KR20080112669A - A circuit of eliminating a leakage signal and a mobile rfid reader including the same - Google Patents

Abstract

A leakage signal eliminative circuit, a mobile RF ID reader including the same, and a leakage signal removal method are provided to prevent the damage of element includes in a receiver by removing transmission leakage signal leaked out from the receiver. A first passing signal corresponding to transmission signal is received through a first port and is outputted through a second port. A first circulator(4210) outputs the first leakage signal corresponding to the transmission signal through a third port. A second circulator(4220) outputs the received signal in which the second leakage signal corresponding to the answer signal and the first passing signal is added. A balun(4230) outputs the leakage removing signal removing the second leakage signal.

Description

A circuit of eliminating a leakage signal and a mobile RFID reader including the same}

1 is a block diagram illustrating a leakage signal removing circuit according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram illustrating a balun included in the leakage signal removing circuit of FIG. 1.

3 is a block diagram illustrating a leakage signal removing circuit according to another exemplary embodiment of the present invention.

Figure 4 is a block diagram showing a mobile wireless reader in accordance with an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

1100, 4210: first circulator

1200, 4220: second circulator

1300, 4230: Balun

The present invention relates to a mobile radio reader, and more particularly, to a leak signal removal circuit, a mobile radio reader and a method for removing the leak signal including the same.

Radio Frequency Identification (RFID), a non-contact recognition system that attaches a small chip to various items and transmits and processes the information of the object and the surrounding environment at radio frequency, is unique to a reader with a reading and decoding function. It consists of a tag with embedded information. The tag has its own unique data or serial number and sends this unique data or serial number to the reader. The reader stores and processes the unique data or serial number received from the tag and delivers it to a wireless recognition system operating terminal such as a mobile phone.

In general, a radio reader continuously transmits a continuous wave (CW) signal to power a tag.

Recently, a wireless reader is used for embedding in a small terminal such as a mobile phone, and as the terminal embedded with the wireless reader becomes smaller, the wireless reader needs to be miniaturized. Therefore, when the reader and the tag transmit and receive data, one antenna that transmits and receives a signal of the same frequency band is used. The RFID reader uses a circulator to separate transmission and reception. For example, the circulator has a separation of about 20dB and the maximum power of the continuous wave signal transmitted by the RFID reader is about 24dBm. When the reader sends out a continuous wave signal with 24dBm of power, about 4dBm of power leaks to the receiver. When the tag transmits and the received signal received by the receiver of the reader has power of about -80dBm ~ -20dBm, when the transmission leakage signal with power of about 4dBm leaks to the receiver, the receiving sensitivity is lowered and the device included in the receiver Problems such as damage can occur. In order to prevent such a problem, a circuit for removing a transmission leakage signal leaking to a receiver and a radio recognition reader including the same are required.

In order to solve the above problems, an object of the present invention is to provide a leakage signal removal circuit that can remove the transmission leakage signal leaked to the receiver.

In addition, an object of the present invention is to provide a mobile wireless recognition reader that can remove the transmission leakage signal leaked to the receiver including the leakage signal removal circuit.

In addition, an object of the present invention is to provide a leakage signal removal method that can remove the transmission leakage signal leaked to the receiver.

In order to achieve the above object, the leakage signal removing circuit according to an embodiment of the present invention includes a first circulator, a second circulator and a balun.

The first circulator receives a transmission signal through a first port, outputs a first pass signal corresponding to the transmission signal through a second port, and outputs a first leakage signal corresponding to the transmission signal through a third port. Output The second circulator receives the first pass signal through a fourth port, outputs a second pass signal corresponding to the first pass signal through a fifth port, and outputs a response signal through the fifth port. The received signal is outputted through the sixth port through a sum of the second leakage signal corresponding to the response signal and the first pass signal. The balun outputs a leakage elimination signal obtained by removing the second leakage signal from the received signal based on the first leakage signal and the received signal.

The balun may receive the reception signal including the second leakage signal and the first leakage signal to cancel the first and second leakage signals.

The first and second leakage signals may have the same magnitude and phase.

The balun may be implemented with a transformer.

The first leakage signal is applied to the first circuit first terminal of the transformer, the received signal is applied to the first circuit second terminal of the transformer, and the leakage cancellation signal is applied to the second order of the transformer. The circuit may be output to the first terminal and the second terminal.

The leakage signal removing circuit adjusts the phase and magnitude of the first leakage signal and outputs the balun to the balun by adjusting the phase and magnitude of the received signal including the first matching circuit and the second leakage signal. A second matching circuit may be further included.

In order to achieve the above object, the mobile wireless reader according to an embodiment of the present invention includes a high frequency front end, a leakage signal cancellation circuit, a transceiver and a digital processor.

The high frequency front end part receives and outputs a response signal. The leakage signal elimination circuit outputs a leakage elimination signal based on the response signal and the transmission signal. The transceiver unit transmits the transmission signal and receives the leakage elimination signal. The digital processing unit digitally processes the leakage elimination signal.

The leakage signal removing circuit includes a first circulator, a second circulator and a balun.

The first circulator receives the transmission signal through a first port, outputs a first pass signal corresponding to the transmission signal through a second port, and a first leakage signal corresponding to the transmission signal through a third port. Outputs The second circulator receives the first pass signal through a fourth port, outputs a second pass signal corresponding to the first pass signal through a fifth port, and outputs the response signal through the fifth port. The received signal is outputted through the sixth port through a sum of the second leakage signal corresponding to the response signal and the first pass signal. The balun outputs a leakage elimination signal obtained by removing the second leakage signal from the received signal based on the first leakage signal and the received signal.

The balun may receive the reception signal including the second leakage signal and the first leakage signal to cancel the first and second leakage signals.

The balun may be implemented with a transformer.

The first leakage signal is applied to the first circuit first terminal of the transformer, the received signal is applied to the first circuit second terminal of the transformer, and the leakage elimination signal is applied to the second terminal of the transformer. The difference circuit can be output to the first terminal and the second terminal.

The mobile RFID reader adjusts the phase and magnitude of the first leakage signal and outputs the balun to the balun by adjusting a phase and magnitude of the received signal including the first matching circuit and the second leakage signal. A second matching circuit may be further included.

In order to achieve the above object, in the leakage signal removal method according to an embodiment of the present invention, receiving a transmission signal through the first port of the first circulator and corresponding to the transmission signal through the second port A first pass signal is output and a first leak signal corresponding to the transmission signal is output through a third port. Receiving the first pass signal through the fourth port of the second circulator, and outputs a second pass signal corresponding to the first pass signal through the fifth port, and receives a response signal through the fifth port The sixth port outputs a reception signal obtained by adding the second leakage signal corresponding to the response signal and the first pass signal. A leakage elimination signal from which the second leakage signal is removed from the received signal is output based on the first leakage signal and the received signal.

The first and second leak signals may be canceled by applying the received signal including the second leak signal and the first leak signal to both ends of the balun.

The method may further include adjusting a phase and a magnitude of the first leak signal and adjusting a phase and a magnitude of the received signal including the second leak signal.

With respect to the embodiments of the present invention disclosed in the text, specific structural to functional descriptions are merely illustrated for the purpose of describing embodiments of the present invention, embodiments of the present invention may be implemented in various forms and It should not be construed as limited to the embodiments described in. As the inventive concept allows for various changes and numerous modifications, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between. Other expressions describing the relationship between components, such as "between" and "immediately between" or "neighboring to" and "directly neighboring", should be interpreted as well. The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof that is described, and that one or more other features or numbers are present. It should be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. .

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. The same reference numerals are used for the same elements in the drawings, and duplicate descriptions of the same elements are omitted.

1 is a block diagram illustrating a leakage signal removing circuit according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the leakage signal removing circuit 1000 includes a first circulator 1100, a second circulator 1200, and a balloon 1300.

The first circulator 1100 receives the transmission signal TX through the first port P1 and outputs a first pass signal PS1 corresponding to the transmission signal TX through the second port P2. The first leakage signal LS1 corresponding to the transmission signal TX is output through the third port P3. The second circulator 1200 receives the first pass signal PS1 through the fourth port P4 and receives the second pass signal PS2 corresponding to the first pass signal PS1 through the fifth port P5. ) And a second leakage signal corresponding to the response signal RS and the first pass signal PS1 through the sixth port P6 by receiving the response signal RS through the fifth port P5. LS2) outputs the summed reception signal RX.

For example, an isolation of the first circulator 1100 is about 20 dB, and the first circulator 1100 transmits a transmission signal TX having a power of about 24 dBm through the first port P1. Can be received. In this case, the first circulator 1100 outputs a first pass signal PS1 having a power of about 20 dBm through the second port P2, and has a power of about 4 dBm through the third port P3. 1 Leak signal LS1 can be output. In addition, the isolation of the second circulator 1200 is about 16 dB, and the second circulator 1200 receives the first pass signal PS1 having a power of about 20 dBm through the fourth port P4. Can be received. In this case, the second circulator 1200 outputs a second pass signal PS2 having a power of about 16 dBm through the fifth port P5, and has a power of about 4 dBm through the sixth port P6. 2 Leak signal LS2 can be output. Here, the first leakage signal LS1 output by the first circulator and the second leakage signal LS2 output by the second circulator are substantially the same in magnitude and phase.

The balloon 1300 outputs the leakage elimination signal LES from which the second leakage signal LS2 is removed from the reception signal RX based on the first leakage signal LS1 and the reception signal RX. That is, the balun 1300 receives the received signal RX including the second leak signal LS2 and the first leak signal LS1 and cancels the first and second leak signals LS1 and LS2 from each other. The leakage elimination signal LES from which the second leakage signal LS2 is removed from the reception signal RX is output. The leakage elimination signal LES is substantially the same as the response signal RS that does not include the second leakage signal. The balloon 1300 may be implemented as a transformer to cancel the first and second leakage signals LS1 and LS2 with each other.

2 is a view showing a balloon according to an embodiment of the present invention.

The balloon 1300 is a transformer including a primary circuit having a first terminal N1 and a second terminal N2 and a secondary circuit having a third terminal N3 and a fourth terminal N4. Can be implemented.

The first leakage signal LS1 is applied to the first terminal N1 of the first circuit of the transformer, and the reception signal RX obtained by adding the second leakage signal LS2 and the response signal RS is the first of the transformer. The first leakage signal LS1 and the second leakage signal LS2 cancel each other by being applied to the differential circuit second terminal N2. As a result, the leakage elimination signal LES substantially equal to the response signal RS is the positive leakage elimination signal LES + and the negative leakage elimination signal LES- as the secondary circuit third terminal N3 and the fourth of the transformer. It is output to the terminal N4.

3 is a block diagram illustrating a leakage signal removing circuit according to another exemplary embodiment of the present invention.

The leakage signal removing circuit 3000 includes a first circulator 3100, a second circulator 3200, a first matching circuit 3300, a second matching circuit 3400, and a balloon 3500.

The first circulator 3100 receives the transmission signal TX through the first port P1 and outputs a first pass signal PS1 corresponding to the transmission signal TX through the second port P2. The first leakage signal LS1 corresponding to the transmission signal TX is output through the third port P3. The second circulator 3200 receives the first pass signal PS1 through the fourth port P4 and receives a second pass signal PS2 corresponding to the first pass signal PS1 through the fifth port P5. ) And a second leakage signal corresponding to the response signal RS and the first pass signal PS1 through the sixth port P6 by receiving the response signal RS through the fifth port P5. LS2) outputs the summed reception signal RX.

The first matching circuit 3300 adjusts the phase and magnitude of the first leakage signal LS1 to output the balun 3500, and the second matching circuit 3400 outputs the phase and magnitude of the second leakage signal LS2. Adjust the output to the balun 3500.

The magnitude of the first leakage signal LS1 output from the first circulator 3100 and the magnitude of the second leakage signal LS2 output from the second circulator 3200 are the first circulator 3100 and the second. When the phase is different due to the internal loss of the circulator 3200 or the phase difference due to the time difference between the first leakage signal LS1 and the second leakage signal LS2 reaching the balun 3500, the first phase The matching circuit 3300 and the second matching circuit 3400 adjust the phases and magnitudes of the first leak signal LS1 and the second leak signal LS2 to adjust the phases and magnitudes of the first leak signal LS1 and the second leak signal LS2. ) Phase and magnitude are the same.

The balloon 3500 receives the first match leakage signal MLS1 output from the first matching circuit 3300, the second match leakage signal MLS2 and the match response signal MRS output from the second matching circuit 3400. When the first and second match leakage signals MLS1 and MLS2 are canceled with each other, the leakage elimination signal LES from which the second leakage signal LS2 is removed from the received signal RX is output.

Figure 4 is a block diagram showing a mobile wireless reader in accordance with an embodiment of the present invention.

The mobile RFID reader 4000 includes a high frequency front end 4100, a leakage signal canceling circuit 4200, a transceiver 4300, and a digital processor 4400.

The high frequency front end 4100 includes an antenna 4110 and a band pass filter 4120, and receives and outputs a response signal RS from the outside.

The leakage signal removing circuit 4200 includes a first circulator 4210, a second circulator 4220, and a balloon 4230.

The first circulator 4210 receives the transmission signal TX through the first port P1 and transmits the first pass signal PS1 corresponding to the transmission signal TX through the second port P2 to the second. The first leakage signal LS1 corresponding to the transmission signal TX is output through the third port P3 to the balun 4230 through the circulator 4220. The second circulator 4220 receives the first pass signal PS1 through the fourth port P4 and receives a second pass signal PS2 corresponding to the first pass signal PS1 through the fifth port P5. ) Is outputted to the high frequency front end 4100, the response signal RS is received through the fifth port P5, and the response signal RS and the first pass signal PS1 are received through the sixth port P6. The second leakage signal LS2 corresponding to the received signal RX is output to the balun 4230. The magnitude and phase of the first leakage signal LS1 output by the first circulator and the second leakage signal LS2 output by the second circulator are substantially the same. However, the magnitude of the first leakage signal LS1 and the magnitude of the second second leakage signal LS2 are different from each other due to the insertion loss of the first circulator 4210 and the second circulator 4220. When the phases are different due to the time difference between the first leakage signal LS1 and the second leakage signal LS2 reaching the balun 4230, the phase and magnitude of the first leakage signal LS1 are adjusted to the balun 4230. A second matching circuit (not shown) for adjusting the phase and magnitude of the received signal RX including the first matching circuit (not shown) and the second leakage signal LS2 to be output to the balun 4230 is further output. It may include.

The balloon 4230 outputs the leakage elimination signal LES from which the second leakage signal LS2 is removed from the reception signal RX based on the first leakage signal LS1 and the reception signal RX. That is, the balun 4230 receives the received signal RX including the second leak signal LS2 and the first leak signal LS1 to cancel the first and second leak signals LS1 and LS2. The leakage elimination signal LES from which the second leakage signal LS2 is removed from the reception signal RX is output. The balun 4230 is a transformer including a primary circuit having a first terminal N1 and a second terminal N2 and a secondary circuit having a third terminal N3 and a fourth terminal N4. Can be implemented. The first leakage signal LS1 is applied to the first terminal N1 of the first circuit of the transformer, and the reception signal RX obtained by adding the second leakage signal LS2 and the response signal RS is the first of the transformer. The first leakage signal LS1 and the second leakage signal LS2 cancel each other by being applied to the secondary circuit second terminal N2. As a result, the leakage elimination signal LES substantially equal to the response signal RS is the positive leakage elimination signal LES + and the negative leakage elimination signal LES- as the secondary circuit third terminal N3 and the fourth of the transformer. It is output to the terminal N4.

The transceiver 4300 includes a transmitter 4310, a frequency synthesizer 4330, and a receiver 4350.

The transmitter 4310 modulates the command signal COM input from the digital processor 4400 to generate the transmission signal TX, and transmits the generated transmission signal TX to the leakage signal removal circuit 4200.

The frequency synthesizer 4330 receives the clock signal CLK from the digital processor 4400, generates a local oscillation signal LO, and outputs the local oscillation signal LO to the transmitter 4310 and the receiver 4350.

The receiver 4350 may include a low noise amplifier 4431, a phase adjuster 4452, an I mixer 4335, a Q mixer 4354, a first low pass filter 4355, a second low pass filter 4354, and a first voltage. Gain amplifier 4357, second voltage gain amplifier 4358, first analog-to-digital converter 4357, and second analog-to-digital converter 4360.

The low noise amplifier 4331 improves reception sensitivity by low noise amplifying the positive leakage cancellation signal LES + and the negative leakage cancellation signal LES− received from the leakage signal removal circuit 4200. The phase adjuster 4432 phase shifts the local oscillation signal LO generated by the frequency synthesizer 4330 by 90 degrees. The I mixer 4335 demodulates the signal output from the phase adjuster 4432 and the signal output from the low noise amplifier 4331 and demodulates it into the I signal IS, and the Q mixer 4354 outputs from the phase adjuster 4432. The signal and the signal output from the low noise amplifier 4331 are mixed and demodulated into a Q signal QS. The first and second low pass filters 4355 and 4356 low pass filter the I signal IS and the Q signal QS to pass only frequencies of a predetermined band. The first and second voltage gain amplifiers 4357 and 4358 amplify the signals received from the first and second low pass filters 4355 and 4356 to a predetermined level and output the first and second analog-to-digital converters. . The first and second analog-to-digital converters 4357 and 4360 convert the analog signals received by the first and second voltage gain amplifiers 4357 and 4358 into digital signals and output the digital signals to the digital processor 4400.

The digital processor 4400 digitally processes the digital signal generated based on the leakage elimination signal LES and transmits the processed signal to an operation terminal such as a mobile phone.

As described above, the mobile wireless reader according to an embodiment of the present invention can remove the transmission leakage signal leaked to the receiver.

By removing the transmission leakage signal leakage to the receiver by the transmission leakage signal removal circuit, the mobile wireless recognition reader and the leakage signal removal method according to the embodiment of the present invention as described above, to improve the reception sensitivity of the mobile wireless recognition reader You can.

In addition, by removing the transmission leakage signal leaked to the receiver by the transmission leakage signal removal circuit, a mobile wireless recognition reader and a leakage signal removal method including the same, it is possible to prevent damage to the elements included in the receiver.

While the present invention has been described with reference to the preferred embodiments, those skilled in the art can variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I will understand.

Claims (14)

A first circulator that receives a transmission signal through a first port, outputs a first pass signal corresponding to the transmission signal through a second port, and outputs a first leakage signal corresponding to the transmission signal through a third port ; Receiving the first pass signal through a fourth port to output a second pass signal corresponding to the first pass signal through a fifth port, and receives a response signal through the fifth port through a sixth port A second circulator configured to output a received signal obtained by adding up the second leakage signal corresponding to the response signal and the first pass signal; And And a balun configured to output a leakage cancellation signal from which the second leakage signal is removed from the received signal based on the first leakage signal and the received signal. The leakage signal removing circuit of claim 1, wherein the balun receives the received signal including the second leak signal and the first leak signal to cancel the first and second leak signals. 3. The leakage signal canceling circuit of claim 2, wherein the first and second leakage signals have the same magnitude and phase. 4. The leakage signal canceling circuit according to claim 3, wherein the balun is implemented with a transformer. 5. The method of claim 4, wherein the first leakage signal is applied to the first circuit first terminal of the transformer, the received signal is applied to the first circuit second terminal of the transformer, and the leakage cancellation signal is Leakage signal elimination circuit, characterized in that output to the first terminal and the second terminal of the secondary circuit of the transformer. The method of claim 1, A first matching circuit adjusting the phase and the magnitude of the first leakage signal and outputting the balun to the balun; And And a second matching circuit configured to adjust a phase and a magnitude of the received signal including the second leaked signal to output the balun. A high frequency front end unit for receiving and outputting a response signal; A leakage signal elimination circuit for outputting a leakage elimination signal based on the response signal and the transmission signal; A transceiver for transmitting the transmission signal and receiving the leakage elimination signal; It includes a digital processing unit for digital processing based on the leakage cancellation signal, The leakage signal removing circuit, A first circuit that receives the transmission signal through a first port, outputs a first pass signal corresponding to the transmission signal through a second port, and outputs a first leakage signal corresponding to the transmission signal through a third port Radar; Receiving the first pass signal through a fourth port to output a second pass signal corresponding to the first pass signal through a fifth port, and receives the response signal through the fifth port to receive a sixth port A second circulator configured to output a received signal obtained by adding up the second leakage signal corresponding to the response signal and the first pass signal; And And a balun configured to output a leakage canceling signal from which the second leakage signal is removed from the received signal based on the first leakage signal and the received signal. The mobile wireless reader of claim 7, wherein the balun receives the received signal including the second leak signal and the first leak signal to cancel the first and second leak signals. The mobile RFID reader of claim 8, wherein the balun is implemented with a transformer. 10. The method of claim 9, wherein the first leakage signal is applied to the first circuit first terminal of the transformer, and the received signal is applied to the first circuit second terminal of the transformer. The mobile wireless reader is output to the first terminal and the second terminal of the secondary circuit of the transformer. The method of claim 7, wherein A first matching circuit adjusting the phase and the magnitude of the first leakage signal and outputting the balun to the balun; And And a second matching circuit for adjusting the phase and magnitude of the received signal including the second leakage signal and outputting the balun to the balun. Receives a transmission signal through a first port of a first circulator, outputs a first pass signal corresponding to the transmission signal through a second port, and outputs a first leakage signal corresponding to the transmission signal through a third port. Doing; Receiving the first pass signal through the fourth port of the second circulator, and outputs a second pass signal corresponding to the first pass signal through the fifth port, and receives a response signal through the fifth port Outputting a received signal obtained by adding the second leakage signal corresponding to the response signal and the first pass signal through a sixth port; And And outputting a leakage elimination signal from which the second leakage signal is removed from the received signal based on the first leakage signal and the received signal. The method of claim 12, wherein the outputting of the leakage elimination signal cancels the first and second leakage signals by applying the received signal including the second leakage signal and the first leakage signal to both ends of the balun. Leakage signal removal method comprising the step of. The method of claim 12, Adjusting phase and magnitude of the first leakage signal; And And adjusting a phase and a magnitude of the received signal including the second leak signal.

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