CN112686357A - Ultrahigh frequency RFID (radio frequency identification) tag and anti-electromagnetic interference module thereof - Google Patents
Ultrahigh frequency RFID (radio frequency identification) tag and anti-electromagnetic interference module thereof Download PDFInfo
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- CN112686357A CN112686357A CN201910990382.XA CN201910990382A CN112686357A CN 112686357 A CN112686357 A CN 112686357A CN 201910990382 A CN201910990382 A CN 201910990382A CN 112686357 A CN112686357 A CN 112686357A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention relates to an ultrahigh frequency RFID label and an anti-electromagnetic interference module thereof, wherein the anti-electromagnetic interference module comprises an input impedance module, a low-pass filter module and a high-pass filter module which are sequentially connected, and the input impedance module is related to the frequency of a working signal and the frequency of an interference signal. By implementing the technical scheme of the invention, the electromagnetic wave interference signals entering the RFID chip can be effectively inhibited, so that the output end of the chip can not output error signals due to the interference of external electromagnetic wave signals; the method has a good inhibition effect on common electromagnetic interference frequency points; the anti-interference capability of the chip of the RFID tag is improved, so that the identification accuracy and speed are greatly improved compared with the similar tags.
Description
Technical Field
The invention relates to the field of radio frequency, in particular to an ultrahigh frequency RFID tag and an anti-electromagnetic interference module thereof.
Background
The working process of the traditional ultrahigh frequency RFID tag is as follows: after the antenna receives the radio-frequency signal sent by the reader-writer, the demodulator removes the carrier wave, converts the radio-frequency signal into a baseband signal and analyzes effective information, and the baseband processor decodes the effective information, reads data in the memory and reflects the data back through a TX channel, so that the reader-writer can receive the data returned by the tag. However, the traditional ultrahigh frequency RFID tag has the problem that the interference of electromagnetic wave signals cannot be effectively suppressed, and if the WIFI electromagnetic wave interference signal strength is strong, the waveform amplitude of a demodulator of a radio frequency signal in the RFID tag chip is too large, which causes decoding failure, and reduces the identification accuracy of the tag.
Disclosure of Invention
The invention aims to solve the technical problem of providing an ultrahigh frequency RFID tag and an anti-electromagnetic interference module thereof, aiming at the defect that the interference of electromagnetic wave signals cannot be effectively inhibited in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: the anti-electromagnetic interference module of the ultrahigh frequency RFID tag is connected with an antenna and a demodulator, the anti-electromagnetic interference module comprises an input impedance module, a low-pass filter module and a high-pass filter module which are connected in sequence, and the input impedance module is related to the frequency of a working signal and the frequency of an interference signal.
Preferably, the input impedance module includes a first capacitor, a second capacitor, a first resistor and a second resistor, where one end of the first capacitor is connected to the antenna after being connected in series with the first resistor, and the other end of the first capacitor is connected to the first end of the low-pass filter module; the second capacitor is connected with the antenna at one end after the second resistor is connected in series, the other end of the second capacitor is connected with the second end of the low-pass filter module, and moreover, the input impedance module meets a preset condition by adjusting the capacitance values of the first capacitor and the second capacitor and adjusting the resistance values of the first resistor and the second resistor, wherein the preset condition is that: the reflection coefficient of the interference signal is larger than a first preset value, the reflection coefficient of the working signal is smaller than a second preset value, and the second preset value is smaller than the first preset value.
Preferably, the input impedance module includes a sixth capacitor, a seventh capacitor, a sixth resistor and a seventh resistor, where after the sixth capacitor is connected in series with the sixth resistor, one end of the sixth capacitor is connected to the antenna, and the other end of the sixth capacitor is connected to the first end of the low-pass filter module; and after the seventh capacitor and the seventh resistor are connected in series, one end of the seventh capacitor is connected with the antenna, the other end of the seventh capacitor is connected with the second end of the low-pass filter module, and the input impedance module meets a preset condition by adjusting the capacitance values of the first capacitor, the second capacitor, the sixth capacitor and the seventh capacitor and adjusting the resistance values of the first resistor, the second resistor, the sixth resistor and the seventh resistor.
Preferably, the low pass filter module comprises a third capacitor and a third resistor connected in parallel.
Preferably, the high-pass filter module includes a fourth resistor, a fifth resistor, a fourth capacitor and a fifth capacitor, wherein after the fourth capacitor is connected in series with the fourth resistor, one end of the fourth capacitor is connected to the first end of the low-pass filter module, the other end of the fourth capacitor is connected to the first end of the demodulator, after the fifth capacitor is connected in series with the fifth resistor, one end of the fifth capacitor is connected to the first end of the low-pass filter module, and the other end of the fifth capacitor is connected to the second end of the demodulator.
The invention also constructs an ultrahigh frequency RFID label, which comprises an antenna and a radio frequency front end module, wherein the radio frequency front end module comprises a demodulator, and the radio frequency front end module also comprises the anti-electromagnetic interference module.
Preferably, the radio frequency front end module further comprises:
and the modulator is used for realizing modulation of the transmitted data.
Preferably, the radio frequency front end module further comprises:
the voltage doubling rectifying circuit is used for converting the radio frequency signal transmitted by the reader-writer into a direct current power supply and storing energy through the energy storage capacitor;
and the linear voltage stabilizer is used for performing voltage stabilization treatment on the voltage of the energy storage capacitor so as to supply power for the RFID tag chip.
Preferably, the mobile terminal further comprises a baseband processor, wherein the baseband processor comprises:
the processor is used for controlling a communication process with the reader-writer;
the decoding module is used for decoding the data output by the demodulator;
and the coding module is used for coding the data to be transmitted.
Preferably, the baseband processor further comprises:
and the display driving module is used for performing display control on the label data under the control of the processor.
The technical scheme of the invention has the following beneficial effects:
1. electromagnetic wave interference signals entering the RFID chip can be effectively inhibited, and further, the output end of the RFID chip cannot output error signals due to external electromagnetic wave signal interference;
2. the method has a good inhibition effect on common electromagnetic interference frequency points;
3. the anti-interference capability of the chip of the RFID tag is improved, so that the identification accuracy and speed are greatly improved compared with the similar tags.
Drawings
In order to illustrate the embodiments of the invention more clearly, the drawings that are needed in the description of the embodiments will be briefly described below, it being apparent that the drawings in the following description are only some embodiments of the invention, and that other drawings may be derived from those drawings by a person skilled in the art without inventive effort. In the drawings:
FIG. 1 is a circuit diagram of a first embodiment of an EMI resistant module according to the present invention;
FIG. 2 is a logic structure diagram of a first embodiment of the UHF RFID tag of the present invention;
FIG. 3 is a simulated waveform diagram of the anti-electromagnetic interference module of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings.
The embodiments/examples described herein are specific embodiments of the present invention, are intended to be illustrative of the concepts of the present invention, are intended to be illustrative and exemplary, and should not be construed as limiting the embodiments and scope of the invention. In addition to the embodiments described herein, those skilled in the art will be able to employ other technical solutions which are obvious based on the disclosure of the claims and the specification of the present application, and these technical solutions include those which make any obvious replacement or modification of the embodiments described herein, and all of which are within the scope of the present invention. In addition, without conflict, the embodiments and features in the embodiments in the present application may be combined with each other, and the order of steps in the following embodiments may be adjusted without conflict.
Fig. 1 is a circuit diagram of a first embodiment of an anti-electromagnetic interference module according to the present invention, in which an anti-electromagnetic interference module 11 of the first embodiment is connected between an antenna of an ultra-high frequency RFID tag and a demodulator 12, and is used for suppressing an electromagnetic interference signal in a radio frequency signal received by the antenna, and the anti-electromagnetic interference module 11 includes an input impedance module, a low-pass filter module, and a high-pass filter module, which are connected in sequence, where the input impedance module mainly implements flexible adjustment of input impedance and can also implement a part of a high-pass filtering function; the low-pass filter module mainly realizes a low-pass filtering function and can also realize partial input impedance adjustment; the high-pass filter module mainly realizes a high-pass filtering function. Furthermore, the input impedance block is associated with the frequency of the operating signal and the frequency of the interfering signal.
In this embodiment, the input impedance module includes a first capacitor C1, a second capacitor C2, a sixth capacitor C6, a seventh capacitor C7, a first resistor R1, a second resistor R2, a sixth resistor R6, and a seventh resistor R7, where one end of the first capacitor C1 is connected to the antenna after being connected in series with the first resistor R1, and the other end of the first capacitor C1 is connected to the first end of the low pass filter module; after the sixth capacitor C6 is connected with the sixth resistor R6 in series, one end of the sixth capacitor C6 is connected with the antenna, and the other end of the sixth capacitor C6 is connected with the first end of the low-pass filter module; one end of a second capacitor C2 is connected with the antenna after being connected with a second resistor R2 in series, and the other end of the second capacitor C2 is connected with the second end of the low-pass filter module; and after the seventh capacitor C7 and the seventh resistor R7 are connected in series, one end of the seventh capacitor C7 is connected with the antenna, and the other end of the seventh capacitor C7 is connected with the second end of the low-pass filter module. Moreover, the input impedance module meets the preset conditions by adjusting the capacitance values of the first capacitor C1, the sixth capacitor C6, the second capacitor C2 and the seventh capacitor C7, and adjusting the resistance values of the first resistor R1, the sixth resistor R6, the second resistor R2 and the seventh resistor R7, wherein the preset conditions are as follows: the reflection coefficient of the interference signal is larger than a first preset value, the reflection coefficient of the working signal is smaller than a second preset value, and the second preset value is smaller than the first preset value. It should be understood that in other embodiments, the sixth capacitor C6, the seventh capacitor C7, the sixth resistor R6, and the seventh resistor R7 may be omitted, or another branch consisting of a resistor and a capacitor may be connected in parallel.
It should be further noted that, when designing the input impedance module, the architecture and device parameters of the input impedance module can be adjusted by continuously modifying the parameter values of each resistor and each capacitor under corresponding software, so that the reflection coefficient S11 of the electromagnetic interference signal is larger under the finally determined parameter values of each device, and thus, the input matching of the electromagnetic interference signal is poor, and most of the electromagnetic interference signal can be reflected out without entering the chip; the reflection coefficient S11 of the normal rf signal (working signal) is small, so that the input matching of the rf signal is good, and most of the rf signal can be transmitted to the inside of the chip. Finally, it should be noted that, when determining the final parameter values of each device of the input impedance module, the reflection coefficient S11 of the interference signal and the reflection coefficient S11 of the working signal may be considered in a compromise manner according to the actual situation, for example, if it is desired that the anti-electromagnetic interference effect is good, the impedance matching effect of a radio frequency signal may be sacrificed; on the contrary, if the impedance matching effect of the radio frequency signal is expected to be good, the effect of resisting electromagnetic interference can be sacrificed.
The calculation process of the reflection coefficient is described in combination with maxwell electromagnetic wave theory as follows:
impedance Z of known antennaAntenna with a shieldComprises the following steps:
Zantenna with a shield＝A+jB，
Input impedance Z of anti-electromagnetic interference moduleANTIApproximation:
the input reflection coefficient Γ is:
finally, calculating S11:
S11＝20logΓ。
in this embodiment, the low pass filter module includes a third capacitor C3 and a third resistor R3 connected in parallel. The high-pass filter module comprises a fourth resistor R4, a fifth resistor R5, a fourth capacitor C4 and a fifth capacitor C5, wherein one end of the fourth capacitor C4 is connected with the fourth resistor R4 in series and is connected with the first end of the low-pass filter module, the other end of the fourth capacitor C4 is connected with the first end of the demodulator 12, one end of the fifth capacitor C5 is connected with the fifth resistor R5 in series and is connected with the first end of the low-pass filter module, and the other end of the fifth capacitor C5 is connected with the second end of the demodulator 12. It should be understood that the resistors or capacitors in the low-pass filter module and the high-pass filter module are equivalent resistors or capacitors, and in other embodiments, the architectures of the low-pass filter module and the high-pass filter module can be adjusted in a series-parallel manner by the resistors and in a series-parallel manner by the capacitors, which is also within the protection scope of the present invention.
It should be noted that, when designing the low-pass filter module and the high-pass filter module, first, the bandwidth of the band-pass filter needs to be determined according to the interference signal, for example, the electromagnetic wave interference frequency points are 450MHz, 1GHz, 2.4GHz, and 5GHz, and the bandwidth is set to 850MHz to 950 MHz. Then, the architectures of the low-pass filter module and the high-pass filter module are designed, and in this embodiment, since the low-pass filter module and the high-pass filter module are applied to the RFID chip, in order to save a space area, both the low-pass filter module and the high-pass filter module are first-order filter modules. Then, simulation and optimization are carried out, the bandwidth of the filter is adjusted according to an actual circuit, the out-of-band rejection capability is improved, and specifically, the out-of-band rejection capability of the low-pass filter module can be improved by increasing the capacitance value of the third capacitor C3 and the resistance value of the third resistor R3; increasing the fourth capacitor C4 and the fourth resistor R4 may improve the out-of-band rejection capability of the high pass filter module.
Fig. 2 is a logical structure diagram of an ultra high frequency RFID tag according to a first embodiment of the present invention, where the ultra high frequency RFID tag includes an antenna, a radio frequency Front end module (RF _ Front)010, a Baseband Processor (Baseband Processor)20, and a Memory (Memory) 30.
The radio frequency front end module 10 includes an anti-electromagnetic interference module 11, a demodulator 12, a modulator 13, a voltage doubling rectification circuit 14 and a linear regulator 15, wherein the structure of the anti-electromagnetic interference module 11 refers to fig. 1, which is not described herein; the demodulator 12 is configured to remove carriers, convert the radio frequency signals into baseband signals, analyze valid data, and send the baseband signals to the baseband processing module 20; the modulator 13 is used for implementing transmission data modulation, for example, adjusting the data after baseband processing by using backscattering similar to a radar system; the voltage doubling rectifying circuit 14 is used for converting a radio frequency signal emitted by the reader-writer into a direct current power supply and storing energy through an energy storage capacitor; the linear voltage regulator 15 is used for performing voltage stabilization processing on the voltage of the energy storage capacitor to supply power for the RFID tag chip.
The baseband processor 20 includes: a Processor (Processor)21, a decoding module (RX Decode)22 and a coding module (TX code)23, wherein the Processor 21 is used for controlling a communication process with the reader/writer; the decoding module 22 is used for decoding the data output by the demodulator; the encoder 23 is used for encoding data to be transmitted, and then sending the data to the rf front-end module 10. In addition, a display driving module (not shown) for performing display control of the tag data under the control of the processor may be further included.
The memory 30 is used to store tag data, and includes, for example: user Data Use-Data, hidden password Hide Key, article identification code EPC, label identity TID and the like.
The working process of the ultrahigh frequency RFID tag is explained as follows:
the reader-writer transmits information to be displayed to the air, induced current is generated when the RFID label enters an effective working area, the voltage doubling rectifying circuit converts radio frequency signals into direct current voltage, and the linear voltage stabilizer outputs stable voltage and supplies power to the RFID label chip. After receiving a radio frequency signal transmitted in the air through an antenna, the radio frequency front-end module 10 firstly suppresses an electromagnetic wave interference signal entering the RFID chip through the anti-electromagnetic interference module 11, and then demodulates effective information DATA through the demodulator, so that an output end of the RFID chip does not output an error signal due to interference of an external electromagnetic wave signal. The baseband processor module 20 then decodes the DATA after it has received the DATA, reads the DATA from the memory, and reflects the DATA back through the TX channel so that the reader can receive the DATA back from the RFID tag.
Fig. 3 is a simulated waveform diagram of the anti-electromagnetic interference module, which has a better suppression effect at the commonly used electromagnetic interference frequency points (450MHz, 1GHz, 2.4GHz, 5GHz), specifically: the suppression at 450MHz is-63 dB, the suppression at 1GHz is-28 dB, the suppression at 2.4GHz is-74 dB, and the suppression at 5GHz is-96 dB, so that most electromagnetic interference signals are reflected and suppressed and do not enter the RFID chip, and the electromagnetic interference (EMI) resistance of the RFID chip is greatly improved.
Therefore, the anti-electromagnetic interference module has the following beneficial effects:
1. the ultrahigh frequency RFID tag chip can effectively inhibit electromagnetic wave interference signals entering the chip, so that the output end of the chip cannot output error signals due to the interference of external electromagnetic wave signals;
2. the method has a good inhibition effect on common electromagnetic interference frequency points, such as micropower wireless frequency point 450MHz, mobile phone frequency point 1GHz, WIFI and Bluetooth frequency points 2.4GHz, 5GHz and the like.
3. The anti-interference capability of the chip of the RFID tag is improved, so that the identification accuracy and speed are greatly improved compared with the similar tags.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (10)
1. The anti-electromagnetic interference module of the ultrahigh frequency RFID tag is connected with an antenna and a demodulator and is characterized by comprising an input impedance module, a low-pass filter module and a high-pass filter module which are sequentially connected, wherein the input impedance module is related to the frequency of a working signal and the frequency of an interference signal.
2. The anti-electromagnetic interference module of the uhf RFID tag of claim 1, wherein the input impedance module comprises a first capacitor, a second capacitor, a first resistor and a second resistor, wherein the first capacitor is connected in series with the first resistor, and then one end of the first capacitor is connected to an antenna, and the other end of the first capacitor is connected to the first end of the low pass filter module; the second capacitor is connected with the antenna at one end after the second resistor is connected in series, the other end of the second capacitor is connected with the second end of the low-pass filter module, and moreover, the input impedance module meets a preset condition by adjusting the capacitance values of the first capacitor and the second capacitor and adjusting the resistance values of the first resistor and the second resistor, wherein the preset condition is that: the reflection coefficient of the interference signal is larger than a first preset value, the reflection coefficient of the working signal is smaller than a second preset value, and the second preset value is smaller than the first preset value.
3. The anti-electromagnetic interference module of the uhf RFID tag of claim 2, wherein the input impedance module comprises a sixth capacitor, a seventh capacitor, a sixth resistor and a seventh resistor, wherein the sixth capacitor is connected in series with the sixth resistor, and then one end of the sixth capacitor is connected to the antenna, and the other end of the sixth capacitor is connected to the first end of the low pass filter module; and after the seventh capacitor and the seventh resistor are connected in series, one end of the seventh capacitor is connected with the antenna, the other end of the seventh capacitor is connected with the second end of the low-pass filter module, and the input impedance module meets a preset condition by adjusting the capacitance values of the first capacitor, the second capacitor, the sixth capacitor and the seventh capacitor and adjusting the resistance values of the first resistor, the second resistor, the sixth resistor and the seventh resistor.
4. The anti-electromagnetic interference module of UHF RFID tag of claim 1, wherein the low pass filter module comprises a third capacitor and a third resistor connected in parallel.
5. The anti-electromagnetic interference module of the uhf RFID tag of claim 1, wherein the high pass filter module comprises a fourth resistor, a fifth resistor, a fourth capacitor and a fifth capacitor, wherein the fourth capacitor is connected in series with the fourth resistor, and has one end connected to the first end of the low pass filter module and the other end connected to the first end of the demodulator, and the fifth capacitor is connected in series with the fifth resistor, and has one end connected to the first end of the low pass filter module and the other end connected to the second end of the demodulator.
6. An ultra high frequency RFID tag comprising an antenna and a radio frequency front end module comprising a demodulator, characterized in that the radio frequency front end module further comprises an anti-electromagnetic interference module as claimed in any one of claims 1 to 5.
7. The uhf RFID tag of claim 6, wherein the rf front-end module further comprises:
and the modulator is used for realizing modulation of the transmitted data.
8. The uhf RFID tag of claim 6, wherein the rf front-end module further comprises:
the voltage doubling rectifying circuit is used for converting the radio frequency signal transmitted by the reader-writer into a direct current power supply and storing energy through the energy storage capacitor;
and the linear voltage stabilizer is used for performing voltage stabilization treatment on the voltage of the energy storage capacitor so as to supply power for the RFID tag chip.
9. The uhf RFID tag of claim 6, further comprising a baseband processor, the baseband processor comprising:
the processor is used for controlling a communication process with the reader-writer;
the decoding module is used for decoding the data output by the demodulator;
and the coding module is used for coding the data to be transmitted.
10. The uhf RFID tag of claim 9, wherein the baseband processor further comprises:
and the display driving module is used for performing display control on the label data under the control of the processor.
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