JP2008022045A - Receiver, transmitter and data communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver, a transmitter and data communication system materializing an inexpensive RFID and a tag in which a local oscillation circuit needing a high frequency amplifier circuit in IF or an intermediate frequency amplifier circuit for mixing a high frequency received signal around a high frequency carrier with another high frequency to produce an intermediate frequency is not provided into a card, and the local oscillation circuit is provided in the transmitter, the transmitter generates a local oscillation signal and transmits the local oscillation signal together with a transmission signal, a mixer in the card obtains a signal with a frequency lower than the original frequency signal by the intermediate frequency, and the card amplifies or demodulates the obtained signal. <P>SOLUTION: The receiver includes an antenna for separately receiving two frequencies, the mixer for mixing a first received signal including a signal to be modulated with a second received signal having frequency different from the frequency of the first received signal, and a filter for generating the intermediate frequency including the signal to be modulated from a received signal resulting from mixing the two received signals in the mixer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a receiver, a transmitter, and a data communication system, and more specifically, data communication that uses a card-like receiver or transmitter, such as RFID (Radio Frequency Identification) or a tag, to transmit and receive data wirelessly. About the system.

  Conventionally, in so-called RFID that performs non-contact authentication using radio, data is transmitted / received to / from the host side (transmitter) in a non-contact manner and requires only a passive operation without requiring a battery. A card or tag having a function of receiving and possibly transmitting a card has been proposed in Patent Document 1 and the like. For wireless reception used for such transmission / reception, the transmitted wireless power is regenerated as a power source, the power as a power source is simply transmitted and received at the card side, and the data to be transmitted by the card is determined by the power. In the case of transmission, a receiver with high frequency may be required, such as amplifying a frequency used for radio while using the same power to demodulate transmission data on the host side.

  In addition, the frequency band used for wireless communication has been widely used in the past because the recent RFID technology often appears to have been completed due to the miniaturization and cost reduction of IC chips used in RFID. In addition to the modulation type of about 120 to 135 kHz or 13.56 MHz band, the microwave band of 860 to 960 MHz, the 2.45 GHz band, and the like are used. In addition to simply generating a reproduction DC power supply on the card side and generating and sending back an ID modulation signal with this power supply, the function of demodulating the data signal modulated on the host side and displaying or recording on the card side is provided. It may be necessary. In any of these cases, the fact that a high-frequency amplifier can be used by using regenerative power has a much higher utility value than when only a passive circuit is used in the circuit configuration.

In general, the transmitter on the host side in these transmission / reception systems has a silicon-based circuit, and since there are few, there is a degree of freedom to mount a high-speed response circuit, but the receiver on the card side is extremely small and inexpensive. There are various restrictions on the circuit because it is required. In particular, when creating extremely inexpensive receiver systems that are made of organic semiconductors and are capable of printing a large number of cards, many are made only by passive operation, and organic FETs are used as active circuits. Often require a power source and are particularly limited in bandwidth.
JP 2005-176090 A

Thus, it is conceivable to use intermediate frequency amplification to down-convert the frequency. However, in order to perform local oscillation, a high frequency circuit is eventually required, and the high frequency circuit cannot be avoided. For example, the frequency used for the intermediate frequency amplification in FIG. 6 showing the configuration of the receiver of the conventional data communication system is to reduce the frequency related to the intermediate frequency amplification as much as possible. A frequency comparable to the carrier frequency f ₁ must be amplified. Therefore, a high frequency amplifier circuit is required for the local oscillation signal supplied from the intermediate frequency amplifier 605 to the local oscillator 603. In FIG. 6, the host machine is a conventional transmitter and is not shown. FIG. 7 is a block diagram showing another configuration of the receiver of the conventional data communication system. In this example, the amplifier used for the received signal needs to use a high-frequency amplifier. As shown in FIG. 7, when the configuration is simpler than that of FIG. 6, the reception data can be demodulated without using an amplifier by using a high frequency amplifier 701 which is a passive detection circuit. However, stable operation due to feedback necessary for gain adjustment for demodulating the received signal cannot be expected.

The present invention is for solving these problems, and a high frequency amplification is performed in an IF or intermediate frequency amplification circuit for mixing a high frequency reception signal centering on a high frequency carrier wave with another high frequency to generate an intermediate frequency. A local oscillator circuit that requires a circuit is not provided in the card, but is placed on the transmitter side, generated, transmitted with the signal, and mixed with the local oscillation signal received by the card from the original signal due to the intermediate frequency An object of the present invention is to provide a transmitter, a receiver, and a data transmission / reception system for obtaining a low-frequency signal, amplifying or demodulating it, and realizing an inexpensive RFID and tag.

  In order to solve the above problems, the receiver of the present invention has an antenna that receives two frequencies separately, and further includes a first received signal including a modulated signal, a first received signal, Is characterized by having a mixer for mixing the second received signals having different frequencies and a filter for generating an intermediate frequency including the modulated signal from the received signals mixed by the mixer. Accordingly, the first reception signal including the data signal can be converted into a low-frequency modulation signal without using a local oscillation circuit that requires a high-frequency amplifier circuit in the card-like receiver, and the organic semiconductor transistor is used. Signal processing using an amplifier circuit becomes possible. In particular, since an amplifier circuit using an organic FET that can be manufactured by a printing technique can be manufactured, an inexpensive receiver can be easily manufactured.

  In addition, by having a gain adjustment circuit that adjusts the gain of the second received signal by the MOS capacitance, the gain adjustment of the local oscillation signal for generating the intermediate frequency of the receiver can be changed by applying a DC bias. With the change of the cutoff frequency of the low-pass filter due to the change of the capacity, the gain control of the second received signal at a frequency higher than the vicinity of the cutoff frequency becomes possible.

  Furthermore, the magnitude of the frequency of the modulated signal transmitted with the carrier wave of the first received signal is at least smaller than the magnitude of the difference frequency between the frequency of the first received signal and the second received signal, so The first received signal including the modulated signal is mixed with the second received signal and can be received and demodulated without the modulation degree of the frequency modulated signal to the low frequency including the modulated signal obtained through the filter being greater than 1.

  Also, by having a DC power supply regeneration circuit that detects the second received signal as power in the receiver and obtains a DC power supply, the transmission power by the transmitter of the first received signal including the modulated data signal is affected. The power by the second transmission signal, which is a local oscillation signal that is not given, can be used as a power source for an amplifier in the receiver.

  Furthermore, it has a modulation part which modulates the response signal with respect to the signal of the 1st received signal with the harmonic which generate | occur | produced the 2nd received signal as it is or through a non-linear element or a non-linear circuit, and the response signal modulated by this modulation part Is transmitted from the receiver to the transmitter side by using the second received signal that hardly affects the first received signal including the modulated wave that is the data signal by the transmitter and using its harmonics. It is now possible to make it difficult to influence the transmission signal.

  In addition, by transmitting the modulated wave to the transmitter side using the same antenna when the second received signal is received, the second frequency harmonic used as the local oscillation signal is used, so Without receiving interference when the first transmission signal is received by the receiver, the antenna on which the receiver receives the second transmission signal from the transmitter can be used as it is, and can be received by the antenna used for transmission of the transmitter. It became so.

  Furthermore, a transmitter according to another invention is characterized in that it transmits a first transmission signal including a modulated signal and transmits a second transmission signal different from the first transmission signal. Therefore, the local oscillation circuit used for frequency conversion of the receiver can be shared by the transmitter side in which the high frequency amplifier circuit can be incorporated.

  Further, the magnitude of the frequency of the modulated signal transmitted together with the carrier wave of the first transmission signal is at least smaller than the magnitude of the difference frequency between the frequency of the first transmission signal and the second transmission signal. Therefore, the modulation degree of the frequency modulation signal to the low frequency including the modulated signal obtained by mixing the first received signal including the modulated signal in the receiver with the second received signal through the filter is greater than 1. Can be received and demodulated.

  Furthermore, the data communication system as another invention is characterized by being constructed including the receiver and the transmitter. Therefore, a local oscillation circuit that requires a high-frequency amplifier circuit is not provided in the card, but is generated by being arranged on the transmitter side, transmitted together with the signal, and mixed with the local oscillation signal received by the card. A signal having a lower frequency than the above signal can be obtained and amplified or demodulated.

  According to the data communication system of the present invention, it is possible to construct a low frequency amplifier circuit without using a high frequency circuit by eliminating the need for a local oscillator in the receiver. A signal having a lower frequency than the original signal due to the intermediate frequency can be obtained and amplified or demodulated by the mixer together with the local oscillation signal transmitted and received by the card.

FIG. 1 is a block diagram showing a system configuration of a data communication system according to a first embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 6 denote the same components. Note that the power supply used in each amplifier is not entered. The receiver 100 of this embodiment shown in the figure has a configuration different from that of the conventional receiver 600 shown in FIG. 6, and a local oscillator 201 is provided on the transmitter 200 side instead of the local oscillator 603 that requires a high-frequency amplifier circuit. The second transmission signal f ₂ generated by the local oscillator 201 is sent to the mixer 602 through the narrow band antenna 202 of the transmitter 200 and the narrow band antenna 103 of the receiver 100. The mixer 602 ideally uses an element having a kind of multiplier characteristic such as a DBM (Double Balanced Mixer) or an FET capable of high-frequency amplification, but the impedance matching can be ensured. A passive configuration is possible with only two wires. Of course, there is no worry about bandwidth. In this way, since a high frequency generation circuit for generating a frequency comparable to the first transmission signal f ₁ used for local oscillation is not required, a high frequency circuit is used by eliminating the need for a local oscillator in the receiver 100. The low-frequency amplifier circuit 102 can also be configured without this. In other words, local oscillation, which is a part in charge of the high frequency circuit, is shared by the transmitter 200 on the host side. Note that a solar cell using an organic semiconductor, a battery that can be printed mainly using an organic material, or the like may be printed together with a circuit, or a DC power source that rectifies a signal received for local oscillation may be used.

In addition, the gain adjustment uses a resistor 302 and an organic semiconductor MOS structure diode 303 as in the gain adjustment control circuit 300 shown in FIG. The output signal 304 can be made as narrow as possible. Furthermore, since the capacitance changes depending on the DC component applied to the MOS capacitor portion of the low-pass filter, the gain curve can be changed within the range including the broken line in FIG. components representing the frequency of the second spectrum of the transmission signal f ₂ of when the input signal frequency higher than the vicinity of the cutoff frequency of the low pass filter can gain control. Since this portion uses high frequency, the transmission impedance of the wiring pattern is naturally matched as necessary. Similarly to the silicon-based MOS capacitor, the depletion layer changes due to the DC bias, and the capacitance can be changed. Therefore, by setting f ₁ and f ₂ so that (difference frequency with carrier wave | f ₁ −f ₂ |)> (frequency magnitude df of modulated signal), amplification at a low frequency is possible. become. The MOS capacitor is a MOS capacitor manufactured by printing using an organic semiconductor.

FIG. 4 is a block diagram showing a system configuration of a data communication system according to the second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same components. Since the circulator 501 of the transmitter 500 and the circulator 401 of the receiver 400 in FIG. 4 are manufactured in a stripline configuration, they can be realized in the range of a passive circuit. According to the second embodiment shown in FIG. 4, the second transmission signal f ₂ used for local oscillation is separated from the first transmission signal f _{1 including the} transmission data signal which is a modulated wave. Therefore, a carrier wave necessary for transmission from the DC power supply regeneration circuit 402 on the receiver 400 side or the receiver 400 side is further generated. That is, it is desirable that the frequency be different from the first transmission signal f ₁ as much as possible (and not a harmonic), and the passive nonlinear element 406 is used to transmit the signal as a sine wave, which is different from the _first transmission signal f _1. The incoming signal can be used after it is received as a sine wave with less distortion through a band filter (not shown). For example, as shown in FIG. 4, only the second harmonic is generated as a frequency of 2 × f ₂ through the bandpass filter 101 and is supplied to the mixer, whereby the transmission data on the receiver side is sent to the antenna by the modulator 403. 103 can be transmitted. Since originally a aerial 103 for f _2, by 2 × aerial 103 with relatively high efficiency in the transmission of the frequency of f ₂ it is possible transmission. The same applies to the antenna 202. A signal having a carrier frequency of 2 × f ₂ received through the antenna 202 on the transmitter side which is the host device is separated by the circulator 501 and amplified and detected through a circuit including the high frequency amplifier 502 on the transmitter side. The received data signal transmitted from can be demodulated. In FIG. 4, since the response signal on the receiver side returns to the transmitter side, the output of the local oscillator 201 can be adjusted in accordance with the response status. Therefore, adjustment means for stable transmission and reception is possible not only from the gain adjustment circuit implemented in the first embodiment shown in FIG. 1, but also from the transmitter side.

Such a data communication system not only allows the transmitter 500 to share high frequencies such as local oscillation, but also serves as a supply source for the DC regenerative power source as the main power by the DC power source regenerative circuit 402. It is possible to add efficient use for use as a carrier wave 2 × f ₂ for transmission from the transmitter 400 side to the transmitter 500 on the host side.

The feedback signal from the low-frequency amplifier 102 is a signal for controlling the gain and filtering frequency of the signal f ₂ corresponding to the local oscillation circuit received from the antenna 103 only by a passive circuit, and the control signal itself is The low-frequency circuit can be composed of a MOS capacitor manufactured by printing using an organic semiconductor and several passive elements. The received data signal by the signal after detection is processed and output as data by the data processing unit 404, and can be used for display on the display unit 405, recording, and response signal processing to the transmitter 500. This is also performed by controlling the conventional local oscillator 603 in FIG. 6 for stable reception in a normal receiver. Of course, it is perfectly possible if a high-frequency circuit can be configured. By separating such local oscillation, the control can be performed only by the operation of the passive circuit or the received reproduction power source.

FIG. 5 is a diagram illustrating gains of the first transmission signal, the second transmission signal, and the difference signal. As shown in the figure, the difference signal is obtained by transmitting the first transmission signal f ₁ (and the modulated signal df) obtained through the antenna 204 of the transmitter 200 and the antenna 601 of the receiver 100 of FIG. This is a difference signal when the _second transmission signal f ₂ oscillated by the local oscillator 201 and received through the antenna 202 of the receiver 100 and the antenna 103 of the receiver 100 is mixed. As can be seen from the figure, a signal which is f ₁ −f ₂ ± df is obtained by the difference frequency with the _second transmission signal f ₂ lower than the first transmission signal f ₁ . Actually, a modulated signal of | f ₁ −f ₂ | ± df is obtained regardless of the magnitude relationship, and the leftmost signal component in the figure is separated by an appropriate filter, so-called intermediate amplification, The modulated signal component can be detected. The magnitude of the frequency difference between the first transmission signal f ₁ and the second transmission signal f ₂ must be at least larger than the magnitude of the frequency df of the modulated signal. Thus, if an appropriate frequency of the second transmission signal is selected, AC amplification in a frequency band close to the frequency of the modulated signal is possible, and stable amplification with low noise becomes possible.

In the above description, the modulation system has not been described. Basically, any modulation system, for example, any of ASK, FSK, PSK, etc., or modulation such as DSB or SSB without the first transmission signal f ₁ is used. A method may be used. In addition to the organic semiconductor FET used in the receiving system, in order to avoid amplification at high frequencies, it is possible to share the local oscillation as in the present invention on the transmitter side and reduce the burden on the card and tag over a wide band. Needless to say.

  The present invention is not limited to the above embodiments, and it goes without saying that various modifications and substitutions are possible as long as they are described in the scope of the claims.

It is a block diagram which shows the system configuration | structure of the data communication system which concerns on the 1st example of an embodiment of this invention. It is a circuit diagram which shows the circuit structure of a gain adjustment control circuit. Frequency of the second spectrum of the transmission signal f ₂ of the - is a characteristic diagram showing a gain curve. It is a block diagram which shows the system configuration | structure of the data communication system which concerns on the 2nd Example of this invention. It is a figure which shows the gain of a 1st transmission signal, a 2nd transmission signal, and a difference signal. It is a block diagram which shows the structure of the receiver of the conventional data communication system. It is a block diagram which shows another structure of the receiver of the conventional data communication system.

Explanation of symbols

100, 400, 600, 700; receiver, 101; bandpass filter,
102; low frequency amplifier, 103, 202, 204, 601; antenna
200,500; transmitter, 201,603; local oscillator,
203, 502; high-frequency amplifier, 300; gain adjustment control circuit,
301; input signal; 302; resistor; 303; diode;
304; output signal, 401, 501; circulator,
402; DC power supply regeneration circuit; 403; modulation unit; 404; data processing unit;
405; display unit, 406; passive nonlinear element, 602; mixer,
604; low-pass filter, 605; intermediate frequency amplifier.

Claims (9)

In a receiver having an antenna that receives two frequencies separately,
A mixer that mixes a first received signal including a modulated signal and a second received signal having a frequency different from that of the first received signal, and includes a modulated signal from the received signal mixed by the mixer And a filter for generating an intermediate frequency.   The receiver according to claim 1, further comprising a gain adjustment circuit that performs gain adjustment with a MOS capacitor on the second reception signal.   The frequency of the modulated signal transmitted together with the carrier wave of the first received signal is at least smaller than the difference frequency between the frequency of the first received signal and the second received signal. The receiver according to claim 1 or 2.   4. The receiver according to claim 1, further comprising: a DC power supply regeneration circuit that detects the second received signal as electric power in the receiver to obtain a DC power supply. 5.   A response signal modulated by the modulation unit, the modulation unit modulating the response signal to the signal of the first reception signal with the second reception signal as it is or with a harmonic generated through a non-linear element or a non-linear circuit; The receiver according to claim 1, wherein the receiver is transmitted to the transmitter side.   The receiver according to any one of claims 1 to 5, wherein a modulated wave is transmitted to the transmitter side using the same antenna when the second received signal is received.   A transmitter characterized by transmitting a first transmission signal including a modulated signal and transmitting a second transmission signal different from the first transmission signal.   The frequency of the modulated signal transmitted together with the carrier wave of the first transmission signal is at least smaller than the difference frequency between the frequency of the first transmission signal and the second transmission signal. The transmitter according to claim 7.   A data communication system comprising the receiver according to any one of claims 1 to 6 and the transmitter according to claim 7 or 8.

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