KR20110027145A - Reader of rfid - Google Patents

Abstract

PURPOSE: An RFID reader is provided to improve the signal receiving sensitivity by reducing noise of AC power which is reflected in a signal receiving mode. CONSTITUTION: A control unit(21) performs overall operation control. An oscillation unit(25) generates oscillation signals in different phase. A transmission unit(221) transmits the transmission signal from control unit to the RFID tag. A reception unit(261) inputs the received signal from the RFID tag to the control unit. Therefore, the signal sensitivity is improved by reducing noise of AC power which is reflected in signal receiving mode.

Description

Reader of RFID {Reader of RFID}

The present invention relates to an RFID reader, and more particularly, to an RFID reader that transmits an AC power source to an RFID tag in a reception mode.

1 shows a system of a typical RFID.

Referring to FIG. 1, in a typical RFID system, each of the readers 111a to 111m of the RFID includes tags 121a to 121n and 191a to a plurality of RFIDs. Tag information is received from 191n and transmitted to the host device 32 via the communication network 31.

Each of the readers 111a to 111m of the RFID includes a controller, an oscillator, a transmitter, and a receiver.

Each of the readers 111a to 111m of the RFID transmits AC power to the tag of the RFID in the reception mode.

As is well known, in the transmission section of each of the RFID readers 111a to 111m, the digital-analog converter uses the first analog differential signal and the second analog differential signal using data for transmission from the control section. These signals pass through a base frequency filter and a transmitting up-mixer and are combined in a transmitting BALUN (BALance to UNbalance transformer) to be transmitted to a tag of an RFID.

Here, each of the readers 111a to 111m of the RFID transmits an AC power to a tag of the RFID in a reception mode, and a part of the AC power may be reflected by the transmit / receive antenna.

In this case, the noise figure of the base frequency filter in the transmitter is relatively large, and there is a fundamental problem in that the reception sensitivity is lowered due to the noise of the AC power reflected in the reception mode.

It is an object of the present invention to provide a reader of an RFID which can fundamentally improve reception sensitivity.

The reader of the RFID of the present invention includes a controller, an oscillator, a transmitter, and a receiver.

The control unit performs the overall control.

The oscillator generates oscillation signals of different phases.

The transmitter transmits the transmission signal from the controller to the tag of the RFID while using the oscillation signals from the oscillator.

The receiver inputs the received signal from the tag of the RFID to the controller while using the oscillation signals from the oscillator.

Here, the transmitter further includes a DC-power supply circuit, where AC power to be transmitted to the tag of the RFID in the reception mode is generated by the DC-power supply circuit.

According to the reader of the RFID of the present invention, a direct and stable DC power can be generated in the DC power supply circuit further included in the transmitter.

Therefore, since the noise of the AC power reflected in the reception mode is greatly reduced, the reception sensitivity can be fundamentally improved.

Figure 2 shows the internal configuration of the reader of the RFID (RFID) according to a first embodiment of the present invention.

2, the reader of the RFID according to the present invention includes a controller 21, an oscillator 25, a transmitter 221 to 228, and a receiver 261 to 266i and 266q.

The control unit 21 performs overall control.

In more detail, the control part 21 outputs the data for transmission St to the transmission parts 221-228, generating control signals Scon in each part. The control unit 31 also modulates and decodes the data Srq of the Q signal and the data Sri of the I signal from the receivers 261 to 266i and 266q, and transmits them to the host device (32 in FIG. 1).

The oscillator 25 generates oscillation signals of different phases. Here, the oscillation signals from the oscillator 34 are oscillation signals of 0 ^o phase, oscillation signals of 90 ^o phase, oscillation signals of 180 ^o phase, and oscillation signals of 270 ^o phase.

The transmitters 221 to 228 transmit the transmission signal St from the controller 21 to the tag of the RFID while using the oscillation signals from the oscillator 25.

The receivers 261 to 266i and 266q input the received signal from the RFID tag to the controller 21 while using the oscillation signals from the oscillator 25.

Here, the transmitters 221 to 228 further include the DC-power supply circuits 223, 224, Va, and Vb, so that the AC power to be transmitted to the tag of the RFID in the reception mode is the DC-power supply circuit 223, 224. , Va, Vb).

Accordingly, direct and stable DC power may be generated in the DC-power supply circuits 223, 224, Va, and Vb further included in the transmitters 221 to 228.

Therefore, since the noise of the AC power reflected in the reception mode is greatly reduced, the reception sensitivity can be fundamentally improved.

Meanwhile, the reader of the RFID according to the present invention includes a transmission / reception antenna 24 and a signal branch element 23. The signal branch element 23 applies the transmission signal from the transmission units 221 to 228 to the transmission and reception antenna 24, and inputs the reception signal from the transmission and reception antenna 24 to the reception units 261 to 266i and 266q.

The transmitters 221 to 228 include a digital-to-analog converter (DAC) 221, a base frequency filter 222, and a transmission up-mixer 225.

The digital-to-analog converter (DAC) 221 generates a first analog differential signal and a second analog differential signal using the data St for transmission from the control unit 21.

The base frequency filter 222 passes only the signals of the base frequency to remove the noise of the first analog differential signal and the second analog differential signal from the digital-to-analog converter (DAC) 221 to remove the base frequency. The first differential signal and the second differential signal are output.

Transmitting up-mixer (Up-Mixer, 225) is a first differential of a radio frequency by mixing with 0 ^o-phase oscillation signals from the first differential signal from the for base frequency filter 222, an oscillating portion 25, the signal (St + ), And the second differential signal from the base frequency filter 222 is mixed with the 180 ^o phase oscillation signal from the oscillator 25 to generate a second differential signal St- of radio frequency.

For reference, when the frequency of the differential signals from the base frequency filter 222 is fb and the frequency of the oscillation signals from the oscillator 25 is fm, the differential signal from the transmitting up-mixer 225 The frequencies ff of the fields St + and St− are obtained by Equation 1 below.

ff = fb + fm

In Equation 1, the frequency fm of the oscillation signals from the oscillator 25 is obtained by Equation 2 or Equation 3 below.

fm = fmp + fn

fm = fmp-fn

In Equations 2 and 3, fmp indicates the frequency of the oscillation signals in the previous period. fn indicates the spacing frequency to be increased or decreased according to the well-known adaptive frequency hopping algorithm.

Here, DC-power supply circuits 223, 224, Va, and Vb, which are further included in the transmitters 221 to 228, are connected between the base frequency filter 222 and the up-mixer 225 for transmission.

More specifically, the DC-power supply circuits 223, 224, Va, and Vb further included in the transmitters 221 to 228 may include a first DC power supply Va, a second DC power supply Vb, and a first switch 223. And a second switch 224.

The first DC power supply Va has the same voltage as the first differential signal from the base frequency filter 222.

The second DC power supply Vb has the same voltage as the second differential signal from the base frequency filter 222.

The first switch 223 operated by the control unit 21 inputs the first differential signal from the base frequency filter 222 to the up-mixer 225 for transmission in the transmission mode, and receives the reception mode. Inputs the voltage of the first DC power supply Va to the up-mixer 225 for transmission.

The second switch 224 operated by the control unit 21 inputs the second differential signal from the base frequency filter 222 to the up-mixer 225 for transmission in the transmission mode, and receives the reception mode. Inputs the voltage of the second DC power supply Vb to the up-mixer 25 for transmission.

In summary, a stable first DC power supply Va in the DC-power supply circuits 223, 224, Va and Vb without using the first and second differential signals from the base frequency filter 222 in the receive mode. ) And the voltage of the second DC power supply (Vb) are used.

Therefore, since the noise of the AC power reflected in the reception mode is greatly reduced, the reception sensitivity can be fundamentally improved.

Furthermore, the transmitters 221 to 228 include radio frequency amplifiers DA and 226, a transmission balun BALUN (BALance to UNbalance transformer 227), and a power amplifier PA (228).

The RF amplifiers 226 primarily amplify the power of the first differential signal St + and the second differential signal St− from the up-mixer 225 for transmission.

The transmission balun BALUN 227 combines the first differential signal and the second differential signal from the radio frequency amplifiers DA 226 to generate a transmission signal.

The power amplifiers PA and 228 finally amplify the power of the transmission signal from the transmission balun BALUN 227 and input it to the signal branch element 23.

Meanwhile, the receivers 261 to 266i and 266q include a reception balun (BALUN: BALance to UNbalance transformer, 261), a Q signal down mixer (Down-Mixer, 263q), and an I signal down mixer (Down-Mixer, 263i). do.

The receiving balun BALUN 261 receives the received signals from the signal branch elements 23 into a first differential signal Sr + and a second differential signal Sr− having a phase difference of 180 ^° (π) from each other. Convert.

The downlink mixer 263q for the Q signal mixes the first differential signal Sr + from the receiving balun BALUN 261 with the oscillation signal of 90 ^o phase from the oscillator 25 to form a base frequency Q + differential signal Srq +. And a second differential signal (Sr-) from the receiving balun (BALUN) 261 with an oscillation signal of 270 ^o phase from the oscillator 25 to generate a base frequency Q-differential signal (Srq-). Generates.

The downlink mixer 263i for the I signal mixes the first differential signal Sr + from the receiving balun BALUN 261 with an oscillation signal of 0 ^o phase from the oscillator 25 to generate a base frequency I + differential signal Sri +. Is generated, and the second differential signal Sr- from the receiving balun BALUN 261 is mixed with the 180 ^o phase oscillation signal from the oscillator 25 to generate the base frequency I-differential signal Sri-. Generates.

For reference, when the frequency of the differential signals from the receiving balun BALUN 261 is ff and the frequency of the oscillation signals from the oscillator 25 is fm, the differential signals from the down mixers 263q and 263i ( The frequencies fb of Srq +, Srq-, Sri +, and Sri-) are obtained by the following equation (4).

fb = ff-fm

In Equation 4, the frequency fm of the oscillation signals from the oscillator 25 is obtained by Equations 2 or 3 above.

Further, the receivers 261 to 266i and 266q include the Q amplifier differential amplifier 264q, the I signal differential amplifier 264i, the Q signal low pass filter 265q, the I signal low pass filter 265i, the first analogue- Digital converter 266q and second analog-to-digital converter 266i.

The Q signal differential amplifier 264q amplifies the difference signal between the Q + differential signal Srq + and the Q- differential signal Srq- from the down mixer 263q for the Q signal to generate a Q signal.

The differential amplifier 264i for the I signal amplifies the difference signal between the I + differential signal Sri + and the I− differential signal Sri− from the down mixer 263i for the I signal to generate an I signal.

The low pass filter 265q for the Q signal removes the high frequency noise of the Q signal from the Q amplifier differential amplifier 264q and inputs it to the first analog-to-digital converter 266q.

The low pass filter 265i for the I signal removes the high frequency noise of the I signal from the differential amplifier 264i for the I signal and inputs it to the second analog-to-digital converter 266i.

The first analog-to-digital converter 266q converts the Q signal from the low pass filter 265q for the Q signal into a digital signal Srq and inputs it to the control unit 21.

The second analog-to-digital converter 266i converts the I signal from the low pass filter 265i for the I signal into a digital signal Sri and inputs it to the control unit 21.

Figure 3 shows the internal configuration of the reader of the RFID (RFID) according to a second embodiment of the present invention. In FIG. 3, the same reference numerals as used in FIG. 2 indicate objects of the same function. Therefore, only the difference with FIG. 2 in FIG. 3 is as follows.

The DC-power supply circuits 223, 224, 220, 229, and V ₁ to V _N further included in the transmitters 221 to 228 may include a plurality of voltages having different voltages so that a user selects the first DC power supply (Va in FIG. 2). A plurality of DC power supplies further comprising a first selection switch 220 of DC power supplies (V ₁ to V _N ), so that a user selects the second DC power supply (Vb in FIG. 2). And a second selection switch 229 of (V ₁ to V _N ).

Accordingly, the convenience of voltage selection can be enhanced.

Figure 4 shows the internal configuration of the reader of the RFID (RFID) according to a third embodiment of the present invention. In FIG. 4, the same reference numerals as used in FIG. 3 indicate objects of the same function. Therefore, only the difference with FIG. 3 in FIG. 4 is as follows.

In the DC-power supply circuits 223, 224, 220, 229, 41, 42, and V ₁ to V _N further included in the transmitters 221 to 228, a first voltage is provided between the first selection switch 220 and the first switch 223. A follower 41 is connected and a second voltage follower 42 is connected between the second selector switch and the second switch.

Accordingly, a constant DC voltage can be transmitted without being affected by the output state.

5 shows an internal configuration of a reader of an RFID according to a fourth embodiment of the present invention. In FIG. 5, the same reference numerals as used in FIG. 3 indicate objects of the same function. Therefore, only the difference with FIG. 3 in FIG. 5 is as follows.

In the DC-power supply circuits 223, 224, 220, 229, 51, and V ₁ to V _N further included in the transmitters 221 to 228, the plurality of DC power supplies V ₁ to V _N and the first selection switch 220. ) And a plurality of voltage followers 51 between the plurality of DC power supplies V ₁ to V _N and the second selection switch 229.

Accordingly, a constant DC voltage can be transmitted without being affected by the output state.

6 shows an internal configuration of a reader of an RFID (RFID) according to a fifth embodiment of the present invention. In FIG. 6, the same reference numerals as used in FIG. 2 indicate objects of the same function. Therefore, only the difference with FIG. 2 in FIG. 6 is as follows.

The DC-power supply circuits 61 to 66 further included in the transmitters 221 to 228 include the first A switch 61, the first capacitor 62, the second A switch 63, the first B switch 64, A second capacitor 65 and a second B switch 66;

FIG. 7 is a timing diagram for describing an operation of the DC-power supply circuit of FIG. 6. In FIG. 7, Tc denotes a charging time of the first capacitor 62 (62 of FIG. 6) and the second capacitor (65 of FIG. 6), and St denotes a differential signal from the base frequency filter 222, S _SW1. Is the control signal applied equally to the 1A switch 61 and the 1B switch 64, S _SW2 is the control signal applied equally to the 2A switch 63 and the 2B switch 66, and Vc Denotes the charging voltage of the first capacitor 62 (FIG. 6) or the second capacitor 65 (FIG. 6), respectively.

6 and 7, the operation of the DC-power supply circuits 61 to 66 of FIG. 6 will be described as follows.

At the initial time Tc of the reception mode, the first A switch 61 and the first B switch 64 are in an on state, and the second A switch 63 and the second B switch 66 are in an "a" contact state. to be.

Accordingly, at the initial time Tc of the reception mode, the first capacitor 62 is charged by the first differential signal (DC voltage in the reception mode) from the base frequency filter 222, and the base frequency filter ( The second capacitor 65 is charged by the second differential signal (DC voltage in the reception mode) from 222. In addition, a first differential signal and a second differential signal from the base frequency filter 222 are input to the up-mixer 225 for transmission, respectively.

Next, in the reception mode, the first A switch 61 and the first B switch 64 are in an off state, and the second A switch 63 and the second B switch 66 are in a "b" contact state.

Accordingly, in the receiving mode, the voltage due to the charging of the first capacitor 62 and the voltage due to the charging of the second capacitor 65 are input to the up-mixer 225 for transmission, respectively.

Next, in the transmission mode, the first A switch 61 and the first B switch 64 are in an off state, and the second A switch 63 and the second B switch 66 are in an "a" contact state.

Accordingly, in the transmission mode, the first differential signal and the second differential signal from the base frequency filter 222 are input to the up-mixer 225 for transmission, respectively.

According to the DC-power supply circuits 61 to 66 operating as described above, there is an additional effect that it is not necessary to use a separate DC power supply.

Figure 8 shows the internal configuration of the reader of the RFID (RFID) according to a sixth embodiment of the present invention. In FIG. 8, the same reference numerals as used in FIG. 6 indicate objects of the same function. Therefore, only the difference with FIG. 6 in FIG. 8 is as follows.

In the DC-power supply circuits 61 to 66, 81 and 82 further included in the transmitters 221 to 228, a first voltage follower between the first capacitor 62 and the second A switch 63, 81 is additionally connected, and a second voltage follower 82 is additionally connected between the second capacitor 65 and the second B switch 66.

That is, in the reception mode, the voltage due to the charging of the first capacitor 62 is input to the uplink mixer 225 for transmission through the first voltage follower 81, and the voltage due to the charging of the second capacitor 65 is input. It is input to the uplink mixer 225 for transmission via the second voltage follower 82 (see FIG. 7).

Accordingly, a constant DC voltage can be transmitted without being affected by the output state.

As described above, according to the reader of the RFID according to the present invention, a direct and stable DC power can be generated in the DC power supply circuit further included in the transmitter.

Therefore, since the noise of the AC power reflected in the reception mode is greatly reduced, the reception sensitivity can be fundamentally improved.

It may be used in systems that require transmission signals for reception in general wireless communications, such as radar (RAdio Detecting And Ranging) systems.

FIG. 1 is a diagram illustrating a system of RFIDs, in which readers of general RFIDs receive tag information from tags of a plurality of RFIDs and transmit the tag information to a host device.

2 is a diagram illustrating an internal configuration of a reader of an RFID according to a first embodiment of the present invention.

3 is a diagram illustrating an internal configuration of a reader of an RFID according to a second embodiment of the present invention.

4 is a diagram illustrating an internal configuration of a reader of an RFID according to a third embodiment of the present invention.

FIG. 5 is a diagram illustrating an internal configuration of a reader of an RFID according to a fourth embodiment of the present invention.

6 is a diagram illustrating an internal configuration of a reader of an RFID according to a fifth embodiment of the present invention.

FIG. 7 is a timing diagram for describing an operation of the DC-power supply circuit of FIG. 6.

8 is a diagram illustrating an internal configuration of a reader of an RFID according to a sixth embodiment of the present invention.

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

21 control unit, 221 to 228 transmission unit,

261 to 266i, 266q ... receiver, 23 ... signal branch element,

24 transmit and receive antennas, 25 oscillator,

222 ... filter for base frequency, 225 ... up-mixer for transmission,

223,224, Va, Vb ... DC-power supply circuit,

223,224,220,229, V ₁ to V _N ... DC-power supply circuit,

223,224,220,229,41,42, V ₁ to V _N ... DC-power supply circuit,

223,224,220,229,51, V ₁ to V _N ... DC-power supply circuit,

61 to 66. DC-power supply circuit,

61 to 66,81,82 ... DC-power supply circuit.

Claims (15)

A control unit for performing overall control; An oscillator for generating oscillation signals of different phases, A transmitting unit which transmits a transmission signal from the control unit to a tag of an RFID while using the oscillation signals from the oscillating unit, and A receiving unit for inputting a received signal from a tag of the RFID to the controller while using the oscillating signals from the oscillating unit, The transmitter further comprises a DC-power supply circuit, The reader of the RFID, wherein the AC power to be transmitted to the tag of the RFID in the reception mode is generated by the DC-power supply circuit. The method of claim 1, Transmit and receive antennas; And And a signal branch element for applying a transmission signal from the transmission unit to the transmission / reception antenna and inputting a reception signal from the transmission / reception antenna to the reception unit. The method of claim 2, wherein the transmitting unit, A digital-analog converter for generating a first analog differential signal and a second analog differential signal using data for transmission from the control unit; To remove noise of the first analog differential signal and the second analog differential signal from the digital-to-analog converter, a base frequency for passing only the base frequency signals and outputting the first differential signal and the second differential signal of the base frequency Filter for; And A first differential signal from the base frequency filter is mixed with an oscillation signal of 0 ^o phase from the oscillator to generate a first differential signal St + of radio frequency, and a second differential signal from the base frequency filter. The RFID reader including an up-mixer for transmitting a second differential signal (St-) of a radio frequency by mixing with an oscillation signal of 180 ^o phase from the oscillator. The method of claim 3, And a DC-power supply circuit further included in the transmitting unit is connected between the base frequency filter and the transmitting up-mixer. According to claim 4, DC-power supply circuit further included in the transmission unit, A first DC power supply having the same voltage as the first differential signal from said base frequency filter; A second DC power supply having the same voltage as the second differential signal from the base frequency filter; In a transmission mode, a first differential signal from the base frequency filter is input to the transmission up-mixer, and in the reception mode, the voltage of the first DC power supply is applied to the transmission up-mixer. A first switch to be inputted to; And The second differential signal from the base frequency filter is input to the up-mixer in the transmission mode in the transmission mode, and the voltage of the second DC power supply is supplied to the up-mixer in the reception mode. RFID reader including a second switch to be input to the mixer. According to claim 5, DC-power supply circuit further included in the transmitting unit, Further comprising a first selection switch of a plurality of DC power supplies having different voltages for a user to select the first DC power supply, And a second selection switch of a plurality of DC power supplies having different voltages to allow a user to select the second DC power supply. According to claim 6, DC-power supply circuit further included in the transmitter, A first voltage follower is connected between the first selector switch and the first switch, And a reader of an RFID, wherein a second voltage follower is connected between the second selector switch and the second switch. According to claim 6, DC-power supply circuit further included in the transmitter, And a plurality of voltage followers connected between the plurality of DC power supplies and the first selection switch and between the plurality of DC power supplies and the second selection switch. According to claim 4, DC-power supply circuit further included in the transmission unit, A first capacitor and a second capacitor, The first capacitor is charged by a first differential signal from the base frequency filter at an initial time of the reception mode, The second capacitor is charged by a second differential signal from the base frequency filter at the initial time of the receive mode, And the voltage of the first capacitor and the voltage of the second capacitor are respectively input to the transmitting up-mixer in the reception mode. The DC-power supply circuit of claim 9, further comprising: a transmitter; And a first differential signal from the base frequency filter and a second differential signal are respectively input to the transmitting up-mixer at an initial time of the reception mode. The DC power supply circuit of claim 10, further comprising: a transmitter; And a first differential signal from the base frequency filter and a second differential signal are respectively input to the transmitting up-mixer in the transmission mode. 12. The DC-power supply circuit of claim 11, further comprising a transmitter. In the receiving mode, a voltage due to charging of the first capacitor is input to the transmitting up-mixer through a first voltage follower, And the voltage of the second capacitor in the receiving mode is input to the transmitting up-mixer via a second voltage follower. The method of claim 3, wherein the transmitting unit, A radio frequency amplifier for first amplifying the power of the first differential signal St + and the second differential signal St− from the transmitting up-mixer; A transmission balun (BALUN: BALance to UNbalance transformer) for generating a transmission signal by combining a first differential signal and a second differential signal from the radio frequency amplifier; And And a power amplifier which finally amplifies the power of the transmission signal from the transmission balun and inputs the signal to the signal branch element. The method of claim 2, wherein the receiving unit, BALUN: BALance to UNbalance for converting the received signal from the signal branch element into a first differential signal Sr + and a second differential signal Sr- having a phase difference of 180 ^o (π). transformer); The first differential signal Sr + from the receiving balun BALUN is mixed with the oscillation signal of 90 ^o phase from the oscillator to generate a Q + differential signal Srq + of the base frequency, and the receiving balun BALUN A down-mixer for a Q signal which generates a base frequency Q-differential signal (Srq-) by mixing a second differential signal (Sr-) from the oscillation signal with a 270 ^o phase oscillation signal from the oscillator; And A first differential signal Sr + from the receiving balun BALUN is mixed with an oscillation signal of 0 ^o phase from the oscillator to generate an I + differential signal Sri + of a base frequency, and the receiving balun BALUN RF including a down-mixer for the I signal which generates a base frequency I-differential signal (Sri-) by mixing a second differential signal (Sr-) from the oscillator with a 180 ^o phase oscillation signal from the oscillator. ID reader. The method of claim 14, wherein the receiving unit, A Q-signal differential amplifier for generating a Q signal by amplifying a difference signal between the Q + differential signal Srq + and the Q- differential signal Srq− from the down mixer for the Q signal; An I-signal differential amplifier for generating an I signal by amplifying a difference signal between the I + differential signal Sri + and the I- differential signal Sri- from the down mixer for the I signal; A low pass filter for the Q signal which removes high frequency noise of the Q signal from the Q amplifier differential amplifier and inputs it to the first analog-to-digital converter; A low pass filter for the I signal that removes high frequency noise of the I signal from the differential amplifier for the I signal and inputs it to the second analog-to-digital converter; A first analog-to-digital converter converting the Q signal from the low pass filter for the Q signal into a digital signal Srq and inputting the digital signal to the controller; And And a second analog-to-digital converter for converting the I signal from the low pass filter for the I signal into a digital signal Sri and inputting the digital signal to the controller.

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