870A1 (en) * 2007-03-14 2008-09-18 Electronics And Telecommunications Research Institute Apparatus and method for managing power of rfid tag
EP1801741B1 (en) 2005-12-22 2009-07-22 Giesecke & Devrient GmbH Portable data carrier with active noncontact interface
US20100044444A1 (en) 2007-09-12 2010-02-25 Devicefidelity, Inc. Amplifying radio frequency signals

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1801741B1 (en) 2005-12-22 2009-07-22 Giesecke & Devrient GmbH Portable data carrier with active noncontact interface
US20080224870A1 (en) * 2007-03-14 2008-09-18 Electronics And Telecommunications Research Institute Apparatus and method for managing power of rfid tag
US20100044444A1 (en) 2007-09-12 2010-02-25 Devicefidelity, Inc. Amplifying radio frequency signals

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SI23785A (en) 2012-12-31

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