KR100737133B1 - Radio frequency identification transmitting and receiving device - Google Patents

Abstract

An RFID transceiver is provided to improve receive sensitivity by doubly preventing the introduction of power of a transmitting stage to a receiving stage, and reduce malfunction probability at the receiving stage by restraining generation of a spurious phenomenon. A signal separator(131) is provided in a carrier processing stage(130), separates an RFID reception signal into an I(In-Phase) signal and a Q(Quadrature-Phase) signal, and transfers them. A switching unit(140) is connected with the I and Q signal paths. A controller controls the switching unit(140) according to whether an RF transmitting stage(114) is operated or according to whether a spurious component signal is received through the signal paths.

Description

Radio Frequency IDentification transmitting and receiving device

1 is a block diagram schematically illustrating the components of an RFID transceiver in accordance with an embodiment of the present invention;

2 is a schematic diagram illustrating circuit connections between components of an RFID transceiver according to an embodiment of the present invention;

3 is a circuit diagram illustrating a circuit configuration of a first switching unit and a second switching unit according to an embodiment of the present invention, and a connection structure with an RF receiver.

4 is a circuit diagram illustrating an exemplary connection configuration between an RF switching unit and an RF receiver according to an exemplary embodiment of the present invention.

5 is a graph measuring output voltages of the RF receiver and the RF transmitter according to a case where an RFID transceiver according to an embodiment of the present invention transmits and receives a signal.

<Explanation of symbols for main parts of drawing>

100: RFID transceiver 110: RF processing stage

112: RF receiver 114: RF transmitter

130: carrier processing stage 131: signal separation unit

132a-132d: Mixer 133: 90 ° Phase Shifter

134: Amplifier 135: Local Oscillator (LO)

136a, 136b: filter 137: signal synthesizer

138: filter 140: switching unit

142: first switching unit 144: second switching unit

The present invention relates to an RFID transceiver.

Currently, ubiquitous network technology has attracted the attention of many people, ubiquitous network technology means a technology that allows to naturally connect to various networks regardless of time and place.

The ubiquitous network technology can be implemented in various manners using communication technologies such as telematics communication, short-range wireless communication, and mobile communication, and this provides a natural connection environment in a space such as a car, a home, a public place, and the like.

As the next generation technology of the ubiquitous network technology, RFID technology may be cited. Among them, RFID technology introduced in commerce is representative.

In general, a commercial RFID system includes an electronic tag attached to a product and embedded with detailed information, an RFID reader that reads the information of the electronic tag using RF communication, an information server that collects information from the RFID reader, and builds a database. The electronic tag attached to the product passes through the area where the RFID reader is located and transmits the information by using RF communication, so that the logistics / distribution management of the product distribution, assembly, price change, sale, etc. is efficient. It provides a foundation that can be addressed.

The RFID system is provided with an RFID transceiver for performing wireless communication to exchange information. Unlike the mobile communication terminal, the transmitting and receiving terminals of the RFID system share the transmitting and receiving signals without separating the transmitting and receiving frequency bands, and transmitting and receiving at the base end. It has a structure that separates and processes the signal.

Therefore, the RFID transceiver may separate the transmitting and receiving antennas in order to distinguish the frequencies of the transmission band and the reception band. Even in this case, when a signal is transmitted and received from a plurality of RFID tags, the isolation between the transmission signal and the reception signal may be reduced due to various factors. do.

First, a reduction in the isolation between the transmission signal and the reception signal of the RFID system is mainly caused by a circuit effect of sharing the transmission / reception signal without separation of the transmission / reception frequency in the transmission / reception terminal of the RFID system.

In general, when an output signal of 30dBm is transmitted from an RFID reader, the output signal flows into the receiver as much as Tx / Rx Isolation is not secured, thus reducing the reception sensitivity (for example, only 25dB output signal is transmitted). 5 dB transmitted to the receiving end of the RFID reader).

In addition, the cause of the degradation of the isolation between the transmission signal and the reception signal of the RFID system is due to environmental factors in which RFID transmission and reception are performed.

For example, in an environment where there are communication obstacles such as obstacles such as misty wetlands, skyscrapers, or weather that contains a lot of moisture in the air, the RF signal transmitted from the RFID reader is fed back to the RFID reader. It can be input as a received signal, and the fed back transmitted signal is not separated from the RF signal received from the RFID tag, thereby reducing the reception sensitivity.

These circuit and environmental factors are a serious problem with regard to the isolation and reception performance of RFID transceivers.

The present invention provides an RFID transceiver having an excellent insertion loss characteristic and improving the selectivity and reception performance of the transceiver due to the large isolation between the transmitter and the receiver.

In addition, the present invention improves the reception sensitivity by removing the DC (Direct Current) Offset component of the input signal, and provides an RFID transceiver for transmitting an output signal corresponding to the received signal to the controller.

The RFID transceiver according to the present invention relates to an RFID transceiver having an RF transmitting / receiving end and a carrier processing end. The RFID transceiver includes an I (In-Phase) signal and a Q (Quadrature-Phase) signal. Signal separation unit for transmitting to separate; A switching unit connected to the I and Q signal paths; And a control unit for controlling the switching unit according to whether the RF transmitter is operated or whether a signal of an undesired component in the signal path is received.

In addition, the RFID transceiver according to the present invention further includes an RF switching unit connected to the RF receiver.

The switching unit of the RFID transceiver according to the present invention may include a first switching unit connected to the I signal path; And a second switching unit connected to the Q signal path, and in blocking the signal paths, a ground terminal is provided to isolate the received signal.

In addition, the RF switching unit of the RFID transceiver according to the present invention, in blocking the signal path of the RF receiver, has a ground terminal to isolate the received signal.

In addition, the RF receiver of the RFID transceiver according to the present invention includes an automatic control amplifier, and the RF switching unit is connected in series or in parallel to the RF receiver.

In addition, the carrier processing stage of the RFID transceiver according to the present invention includes a reception filter connected to the I signal path and the Q signal path after the signal separation unit, and the switching unit is connected to the rear end of the reception filter.

In addition, the controller of the RFID transceiver according to the present invention blocks the signal path of the switching unit when the RF transmitter is operated or the signal received through the signal path is determined to be a signal of an unwanted component, and the signal received through the signal path. If it is determined that the RFID received signal to connect the switching unit.

Hereinafter, an RFID transceiver according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically illustrating components of an RFID transceiver 100 according to an embodiment of the present invention.

Referring to FIG. 1, an RFID transceiver 100 according to an embodiment of the present invention includes an RF processing stage 110, an RF switching unit 120, a carrier processing stage 130, a switching unit 140, and a baseband. It is configured to include a processing stage 150, the control unit 160.

The RF processing unit 110 is connected to an antenna to transmit and receive an RF signal, and process the transmitted and received signals, the RF switching unit 120 is connected to the received signal path of the RF processing unit 110 is the control unit ( The received signal path is blocked / connected according to the control signal of 160.

In addition, the carrier processor 130 separates the signal received from the RF processor 110 into an in-phase (I) signal and a quadrature-phase (Q) signal according to the control signal of the controller 160. Transmitted to the baseband processing stage 150, or synthesized I signal and Q signal transmitted from the baseband processing stage 150 to the RF processing stage 110.

In addition, the switching unit 140 receives a control signal from the control unit 160 to block / connect the reception signal path of the carrier processing stage 130.

The baseband processor 150 converts I and Q signals received from the carrier processor 130 into digital signals and processes data of a MAC (Media Access Controller) layer and an RFID network layer ( For example, synchronization of digital signals, device identification, transmission error checking, retransmission request, error detection, etc.).

The baseband processor 150 transmits the processed digital signal to the controller 160, and the controller 160 processes the digital signal through an application program to process each component of the RFID transceiver 100. To control.

Hereinafter, the components of the RF processing stage 110 and the carrier processing stage 130 will be described.

2 is a diagram schematically illustrating a circuit connection between components of an RFID transceiver according to an embodiment of the present invention.

Referring to FIG. 2, the RFID transceiver 100 according to the embodiment of the present invention includes an antenna, an RF processing terminal 110, a carrier processing terminal 130, and a switching unit 140.

First, the RF processing stage 110 is composed of an RF receiver 112 and an RF transmitter 114 including one or more amplifiers and filters.

Particularly, the RF receiver 112 suppresses noise components of the RF signal received from the antenna as much as possible, thereby eliminating noise of a low noise amplifier and a high frequency component that amplify only a tag signal of an RFID frequency band, and filtering a received signal. (LPF; Low Pass Filter) is preferably provided.

Here, the RF receiver 112 is provided with an RF switching unit (which will be described in detail with reference to FIG. 4), and the signal transmitted to the RF receiver 112 is, for example, an RFID tag through the antenna. The RF signal received from the RF signal, the feedback component signal, the fading signal, etc. introduced from the transmission signal processed by the RF transmitter 114, wherein the RF switching unit RF receiver 112 is received from the RFID tag RF Block incoming signal except in case of processing signal.

That is, according to the control signal transmitted from the control unit 160, the RF switching unit selectively connects only the signal received from the RFID tag among the RF signals received from the antenna to the reception signal path of the RF receiver 112 and the In other cases, the received signal path is blocked.

In addition, the carrier processing stage 130 is a signal separator 131, mixers 132a, 132b, 90-degree phase shifter 133, amplifier 134, local oscillator 135, a plurality of filters 136a, 136b and 138 and a signal synthesizing unit 137, wherein the signal separating unit 131 separates the RFID received signal into an I signal and a Q signal, and transmits the signal path.

The mixers 132a and 132b allow the separated signals to have a phase difference (e.g., multiply the cosine and sine signals by the I and Q signals to generate a phase difference) to ensure the accuracy of signal processing, and the filter 136a and 136b pass through a mixer to filter signals of mixed noise components.

In this case, the signal calculated on the I signal and the Q signal to generate the phase difference may include an oscillation signal generated by the local oscillator 135 being amplified by the amplifier 134 and a 90 degree phase shifter 133. It is made by phase shifting through.

The I and Q signals are phase shifted by 90 degrees and are orthogonal or quadrature with each other, and these signals are two independent components without interference from each other.

The filters 136a and 136b filter the mixed I and Q signals, and a low pass filter (LPF) may be generally used. Noise components in the high frequency region are removed by passing through the filters 136a and 136b.

When the RFID transmission signal is processed, the mixers 132c and 132d, a signal mixing unit 137, a filter 138, and the like are provided, and the I and Q signals transmitted from the baseband processor 150 are It is calculated to have the same phase through the mixers 132c and 132d, synthesized into one RF transmission signal by the signal synthesizing unit 137, and then transferred to the filter 138.

The filter 138 removes the noise of the RF signal received from the signal mixer 137 and transmits the noise to the RF transmitter 114.

The RF transmitter 114 transmits a transmission signal to the RFID tag, and is generally output at a power of about 30 dBm.

In addition, the switching unit 140 blocks / connects the I signal path and the Q signal path according to the control signal. Components of the switching unit 140 will be described with reference to FIG. 3.

FIG. 3 is a circuit diagram illustrating a circuit configuration of the first switching unit 142 and the second switching unit 144 and a connection structure of the RF receiving terminal 112 according to an embodiment of the present invention.

Referring to FIG. 3, the first switching unit 142 and the second switching unit 144 according to an embodiment of the present invention include two capacitors connected in series to an I signal receiving path and a Q signal receiving path, respectively, and an input side. The terminal is connected in parallel with the capacitor and the output terminal is composed of two switching elements connected with the ground terminal.

The carrier processing stage 130 includes reception filters 136a and 136b connected to the I signal path and the Q signal path after the signal separation unit 131, respectively, and the first switching unit 142 and the second switch. The switching unit 144 is connected between the reception filters 136a and 136b and the baseband processing stage 150, respectively.

In addition, the switching device is implemented as a semiconductor device integrated on a substrate, the control unit 160 may control the switching by applying a control voltage to the switching unit 140, the first and second switching unit ( 142 and 144 include a decoding circuit to analyze the control voltage and selectively open and close the switching circuit according to the analysis result.

The control unit 160 controls the first and second switching units 142 and 144 when the RF transmitter 112 is operating or when the signal transmitted through the reception signal path is a signal of an unwanted component. When the paths are blocked, and the I and Q signals are determined to be RFID reception signals, the first and second switching units 142 and 144 are controlled to connect the signal paths.

That is, when the signal paths are blocked, the switching elements S1 and S2 are connected to the ground terminal to isolate the received signal, and when the signal paths are connected, the switching elements S1 and S2 are open. ) State.

Therefore, when the RF signal is received from the RFID tag, the switching elements S1 and S2 of the first and second switching units 142 and 144 connect the I signal and Q signal paths, and the RF received from the RFID tag. The signal is passed through the capacitor to the A / D converter.

At this time, each capacitor blocks the signal of the DC component that can be drawn through the switching elements S1, S2.

On the other hand, when the RF signal is not received from the RFID tag, the signal transmitted to the first and second switching units 142 and 144 is connected to the switching elements S1 and S2 to the ground terminal and the baseband processing stage 150. Is blocked.

In the following, the connection structure of the RF switching unit connected to the RF receiver 112 and the components of the RF receiver 112 will be described.

4 is a circuit diagram exemplarily illustrating a connection configuration between the RF switching unit 120 and the RF receiver 112 according to an exemplary embodiment of the present invention.

According to Figure 4, the RF switching unit 120 according to an embodiment of the present invention, one terminal is connected in parallel to the RF receiving terminal 112, the other terminal is connected to the ground terminal, as described above The RF receiver 112 includes a reception amplifier 112a and a reception filter 112b.

 The RF switching unit 120 is connected to the signal path of the RF receiver 112, and when the RF transmitter 114 is operated or a signal transmitted through the signal path is determined to be a signal of an unwanted component, the RF switching The unit 120 blocks the signal path according to a control signal, and when it is determined that the signal received by the antenna is an RFID reception signal, the RF switching unit 120 connects the signal path according to the control signal.

When the signal path is blocked, the RF switching unit 120 is connected to the ground terminal to isolate the signal, and when the signal path is connected, the RF switching unit 120 is connected to the S terminal.

At this time, the S terminal is a resistance component of infinite impedance is connected or short-circuited, when the switching circuit of the RF switching unit 120 is connected to the S terminal, the signal received by the antenna can be delivered to the RF receiver 112. Make sure

The RF receiver 112 includes a reception amplifier 112a and a reception filter 112b. The reception amplifier 112a suppresses noise components of the RF signal received from the antenna as much as possible and amplifies only the RFID reception signal. A low noise / automatic control amplifier may be used, and the reception filter 112b may use a low pass filter (LPF) that removes noise of high frequency components and filters the received signal.

However, the RF switching unit 120 may be configured to be connected in series to the RF receiver 112 to perform the same function, and may be implemented through a semiconductor switching device such as a single pole double throw (SPDT).

Hereinafter, when the DC offset is removed, the output characteristics of the RFID transceiver 100 will be described.

5 is a graph measuring output voltages of an RF receiver and an RF transmitter according to a case where an RFID transceiver according to an embodiment of the present invention transmits and receives a signal.

According to FIG. 5, the x-axis means measurement time and uses units of [ms], and the y-axis means voltage and uses units of [Volt].

The RF signal is not received from the RFID tag when the measurement time is t0 to t1, and the RF signal is received from the RFID tag when the measurement time is t1 to t2.

Therefore, when the measurement time is in the period t0 to t1 (when no RF signal is received from the RFID tag), the RF switching unit 120 is connected to the ground terminal and the first and second switching units 142 and 144 The switching elements S1 and S2 are connected to the ground terminal, so that the incoming transmission signal and the signal of the unwanted component are isolated through the ground.

In addition, when the measurement time is a period t1 ~ t2 (when an RF signal is received from the RFID tag), the RF switching unit 120 is connected to the S terminal, the switching element S1 of the first switching unit 142 Is the I signal path, and the switching element S2 of the second switching unit 144 is connected to the Q signal path.

Looking at the graph measuring the output of the RFID transceiver 100, there are shown two measurement lines, the upper measurement line (channel 1) is the voltage measured on the RF transmitter end 114 side, the lower measurement line (Channel 2) measures the voltage at the RF receiver 112 side.

When the measurement time is in the period t0 to t1, for example, when the transmission signal is processed, the voltage at the RF transmitter 114 may be maintained at about 5V, while the voltage at the RF receiver 112 may be maintained at about 0V. .

In addition, when the measurement time is in the period t1 to t2, that is, when the received signal is processed, the voltage at the RF receiver 112 is maintained at about 900 mV, and the rising edge is almost vertical. .

The present invention has been described above with reference to the preferred embodiments, which are merely examples and are not intended to limit the present invention, and those skilled in the art to which the present invention pertains do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications are not possible that are not illustrated above. For example, each component specifically shown in the embodiment of the present invention can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

According to the RFID transceiver according to the present invention, it is possible to implement a product having improved reception performance by using a basic device having a low cost, and improve the isolation of the receiver to improve transmission and reception data error rate and stability due to changes in the radio wave environment. In addition, the recognition distance can be improved.

In addition, since the inflow of power from the transmitting end to the receiving end is doubled, the reception sensitivity can be improved by 3 to 4 dB or more and the spurious phenomenon can be suppressed from the receiving end, thereby reducing the probability of malfunction at the receiving end. .

Claims (7)

An RFID transceiver having an RF transmitting / receiving end and a carrier processing end, A signal separation unit provided in the carrier processing stage for separating and transmitting an RFID received signal into an I (In-Phase) signal and a Q (Quadrature-Phase) signal; A switching unit connected to the I and Q signal paths; And a control unit for controlling the switching unit according to whether the RF transmitter is operating or receiving a signal of an undesired wave component in the signal path. The method of claim 1, RFID transceiver further comprises an RF switching unit connected to the RF receiver. The method of claim 1, wherein the switching unit A first switching unit connected to the I signal path; And A second switching unit connected to the Q signal path, And blocking the signal paths, comprising a ground terminal to isolate the received signal. The method of claim 2, wherein the RF switching unit In blocking the signal path of the RF receiver, the RFID transceiver comprising a ground terminal to isolate the received signal. The method of claim 2, The RF receiver has an automatic control amplifier, The RF switching unit is an RFID transceiver, characterized in that connected to the RF receiver in series or in parallel. The method of claim 1, The carrier processing stage includes a reception filter connected to the I signal path and the Q signal path after the signal separation unit, And the switching unit is connected to a rear end of the reception filter. The method of claim 1, wherein the control unit When the RF transmitter is operated or a signal received through the signal path is determined to be a signal of an unwanted component, the signal path of the switching unit is blocked, and when the signal received through the signal path is determined to be an RFID reception signal, the switching unit is connected. RFID transceiver, characterized in that.

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