JP5181300B2 - Contactless communication system - Google Patents

Description

  The present invention relates to a communication system that performs signal transmission without contact, and more particularly, to a communication system that performs signal transmission via a capacitor formed between electrodes.

  In recent years, various proposals regarding non-contact transmission using capacitive coupling, inductive coupling, electromagnetic waves, and the like have been made as methods for transmitting a signal even in a situation where electrical contact between electrodes is difficult. However, the non-contact transmission has a problem that a low-speed signal cannot be transmitted because the signal transition is received and received.

  Therefore, in a conventional communication system (see, for example, Patent Document 1 and Patent Document 2), a signal transition is captured and then the signal level is held so that a low-speed signal can be received.

  The conventional communication system 101 of FIG. 6 is the communication system of FIG. As shown in FIG. 6, in the communication system 101, a signal is received by changing the voltage of the node 103 connected to the reception electrode 102 in the latch operation.

  Further, the conventional communication system 111 of FIG. 7 is the communication system of FIG. As shown in FIG. 7, the communication system 111 receives a signal by changing the reference voltage 113 of the comparator 112.

US Pat. No. 6,987,412 (patented on January 17, 2006) JP 2009-135632 A (released on June 18, 2009)

  However, in the communication system 101 of Patent Document 1, for example, when a large load capacity is connected to a node connected to the receiving electrode due to an increase in wiring length, for example, the load capacity needs to be charged, so the transmission speed is high. There was a problem of being lowered.

  Further, the communication system 111 of Patent Document 2 requires a time for the comparator 112 to compare the input voltage 114 and the reference voltage 113, and thus has a problem that it is difficult to improve the transmission speed.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a contactless communication system capable of transmitting a wide range of signals from low-speed signals to high-speed signals. .

  In order to solve the above problems, a non-contact communication system of the present invention is a non-contact communication system that performs non-contact signal transmission, and includes a transmission circuit that transmits a transmission signal, and a transmission electrode that is connected to the transmission circuit A reception electrode that receives the transmission signal from the transmission electrode, a precharge circuit that applies a steady voltage to a node connected to the reception electrode, and a threshold variable circuit that receives the reception signal received by the reception electrode And a first inverter circuit and a second inverter circuit for amplifying an output signal of the threshold variable circuit, wherein the first inverter circuit and the second inverter circuit are cascade-connected, The output of the first inverter circuit is fed back to the threshold variable circuit to change the threshold of the threshold variable circuit. In the non-contact, the transmitting electrode and the receiving electrode are electrically connected to each other. Characterized in that indicating the contact.

  According to the above invention, the precharge circuit can hold the node connected to the precharge circuit at a voltage located near the middle of the plurality of thresholds included in the threshold variable circuit. Therefore, even when the reception signal output from the reception electrode is very small, the threshold value variable circuit can perform a signal latch operation.

  Further, according to the invention, the output signal of the threshold variable circuit can be amplified by the first inverter circuit and the second inverter circuit, and the threshold value is determined according to the feedback signal from the first inverter circuit. The threshold value of the variable circuit can be changed. This configuration is equivalent to changing the threshold value of the inverter circuit by changing the drive capability of the inverter circuit according to the feedback signal. With this configuration, since the feedback signal is not directly connected to the signal path, it is possible to operate faster than conventional communication systems, and to transmit a wide range of signals from low-speed signals to high-speed signals. A non-contact communication system that can be provided can be provided.

  In the non-contact communication system, the precharge circuit may include a resistance unit formed by a switch that is always in a conductive state, and a first inverter unit in which an input and an output are short-circuited by the resistance unit. Good. As a result, the node connected to the precharge circuit can be held at a voltage located near the middle of the plurality of threshold values of the threshold variable circuit.

  In the non-contact communication system, the threshold variable circuit may include an amplitude limiting circuit. According to this configuration, when there is no transition in the transmission signal, the output signal is adjusted so as to be located at a certain distance from the power supply voltage or the ground voltage. As a result, when the transmission signal transitions next time, the output of the threshold variable circuit can exceed the threshold of the first inverter circuit.

  In the non-contact communication system, the threshold variable circuit includes a first transistor in which a feedback signal by the feedback is input to a gate terminal, a power supply voltage is applied to a source terminal, and a drain terminal is connected to a first node. A second transistor having a gate terminal connected to the input of the threshold variable circuit, a source terminal connected to the first node, a drain terminal connected to the output of the threshold variable circuit, and a gate terminal connected to the input , A source terminal connected to the second node, a drain terminal connected to the output, a gate terminal to which the feedback signal is input, a source terminal is electrically grounded, a drain A fourth transistor having a terminal connected to the second node, a gate terminal connected to the input, the source voltage applied to a source terminal, A fifth transistor having an in terminal connected to the output; a sixth transistor having a gate terminal connected to the input; a source terminal electrically grounded; and a drain terminal connected to the output. Also good.

  According to the above configuration, the threshold of the threshold variable circuit can be changed by turning on or off the first transistor and the fourth transistor in accordance with the feedback signal.

  In the non-contact communication system, the amplitude limiting circuit may be configured by short-circuiting the input of the second inverter unit and the output of the second inverter unit. Thereby, when there is no transition in the transmission signal, the output signal can be adjusted so as to be located at a certain distance from the power supply voltage or the ground voltage.

  In order to solve the above problems, the non-contact communication system of the present invention is a communication system that performs non-contact signal transmission, a transmission circuit that transmits a transmission signal, a transmission electrode connected to the transmission circuit, A reception electrode that receives the transmission signal from the transmission electrode, a low-pass filter that receives the reception signal via the transmission line and that receives the reception signal via the transmission line, and a node to which an output of the low-pass filter is connected. A first precharge circuit that provides a steady voltage of the first, a capacitor having one end connected to the output of the first precharge circuit, and a second steady voltage applied to a node to which the other end of the capacitor is connected. 2 precharge circuits, a threshold variable circuit that receives a signal via the capacitor, and a first inverter circuit and a second inverter circuit for amplifying the output signal of the threshold variable circuit And the first inverter circuit and the second inverter circuit are connected in cascade, and the output of the first inverter circuit is fed back to the threshold variable circuit to change the threshold of the threshold variable circuit, The non-contact indicates that the transmission electrode and the reception electrode are electrically non-contact.

  According to the above invention, when there is a long transmission line between the reception electrode and the low-pass filter, there is a possibility that ringing of the signal occurs by the transmission line and the ringing is erroneously received as a signal.

  Since the frequency of ringing is usually higher than the frequency of the signal, it is possible to block the high-frequency signal by disposing the low-pass filter so that the ringing is not transmitted to the circuit subsequent to the low-pass filter.

  If the low-pass filter is inserted, the amplitude of the signal is reduced, and an amplifier circuit is required. For this reason, in the non-contact communication system, by using the characteristic of the first precharge circuit, that is, the characteristic that functions as an amplifier circuit in a high frequency band, the signal output from the low-pass filter is converted to the first precharge circuit. Can be amplified with a charge circuit.

  The second precharge circuit can hold a node connected to the second precharge circuit at a voltage located in the vicinity of the middle of the plurality of thresholds included in the threshold variable circuit. Therefore, even when the reception signal output from the reception electrode is very small, the threshold value variable circuit can perform a signal latch operation.

  Further, according to the invention, the first inverter circuit and the second inverter circuit can amplify the output signal of the threshold variable circuit, and the threshold value is determined according to a feedback signal from the first inverter circuit. The threshold value of the variable circuit can be changed. This configuration is equivalent to changing the threshold value of the inverter circuit by changing the drive capability of the inverter circuit according to the feedback signal. With this configuration, since the feedback signal is not directly connected to the signal path, a high-speed operation is possible, and a wide range of signals from a low-speed signal to a high-speed signal can be transmitted.

  In the non-contact communication system, the low-pass filter has a resistor having one end connected to the receiving electrode via the transmission line and a capacitance of an electrostatic discharge countermeasure circuit having one end connected to the other end of the resistor. The other end of the capacitance of the electrostatic discharge countermeasure circuit may be applied with a power supply voltage or electrically grounded. Thereby, it is possible to prevent ringing from being transmitted to a circuit subsequent to the low-pass filter.

  In the non-contact communication system, the second precharge circuit includes a resistance unit formed by a switch that is always in a conductive state, and a first inverter unit in which an input and an output are short-circuited by the resistance unit. The first precharge circuit includes another resistor portion formed by another switch that is always in a conductive state, and a third inverter portion in which an input and an output are short-circuited by the other resistor portion. You may have.

  As a result, the node connected to the second precharge circuit can be held at a voltage located near the middle of the plurality of thresholds of the threshold variable circuit. Further, the signal output from the low-pass filter can be amplified by the first precharge circuit.

  In the non-contact communication system, the threshold variable circuit may include an amplitude limiting circuit. According to this configuration, when there is no transition in the transmission signal, the output signal is adjusted so as to be located at a certain distance from the power supply voltage or the ground voltage. As a result, when the transmission signal transitions next time, the output of the threshold variable circuit can exceed the threshold of the first inverter circuit.

  As described above, the contactless communication system of the present invention includes a transmission circuit that transmits a transmission signal, a transmission electrode connected to the transmission circuit, a reception electrode that receives the transmission signal from the transmission electrode, A precharge circuit that applies a steady voltage to a node connected to the reception electrode; a threshold variable circuit that receives a reception signal received by the reception electrode; and a first voltage for amplifying the output signal of the threshold variable circuit An inverter circuit and a second inverter circuit, wherein the first inverter circuit and the second inverter circuit are connected in cascade, and an output of the first inverter circuit is fed back to the threshold variable circuit to provide the threshold value The threshold value of the variable circuit is changed, and non-contact indicates that the transmission electrode and the reception electrode are electrically non-contact.

  Further, as described above, the non-contact communication system of the present invention includes a transmission circuit that transmits a transmission signal, a transmission electrode connected to the transmission circuit, and a reception electrode that receives the transmission signal from the transmission electrode. A low-pass filter that receives a reception signal via the transmission line and receives a reception signal via the transmission line, a first precharge circuit that applies a first steady voltage to a node to which the output of the low-pass filter is connected, and one end Includes a capacitor connected to the output of the first precharge circuit, a second precharge circuit for applying a second steady voltage to a node to which the other end of the capacitor is connected, and a signal via the capacitor. A threshold variable circuit as an input; and a first inverter circuit and a second inverter circuit for amplifying an output signal of the threshold variable circuit, wherein the first inverter circuit and the second inverter circuit The inverter circuit is cascade-connected, and the output of the first inverter circuit is fed back to the threshold variable circuit to change the threshold of the threshold variable circuit. In the non-contact state, the transmission electrode and the reception electrode are electrically connected It indicates that it is non-contact.

  Therefore, there is an effect of providing a contactless communication system capable of transmitting a wide range of signals from a low speed signal to a high speed signal.

1 is a block diagram of a contactless communication system according to an embodiment of the present invention. It is a block diagram of the non-contact communication system concerning the other Example of this invention. It is a block diagram of the non-contact communication system concerning another Example of this invention. It is the perspective view which showed the application example of the non-contact communication system which concerns on the other Example of this invention. It is a timing diagram explaining operation | movement of the non-contact communication system concerning the Example of this invention. It is a block diagram of the conventional communication system. It is a block diagram of the conventional communication system.

  An embodiment of the present invention will be described below with reference to FIGS. First, a schematic configuration of a contactless communication system 1 according to an embodiment of the present invention will be described with reference to FIG.

[Example 1]
FIG. 1 is a block diagram illustrating a configuration of a contactless communication system 1 according to the first embodiment. The non-contact communication system 1 is a non-contact communication system that performs non-contact signal transmission, and is connected to a transmission circuit 2, a transmission electrode 3 connected to the transmission circuit 2, a reception circuit 4, and a reception circuit 4. A receiving electrode 5 is provided. The simplest transmission circuit is an inverter circuit. A transmission signal Vs is transmitted from the output of the transmission circuit 2.

  The receiving circuit 4 includes a precharge circuit 6 (precharge circuit, second precharge circuit), a threshold variable circuit 7, an inverter circuit 8a (first inverter circuit), and an inverter circuit 8b (second circuit). And a signal from the inverter circuit 8a is fed back to the threshold variable circuit 7. The inverter circuit 8a and the inverter circuit 8b are cascade-connected. That is, the output of the inverter circuit 8a is connected to the input of the inverter circuit 8b.

  The precharge circuit 6 is a circuit that applies a steady voltage (steady voltage, second steady voltage) to a node connected to the receiving electrode 5, and is an inverter circuit (first inverter unit) configured by transistors T20 and T21. In this configuration, the input and output are short-circuited with a resistor. Here, the transistors T1 and T2 (switches and resistance units) that are always in a conductive state are used as resistors.

  The role of the precharge circuit 6 is to hold a node connected to the precharge circuit 6 at a voltage located near the middle of a plurality of threshold values included in the threshold variable circuit 7, thereby receiving a reception signal output from the reception electrode 5. Even when Vr is very small, the threshold variable circuit 7 can perform a signal latch operation.

  The simplest circuit of the variable threshold circuit 7 is a Schmitt inverter circuit. However, in the Schmitt inverter circuit, the threshold value is changed according to the output voltage by the transistor whose gate is connected to the output, but the amplification factor is not so high as compared with other amplifier circuits. For this reason, when the amplitude of the input signal is very small, the amplitude of the output signal is also small, and the change in the threshold value may not be an appropriate value.

Therefore, the variable threshold circuit 7, the feedback signal V _R by the feedback is input to the gate terminal, the power supply voltage VDD is applied to the source terminal, the transistor drain terminal connected to the node N1 (first node) T3 ( A first transistor), a gate terminal connected to the input IN, a source terminal connected to the node N1, a drain terminal connected to the output OUT, and a gate terminal connected to the input IN. is connected, a source terminal connected to the node N2 (second node), the transistor T5 which a drain terminal connected to the output OUT (third transistor), the feedback signal V _R is inputted to the gate terminal, a source terminal Is electrically grounded and has a drain terminal connected to the node N2, a transistor T6 (fourth transistor), and a gate terminal Is connected to the input IN, the source voltage VDD is applied to the source terminal, the drain terminal is connected to the output OUT, the transistor T7 (fifth transistor), the gate terminal is connected to the input IN, and the source terminal is electrically connected And a transistor T8 (sixth transistor) having a drain terminal connected to the output OUT. An output signal V _L is output from the output OUT of the threshold variable circuit 7.

Depending on the feedback signal V _R, the transistor T3 and the transistor T6 is, it is possible to change the threshold value of the threshold changing circuit 7 by turning on or off. This arrangement, by changing the driving capability of the inverter circuit in response to the feedback signal V _R, which is equivalent to changing the threshold value of the inverter circuit. By this configuration, since the feedback signal V _R is not be directly connected to the signal path, than conventional communication system enables high-speed operation, to transmit a wide range of signals from the low-speed signals to high signals It is possible to provide a contactless communication system 1 that can be used.

  In the contactless communication system 1, the precharge circuit 6 includes transistors T1, T2, T20, and T21. The gate of the transistor T20, the gate of the transistor T21, the source of the transistor T1, and the source of the transistor T2 are connected to the receiving electrode 5. A power supply voltage VDD is applied to the source terminal of the transistor T20. The gate of the transistor T1 is electrically grounded. A power supply voltage VDD is applied to the gate of the transistor T2. The source terminal of the transistor T21 is electrically grounded. The drain of the transistor T1, the drain of the transistor T2, the drain of the transistor T20, and the drain of the transistor T21 are connected to the input IN of the threshold variable circuit 7.

The inverter circuit 8a includes a transistor T9 and a transistor T10. The gate of the transistor T9 and the gate of the transistor T10 are connected to the output OUT of the threshold variable circuit 7. A power supply voltage VDD is applied to the source terminal of the transistor T9. The source terminal of the transistor T10 is electrically grounded. The drain of the transistor T9 and the drain of the transistor T10 are connected to the node _R and output a feedback signal VR.

  The inverter circuit 8b includes a transistor T11 and a transistor T12. The gate of the transistor T11 and the gate of the transistor T12 are connected to the node R. The power supply voltage VDD is applied to the source terminal of the transistor T11. The source terminal of the transistor T12 is electrically grounded. The drain of the transistor T11 and the drain of the transistor T12 are connected to the node O and output the output signal Vo of the receiving circuit 4.

[Example 2]
Another embodiment of the present invention will be described with reference to FIG. The configurations other than those described in the present embodiment are the same as those in the first embodiment. For convenience of explanation, members having the same functions as those shown in the drawings of the first embodiment are given the same reference numerals, and explanation thereof is omitted.

  FIG. 2 is a block diagram illustrating the configuration of the non-contact communication system 11 according to the second embodiment. The non-contact communication system 11 has a configuration in which an amplitude limiting circuit 12 is added to the threshold variable circuit 7 in the non-contact communication system 1 of the first embodiment.

In the non-contact communication system 1 of Figure 1, when the transmission signal Vs does not transition, the output signal V _L by the feedback signal V _R becomes very close to the power supply voltage VDD or the ground voltage VSS. For this reason, when the transmission signal Vs transits next time, the output OUT of the threshold variable circuit 7 may not exceed the threshold of the inverter circuit 8a.

Therefore, the amplitude limiting circuit 12 adjusts the output signal _{VL so} that the output signal _VL is located at a certain distance from the power supply voltage VDD or the ground voltage VSS when there is no transition in the transmission signal Vs. As a result, the next time the transmission signal Vs transitions, the output of the threshold variable circuit 7 can exceed the threshold of the inverter circuit 8a.

The threshold value changing circuit 7 tries to set the voltage of the node V _L (output signal V _L ) to the power source voltage VDD or the ground voltage VSS. However, the amplitude limiting circuit 12 is short-circuited between the input and the output, and tries to make the voltage of the node _VL an intermediate voltage between the power supply voltage VDD and the ground voltage VSS. For this reason, the voltage of the node _VL is a voltage higher than the intermediate voltage with respect to the power supply voltage VDD and the ground voltage VSS. The voltage at the node V _L is determined by the difference between the drive capability of the threshold value changing circuit 7 and the drive capability of the amplitude limiting circuit 12.

  In the non-contact communication system 11, the amplitude limiting circuit 12 includes transistors T22 and T23. The amplitude limiting circuit 12 includes an input of an inverter circuit (second inverter unit) configured by the transistors T22 and T23 and transistors T22 and T23. The output of the inverter circuit is short-circuited.

  In the amplitude limiting circuit 12, the gate of the transistor T22 and the gate of the transistor T23 are connected to the output OUT of the threshold variable circuit 7. That is, the gate of the transistor T22 and the gate of the transistor T23 are connected to the drain of the transistor T7, the drain of the transistor T8, the drain of the transistor T7, the drain of the transistor T4, and the drain of the transistor T3. A power supply voltage VDD is applied to the source terminal of the transistor T22. The source terminal of the transistor T23 is electrically grounded. The drain of the transistor T22 and the drain of the transistor T23 are connected to the output OUT of the threshold variable circuit 7.

Example 3
Still another embodiment of the present invention will be described with reference to FIG. The configurations other than those described in the present embodiment are the same as those in the first embodiment. For convenience of explanation, members having the same functions as those shown in the drawings of the first embodiment are given the same reference numerals, and explanation thereof is omitted.

  FIG. 3 is a block diagram illustrating the configuration of the non-contact communication system 21 according to the third embodiment. The non-contact communication system 21 has a configuration in which a low-pass filter LPF and a precharge circuit 6 ′ (first precharge circuit) are added to the reception circuit 4 in the non-contact communication system 1 of the first embodiment.

  The precharge circuit 6 ′ is a circuit that applies a steady voltage (first steady voltage) to a node to which the output of the low-pass filter LPF is connected. The precharge circuit 6 ′ is an inverter circuit (third inverter unit) composed of transistors T30 and T31. In this configuration, the input and output are short-circuited with a resistor. Here, the transistors T41 and T42 (other switches and other resistor units) that are always in a conductive state are used as resistors.

  As shown in FIG. 3, when there is a long transmission line D from the reception electrode 5 to the reception circuit 4, that is, between the reception electrode 5 and a low-pass filter LPF described later, signal ringing occurs by the transmission line D. The receiving circuit 4 is configured to be able to receive even if the received signal changes very little. For this reason, ringing may be erroneously received as a signal.

  Usually the ringing frequency is higher than the signal frequency. For this reason, a low-pass filter LPF is arranged in front of the receiving circuit 4 to block a high-frequency signal so that ringing is not transmitted to the receiving circuit 4 (not to transmit ringing to a circuit subsequent to the low-pass filter LPF). Can).

The simplest configuration of the low-pass filter LPF is a combination of a resistor and a capacitor. However, when an ESD (Electrostatic Discharge) countermeasure circuit is used, the capacitances ESD _C1 and ESD _C2 of the ESD countermeasure circuit are used. (Capacitance of the electrostatic discharge countermeasure circuit) can be used as the capacitance of the low-pass filter LPF.

  However, when the low-pass filter LPF is inserted, the amplitude of the signal is reduced, and an amplifier circuit is required. For this reason, in the non-contact communication system 21 of FIG. 3, the characteristic output from the low-pass filter LPF is amplified by using the characteristic of the precharge circuit 6 ', that is, the characteristic that functions as an amplifier circuit in a high frequency band.

  The precharge circuit 6 ′ has an input / output connected by a resistor, and has a configuration like an LPF with the parasitic capacitance associated with the resistor and the input / output. That is, in the low frequency region, the output behaves as if it is short-circuited with the input. On the other hand, in a high frequency region, the output cannot be fed back to the input and behaves like an inverter circuit.

  In addition, when the precharge circuit 6 ′ is simply connected in cascade, a value (direct current: DC value (direct current value)) output from the precharge circuit 6 in the subsequent stage is caused by variations in the electrical characteristics of the precharge circuit 6 ′. There is a possibility of deviation from the voltage to be set. For this reason, a capacitor C is arranged between the precharge circuit 6 'and the precharge circuit 6 so that a DC signal is not transmitted.

In the non-contact communication system 21, the low pass filter LPF has a resistor R1 and capacitances ESD _C1 and ESD _{C2 of} an ESD countermeasure circuit. The precharge circuit 6 ′ includes transistors T30, T31, T41, and T42.

  In the non-contact communication system 21, the reception electrode 5 is connected to one end of the transmission line D. The other end of the transmission line D is connected to one end of the resistor R1.

The other end of the resistor R1 is one end of the ESD protection circuit capacitor ESD _C1 , one end of the ESD protection circuit capacitor ESD _C2 , the gate of the transistor T30, the gate of the transistor T31, the source of the transistor T41, and the transistor T42. Connected to the source.

The power supply voltage VDD is applied to the other end of the capacitor ESD _C1 of the ESD countermeasure circuit and the source of the transistor T30. The other end of the capacitor ESD _C2 of the ESD countermeasure circuit and the source of the transistor T31 are electrically grounded.

  The drain of the transistor T30, the drain of the transistor T31, the drain of the transistor T41, and the drain of the transistor T42 are connected to one end of the capacitor C. The other end of the capacitor C is connected to the gate of the transistor T20, the gate of the transistor T21, the source of the transistor T1, and the source of the transistor T2.

  Note that the non-contact communication system 21 may include the amplitude limiting circuit 12 similarly to the non-contact communication system 11.

[Application examples of non-contact communication systems]
FIG. 4 is a perspective view illustrating an application example of the contactless communication system 11 according to the second embodiment and the contactless communication system 21 according to the third embodiment. The chip 40 and the interposer 41 are electrically connected by electrodes 42 and 43.

  A signal output from the electrode 42 of the chip 40 is transmitted to the transmission electrode 45 formed on the back surface of the interposer 41 through the transmission path D1, the via 44, and the transmission path D2. The transmission path D1 is formed on the front surface of the interposer 41, the transmission path D2 is formed on the back surface of the interposer 41, and the via 44 connects the transmission path D1 and the transmission path D2. A signal is transmitted through a capacitor C1 formed by the transmission electrode 45 and the reception electrode 47 formed on the chip 46, and the signal is demodulated by the reception circuit in the chip 46. The system described above is an application example of the contactless communication system 11 shown in FIG.

  Conversely, the signal output from the chip 46 is transmitted to the transmission electrode 48 formed on the chip 46 and transmitted to the reception electrode 49 formed on the back surface of the interposer 41 in a non-contact manner. The transmission electrode 48 and the reception electrode 49 constitute a capacitor C2. A signal output from the reception electrode 49 is transmitted to the electrode 43 of the chip 40 through the transmission path D3, the via 50, and the transmission path D4, and the signal is restored by the reception circuit in the chip 40. The transmission path D3 is formed on the back surface of the interposer 41, the transmission path D4 is formed on the front surface of the interposer 41, and the via 50 connects the transmission path D3 and the transmission path D4. The system described above is an application example of the non-contact communication system 21 shown in FIG.

[Operation of contactless communication system]
FIG. 5 is a timing chart for explaining the operation of the contactless communication system 1 according to the first embodiment. The voltage of the node connected to the receiving electrode 5 is held at a voltage set in advance by the precharge circuit 6 (set voltage, VDD / 2 as an example in FIG. 5). The reception signal Vr changes from the set voltage VDD / 2 to the power supply voltage VDD side when the transmission signal Vs rises, and changes to the ground voltage VSS side when the transmission signal Vs falls.

  The capacitance formed by the transmission electrode 3 and the reception electrode 5 does not pass the DC component. For this reason, the reception signal Vr gradually approaches the set voltage VDD / 2 by the precharge circuit 6.

  In a state where the transmission signal Vs rises and does not transition, the threshold value of the threshold variable circuit 7 is on the ground voltage VSS side with respect to the voltage set by the precharge circuit 6. Therefore, the output signal Vo of the receiving circuit 4 does not transition.

  On the contrary, in a state where the transmission signal Vs falls and does not transition, the threshold value of the threshold variable circuit 7 is on the power supply voltage VDD side with respect to the voltage set by the precharge circuit 6. Therefore, the output signal Vo of the receiving circuit 4 does not transition.

  Note that non-contact in the present embodiment indicates that the transmission electrode 3 and the reception electrode 5 are electrically non-contact.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can provide a non-contact communication system capable of transmitting a wide range of signals from a low-speed signal to a high-speed signal, and is therefore suitably used for signal transmission in a situation where electrical contact between electrodes is difficult. be able to.

DESCRIPTION OF SYMBOLS 1,11,21 Non-contact communication system 2 Transmission circuit 3 Transmission electrode 4 Reception circuit 5 Reception electrode 6 Precharge circuit (precharge circuit, 2nd precharge circuit)
6 'precharge circuit (first precharge circuit)
7 Threshold variable circuit 8a Inverter circuit (first inverter circuit)
8b Inverter circuit (second inverter circuit)
12 Amplitude limiting circuit 40, 46 Chip 41 Interposer 42, 43 Electrode 44, 50 Via 45, 48 Transmitting electrode 47, 49 Receiving electrode C, C1, C2 Capacitance D, D1-D4 Transmission line ESD _C1 , ESD _C2 ESD countermeasure circuit Capacitance IN input (input of variable threshold circuit)
LPF Low-pass filter N1 node (first node)
N2 node (second node)
O, R node OUT output (output of threshold variable circuit)
R1 resistor T1, T2 transistor (resistor part)
T3 transistor (first transistor)
T4 transistor (second transistor)
T5 transistor (third transistor)
T6 transistor (fourth transistor)
T7 transistor (fifth transistor)
T8 transistor (sixth transistor)
T20, T21 transistor (first inverter)
T22, T23 transistor (second inverter)
T30, T31 transistor (third inverter)
T41, T42 Transistor (other resistance part)
T9~T12 transistor VDD supply voltage V _R feedback signal Vo, _{V L} output signal Vr received signal VSS a ground voltage Vs transmitted signal

Claims (9)

A non-contact communication system for non-contact signal transmission,
A transmission circuit for transmitting a transmission signal;
A transmission electrode connected to the transmission circuit;
A receiving electrode for receiving the transmission signal from the transmitting electrode;
A precharge circuit for applying a steady voltage to a node connected to the receiving electrode;
A threshold variable circuit that receives a received signal received by the receiving electrode;
A first inverter circuit and a second inverter circuit for amplifying the output signal of the threshold variable circuit;
The first inverter circuit and the second inverter circuit are cascade-connected,
Feedback the output of the first inverter circuit to the threshold variable circuit to change the threshold of the threshold variable circuit;
The non-contact communication system indicates that the transmission electrode and the reception electrode are electrically non-contact.   The said precharge circuit has a resistance part formed with the switch which is always a conduction | electrical_connection state, and the 1st inverter part by which the input and the output were short-circuited by the said resistance part, It is characterized by the above-mentioned. Non-contact communication system.   The contactless communication system according to claim 1, wherein the threshold variable circuit includes an amplitude limiting circuit. The threshold variable circuit includes:
A first transistor in which a feedback signal by the feedback is input to a gate terminal, a power supply voltage is applied to a source terminal, and a drain terminal is connected to a first node;
A second transistor having a gate terminal connected to the input of the threshold variable circuit, a source terminal connected to the first node, and a drain terminal connected to the output of the threshold variable circuit;
A third transistor having a gate terminal connected to the input, a source terminal connected to a second node, and a drain terminal connected to the output;
A fourth transistor in which the feedback signal is input to a gate terminal, a source terminal is electrically grounded, and a drain terminal is connected to the second node;
A fifth transistor having a gate terminal connected to the input, the source voltage applied to a source terminal, and a drain terminal connected to the output;
The contactless communication system according to claim 1, further comprising: a sixth transistor having a gate terminal connected to the input, a source terminal electrically grounded, and a drain terminal connected to the output.   The contactless communication system according to claim 3, wherein the amplitude limiting circuit is configured by short-circuiting an input of the second inverter unit and an output of the second inverter unit. A communication system that performs non-contact signal transmission,
A transmission circuit for transmitting a transmission signal;
A transmission electrode connected to the transmission circuit;
A receiving electrode for receiving the transmission signal from the transmitting electrode;
A low-pass filter that receives the reception electrode and receives a reception signal via a transmission line; and
A first precharge circuit that applies a first steady voltage to a node to which the output of the low-pass filter is connected;
A capacitor having one end connected to the output of the first precharge circuit;
A second precharge circuit that applies a second steady voltage to a node to which the other end of the capacitor is connected;
A threshold variable circuit that receives a signal through the capacitor;
A first inverter circuit and a second inverter circuit for amplifying the output signal of the threshold variable circuit;
The first inverter circuit and the second inverter circuit are cascade-connected,
Feedback the output of the first inverter circuit to the threshold variable circuit to change the threshold of the threshold variable circuit;
The non-contact communication system indicates that the transmission electrode and the reception electrode are electrically non-contact. The low-pass filter has a resistor having one end connected to the receiving electrode through the transmission line, and a capacitance of an electrostatic discharge countermeasure circuit having one end connected to the other end of the resistor,
The contactless communication system according to claim 6, wherein the other end of the capacitance of the electrostatic discharge countermeasure circuit is applied with a power supply voltage or is electrically grounded. The second precharge circuit includes a resistance unit formed by a switch that is always in a conductive state, and a first inverter unit in which an input and an output are short-circuited by the resistance unit,
The first precharge circuit has another resistor portion formed by another switch that is always in a conductive state, and a third inverter portion whose input and output are short-circuited by the other resistor portion. The non-contact communication system according to claim 6.   The contactless communication system according to claim 6, wherein the threshold variable circuit includes an amplitude limiting circuit.

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