Receiving device, communication system, and control method for the receiving device

Abstract

To provide a receiving device, a communication system, and a control method for the receiving device that keep a received signal within an input dynamic range of a receiving circuit even when noise occurs.SOLUTION: In a communication system 100, a receiving unit 120 has a receiving circuit 123 into which a receiving signal is input and a current consumption summing unit 151 and a feedback voltage generation unit 152, which are control units that control the receiving signal to be input into the receiving circuit 123 in accordance with the current consumption of the receiving circuit 123.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a receiving device, a communication system, and a control method for a receiving device. [Background technology]

[0002] In recent years, production systems, robotic devices, and the like have been equipped with devices that communicate large amounts of data, such as cameras, and systems that transmit data at high speed without contact between mechanical moving parts and fixed parts are becoming more common. Patent Document 1 discloses a non-contact data communication device that has a coupled electrode that handles data communication and a non-coupled electrode that receives spatial noise. This non-contact data communication device amplifies the difference in voltage generated between the two electrodes, thereby subtracting spatial noise from the received data signal that is contaminated with spatial noise and improving the quality of the received signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-159480 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the amount of data transmitted within and between devices has been increasing, necessitating the realization of high-speed communication in wireless communication systems. In Patent Document 1, wireless communication is achieved using electromagnetic field coupling with two receiving electrodes. However, the electromagnetic field strength of spatial noise is strong compared to the signal amplitude. In Patent Document 1, if a voltage exceeding the input dynamic range of the differential amplifier that amplifies the difference between the voltages generated at the two electrodes is input, it becomes difficult to properly subtract the spatial noise, which may result in a significant degradation in the quality of the received data signal.

[0005] An object of the present disclosure is to ensure that the received signal falls within the input dynamic range of the receiving circuit even when noise occurs. [Means for solving the problem]

[0006] The receiving device has a receiving circuit that receives a received signal, and a control unit that controls the received signal input to the receiving circuit in accordance with the current consumption of the receiving circuit. [Effects of the Invention]

[0007] According to the present disclosure, even when noise occurs, the received signal can be kept within the input dynamic range of the receiving circuit. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram illustrating an example of a basic configuration of a communication system. [Figure 2] 3A and 3B are diagrams illustrating time waveforms of each part of the communication system. [Figure 3] 1 is a block diagram illustrating an example of a basic configuration of a communication system. [Figure 4] 3A and 3B are diagrams illustrating time waveforms of each part of the communication system. [Figure 5] FIG. 1 is a block diagram illustrating an example of the configuration of a communication system. [Figure 6] FIG. 2 is a diagram illustrating a configuration example of a receiving circuit. [Figure 7] FIG. 2 is a circuit diagram showing an example of the configuration of a receiving unit. [Figure 8] FIG. 2 is a circuit diagram showing an example of the configuration of a receiving unit. [Figure 9] FIG. 2 is a circuit diagram showing an example of the configuration of a receiving unit. [Figure 10] FIG. 10 is a diagram illustrating a simulation result of the receiving section. [Figure 11] FIG. 1 is a block diagram illustrating an example of the configuration of a communication system. [Figure 12] FIG. 1 is a block diagram illustrating an example of the configuration of a communication system. [Figure 13] FIG. 2 is a diagram illustrating a configuration example of a receiving circuit. [Figure 14] FIG. 2 is a diagram illustrating a configuration example of a differential amplifier. [Figure 15] FIG. 2 is a diagram illustrating a configuration example of a differential amplifier. [Figure 16] FIG. 1 is a block diagram illustrating an example of the configuration of a communication system. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) FIG. 1 is a block diagram showing an example of the basic configuration of a communication system 100 according to the first embodiment. The basic operation of the communication system 100 will be described using FIG. 1. The communication system 100 performs data communication between electrodes 111a, 111b, 121a, and 121b that are close to each other by electric field or magnetic field coupling. The electrodes 111a and 121a are couplers that are mutually coupled by electric field or magnetic field. The electrodes 111b and 121b are also couplers that are mutually coupled by electric field or magnetic field. The communication system 100 has a transmitting unit 110 and a receiving unit 120.

[0010] The transmitter 110 has an electrode 111a, an electrode 111b, and a transmission circuit 112. The transmission circuit 112 outputs a transmission signal Vt. An output terminal TXp of the transmission circuit 112 outputs a transmission voltage Vtp to the electrode 111a. An output terminal TXn of the transmission circuit 112 outputs a transmission voltage Vtn to the electrode 111b. The transmission voltages Vtp and Vtn are differential signals of opposite phases to each other, as shown in FIG. 2. The transmission signal Vt is a voltage obtained by subtracting the transmission voltage Vtn from the transmission voltage Vtp. The electrode 111a wirelessly transmits the transmission voltage (transmission power) Vtp to the electrode 121a by electric field or magnetic field coupling. The electrode 111b wirelessly transmits the transmission voltage (transmission power) Vtn to the electrode 121b by electric field or magnetic field coupling.

[0011] The receiving unit 120 has an electrode 121a, an electrode 121b, and a receiving circuit 123. A receiving voltage Vrp corresponding to a transmitting voltage Vtp is generated at the electrode 121a. A receiving voltage Vrn corresponding to a transmitting voltage Vtn is generated at the electrode 121b. The receiving voltages Vrp and Vrn are differential signals of opposite phases to each other, as shown in FIG. 2. The receiving signal Vr is a voltage obtained by subtracting the receiving voltage Vrn from the receiving voltage Vrp.

[0012] The receiving circuit 123 amplifies or impedance converts the receiving signal Vr and outputs an output signal Vo. The input terminal INp of the receiving circuit 123 inputs the receiving voltage Vrp. The input terminal INn of the receiving circuit 123 inputs the receiving voltage Vrn. The output terminal OUTp of the receiving circuit 123 outputs the output voltage Vop. The output terminal OUTn of the receiving circuit 123 outputs the output voltage Von. The output voltages Vop and Von are differential signals of opposite phases. The output signal Vo is the voltage obtained by subtracting the output voltage Von from the output voltage Vop.

[0013] Figure 2 is a voltage waveform diagram showing an example of the transmission signal Vt, reception signal Vr, and output signal Vo of Figure 1. The transmission signal Vt is the voltage obtained by subtracting the transmission voltage Vtn from the transmission voltage Vtp. The reception signal Vr is the voltage obtained by subtracting the reception voltage Vrn from the reception voltage Vrp. The output signal Vo is the voltage obtained by subtracting the output voltage Von from the output voltage Vop.

[0014] Here, the reception voltages Vtp and Vtn do not contain spatial noise. Therefore, the reception voltages Vtp and Vtn have waveforms similar to those of the transmission voltages Vtp and Vtn. If the transmission circuit 112 is set to output transmission voltages Vtp and Vtn with a constant amplitude, the reception voltages Vrp and Vrn will not exceed the input dynamic range DR of the reception circuit 123, and the communication system 100 will be able to perform stable communication.

[0015] FIG. 3 is a block diagram showing an example of the basic configuration of an electromagnetic noise source 130 and a communication system 100. FIG. 3 is a diagram in which the electromagnetic noise source 130 is added to FIG. 1. The electromagnetic noise source 130 generates a noise voltage Vn. Spatial noise based on the noise voltage Vn is mixed into the received voltages Vrp and Vrn. The noise voltage Vn is mixed into the received voltages Vrp and Vrn in the form of electromagnetic waves propagating through space or fluctuations in the reference potential (ground potential). Here, it is assumed that the physical distance between the electrodes 121a and 121b is sufficiently close to the wavelength (frequency) of the noise voltage Vn. In this case, the received voltages Vrp and Vrn are considered to be mixed with spatial noise whose phase and frequency are nearly synchronized with the noise voltage Vn and whose amplitude is reduced, as shown in FIG. 4. In other words, the received voltages Vrp and Vrn are mixed with spatial noise similar to the noise voltage Vn.

[0016] Figure 4 is a voltage waveform diagram showing an example of the transmission signal Vt, reception signal Vr, and output signal Vo of Figure 3. The transmission signal Vt is the voltage obtained by subtracting the transmission voltage Vtn from the transmission voltage Vtp. The reception signal Vr is the voltage obtained by subtracting the reception voltage Vrn from the reception voltage Vrp. The output signal Vo is the voltage obtained by subtracting the output voltage Von from the output voltage Vop.

[0017] 2 are superimposed on spatial noise based on the noise voltage Vn. If the received voltages Vrp and Vrn exceed the input dynamic range DR of the receiver circuit 123 at a certain timing, distortion occurs in the output signal Vo. As a result, the signal quality of the output signal Vo deteriorates, and the probability of data errors occurring increases.

[0018] To suppress such degradation in the signal quality of the output signal Vo, it is desirable to estimate in advance the maximum value of spatial noise due to the noise voltage Vn that may be mixed in and design the receiver circuit 123 so that its input dynamic range DR is large enough to accommodate the maximum spatial noise value. However, it is generally difficult to design a receiver circuit 123 with a large input dynamic range DR while satisfying constraints such as high-frequency performance, cost, and size. For example, if a receiver circuit 123 is designed to accept 10-Gbps reception voltages Vrp and Vrn, the semiconductor elements used in the receiver circuit 123 must operate in a frequency band of at least 10 to 20 GHz. The input voltage range that such high-frequency semiconductors can tolerate is generally 10 V or less. However, the noise voltage Vn, such as electrostatic noise, may be several kV to several tens of kV. In this case, the spatial noise due to the noise voltage Vn will be at least 10 V or more. As is clear from this example, in order to increase the input dynamic range DR of the receiver circuit 123, a new method for suppressing spatial noise due to the noise voltage Vn mixed in the reception voltages Vrp and Vrn is required in addition to the design.

[0019] Fig. 5 is a block diagram showing an example of the configuration of a communication system 100 according to the first embodiment. The communication system 100 has a transmitting unit 110 and a receiving unit 120. The transmitting unit 110 in Fig. 5 has an electrode 111a, an electrode 111b, and a transmitting circuit 112, similar to the transmitting unit 110 in Fig. 1. The receiving unit 120 in Fig. 5 additionally includes current consumption detection units 150a and 150b, a current consumption total calculation unit 151, a feedback voltage generation unit 152, and addition units 153a and 153b in addition to the receiving unit 120 in Fig. 1. A method for controlling the communication system 100 will now be described.

[0020] A receiving voltage Vrp corresponding to the transmitting voltage Vtp is generated at the electrode 121a. A receiving voltage Vrn corresponding to the transmitting voltage Vtn is generated at the electrode 121b. The adder 153a adds the feedback voltage V5 to the receiving voltage Vrp and outputs the receiving voltage V1p. The adder 153b adds the feedback voltage V5 to the receiving voltage Vrn and outputs the receiving voltage V1n.

[0021] The input terminal INp of the receiving circuit 123 receives the received voltage V1p. The input terminal INn of the receiving circuit 123 receives the received voltage V1n. The output terminal OUTp of the receiving circuit 123 outputs the output voltage Vop. The output terminal OUTn of the receiving circuit 123 outputs the output voltage Von. The receiving circuit 123 amplifies or impedance-converts the received voltages V1p and V1n, and outputs the output voltages Vop and Von.

[0022] The current consumption detector 150a detects the current consumption Ip flowing through the power supply terminal Vcc1 of the receiving circuit 123. The current consumption detector 150b detects the current consumption In flowing through the power supply terminal Vcc2 of the receiving circuit 123. The current consumption sum calculator 151 calculates the sum Isum of the current consumption Ip and the current consumption In. The feedback voltage generator 152 generates a feedback voltage V5 by multiplying the sum Isum by a negative constant. The adder 153a adds the feedback voltage V5 to the receiving voltage Vrp and outputs the receiving voltage V1p. The adder 153b adds the feedback voltage V5 to the receiving voltage Vrn and outputs the receiving voltage V1n.

[0023] Fig. 6 is a circuit diagram showing an example configuration of the receiving circuit 123 of Fig. 5. The receiving circuit 123 has amplifiers 160a and 160b. The amplifiers 160a and 160b are two independent amplifiers that operate based on a reference potential (ground potential).

[0024] The amplifier 160a is connected to an input terminal INp, an output terminal OUTp, and a power supply terminal Vcc1. The input terminal INp receives the received voltage V1p of FIG. 5. The output terminal OUTp outputs the output voltage Vop of FIG. 5. The power supply terminal Vcc1 is connected to the power supply potential node of FIG. 5. The amplifier 160a amplifies the received voltage V1p at the input terminal INp, and outputs the output voltage Vop to the output terminal OUTp.

[0025] The amplifier 160b is connected to an input terminal INn, an output terminal OUTn, and a power supply terminal Vcc2. The input terminal INn receives the received voltage V1n of FIG. 5. The output terminal OUTn outputs the output voltage Von of FIG. 5. The power supply terminal Vcc2 is connected to the power supply potential node of FIG. 5. The amplifier 160b amplifies the received voltage V1n of the input terminal INn, and outputs the output voltage Von to the output terminal OUTn.

[0026] As the amplitude of the received voltage V1p increases, the consumption current Ip flowing through the power supply terminal Vcc1 also increases in proportion to the amplitude of the received voltage V1p. Similarly, as the amplitude of the received voltage V1n increases, the consumption current In flowing through the power supply terminal Vcc2 also increases in proportion to the amplitude of the received voltage V1n. This is because as the amplitude of the received voltages V1p and V1n increases, the power supplied to the load resistors connected to the output terminals OUTp and OUTn increases. In other words, there is a strong correlation between the amplitude of the received voltages V1p and V1n and the consumption currents Ip and In flowing through the power supply terminals Vcc1 and Vcc2. In this embodiment, the receiver 120 utilizes this strong correlation to suppress spatial noise due to the noise voltage Vn mixed into the received voltages Vrp and Vrn.

[0027] Equation (1) represents the received voltage Vrp in Figure 5, and equation (2) represents the received voltage Vrn in Figure 5. The received voltages Vrp and Vrn are mixed with spatial noise based on the noise voltage Vn. For simplicity, it is assumed that the transmitted voltages Vtp and Vtn and the noise voltage Vn are sinusoidal waves. The first terms in equations (1) and (2) are received voltages (data signals) based on the transmitted voltages Vtp and Vtn, respectively, and are differential signals. Therefore, the first terms in equations (1) and (2) have opposite signs. The second terms in equations (1) and (2) are spatial noise based on the noise voltage Vn. ω d is the angular frequency of the received voltage (data signal) based on the transmitted voltages Vtp and Vtn. n is the angular frequency of the spatial noise based on the noise voltage Vn. Note that the angular frequency ω d and ω nIn either case, the receiving section 120 can suppress spatial noise due to the noise voltage Vn that mixes into the received voltages Vrp and Vrn.

[0028]

number

[0029] Equation (3) represents the received voltage V1p in FIG. 5, and equation (4) represents the received voltage V1n in FIG. 5. Adder 153a adds feedback voltage V5 to received voltage Vrp and outputs received voltage V1p. Adder 153b adds feedback voltage V5 to received voltage Vrn and outputs received voltage V1n. Initially, feedback voltage V5 is assumed to be zero. In this case, received voltage V1p is the same as received voltage Vrp, and received voltage V1n is the same as received voltage Vrn.

[0030]

number

[0031] Equation (5) represents the current consumption Ip in FIG. 5, and equation (6) represents the current consumption In in FIG. 5. The current consumption detector 150a detects the current consumption Ip flowing through the power supply terminal Vcc1 of the receiving circuit 123. The current consumption detector 150b detects the current consumption In flowing through the power supply terminal Vcc2 of the receiving circuit 123. As mentioned above, there is a strong correlation between the amplitude of the receiving voltages V1p and V1n and the current consumption Ip and In. The current consumption Ip is proportional to the receiving voltage V1p, and the current consumption In is proportional to the receiving voltage V1n. Using the proportionality constant α, the current consumption Ip is expressed by equation (7), and the current consumption In is expressed by equation (8).

[0032]

number

[0033] Equation (9) is an equation showing the sum Isum in Fig. 5. The current consumption sum calculation unit 151 calculates the sum Isum of the current consumption Ip and the current consumption In.

[0034]

number

[0035] Equation (10) represents the feedback voltage V5 in FIG. 5, and equation (11) represents the voltage gain Ga. The feedback voltage generating unit 152 generates the feedback voltage V5 by multiplying the sum Isum by the voltage gain Ga. The voltage gain Ga is a negative constant. By substituting equation (11) into equation (10), equation (12) is obtained.

[0036]

number

[0037] Equation (13) is an equation that represents the received voltage V1p in FIG. 5, and equation (14) is an equation that represents the received voltage V1n in FIG. 5. The adder 153a adds the feedback voltage V5 to the received voltage Vrp and outputs the received voltage V1p. The adder 153b adds the feedback voltage V5 to the received voltage Vrn and outputs the received voltage V1n. Substituting equation (12) for the feedback voltage V5 in equation (13), the received voltage V1p is calculated as follows: n t) is removed, and the received voltage (data signal) sin(ω) is calculated based on the transmitted voltage Vtp. d Furthermore, when equation (12) is substituted into the feedback voltage V5 in equation (14), the received voltage V1n is the spatial noise sin(ω n t) is deleted, and the received voltage (data signal) -sin(ω) is calculated based on the transmitted voltage Vtn. d Only t) remains.

[0038]

number

[0039] The receiving circuit 123 amplifies the receiving voltages V1p and V1n from which spatial noise has been removed. Because the receiving voltages V1p and V1n have had spatial noise removed, the receiving unit 120 can prevent the receiving voltages V1p and V1n from exceeding the input dynamic range DR of the receiving circuit 123. This allows the receiving unit 120 to suppress distortion of the output signal Vo, improve the signal quality of the output signal Vo, and reduce the probability of data errors occurring.

[0040] As described above, even if spatial noise is mixed into the reception voltages Vrp and Vrn, the reception section 120 can input the reception voltages V1p and V1n from which the spatial noise has been removed to the reception circuit 123.

[0041] It is desirable that the voltage gain Ga in equation (11) be appropriately designed in consideration of the relationship between the input impedance of amplifiers 160a and 160b and the output impedance of feedback voltage generating section 152.

[0042] The principle of spatial noise suppression explained so far can be considered as so-called negative feedback of spatial noise. Furthermore, it is considered that the stronger the degree of spatial noise suppression, the more preferable it is in many cases. Therefore, the voltage gain Ga of the feedback voltage generator 152 is set to ω n Although it is desirable to have a sufficiently large voltage gain Ga in the

[0043] The sum Isum may be proportional to the sum of the current consumption Ip and the current consumption In. If the feedback voltage V5 corresponds to equation (12), the adders 153a and 153b can output reception voltages V1p and V1n with suppressed spatial noise. Furthermore, even if the sum Isum is proportional to the sum of the current consumption Ip and the current consumption In via a negative proportionality constant and the voltage gain Ga in equation (11) is a positive constant, spatial noise can be suppressed.

[0044] 7 is a circuit diagram showing an example of the configuration of the receiving unit 120 according to the first embodiment. The receiving unit 120 has an electrode 121a, an electrode 121b, a receiving circuit 123, a current consumption detection unit 170, a current consumption sum calculation unit 171, and an adder 172. The current consumption detection unit 170 corresponds to the current consumption detection units 150a and 150b in FIG. 5. The current consumption sum calculation unit 171 corresponds to the current consumption sum calculation unit 151 and the feedback voltage generation unit 152 in FIG. 5. The adder 172 corresponds to the adders 153a and 153b in FIG. The receiving circuit 123 has the same configuration as the receiving circuit 123 in FIG. 6.

[0045] The current consumption detection unit 170 has resistors R1a and R1b and capacitors C1a and C1b. The resistor R1a is connected between a power supply potential node Vcc and a power supply terminal Vcc1. The resistor R1b is connected between a power supply potential node Vcc and a power supply terminal Vcc2. The capacitor C1a is connected between the power supply terminal Vcc1 and a reference potential node. The capacitor C1b is connected between the power supply terminal Vcc2 and a reference potential node.

[0046] Resistors R1a and R1b are current consumption detection resistors that generate voltage drops proportional to the current consumptions Ip and In consumed by amplifiers 160a and 160b, respectively. As the current consumptions Ip and In increase, the voltage drops across resistors R1a and R1b also increase. As a result, the voltages at power supply terminals Vcc1 and Vcc2 become voltages proportional to the current consumptions Ip and In with a negative proportionality constant. As described above, current consumption detection unit 170 generates voltages proportional to the current consumptions Ip and In with a negative proportionality constant as the voltages at power supply terminals Vcc1 and Vcc2.

[0047] The capacitors C1a and C1b are decoupling capacitors. The capacitors C1a and C1b decouple the high frequency band (the angular frequency ω nThe impedance of the power supply terminals Vcc1 and Vcc2 in the frequency band (higher than 1 / 100 Hz) is reduced, and the operation of the amplifiers 160a and 160b can be stabilized. Note that the cutoff frequency of the low-pass filter characteristics formed by the resistors R1a and R1b and the capacitors C1a and C1b is set to the angular frequency ω n It is desirable to set the frequency higher than

[0048] The current consumption total calculation unit 171 has resistors R2a and R2b. Resistor R2a is connected between power supply terminal Vcc1 and node N1. Resistor R2b is connected between power supply terminal Vcc2 and node N1. The voltage at node N1 corresponds to the sum of the voltages at power supply terminal Vcc1 and Vcc2. That is, the current consumption total calculation unit 171 generates, as the voltage at node N1, a voltage that corresponds to the sum of a voltage proportional to the current consumption Ip by a negative proportional constant and a voltage proportional to the current consumption In by a negative proportional constant. The voltage at node N1 corresponds to the feedback voltage V5 in FIG. 5.

[0049] The current consumption total calculation unit 171 may be configured with a high-input impedance amplifier such as an operational amplifier. Furthermore, there may be cases where the characteristics of the amplifiers 160a and 160b are well matched, and the bias currents (current consumption when no signal is input) of the amplifiers 160a and 160b are close to each other. In such cases, the resistors R2a and R2b of the current consumption total calculation unit 171 may both be shorted out.

[0050] The adder 172 has resistors R3a and R3b. The electrode 121a is connected to the input terminal INp. The electrode 121b is connected to the input terminal INn. The resistor R3a is connected between the node N1 and the input terminal INp. The resistor R3b is connected between the node N1 and the input terminal INn. The adder 172 adds the voltage at the node N1 to the received voltage at the electrode 121a, and adds the voltage at the node N1 to the received voltage at the electrode 121b. The voltage at the input terminal INp corresponds to the received voltage V1p in FIG. 5 and is a voltage in which spatial noise has been suppressed. The voltage at the input terminal INn corresponds to the received voltage V1n in FIG. 5 and is a voltage in which spatial noise has been suppressed.

[0051] As described above, the receiving unit 120 has the effect of suppressing the spatial noise components of the voltage at the input terminal INp and the spatial noise components of the voltage at the input terminal INn. Note that the relationship between the DC potentials (bias potentials) at each point in the circuit and the function for adjusting them are not described here. It is necessary to add a function for adjusting the DC potential (bias potential) appropriately so that the DC potential (bias potential) is set within a range in which the semiconductor element can operate properly. In this case, it is desirable to insert a coupling capacitor with sufficiently low impedance at the lowest angular frequency of the noise voltage Vn into the feedback path of the feedback voltage V5.

[0052] Fig. 8 is a circuit diagram showing another example of the configuration of the receiving unit 120 according to the first embodiment. The receiving unit 120 in Fig. 8 is obtained by adding a feedback voltage generating unit 180 to the receiving unit 120 in Fig. 7. The differences between Fig. 8 and Fig. 7 will be described below.

[0053] The feedback voltage generating unit 180 includes an npn bipolar transistor Qa1 and a resistor Ra4, and is configured as a common-collector amplifier circuit. The npn bipolar transistor Qa1 has a collector connected to a power supply potential node Vcc, a base connected to a node N1, and an emitter connected to a node N2. The resistor Ra4 is connected between the node N2 and a reference potential node. The resistor R3a is connected between the node N2 and an input terminal INp. The resistor R3b is connected between the node N2 and an input terminal INn. The voltage at the node N2 corresponds to the feedback voltage V5 in FIG. 5.

[0054] Providing the feedback voltage generating unit 180 has the effect of improving isolation between the total current consumption calculation unit 171 and the adder 172. Furthermore, the feedback voltage generating unit 180 reduces the impedance of the node N2, and can supply a voltage to the node N2 that is sufficient to suppress spatial noise even when the input impedances of the amplifiers 160a and 160b are low.

[0055] Fig. 9 is a circuit diagram showing another example of the configuration of the receiving unit 120 according to the first embodiment. The receiving unit 120 in Fig. 9 is obtained by adding a feedback voltage generating unit 190 to the receiving unit 120 in Fig. 7. The differences between Fig. 9 and Fig. 7 will be described below.

[0056] The feedback voltage generating unit 190 includes an npn bipolar transistor Qa2, resistors Ra5, Ra6, and Ra7, and a capacitor Ca2, and is configured as a common-base amplifier circuit. Resistor Ra5 is connected between a power supply potential node Vcc and a node N3. The npn bipolar transistor Qa2 has a collector connected to the node N3 and a base connected to a bias potential node Vbi. Capacitor Ca2 is connected between the base of the npn bipolar transistor Qa2 and a reference potential node. Resistor Ra6 is connected between the emitter of the npn bipolar transistor Qa2 and a node N1. Resistor Ra7 is connected between the node N1 and the reference potential node. Resistor R3a is connected between the node N3 and an input terminal INp. Resistor R3b is connected between the node N3 and an input terminal INn. The voltage at node N3 corresponds to the feedback voltage V5 in FIG. 5.

[0057] Providing the feedback voltage generating unit 190 has the effect of improving the isolation between the total current consumption calculation unit 171 and the adder 172. Furthermore, the feedback voltage generating unit 190 reduces the impedance of the node N3, and can supply a voltage to the node N3 that is sufficient to suppress spatial noise even when the input impedances of the amplifiers 160a and 160b are low.

[0058] Furthermore, since the feedback voltage generating unit 190 is configured by a common-base amplifier circuit, the voltage gain of the feedback voltage generating unit 190 can be increased compared to the receiving unit 120 in Figures 7 and 8. As described above, the voltage gain of the feedback voltage generating unit 190 is determined by the angular frequency ω n In this case, it is desirable for the feedback voltage generating unit 190 to have a sufficiently large voltage gain, but strict design is not necessary. Therefore, since the feedback voltage generating unit 190 is configured by a grounded base amplifier circuit, it is possible to enhance the effect of suppressing spatial noise.

[0059] FIG. 10(a) shows a circuit model of the receiver 120 shown in FIG. 9 created using a circuit simulator. The current consumption detector 204 corresponds to the current consumption detector 170 shown in FIG. 9 and detects the current consumption of the amplifiers (grounded collector amplifier circuits) Q1 and Q2. The amplifiers Q1 and Q2 correspond to the amplifiers 160a and 160b shown in FIG. 9. The resistors R8 and R34 are current consumption detection resistors that generate a voltage drop proportional to the current consumption of the amplifiers Q1 and Q2. As the current consumption of the amplifiers Q1 and Q2 increases, the voltage drop across the resistors R8 and R34 also increases. In other words, the resistors R8 and R34 can generate a voltage proportional to the current consumption of the amplifiers Q1 and Q2 with a negative proportionality constant. The capacitors C1 and C6 are decoupling capacitors. The capacitors C1 and C6 stabilize the operation of the amplifiers Q1 and Q2 in the high-frequency band.

[0060] 9, the current consumption sum calculation unit 205 calculates the sum of voltages proportional to the current consumption values ​​of the amplifiers Q1 and Q2, generated by resistors R8 and R34, via resistors R1 and R6, with a negative proportionality constant. Here, the amplifiers Q1 and Q2 use the same transistors, and their performance is well matched. Therefore, because the bias currents of the amplifiers Q1 and Q2 are close to each other, both resistors R1 and R6 of the current consumption sum calculation unit 205 may be shorted.

[0061] The feedback voltage generating section 203 corresponds to the feedback voltage generating section 190, and amplifies the output voltage of the total current consumption calculating section 205 to generate a feedback voltage.

[0062] Adder 202 corresponds to adder 172 in Fig. 9 and adds the feedback voltage generated via resistors R3 and R4 to the received voltage output from capacitors C25 and C26 of coupler 201. Coupler 201 corresponds to electrodes 121a and 121b in Fig. 9.

[0063] Voltage source 200 simulates electromagnetic noise source 130 in Fig. 3. The noise voltage generated by voltage source 200 is input with the same phase and amplitude to capacitors C25 and C26 of coupler 201. In other words, common-mode noise is input to capacitors C25 and C26.

[0064] Fig. 10(b) is a diagram showing the transfer characteristics from the input node Na to the output node Nb when the total current consumption calculation unit 205 and the feedback voltage generation unit 203 in Fig. 10(a) are disconnected. Fig. 10(c) is a diagram showing the transfer characteristics from the input node Na to the output node Nb when the total current consumption calculation unit 205 and the feedback voltage generation unit 203 in Fig. 10(a) are connected.

[0065] The transfer characteristics of Fig. 10(b) and Fig. 10(c) are compared for 1 MHz, 10 MHz, and 100 MHz. At 1 MHz, the transfer characteristic of Fig. 10(b) is -50 dB, and the transfer characteristic of Fig. 10(c) is -72 dB. The transfer characteristic of Fig. 10(c) (-72 dB) is a 22 dB reduction in noise voltage compared to the transfer characteristic of Fig. 10(b) (-50 dB), due to the effect of this embodiment.

[0066] At 10 MHz, the transfer characteristic in Fig. 10(b) is -30 dB, and the transfer characteristic in Fig. 10(c) is -52 dB. The transfer characteristic in Fig. 10(c) (-52 dB) is a 22 dB reduction in noise voltage compared to the transfer characteristic in Fig. 10(b) (-30 dB) due to the effect of this embodiment.

[0067] At 100 MHz, the transfer characteristic in Fig. 10(b) is -13 dB, and the transfer characteristic in Fig. 10(c) is -27 dB. The transfer characteristic in Fig. 10(c) (-27 dB) is a 14 dB reduction in noise voltage compared to the transfer characteristic in Fig. 10(b) (-13 dB) due to the effect of this embodiment.

[0068] The above results show that the receiving unit 120 can reduce the noise voltage to about one-tenth with a relatively simple circuit configuration by providing the adding unit 202, the feedback voltage generating unit 203, the current consumption detecting unit 204, and the total current consumption calculating unit 205. The effects of this embodiment are not limited to the communication system 100. When the conditions of the fourth embodiment described below are met, the effects of this embodiment are likely to be realized even when the transmitting unit 110 and the receiving unit 120 are directly connected by wire.

[0069] As described above, the communication system 100 has a transmitting unit 110 and a receiving unit 120. The transmitting unit 110 is a transmitting device, and the receiving unit 120 is a receiving device. The transmitting unit 110 has electrodes 111a and 111b. The receiving unit 120 has electrodes 121a and 121b. The electrodes 111a and 121a are coupled to each other in an electric field or a magnetic field. The electrodes 111b and 121b are coupled to each other in an electric field or a magnetic field. The transmitting unit 110 transmits a signal to the receiving unit 120.

[0070] The receiving circuit 123 receives received signals at input terminals INp and INn. The feedback voltage generating unit 152 and the like are control units that control the received signals input to the receiving circuit 123 in accordance with the current consumption of the receiving circuit 123. Specifically, the feedback voltage generating unit 152 and the like control the received signals input to the receiving circuit 123 so that they fall within the input dynamic range DR of the receiving circuit 123. Furthermore, the feedback voltage generating unit 152 and the like suppress noise components of the received signals input to the receiving circuit 123 in accordance with the current consumption of the receiving circuit 123. The noise components are spatial noise based on the noise voltage Vn.

[0071] The feedback voltage generating unit 152 etc. generates a feedback signal according to the current consumption of the receiving circuit 123. The feedback signal is, for example, a feedback voltage V5. The receiving circuit 123 receives as input a signal obtained by adding the feedback signal to the received signal. The feedback signal is, for example, the feedback voltage V5 in equation (10), which is a signal obtained by multiplying the current consumption of the receiving circuit 123 by a negative coefficient. The negative coefficient is, for example, a voltage gain Ga.

[0072] Electrodes 121a and 121b each receive a reception signal through electric field or magnetic field coupling. Electrode 121a is connected to input terminal INp of reception circuit 123. Electrode 121b is connected to input terminal INn of reception circuit 123. Reception circuit 123 amplifies or converts the impedance of the input reception signal.

[0073] The receiving circuit 123 has an amplifier 160a and an amplifier 160b. The amplifier 160a amplifies the received signal at the input terminal INp. The amplifier 160b amplifies the received signal at the input terminal INn. The feedback voltage generating unit 152 and the like control the received signal at the input terminal INp and the received signal at the input terminal INn according to the sum of the current consumption Ip of the amplifier 160a and the current consumption In of the amplifier 160b. The received signal at the input terminal INp and the received signal at the input terminal INn are differential signals. The electrode 121a is connected to the input terminal of the amplifier 160a. The electrode 121b is connected to the input terminal of the amplifier 160b.

[0074] 8 includes an npn bipolar transistor Qa1 and a resistor Ra4, and is configured as a grounded collector amplifier circuit that amplifies the feedback signal.

[0075] 9 includes an npn bipolar transistor Qa2, resistors Ra5, Ra6, and Ra7, and a capacitor Ca2, and is configured as a common-base amplifier circuit that amplifies the feedback signal.

[0076] As described above, according to this embodiment, even if the electromagnetic field strength of spatial noise is strong compared to the amplitude of the received signal, the receiving unit 120 can suppress the maximum amplitude of the received signal to within the input dynamic range DR of the amplifiers 160a and 160b, thereby enabling the receiving unit 120 to improve the quality of the received signal.

[0077] (Second embodiment) Fig. 11 is a block diagram showing an example of the configuration of a communication system 100 according to the second embodiment. In Fig. 11, a control unit 210 is provided instead of the total current consumption calculation unit 151 and the feedback voltage generation unit 152 of Fig. 5. The control unit 210 has analog-to-digital converters (ADC) 211a and 211b, a total current consumption calculation unit 212, a feedback voltage generation unit 213, and a digital-to-analog converter (DAC) 214. This control unit 210 can be configured using a microcontroller unit or an FPGA.

[0078] The ADC 211a converts a voltage value proportional to the current consumption Ip detected by the current consumption detection unit 150a with a positive proportional constant (or a negative proportional constant) into a digital value. The ADC 211b converts a voltage value proportional to the current consumption In detected by the current consumption detection unit 150b with a positive proportional constant (or a negative proportional constant) into a digital value.

[0079] The current consumption total calculation unit 212 calculates the sum of the digital values ​​converted by the ADC 211a and the digital values ​​converted by the ADC 211a. The feedback voltage generation unit 213 calculates a feedback voltage by multiplying the sum of the digital values ​​calculated by the current consumption total calculation unit 212 by a predetermined coefficient. The DAC 214 converts the digital value corresponding to the feedback voltage calculated by the feedback voltage generation unit 213 into an analog feedback voltage V5.

[0080] The adder 153a adds the feedback voltage V5 converted by the DAC 214 to the received voltage Vrp, and outputs the received voltage V1p to the input terminal INp. The adder 153b adds the feedback voltage V5 converted by the DAC 214 to the received voltage Vrn, and outputs the received voltage V1n to the input terminal INn.

[0081] As described above, the control unit 210 generates a feedback signal (feedback voltage V5) by digital signal processing. This embodiment achieves the same noise voltage reduction effect as the first embodiment. The control unit 210 performs calculations related to negative feedback by software processing, which has the advantage that even if the noise situation changes, parameters can be set to enhance the noise voltage reduction effect simply by changing the software.

[0082] (Third embodiment) Fig. 12 is a block diagram showing an example of the configuration of a communication system 100 according to the third embodiment. In Fig. 12, the current consumption total calculation unit 151 and the current consumption detection unit 150b are omitted from Fig. 5.

[0083] 13 is a circuit diagram showing an example configuration of the receiving circuit 123 of FIG. 12. The receiving circuit 123 has a differential amplifier 230. The differential amplifier 230 is connected to input terminals INp and INn, output terminals OUTp and OUTn, and a power supply terminal Vcc1. The input terminal INp inputs the receiving voltage V1p of FIG. 12. The input terminal INn inputs the receiving voltage V1n of FIG. 12. The output terminal OUTp outputs the output voltage Vop of FIG. 12. The output terminal OUTn outputs the output voltage Von of FIG. 12. The power supply terminal Vcc1 is connected to the power supply potential node of FIG. 12. The differential amplifier 230 amplifies the difference between the receiving voltage V1p of the input terminal INp and the receiving voltage V1n of the input terminal INn, and outputs the output voltage Vop of the output terminal OUTp and the output voltage Von of the output terminal OUTn.

[0084] Fig. 14 is a circuit diagram showing an example of the configuration of differential amplifier 230 of Fig. 13. Differential amplifier 230 has npn bipolar transistors 241 and 242, a current source resistor 240, resistors 243a, 243b, 244a, 244b, 245a, and 245b, and capacitors 246a and 246b.

[0085] Resistor 243a is connected between power supply terminal Vcc1 and output terminal OUTn. Npn bipolar transistor 241 has a collector connected to output terminal OUTn and a base connected to input terminal INp. Resistor 245a is connected between input terminal INp and bias potential node Vbi. Capacitor 246a is connected between bias potential node Vbi and the reference potential node. Resistor 244a is connected between the emitter of npn bipolar transistor 241 and node N4.

[0086] Resistor 243b is connected between power supply terminal Vcc1 and output terminal OUTp. Npn bipolar transistor 242 has a collector connected to output terminal OUTp and a base connected to input terminal INn. Resistor 245b is connected between input terminal INn and bias potential node Vbi. Capacitor 246b is connected between bias potential node Vbi and the reference potential node. Resistor 244b is connected between the emitter of npn bipolar transistor 242 and node N4. Current source resistor 240 is connected between node N4 and the reference potential node.

[0087] When noise signals of the same phase and amplitude are input to input terminals INp and INn, the base potentials of npn bipolar transistors 241 and 242 increase or decrease in proportion to the input noise signals. At the same time, the emitter potentials of npn bipolar transistors 241 and 242 also increase or decrease in proportion to the input noise signals. Therefore, the current consumption flowing through current source resistor 240 also increases or decreases in proportion to the input noise signals. In other words, the current consumption flowing from power supply terminal Vcc1 also increases or decreases in proportion to the input noise signals. Therefore, there is a strong correlation between the input noise signals and the value of the current consumption flowing from power supply terminal Vcc1.

[0088] 12, current consumption detector 150a detects current consumption Ip flowing through power supply terminal Vcc1 of receiver circuit 123. Feedback voltage generator 152 generates feedback voltage V5 by multiplying current consumption Ip detected by current consumption detector 150a by voltage gain Ga. Voltage gain Ga is a negative constant. Adder 153a adds feedback voltage V5 to received voltage Vrp and outputs received voltage V1p to input terminal INp. Adder 153b adds feedback voltage V5 to received voltage Vrn and outputs received voltage V1n to input terminal INn.

[0089] Like the first and second embodiments, this embodiment can achieve the effect of reducing spatial noise.

[0090] FIG. 15 is a circuit diagram showing another example of the differential amplifier 230 shown in FIG. 13. In FIG. 15, a current source 250 is provided instead of the current source resistor 240 shown in FIG. 14. The current source 250 is connected between node N4 and the reference potential node. In this case, there is no correlation between the input noise signal and the current consumption value flowing from the power supply terminal Vcc1. Therefore, in principle, it is difficult to achieve a noise voltage reduction effect when the differential amplifier 230 shown in FIG. 15 is used in the receiver 120 shown in FIG. 12. However, when the differential amplifier 230 shown in FIG. 15 is actually manufactured, the individual variations in the current source 250, its frequency characteristics, the allowable common-mode noise voltage dynamic range, and other factors make it impossible to achieve ideal performance. Therefore, when the differential amplifier 230 shown in FIG. 15 is used in the receiver 120 shown in FIG. 12, a certain level of noise reduction effect can be expected.

[0091] As described above, the receiving circuit 123 has the differential amplifier 230. The differential amplifier 230 amplifies the difference between the received signal at the input terminal INp and the received signal at the input terminal INn. As in FIG. 7 and other figures, the electrodes 121a and 121b are connected to the input terminals INp and INn of the differential amplifier 230, respectively. The feedback voltage generating unit 152 and other units control the received signal at the input terminals INp and INn in accordance with the current consumption of the differential amplifier 230.

[0092] According to this embodiment, the receiving unit 120 can suppress the spatial noise component of the received signal, similarly to the first and second embodiments.

[0093] (Fourth embodiment) Fig. 16 is a block diagram showing an example of the configuration of a communication system 100 according to the fourth embodiment. In Fig. 16, two transmission circuits 112a and 112b are provided instead of the transmission circuit 112 in Fig. 5, and two reception circuits 123a and 123b are provided instead of the reception circuit 123. The transmission circuits 112a and 112b are transmission circuits independent of each other. The reception circuits 123a and 123b are reception circuits independent of each other.

[0094] The transmitting circuit 112a outputs a transmitting voltage Vtp to the electrode 111a. The transmitting circuit 112b outputs a transmitting voltage Vtn to the electrode 111b. The receiving circuit 123a amplifies the receiving voltage V1p and outputs an output voltage Vop. The receiving circuit 123b amplifies the receiving voltage V1n and outputs an output voltage Von. The current consumption detector 150a detects the current consumption Ip flowing through the power terminal of the receiving circuit 123a. The current consumption detector 150b detects the current consumption Ib flowing through the power terminal of the receiving circuit 123b. In other respects, the communication system 100 of FIG. 16 is similar to the communication system 100 of FIG. 5.

[0095] When the communication system 100 in FIG. 16 satisfies the following first and second conditions, it is possible to obtain the effect of suppressing noise voltage, similar to the first to third embodiments.

[0096] First condition: The transmission voltage Vtp output by the transmission circuit 112a and the transmission voltage Vtr output by the transmission circuit 112b are both random signals, and are signals with low correlation with each other.

[0097] Second condition: The distance between electrodes 111a, 111b, 121a, and 121b is sufficiently small compared to the wavelength (frequency) of the noise voltage, and spatial noise (noise voltage) of approximately the same phase and amplitude is mixed into electrodes 121a and 121b.

[0098] Alternatively, the communication system 100 of FIG. 16 can also achieve the effect of suppressing noise voltage when the following third and fourth conditions are satisfied.

[0099] Third condition: The transmission voltage Vtp output by the transmission circuit 112a and the transmission voltage Vtn output by the transmission circuit 112b form a differential signal pair.

[0100] Fourth condition: The distance between electrodes 111a, 111b, 121a, and 121b is sufficiently small compared to the wavelength (frequency) of the noise voltage, and spatial noise (noise voltage) of approximately the same phase and amplitude is mixed into electrodes 121a and 121b.

[0101] It should be noted that the above-described embodiments merely illustrate specific examples of implementing the present disclosure, and the technical scope of the present disclosure should not be construed as being limited by these embodiments. In other words, the present disclosure can be implemented in various forms without departing from its technical concept or main features.

[0102] The disclosure of this embodiment includes the following configurations and methods. (Configuration 1) a receiving circuit for inputting a received signal; a control unit that controls a reception signal input to the reception circuit in accordance with a current consumption of the reception circuit; A receiving device comprising: (Configuration 2) 2. The receiving device according to claim 1, wherein the control unit controls the received signal input to the receiving circuit so that the received signal falls within an input dynamic range of the receiving circuit. (Configuration 3) 3. The receiving device according to configuration 1 or 2, wherein the control unit suppresses noise components in the received signal input to the receiving circuit in accordance with the current consumption of the receiving circuit. (Configuration 4) the control unit generates a feedback signal in response to a current consumption of the receiving circuit; 4. The receiving device according to any one of configurations 1 to 3, wherein the receiving circuit inputs a signal obtained by adding the feedback signal to the received signal. (Configuration 5) 5. The receiving device according to configuration 4, wherein the feedback signal is a signal obtained by multiplying the current consumption of the receiving circuit by a negative coefficient. (Configuration 6) a first electrode for receiving a received signal; 6. The receiving device according to any one of configurations 1 to 5, wherein the first electrode is connected to an input terminal of the receiving circuit. (Configuration 7) 7. The receiving device according to configuration 6, wherein the first electrode receives the reception signal by electric field or magnetic field coupling. (Configuration 8) 8. The receiving device according to any one of configurations 1 to 7, wherein the receiving circuit amplifies or converts impedance of an input received signal. (Configuration 9) The receiving circuit a first amplifier for amplifying the first received signal; a second amplifier for amplifying the second received signal; The receiving device according to any one of configurations 1 to 8, wherein the control unit controls the first received signal and the second received signal according to the sum of the current consumption of the first amplifier and the current consumption of the second amplifier. (Configuration 10) 10. The receiving device according to configuration 9, wherein the first receiving signal and the second receiving signal are differential signals. (Configuration 11) a first electrode that receives the first received signal; a second electrode for receiving the second received signal; the first electrode is connected to an input terminal of the first amplifier; 11. The receiving device according to configuration 9 or 10, wherein the second electrode is connected to an input terminal of the second amplifier. (Configuration 12) the receiving circuit has a differential amplifier that amplifies a difference between a first receiving signal and a second receiving signal; 9. The receiving device according to any one of configurations 1 to 8, wherein the control unit controls the first received signal and the second received signal in accordance with a current consumption of the differential amplifier. (Configuration 13) a first electrode that receives the first received signal; a second electrode for receiving the second received signal; 13. The receiving device according to configuration 12, wherein the first electrode and the second electrode are connected to a first input terminal and a second input terminal of the differential amplifier, respectively. (Configuration 14) 6. The receiving device according to configuration 4 or 5, wherein the control unit has a common collector amplifier circuit or a common base amplifier circuit that amplifies the feedback signal. (Configuration 15) 6. The receiving device according to configuration 4 or 5, wherein the control unit generates the feedback signal by digital signal processing. (Configuration 16) a receiving device according to configuration 7; a transmitting device for transmitting a signal to the receiving device, A communication system, wherein the transmitting device has a third electrode that is electrically or magnetically coupled to the first electrode. (Method 1) A control method for a receiving device having a receiving circuit that receives a received signal, comprising: 10. A control method for a receiving device, comprising the step of controlling a received signal input to the receiving circuit in accordance with a current consumption of the receiving circuit. [Explanation of symbols]

[0103] 100 communication system, 110 transmitting unit, 120 receiving unit, 111a, 111b, 121a, 121b electrodes, 103 electromagnetic noise source, 123 receiving circuit, 160a, 160b amplifier, 150a, 150b current consumption detection unit, 151 current consumption total calculation unit, 152 feedback voltage generation unit, 153a, 153b addition unit

Claims

1. A coupler for receiving a signal from another communication device via electric field coupling or magnetic field coupling; a receiving circuit for inputting a signal received by the coupler; a detection means for detecting a current consumption of the receiving circuit; a control means for controlling a reception signal input to the reception circuit,

2. The receiving device as described in Claim 1, characterized in that the control means controls the receiving signal input to the receiving circuit based on the detected current consumption.

3. 2. The receiving device according to claim 1, wherein said control means controls the received signal input to said receiving circuit so that the received signal falls within an input dynamic range of said receiving circuit.

4. 2. The receiving device according to claim 1, wherein the control means suppresses noise components of the received signal input to the receiving circuit based on a current consumption of the receiving circuit.

5. The control means has a feedback voltage generating means for generating a feedback signal, 2. The receiving device according to claim 1, further comprising a control circuit for controlling a signal obtained by adding the feedback signal to the signal received by the coupler to be input to the receiving circuit.

6. 6. The receiving device according to claim 5, wherein the feedback signal is a signal obtained by multiplying a current consumption of the receiving circuit by a negative coefficient.

7. The coupler has a first electrode, 2. The receiving device according to claim 1, wherein the first electrode is connected to an input terminal of the receiving circuit.

8. The coupler has a second electrode, 7. The receiving device according to claim 6, wherein the second electrode is connected to an input terminal of the receiving circuit.

9. 2. The receiving device according to claim 1, wherein the receiving circuit amplifies or converts impedance of an input received signal.

10. The receiving circuit includes: a first amplifier for amplifying the first received signal; a second amplifier for amplifying the second received signal; 2. The receiving device according to claim 1, wherein the control means controls the first received signal and the second received signal based on a sum of a current consumption of the first amplifier and a current consumption of the second amplifier.

11. 11. The receiving device according to claim 10, wherein the first receiving signal and the second receiving signal are differential signals.

12. the receiving circuit has a differential amplifier that amplifies a difference between a first receiving signal and a second receiving signal; 2. The receiving device according to claim 1, wherein the control means controls the first received signal and the second received signal based on a current consumption of the differential amplifier.

13. a first electrode for receiving the first received signal; a second electrode for receiving the second received signal; 13. The receiving device according to claim 12, wherein the first electrode and the second electrode are connected to a first input terminal and a second input terminal of the differential amplifier, respectively.

14. The receiving device according to claim 5, wherein the feedback voltage generating means has a collector grounded amplifier circuit or a base grounded amplifier circuit for amplifying a signal.

15. The receiving device according to claim 5, wherein the feedback voltage generating means comprises an analog-to-digital converter and a digital-to-analog converter.

16. A receiving device according to claim 7; a transmitting device for transmitting a signal to the receiving device, A communication system, wherein the transmitting device has a third electrode that is electrically or magnetically coupled to the first electrode.

17. A method for controlling a receiving device having a receiving circuit to which a received signal is input, comprising the steps of:

13. A control method for a receiving device, comprising the step of controlling a receiving signal input to the receiving circuit based on a current consumption of the receiving circuit.

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