WO2022246645A1 - Circuit d'envoi d'émetteur-récepteur de réseau de zone de commande (can) et émetteur-récepteur de can - Google Patents

Circuit d'envoi d'émetteur-récepteur de réseau de zone de commande (can) et émetteur-récepteur de can Download PDF

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Publication number
WO2022246645A1
WO2022246645A1 PCT/CN2021/095794 CN2021095794W WO2022246645A1 WO 2022246645 A1 WO2022246645 A1 WO 2022246645A1 CN 2021095794 W CN2021095794 W CN 2021095794W WO 2022246645 A1 WO2022246645 A1 WO 2022246645A1
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signal
voltage
module
current
differential
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PCT/CN2021/095794
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English (en)
Chinese (zh)
Inventor
王阳
陈亮
韩中良
梁永涛
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华为技术有限公司
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Priority to CN202180088442.4A priority Critical patent/CN116783830A/zh
Priority to PCT/CN2021/095794 priority patent/WO2022246645A1/fr
Publication of WO2022246645A1 publication Critical patent/WO2022246645A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits

Definitions

  • the application relates to the technical field of automobiles, in particular to a sending circuit of a controller area network CAN transceiver and the CAN transceiver.
  • EMC electromagnetic compatibility
  • Electromagnetic compatibility is generally characterized by EMC testing.
  • EMC testing includes a comprehensive assessment of the magnitude of electromagnetic interference (electro-magnetic interference, EMI) and electromagnetic susceptibility (electro-magnetic susceptibility, EMS) of electronic and electrical equipment, where electromagnetic susceptibility also represents the anti-interference ability to external electromagnetic interference.
  • EMI electromagnetic interference
  • EMS electromagnetic susceptibility
  • CAN controller area network
  • the CAN transceiver is the interface between the CAN node and the CAN bus, so it also becomes the key to determine the electromagnetic susceptibility.
  • the controller area network is widely used in industries such as new energy vehicles, rail transit, medical treatment, coal mines, and motor drives.
  • the electromagnetic interference in these occasions is relatively serious, and there are certain requirements for the anti-interference ability of the CAN transceiver.
  • the present application proposes a transmitting circuit of a controller area network CAN transceiver and a CAN transceiver.
  • the transmitting circuit of the controller area network CAN transceiver of the embodiment of the present application it can effectively suppress common-mode interference and differential-mode interference, and output a higher-accuracy differential signal to the CAN bus.
  • the transmitting circuit is applied to a CAN transceiver, Under the premise of controlling the cost, the anti-interference ability of the transceiver can be improved.
  • the embodiment of the present application provides a transmission circuit of a controller area network CAN transceiver, including: a sampling module, which is used to sample the two differential voltage signals output by the driving module, and generate the first sampling signal and the first sampling signal respectively.
  • the second sampling signal a common mode detection module, configured to generate a first current signal or a second current signal according to the first sampling signal and the second sampling signal, and the first current signal indicates the first sampling There is common-mode interference in the signal and the second sampling signal that makes the voltage value larger, and the second current signal indicates that there is a common-mode interference in the first sampling signal and the second sampling signal that makes the voltage value smaller Interference; a differential mode detection module, configured to generate a first voltage signal according to the first sampling signal and the second sampling signal, and the first voltage signal indicates the first sampling signal and the second sampling signal There is differential mode interference that makes the voltage difference larger or smaller; the driving module includes a voltage-controlled current source, a first mirror current source, and a second mirror current source, and is used to drive the voltage-controlled current source according to the current of the voltage-controlled current source.
  • the first mirror current source and the second mirror current source output the two differential voltage signals to the CAN bus, and control the first mirror current source or the second current signal through the first current signal or the second current signal.
  • the second mirror current source is used to reduce common-mode interference in the differential voltage signal, and the voltage-controlled current source is controlled by the first voltage signal to reduce differential-mode interference in the differential voltage signal.
  • the differential voltage signal output by the driving module is sampled by the sampling module to generate the first sampling signal and the second sampling signal, so that the differential voltage signal output by the driving module is affected by the environment and there is common-mode interference and/or differential mode interference, common mode interference and/or differential mode interference can be obtained in the first sampling signal and the second sampling signal;
  • the common mode detection module can determine the difference between the two according to the first sampling signal and the second sampling signal Whether the voltage value is too large or too small, so that the sending circuit can identify the common mode interference and respond to generate the first current signal or the second current signal;
  • the differential mode detection module can determine the two according to the first sampling signal and the second sampling signal Whether the voltage difference is too large or too small, so that the sending circuit can identify the differential mode interference and make a response to generate the first voltage signal;
  • the driving module drives the first mirror current source and the second mirror current source according to the current of the voltage-controlled current source.
  • the CAN outputs the two-way differential signal, so that the differential voltage signal can be output to the CAN bus, and the drive module controls the first mirror current source or the second mirror current source through the first current signal or the second current signal to reduce the difference Common-mode interference in the voltage signal, and controlling the voltage-controlled current source by the first voltage signal to reduce the differential-mode interference in the differential voltage signal, so that the common-mode interference and/or differential-mode interference in the output differential voltage signal can be eliminated Suppression is performed to improve the accuracy of the differential voltage signal output from the sending circuit to the CAN bus.
  • the common mode detection module includes a first detection submodule and a second detection submodule
  • the first detection submodule includes a first comparison module and a first current generation module
  • the first comparison module receives the first sampling signal, compares the voltage value of the first sampling signal with the voltage value of the first reference voltage, and obtains a first comparison signal
  • the first current generation module generates the first current signal according to the first comparison signal
  • the second detection submodule includes a second comparison module and a second current generation module
  • the second comparison module receives the first Two sampling signals, comparing the voltage value of the second sampling signal with the voltage value of the second reference voltage to obtain a second comparison signal
  • the second current generation module generates the second current generation module according to the second comparison signal current signal.
  • the first current signal or the second current signal is generated, which further affects the final output of the driving module, so that the first sampling signal and the second
  • one of the first detection sub-module and the second detection sub-module in the common-mode detection module can generate a current signal for reducing the common-mode interference in the differential voltage signal, so that the drive The module can respond to the current signal from the first detection sub-module or the second detection sub-module, and reduce the common mode interference in the differential voltage signal.
  • the first current generating module includes a first field effect transistor, and the first field effect transistor
  • the gate receives the first comparison signal, the source of the first field effect transistor is connected to the power supply voltage, and the drain is used as the third terminal of the common mode detection module, and the first comparison signal makes the first field
  • the second current generation module includes a second A field effect transistor, the gate of the second field effect transistor receives the second comparison signal, the source of the second field effect transistor is connected to the ground, and the drain is used as the fourth terminal of the common mode detection module, so
  • the second comparison signal makes the second field effect transistor turn on, the drain of the second field effect transistor generates the second current signal, and when the second field effect transistor is not turned on, no current signal is generated.
  • the first current generation module and the second current generation module can receive the first comparison signal and the second comparison signal, and generate the first current signal or the second current signal.
  • the driving module can respond according to the first current signal or the second current signal, and output a differential voltage signal with reduced common-mode interference.
  • the first comparison module includes a first switch, a second switch, and a first comparison One end of the first switch is used as the first end of the common mode detection module to receive the first sampling signal, and the other end is connected to the other end of the second switch and the first input end of the first comparator ; One end of the second switch is connected to the third reference voltage; the second input end of the first comparator is connected to the first reference voltage, and the output end outputs the first comparison signal; the second comparison module includes A third switch, a fourth switch, and a second comparator, one end of the third switch is used as the second end of the common mode detection module to receive the second sampling signal, and the other end is connected to the fourth switch. The other terminal is connected to the first input terminal of the second comparator; one terminal of the fourth switch is connected to the fourth reference voltage; the second input terminal of the second comparator is connected to the second reference voltage, and the output terminal outputs the second comparison signal.
  • the first current signal or the second current signal is generated, which further affects the final output of the driving module, so that the first sampling signal and the second
  • one of the first detection sub-module and the second detection sub-module in the common-mode detection module can generate a current signal for reducing the common-mode interference in the differential voltage signal, so that the drive The module can respond to the current signal from the first detection sub-module or the second detection sub-module, and reduce the common mode interference in the differential voltage signal.
  • the fourth possible implementation manner of the sending circuit when the control signal from the microcontroller causes the first switch to be closed and the second switch to be off When on, the first sampling signal is input to the first comparator, so that the first comparator can output the first comparison signal; when the control signal from the microcontroller makes the third switch closed and When the fourth switch is turned off, the second sampling signal is input to the second comparator, so that the second comparator can output the second comparison signal.
  • the first comparison module and the second comparison module can respond to the first sampling signal and the second sampling signal, and output the first comparison signal and the second comparison signal, so that the common
  • the mode detection module can output the first current signal or the second current signal according to the first comparison signal and the second comparison signal, so that when the first current signal or the second current signal acts on the driving module, the driving module can output a reduced common mode interfering differential voltage signal.
  • the first detection submodule generates the first sampling signal when the first sampling signal is relatively large.
  • a current signal the second detection submodule does not generate the second current signal when the second sampling signal is relatively large; the first detection submodule does not generate the second current signal when the first sampling signal is relatively small
  • the second detection submodule generates the second current signal when the second sampling signal is relatively small.
  • the common mode detection module can determine whether there is common mode interference in the differential voltage signal and confirm the type of common mode interference.
  • the differential mode detection module includes a sampling amplifier and an error amplifier, and the sampling The first input terminal of the amplifier is used as the first terminal of the differential mode detection module to receive the first sampling signal, and the second input terminal is used as the second terminal of the differential mode detection module to receive the second sampling signal,
  • the output terminal is connected to the first input terminal of the error amplifier; the second input terminal of the error amplifier is connected to the fifth reference voltage, and the output terminal is used as the third terminal of the differential mode detection module to output the first voltage signal.
  • the differential mode detection module can respond to the first sampling signal and the second sampling signal, and complete the function of outputting the first voltage signal.
  • the driving module can respond according to the first voltage signal, and output a differential voltage signal with reduced differential mode interference.
  • the differential mode detection module is configured to, between the first sampling signal and the second sampling When the voltage difference of the signal is relatively large, the voltage value of the first voltage signal is reduced; when the voltage difference between the first sampling signal and the second sampling signal is relatively small, the first A voltage value of the voltage signal increases.
  • the differential mode detection module can output a smaller first voltage signal when the transmission signal of the CAN bus is subjected to differential mode interference caused by voltage difference overvoltage; In the case of differential mode interference caused by voltage difference and undervoltage, a first voltage signal that becomes larger is output.
  • the smaller or larger first voltage signal is input to the driving module, the accuracy of the differential voltage signal output from the driving module to the CAN bus can be improved.
  • the CAN bus includes a first CAN signal line, a second CAN signal line , one end of the first mirror current source obtains the first current signal, the other end of the first mirror current source is connected to the second CAN signal line; one end of the second mirror current source obtains the first Two current signals, the other end of the second mirror current source is connected to the first CAN signal line; the voltage-controlled current source is connected to the one end of the first mirror current source and the second mirror current source Between said one end of said first voltage signal for receiving said first voltage signal, and generating a current according to said first voltage signal.
  • the drive module can adjust the current that the second CAN signal line flows into the other end of the first mirror current source, thereby adjusting the voltage value of the differential voltage signal; in response to the second current signal, the drive module can adjust the second The other end of the mirror current source flows out to the current of the first CAN signal line, so that the voltage value of the differential voltage signal can be adjusted; in response to the first voltage signal, the drive module can generate current through the voltage-controlled current source to adjust the second CAN signal line to flow into The other end of the first mirror current source and the other end of the second mirror current source flow out to the first CAN signal line, so that the voltage value of the differential voltage signal can be adjusted. In this way, the driving module can reduce the common-mode interference in the differential voltage signal according to the first current signal or the second current signal, and reduce the differential-mode interference in the differential voltage signal according to the first voltage signal.
  • the second CAN signal line flows into the The current of the driving module increases, and the voltage value of the two differential voltage signals output by the driving module decreases; when the driving module obtains the second current signal, the first CAN signal line flows out of the driving module. As the current increases, the voltage values of the two differential voltage signals output by the driving module increase.
  • the drive module can output a differential voltage signal with a reduced voltage value, and the negative jitter of the differential voltage signal enables the drive module to obtain the second current signal.
  • the driving module can output a differential voltage signal with an increased voltage value, so as to improve the accuracy of the differential voltage signal output from the driving module to the CAN bus.
  • the driving module when the voltage value of the first voltage signal decreases, the When the driving module receives the first voltage signal, the current flowing into the driving module from the second CAN signal line and the current flowing out of the driving module from the first CAN signal line both decrease, and the output of the driving module
  • the voltage difference between the two differential voltage signals decreases; when the voltage value of the first voltage signal increases, when the drive module receives the first voltage signal, the current flowing into the drive module from the second CAN signal line and the current flowing out of the driving module from the first CAN signal line both increase, and the voltage difference between the two differential voltage signals output by the driving module increases.
  • the driving module can reduce the voltage difference of the output differential voltage signal, and when the voltage difference of the differential voltage signal is undervoltage so that When the increased first voltage signal is input to the driving module, the driving module can increase the voltage difference of the output differential voltage signal, so as to improve the accuracy of the differential voltage signal output from the driving module to the CAN bus.
  • the sending circuit receives The enable signal of the device, when the enable signal is not received, the common mode detection module and the differential mode detection module are in a non-enabled state; when the enable signal is received, the common mode The detection module and the differential mode detection module enter an enabled state from an unenabled state, and in the enabled state, the first comparator, the second comparator, and the The sampling amplifier and the error amplifier in the differential mode detection module work normally.
  • the power consumption of the transmission circuit can be reduced. Further, the power consumption of the transceiver can be reduced.
  • the sending circuit receives a control signal from the microcontroller, and the control signal indicates The first CAN signal line and the second CAN signal line transmit a differential voltage signal of a dominant state.
  • the first switch and the The third switch is turned off, the second switch and the fourth switch are closed; when the control signal is received, the first switch and the third switch in the common mode detection module are closed, The second switch and the fourth switch are turned off.
  • control signal is associated with the dominant state of the differential voltage signal transmitted by the transceiver to the CAN bus, so that when the transceiver transmits the differential voltage signal of this state, the common mode detection module in the sending circuit 20 can The control signal can be responded to to improve the accuracy of the output differential voltage signal. And setting the switch controlled by the control signal makes the power consumption of the transmission circuit lower than that of the dominant state when transmitting the recessive state, which can further reduce the power consumption of the transmission circuit and the transceiver.
  • the embodiment of the present application provides a CAN transceiver, including the sending circuit described in the above first aspect and any one of the implementation manners of the first aspect.
  • the CAN transceiver in the first possible implementation manner of the CAN transceiver, includes a sending circuit and a receiving circuit, the receiving circuit includes the sampling module, and in the sending circuit, the The drive module receives the logic signal output by the CAN controller and converts it into the differential voltage signal; when the common mode detection module and the differential mode detection module are in an enabled state, and the common mode detection module receives the When controlling the signal, the sending circuit outputs the two differential voltage signals through the driving module.
  • the sending circuit can be used in combination with the receiving circuit in the transceiver, so as to reduce the hardware cost of the sending circuit and further reduce the hardware cost of the transceiver.
  • the common-mode detection module and differential-mode detection module of the transmitting circuit can be arranged inside the transceiver, and the voltage-controlled current source can be embedded in the drive module, which does not occupy the space of the plate connected to the transceiver, and can reduce the area of the plate.
  • Fig. 1 shows the schematic diagram of the connection mode of the CAN bus and nodes of the prior art
  • FIG. 2 shows an exemplary application scenario of a sending circuit of a controller area network CAN transceiver according to an embodiment of the present application
  • FIG. 3 shows an exemplary structural diagram of a transmitting circuit of a controller area network CAN transceiver according to an embodiment of the present application
  • Fig. 4 shows an exemplary structural diagram of a sampling module according to an embodiment of the present application
  • FIG. 5 shows an exemplary structural schematic diagram of a common mode detection module according to an embodiment of the present application
  • Fig. 6a shows an exemplary structural diagram of a first comparison module, a second comparison module, a first current generation module and a second current generation module according to an embodiment of the present application;
  • Fig. 6b shows an exemplary structural diagram of a first comparison module, a second comparison module, a first current generation module and a second current generation module according to an embodiment of the present application;
  • FIG. 7 shows an exemplary structural schematic diagram of a differential mode detection module according to an embodiment of the present application.
  • Fig. 8 shows an exemplary structural diagram of a driving module according to an embodiment of the present application
  • FIG. 9 shows an exemplary schematic diagram of reducing common-mode interference by a transmitting circuit according to an embodiment of the present application.
  • FIG. 10 shows another exemplary schematic diagram of reducing common-mode interference by a transmitting circuit according to an embodiment of the present application
  • FIG. 11 shows an exemplary schematic diagram of reducing differential mode interference by a transmitting circuit according to an embodiment of the present application
  • FIG. 12 shows another exemplary schematic diagram of reducing differential mode interference by a transmitting circuit according to an embodiment of the present application
  • FIG. 13 shows an exemplary schematic diagram of reducing common-mode interference and differential-mode interference by a sending circuit according to an embodiment of the present application.
  • the CAN bus includes the first CAN signal line (CANH) and the second CAN signal line (CANL), which together form a set of differential signal lines. form of communication.
  • Multiple communication nodes (such as nodes 1-N) can be mounted on the CAN bus, and the signals between nodes are transmitted through the bus to realize inter-node communication.
  • Each CAN node includes a CAN controller and a CAN transceiver. Taking the ath node as an example (1 ⁇ a ⁇ N and an integer), the CAN controller and the CAN transceiver are connected through the TX_a and RX_a signal lines.
  • Logic signals are transmitted on the TX_a and RX_a signal lines, and the CAN transceiver is respectively connected to the first CAN signal line (CANH) and the second CAN signal line (CANL) of the CAN bus through the CANH_a signal line and the CANL_a signal line.
  • CANH first CAN signal line
  • CANL second CAN signal line
  • the CAN transceiver When the CAN transceiver acts as a receiver, it receives the differential voltage signal transmitted on the CAN bus through the CANH_a signal line and the CANL_a signal line, and the CAN transceiver converts the differential voltage signal into a logic signal, and outputs the logic signal to CAN through the RX_a signal line Controller; when the CAN transceiver is used as a transmitter, the CAN controller inputs the logic signal to be sent to the CAN transceiver through the TX_a signal line, and the CAN transceiver converts the logic signal into a differential voltage signal, and passes the CANH_a signal line and CANL_a The signal line is output to the CAN bus.
  • the CANH_a signal line and the CANL_a signal line are usually inside the CAN transceiver, the CANH_a signal line and the CANL_a signal line can be connected to the interface of the CAN transceiver, and the interface is connected to the CAN bus.
  • the output signal of the CAN transceiver is output to the CAN bus through the CANH_a signal line and the CANL_a signal line through the interface.
  • any CAN transceiver connected to the CAN bus is used as a transmitter
  • one or more CAN transceivers in the remaining CAN transceivers can be used as a receiver, and the CAN transceiver as a transmitter can pass the differential voltage signal transmitted by the CAN bus.
  • the voltage value of the signal changes, so that each CAN transceiver as a receiver can receive the differential voltage signal and respond according to its voltage value.
  • the differential voltage signal transmitted on the CAN bus can be divided into dominant state and recessive state.
  • the voltage difference between the differential voltage signals transmitted by the first CAN signal line (CANH) and the second CAN signal line (CANL) in the dominant state is unity
  • the voltage difference between the differential voltage signals transmitted by the first CAN signal line (CANH) and the second CAN signal line (CANL) is zero (or close to 0), and the recessive state is used to represent logic "1".
  • At least one CAN transceiver When there are multiple CAN transceivers connected to the CAN bus, at least one CAN transceiver outputs a differential voltage signal of a dominant state, and the differential voltage signal transmitted by the CAN bus is the dominant state, which is equivalent to the signal sent by only one CAN transceiver Corresponding to logic 0, the differential voltage signal transmitted by the CAN bus corresponds to logic 0; all CAN transceivers output differential voltage signals in the recessive state, and the differential voltage signal transmitted by the CAN bus is the recessive state, which is equivalent to all CAN transceivers
  • the signal sent by the device corresponds to logic 1
  • the differential voltage signal transmitted by the CAN bus corresponds to logic 1. Therefore, the dominant state represents logic 0, and the recessive state represents logic 1.
  • an example of the voltage value of the differential voltage signal is that in the dominant state, the voltage value of the signal transmitted on the first CAN signal line (CANH) can be, for example, 3.5 V, the voltage value of the signal transmitted on the second CAN signal line (CANL) can be, for example, 1.5V, and the voltage difference of the signal transmitted on the first CAN signal line (CANH) and the second CAN signal line (CANL) can be, for example, 2V.
  • the voltage value of the signal transmitted on the first CAN signal line (CANH) and the second CAN signal line (CANL) can be the same, for example, both are 2.5V, the first CAN signal line (CANH) and the second CAN
  • the voltage difference of the signal transmitted on the signal line (CANL) may be 0V, for example.
  • the embodiments of the present application take the above voltage value as an example for illustration. Those skilled in the art should understand that in practical applications, the above voltage value can adopt other specific values according to relevant standards and other factors.
  • the differential voltage signal transmitted on the CAN bus may be subject to differential-mode interference and common-mode interference from the external electromagnetic environment, causing a certain error in the voltage value of the differential voltage signal.
  • the differential-mode interference makes two of the differential voltage signals The voltage difference of the signal becomes larger or smaller, and the common mode interference makes the two signals in the differential voltage signal both larger or smaller with the same amplitude.
  • Differential-mode interference and common-mode interference can occur simultaneously or separately. Therefore, it is necessary to improve the anti-interference ability of the CAN transceiver to suppress differential mode interference and common mode interference in the differential voltage signal transmitted on the CAN bus, and improve the accuracy of the differential voltage signal transmitted on the CAN bus.
  • the signal line CANGND is added to the CAN bus, the signal line CANGND is connected to the ground potential of the CAN transceiver, and a three-wire system is used for signal transmission, which can inhibit certain Common mode interference within the range, but increases the wiring difficulty and hardware cost of the CAN bus in practical applications, and cannot completely suppress the large-scale interference; or use the CAN bus with shielding layer, wrapped by aluminum foil and oxygen-free copper wire layer shielding net
  • the signal line can well resist the interference of the electric field, but in practical applications, the shielding layer needs to be grounded, which increases the difficulty of wiring the CAN bus, and the anti-interference effect for the CAN bus with a long distance is not good; or add a CAN to optical fiber converter , to convert the CAN bus signal into an optical fiber signal for transmission, but the cost of the optical fiber is high and cannot be widely used.
  • prior art 1 proposes a method of adding a common-mode choke coil at the output end of the CAN transceiver to suppress common-mode interference.
  • the working principle of the common mode choke coil is that when the working current flows through two oppositely wound coils, two magnetic fields that cancel each other are generated. damping; if there is a common-mode interference signal flowing through the coil, the coil will present a high impedance, resulting in a strong damping effect, which can attenuate the interference signal and isolate the high-frequency interference.
  • Prior Art 1 Although the common-mode interference can be suppressed when the CAN transceiver is used as the transmitter, the suppression of the differential-mode interference signal is not obvious. At the same time, the common-mode choke coil has a large area and needs to be connected outside the CAN transceiver, occupying too much space. Multi-level board space.
  • Prior art 2 uses threshold voltage adjustment technology to improve the common-mode interference suppression capability of the transceiver.
  • the principle is that the sampling resistor group, the front-end amplifier, and the comparator are connected in sequence, and the reference generator is connected to the front-end amplifier and comparator.
  • the real-time voltage of the differential voltage signal of the CAN bus is obtained by sampling, the sampled voltage is amplified by the front-end amplifier, and output to the negative input terminal of the comparator; the front-end amplifier simultaneously generates the common-mode voltage of the input signal of the CAN bus, and is input to the reference generator , the reference generator then subtracts the bandgap voltage from the common-mode voltage to the positive input of the comparator according to the logic level of the signal input by the front-end amplifier, and the comparator obtains a logic signal based on the output of the front-end amplifier and the output of the reference generator, That is, when the common-mode voltage of the differential voltage signal of the CAN bus changes, the input signal at the positive input terminal of the comparator changes accordingly, so that the logic signal output by the transceiver as a receiver is not affected by common-mode interference.
  • the second prior art can only guarantee that the common-mode interference can be suppressed when the CAN transceiver acts as a receiver.
  • the CAN transceiver when used as a transmitter, it cannot guarantee that the signal sent to the CAN bus is a signal that suppresses common-mode interference and differential-mode interference, so that the signal transmitted on the CAN bus still has errors.
  • the transceiver proposed in prior art 3 uses an ultra-wide input voltage receiving circuit to suppress common-mode interference.
  • the principle is to connect the input terminals of two differential amplifiers respectively through the sampling resistor group, and first obtain the differential signal of the CAN bus through the sampling resistor group.
  • the sampled voltage is amplified by two differential amplifiers.
  • the common-mode input voltage is large and the common-mode input voltage is small, the two differential amplifiers work separately.
  • the amplified signal is then converted by a differential-to-single-ended amplifier to obtain two digital output signals.
  • the two digital output signals pass through the adder to obtain logic signals.
  • the embodiment of the present application proposes a transmission circuit of a controller area network CAN transceiver and a CAN transceiver.
  • the transmission circuit of the controller area network CAN transceiver in the embodiment of the application can effectively suppress common-mode interference and differential-mode interference. Interference, output a higher accuracy differential signal to the CAN bus, when the sending circuit is applied to the CAN transceiver, the anti-interference ability of the transceiver can be improved under the premise of controlling the cost.
  • Fig. 2 shows an exemplary application scenario of a transmitting circuit of a CAN transceiver of a controller area network according to an embodiment of the present application.
  • the CAN transceiver 1100 is connected to a CAN controller 1200 and a microcontroller (microprogrammed control unit, MCU) 1300, and the CAN controller 1200 can be integrated in the microcontroller 1300, that is, realized by the microcontroller 1300 Function of the CAN controller 1200 .
  • the CAN transceiver 1100 includes a transmitting circuit 20 , a receiving circuit 30 , and a bias circuit 40 .
  • the structures of the receiving circuit 30 and the biasing circuit 40 can be implemented based on existing technologies.
  • the sending circuit 20 includes a sampling module 101, a common-mode detection module 102, a differential-mode detection module 103 and a drive module 104, the receiving circuit 30 includes a sampling module 101 and a differential signal comparator (not shown), and the bias circuit 40 includes a reference amplifier (not shown).
  • FIG. 2 shows the situation that the sending circuit 20 and the receiving circuit 30 share the sampling module 101 .
  • the sending circuit 20 and the receiving circuit 30 may also include different sampling modules, as long as the corresponding functions of the circuits or modules herein can be realized.
  • the receiving circuit 30 is used to receive the differential voltage signal from the CAN bus when the CAN transceiver 1100 is used as a receiver, and the sampling module 101 in the receiving circuit 30 pairs the differential voltage signal from the CAN bus After sampling, the differential signal comparator converts the sampling result into a logic signal, and outputs it to the CAN controller 1200 through the signal line RX, so that the CAN controller 1200 can obtain the logic signal corresponding to the differential voltage signal of the CAN bus.
  • the sampling module 101 in the receiving circuit 30 is used as a part of the transmitting circuit 20 for receiving the differential voltage signal from the driving module 104 and outputting the sampling result (see the first sampling signal and second sampling signal) in order to correct the differential voltage signal.
  • the sending circuit 20 is used to receive the logic signal from the CAN controller 1200 when the CAN transceiver 1100 acts as a transmitter, and when the logic signal is 0, control the drive module 104 to work normally, so that the differential voltage signal of the dominant state is output to the CAN Bus; when the logic signal is 1, the control drive module 104 stops working, so that the differential voltage signal is in a recessive state.
  • the sampling module 101, the common-mode detection module 102, the differential-mode detection module 103 and the drive module 104 in the transmission circuit 20 form a
  • the feedback loop is to sample the output of the drive module 104 through the sampling module 101, and respond to the interference in the differential voltage signal shown in the sampling result through the common mode detection module 102, differential mode detection module 103, etc. below, and generate The current signal and/or the voltage signal act on the driving module 104 to reduce the interference in the differential voltage signal output by the driving module 104 .
  • the bias circuit 40 is used to provide a bias voltage, so that when the CAN transceiver 1100 acts as a transmitter and the logic signal from the CAN controller 1200 is 1, the sampling module 101 controls the voltage values of the two differential voltage signals of the CAN bus equal and equal to the bias voltage (eg 2.5V).
  • the functions of the receiver and transmitter performed by the above CAN transceiver do not interfere with each other, so the sampling module 101 can be shared by the sending circuit 20 and the receiving circuit 30 .
  • An exemplary working mode of the CAN transceiver 1100 as a receiver is introduced below. Taking the CAN transceiver 1100 set in node 1 in FIG.
  • the differential voltage signal is input to the receiving circuit 30 through the CAN_1 signal line and CANL_1, and in the receiving circuit 30, via the sampling module 101 Sampling to obtain two sampling signals, and compare the two sampling signals to obtain a logic signal (0 or 1) via other devices (such as a differential signal comparator, not shown in the figure) of the receiving circuit 30, and complete the differential voltage signal to logic Signal conversion, the converted logic signal is output to the CAN controller 1200 through the RX signal line.
  • the microcontroller 1300 When the CAN transceiver 1100 is used as a transmitter, the microcontroller 1300 outputs an enabling signal to the transmitting circuit 20 to enable the common mode detection module 102 and the differential mode detection module 103 . In the enabled state, the differential mode detection module 103 can respond to the sampling signal from the sampling module 101 . The microcontroller 1300 also determines whether the differential voltage signal to be sent is dominant or recessive, and enables the CAN controller 1200 to input the logic signal corresponding to the state to the sending circuit 20 of the CAN transceiver 1100 through the TX signal line.
  • the driving module 104 works normally, and the differential voltage signal of the dominant state is output by the driving module 104, so that the differential voltage signal transmitted by the CAN bus is also in the dominant state (such as 3.5V and 1.5V), the differential voltage signal output by the driving module 104 to the CAN bus is also input to the sampling module 101, so that the sampling module 101 outputs two sampling signals of the differential voltage signal.
  • the microcontroller 1300 enables the CAN controller 1200 to input a logic signal 0 to the sending circuit 20, and at the same time input a control signal to the sending circuit 20, and the control signal enables the common mode detection module 102 of the sending circuit 20 to detect The sampling signal from the sampling module 101 responds.
  • the common-mode detection module 102 and the differential-mode detection module 103 can determine whether the differential voltage signal output by the CAN transceiver 1100 as a transmitter has common-mode interference and differential-mode interference according to the input sampling signal.
  • the driving module 104 works normally, so the driving module 104
  • the signals generated by the common-mode detection module 102 and the differential-mode detection module 103 can be combined to reduce the common-mode interference and/or differential-mode interference in the differential voltage signal output by the drive module 104, so that the differential voltage signal transmitted by the CAN bus is closer to the ideal Dominant state voltage values (for example, 3.5V and 1.5V) for the case.
  • the driving module 104 stops working, and the voltage of the CAN bus is controlled by a reference amplifier (not shown) in the bias circuit 40, so that the differential voltage signal transmitted by the CAN bus is in a recessive state (such as 2.5V) .
  • FIG. 3 shows an exemplary structural diagram of a transmitting circuit of a controller area network CAN transceiver according to an embodiment of the present application.
  • the transmitting circuit 20 includes:
  • the sampling module 101 is configured to sample the two differential voltage signals output by the driving module 104, and generate a first sampling signal and a second sampling signal respectively;
  • the common-mode detection module 102 is configured to generate a first current signal or a second current signal according to the first sampling signal and the second sampling signal, and the first current signal indicates that there is a voltage deviation between the first sampling signal and the second sampling signal Large common-mode interference, the second current signal indicates that there is common-mode interference in the first sampling signal and the second sampling signal that makes the voltage value smaller;
  • the differential mode detection module 103 is configured to generate a first voltage signal according to the first sampling signal and the second sampling signal, and the first voltage signal indicates that there is a voltage difference between the first sampling signal and the second sampling signal that makes the voltage difference larger or smaller.
  • differential mode interference
  • the driving module 104 includes a voltage-controlled current source, a first mirror current source and a second mirror current source, and is used to drive the first mirror current source and the second mirror current source to output the two mirror current sources to the CAN bus according to the current of the voltage-controlled current source.
  • differential voltage signal and control the first mirror current source or the second mirror current source through the first current signal or the second current signal to reduce the common mode interference in the differential voltage signal, and control the voltage-controlled current through the first voltage signal source to reduce differential mode interference in differential voltage signals.
  • the differential voltage signal output by the driving module is sampled by the sampling module to generate the first sampling signal and the second sampling signal, so that the differential voltage signal output by the driving module is affected by the environment and there is common-mode interference and/or differential mode interference, common mode interference and/or differential mode interference can be obtained in the first sampling signal and the second sampling signal;
  • the common mode detection module can determine the difference between the two according to the first sampling signal and the second sampling signal Whether the voltage value is too large or too small, so that the sending circuit can identify the common mode interference and respond to generate the first current signal or the second current signal;
  • the differential mode detection module can determine the two according to the first sampling signal and the second sampling signal Whether the voltage difference is too large or too small, so that the sending circuit can identify the differential mode interference and make a response to generate the first voltage signal;
  • the driving module drives the first mirror current source and the second mirror current source according to the current of the voltage-controlled current source.
  • the CAN outputs the two-way differential signal, so that the differential voltage signal can be output to the CAN bus, and the drive module controls the first mirror current source or the second mirror current source through the first current signal or the second current signal to reduce the difference Common-mode interference in the voltage signal, and controlling the voltage-controlled current source by the first voltage signal to reduce the differential-mode interference in the differential voltage signal, so that the common-mode interference and/or differential-mode interference in the output differential voltage signal can be eliminated Suppression is performed to improve the accuracy of the differential voltage signal output from the sending circuit to the CAN bus.
  • sampling module 101 The exemplary structures of the sampling module 101, the common mode detection module 102, the differential mode detection module 103 and the driving module 104 are given below in conjunction with FIGS. process.
  • the sampling module 101 can be implemented based on the existing technology. As shown in FIG. 4 , the sampling module 101 includes: a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4 . One end a1 of the first resistance R1 is used as the first end (A end) of the sampling module 101, and the other end b1 of the first resistance R1 is connected to one end a2 of the second resistance R2, and is used as the second end (B end) of the sampling module 101.
  • the other end b2 of the second resistor R2 is connected to one end a3 of the third resistor R3; the other end b3 of the third resistor R3 is connected to one end a4 of the fourth resistor R4, and serves as the third end (C end) of the sampling module 101; The other end b4 of the fourth resistor R4 serves as the fourth end (D end) of the sampling module 101 .
  • the first end (A end) and the fourth end (D end) of the sampling module 101 are respectively connected to the first CAN signal line (CANH) and the second CAN signal line (CANL) of the CAN bus, so that the CAN transceiver only When used as a receiver, the sampling module 101 can receive a differential voltage signal from the CAN bus.
  • CANH first CAN signal line
  • CANL second CAN signal line
  • the two sampling signals (CANH_SEN and CANL_SEN) can be further processed by a differential signal comparator (not shown), and the two sampling signals are also input to the common-mode detection module 102 and the differential-mode detection module 103 of the transmitting circuit 20, but when the CAN transceiver is only used as a receiver
  • the common-mode detection module 102 and the differential-mode detection module 103 are not enabled, so they will not respond to the signal output by the sampling module.
  • the first end (A end) and the fourth end (D end) of the sampling module 101 are also respectively connected to two output ends (M end and O end hereinafter) of the driving module 104, so that the CAN transceiver acts as a transmitter and sends
  • the sampling module 101 can receive the differential voltage signal from the drive module 104.
  • the common mode detection module 102 and the differential mode detection module 103 are enabled, and in combination with the control signal, the sampling module 101 outputs
  • the two sampling signals of can be further processed by the common-mode detection module 102 and the differential-mode detection module 103 of the sending circuit 20, so that the driving module 104 outputs a differential voltage signal with reduced interference.
  • the two sampling signals can also be input to the differential signal comparator, and converted into logic signals for the CAN controller to monitor the differential voltage signal output by the CAN transceiver.
  • the sampling module 101 can not only complete the sampling of the signal input by the CAN bus, but also can complete the sampling of the signal output to the CAN bus, so that the sampling module 101 can work in the CAN transceiver as a receiver and as a transmitter in two different processes.
  • the reference amplifier A1 can be, for example, an inverting closed-loop amplifier, and its positive The input end is connected to the reference voltage V1, and the voltage value of the reference voltage V1 may be equal to the voltage value of the differential voltage signal in the recessive state, for example equal to 2.5V.
  • the bias voltage VBIAS output from the output terminal of the reference amplifier A1 is also 2.5V.
  • the second resistor R2 and the third resistor R3 have the same resistance value (for example, R), the first resistor R1 and the fourth resistor R4 have the same resistance value (for example, 24*R), the first CAN signal line (CANH) and the second CAN
  • the signal line (CANL) inputs the differential voltage signal to the first terminal (A terminal) and the fourth terminal (D terminal) of the sampling module 101, and the first resistor R1 and the fourth resistor R4 respectively divide the input differential voltage signal,
  • the reduced first sampling signal CANH_SEN and the second sampling signal CANL_SEN are obtained.
  • the first sampling signal CANH_SEN can be output from the second terminal (B terminal) of the sampling module 101
  • the second sampling signal CANL_SEN can be output from the third terminal (C terminal) of the sampling module 101 , for example.
  • the specific structure of the sampling module 101 is not limited thereto, as long as the output of the driving module 104 can be sampled to obtain sampling signals suitable for processing by the common-mode detection module 102 and the differential-mode detection module 103 .
  • the resistance values of the resistors in the sampling module can also be set to other values, as long as the resistance values of the second resistor R2 and the third resistor R3 are the same, and the resistance values of the first resistor R1 and the fourth resistor R4 are the same. No limit.
  • the common mode interference can be divided into two cases, one is the common mode interference caused by the positive voltage jitter, which makes the two differential voltage signals increase and the increase rate is the same, and the other is the common mode interference caused by the negative voltage jitter.
  • the differential voltage signals of the two paths are all reduced and the reduction range is the same.
  • the ideal voltage value of the input signal at the first terminal (A terminal) of the sampling module 101 can be equal to 3.5V
  • the input signal at the second terminal (B terminal) of the sampling module 101 The ideal voltage value can be equal to 1.5V.
  • the voltage value of the first CAN signal line is greater than the first voltage threshold (for example, 5V, the ideal voltage value of the first CAN signal line is 3.5V and the allowable The sum of the deviation of 1.5V) or the voltage value of the second CAN signal line is greater than the second voltage threshold (for example, 3V, the sum of the ideal voltage value of the second CAN signal line of 1.5V and the allowable deviation of 1.5V), it is considered a differential voltage signal
  • the voltage value is too large, and it is necessary to suppress the common-mode interference caused by voltage forward jitter; the voltage value of the first CAN signal line is less than the third voltage threshold (for example, 2V, the ideal voltage value of the first CAN signal line is 3.5V and the allowable deviation 1.5V difference) or the voltage value of the second CAN signal line is less than the fourth voltage threshold (for example, 0V, the difference between the ideal voltage value of the second CAN signal line 1.5V and the allow
  • the common mode detection module determines whether the voltage values of the two sampling signals corresponding to the two differential voltage signals are too large or too small, and then determines whether common mode interference occurs in the two sampling signals, and indirectly determines the two differential voltages Whether the signal includes common-mode interference that needs to be suppressed, and when the common-mode interference that needs to be suppressed is detected, a signal indicating that the voltage value of the sampling signal is too large or too small is generated.
  • the common mode detection module 102 includes a first detection submodule 1021 and a second detection submodule 1022, and the first detection submodule 1021 includes a first comparison module 10211 and a first The current generation module 10212, the first comparison module 10211 receives the first sampling signal CANH_SEN, compares the voltage value of the first sampling signal CANH_SEN with the voltage value of the first reference voltage (reference voltage V3), and obtains the first comparison signal VC_UP, the second A current generation module 10212 generates a first current signal according to the first comparison signal VC_UP; the second detection sub-module 1022 includes a second comparison module 10221 and a second current generation module 10222, and the second comparison module 10221 receives the second sampling signal CANL_SEN, for The voltage value of the second sampling signal CANL_SEN is compared with the voltage value of the second reference voltage (reference voltage V5 ) to obtain a second comparison signal VC_DN, and the second current generation module
  • the values of the reference voltage V3 and the reference voltage V5 are related to the allowable deviation of the voltage value of the differential voltage signal and the information indicated by the first current signal and the second current signal.
  • An example of how the reference voltage V3 and the reference voltage V5 are taken when the interference detection is completed based on the common-mode detection module in FIG. 5 is given below.
  • VBIAS represents the voltage value output from the reference amplifier A1 to the second resistor and the third resistor
  • VBIAS is a constant value equal to the reference voltage V1 (for example, 2.5V)
  • R2 represents the resistance value of the second resistor (for example, R)
  • R1 represents the resistance value of the first resistor (for example, 24*R)
  • CANH represents the voltage value of the first CAN signal line.
  • R3 represents the resistance value of the third resistor (such as R)
  • R4 represents the resistance value of the fourth resistor (such as 24*R)
  • CANL represents the voltage value of the second CAN signal line.
  • the first detection submodule can be set to generate the first current signal when the first sampling signal is too large, and the second detection submodule does not generate the second current signal when the second sampling signal is too large, The first detection sub-module does not generate the first current signal when the first sampling signal is relatively small, and the second detection sub-module generates the second current signal when the second sampling signal is relatively small.
  • the second current signal it means that there is common-mode interference caused by voltage positive jitter in the first sampling signal and the second sampling signal.
  • the second current signal is generated without generating the first current signal, it means that the first sampling signal and the second Common mode interference caused by voltage negative jitter exists in the secondary sampling signal.
  • the common mode detection module can determine whether there is common mode interference in the differential voltage signal and confirm the type of common mode interference.
  • the value of the first sampling signal CANH_SEN is equal to 2.6V.
  • the second voltage threshold (3V) into formula (2) as the voltage value of the second CAN signal line, and obtain the value of the second sampling signal CANL_SEN equal to 2.52V, and use the third voltage threshold (2V) as the first CAN signal line
  • the voltage value of the voltage value of the second CAN signal line is brought into the formula (1), and the value of the first sampling signal CANH_SEN is equal to 2.48V, and the fourth voltage threshold (0V) is brought into the formula (2) as the voltage value of the second CAN signal line, and the second sampling signal is obtained
  • the value of the signal CANL_SEN is equal to 2.4V.
  • the reference voltages V3 and V5 can be set so that when the voltage value of the first CAN signal line is greater than the first voltage threshold (5V), and the voltage value of the second CAN signal line is greater than the second voltage threshold (3V), the first detection submodule Generate the first current signal, but the second detection sub-module does not generate the second current signal, and make the voltage value of the first CAN signal line less than the third voltage threshold (2V), and the voltage value of the second CAN signal line is less than the fourth When the voltage threshold (0V), the second detection sub-module generates the second current signal, while the first detection sub-module does not generate the first current signal.
  • the preset voltage value of the reference voltage V3 is equal to 2.6V.
  • the voltage value of the reference voltage V5 is equal to 2.4V. It can be seen from formula (1) that when CANH becomes larger, CANH_SEN also becomes larger. In this case, when the voltage value CANH of the first CAN signal line is greater than 5V, the value of the first sampling signal CANH_SEN is also greater than 2.6V.
  • the first comparison signal may, for example, indicate that the voltage value of the first sampling signal CANH_SEN is larger than the reference voltage V3 (2.6V), and the first current signal generated according to the first comparison signal indicates that the voltage value of the first sampling signal CANH_SEN is too large , and, the value of the second sampling signal CANL_SEN is greater than 2.52V, that is, greater than the reference voltage V5 (2.4V), the second comparison signal may, for example, indicate that the voltage value of the second sampling signal CANL_SEN is larger than the reference voltage V5, which may make No second current signal is generated based on the second comparison signal.
  • the fact that the first detection sub-module generates the first current signal and the second detection sub-module does not generate the second current signal indicates that common-mode interference caused by positive voltage jitter is detected between the first sampling signal and the second sampling signal, indirectly It indicates that the voltage value of the first CAN signal line is larger than the preset first voltage threshold, and the voltage value of the second CAN signal line is larger than the preset second voltage threshold, that is, the differential voltage signal is detected There is common-mode interference caused by positive voltage jitter in the circuit.
  • CANL_SEN becomes smaller as CANL becomes smaller.
  • the value of the second sampling signal CANL_SEN is also less than 2.4V.
  • the second comparison signal may, for example, indicate that the voltage value of the second sampling signal CANL_SEN is smaller than the reference voltage V5 (2.4V), and the second current signal generated according to the second comparison signal indicates that the voltage value of the second sampling signal CANL_SEN is relatively small , and, the value of the first sampling signal CANH_SEN is less than 2.48V, that is, less than the reference voltage V3 (2.6V), the first comparison signal may, for example, indicate that the voltage value of the first sampling signal CANH_SEN is smaller than the reference voltage V3, which may make A first current signal is not generated based on the first comparison signal.
  • the second detection sub-module generates the second current signal
  • the first detection sub-module does not generate the first current signal, which can indicate the detection of common-mode interference caused by voltage negative jitter in the first sampling signal and the second sampling signal, Indirect indication that the voltage value of the first CAN signal line is smaller than the preset third voltage threshold, and the voltage value of the second CAN signal line is smaller than the preset fourth voltage threshold, that is, the differential voltage is detected There is common-mode interference caused by voltage negative jitter in the signal.
  • the first detection submodule can be set to generate the first current signal when the first sampling signal is relatively small, and the second detection submodule does not generate the first current signal when the second sampling signal is relatively small.
  • Two current signals the first detection sub-module generates the first current signal when the first sampling signal is too small, and the second detection sub-module does not generate the second current signal when the second sampling signal is too small, thus, the first current can be generated When the signal does not generate the second current signal, it means that there is common-mode interference caused by voltage negative jitter in the first sampling signal and the second sampling signal.
  • the voltage value of the reference voltage V3 may be equal to 2.48V
  • the voltage value of the reference voltage V5 may be equal to 2.52V, for example.
  • CANH_SEN becomes smaller as CANH becomes smaller.
  • the first comparison signal may, for example, indicate that the voltage value of the first sampling signal CANH_SEN is smaller than the reference voltage V3 (2.48V), and the first current signal generated according to the first comparison signal indicates the voltage of the first sampling signal CANH_SEN
  • the second comparison signal may, for example, indicate that the voltage value of the second sampling signal CANL_SEN is smaller than the reference voltage V5 , so that the second current signal is not generated according to the second comparison signal.
  • the first detection sub-module generates the first current signal
  • the second detection sub-module does not generate the second current signal, which can indicate that there is common-mode interference caused by voltage negative jitter in the first sampling signal and the second sampling signal, Indirectly indicating that the voltage value of the first CAN signal line is smaller than the preset first voltage threshold, and the voltage value of the second CAN signal line is smaller than the preset fourth voltage threshold, that is, the differential voltage is detected There is common-mode interference caused by voltage negative jitter in the signal.
  • CANL_SEN becomes larger as CANL becomes larger.
  • the value of the second sampling signal CANL_SEN is also greater than 2.52V.
  • the second comparison signal may, for example, indicate that the voltage value of the second sampling signal CANL_SEN is larger than the reference voltage V5 (2.52V), and the second current signal generated according to the second comparison signal indicates that the voltage value of the second sampling signal CANL_SEN is larger , and, the value of the first sampling signal CANH_SEN is greater than 2.6V, that is, greater than the reference voltage V3 (2.48V), the first comparison signal may, for example, indicate that the voltage value of the first sampling signal CANH_SEN is larger than the reference voltage V3, which may make A first current signal is not generated based on the first comparison signal.
  • the second detection sub-module generates the second current signal
  • the first detection sub-module does not generate the first current signal, which indicates that common-mode interference caused by positive voltage jitter is detected between the first sampling signal and the second sampling signal, and indirectly Indicates that the first CAN signal line is larger than the preset first voltage threshold, and the voltage value of the second CAN signal line is larger than the preset second voltage threshold, that is, it is detected that there is a voltage in the differential voltage signal Common-mode interference caused by forward jitter.
  • the allowable deviation of the differential voltage signal can be set according to actual needs, and the first voltage threshold, the second voltage threshold, the third voltage threshold, and the fourth voltage threshold can be set according to the allowable deviation of the differential voltage signal
  • the voltage values of the reference voltage V3 and the reference voltage V5 can also be set to other values, as long as the first sampling signal is compared with the reference voltage V3, it can be determined whether the voltage value of the first CAN signal line exceeds the allowable deviation, By comparing the second sampling signal with the reference voltage V5, it is enough to determine whether the voltage value of the second CAN signal line exceeds the allowable deviation.
  • the application does not limit the voltage values of the reference voltage V3 and the reference voltage V5.
  • the first current signal or the second current signal is generated, which further affects the final output of the driving module, so that the first sampling signal and the second
  • one of the first detection sub-module and the second detection sub-module in the common-mode detection module can generate a current signal for reducing the common-mode interference in the differential voltage signal, so that the drive The module can respond to the current signal from the first detection sub-module or the second detection sub-module, and reduce the common mode interference in the differential voltage signal.
  • the first comparison module According to the information indicated by the first current signal and the second current signal, there are multiple options for setting the first comparison module, the first current generation module, the second comparison module, and the second current generation module.
  • An exemplary structure of the first comparison module, the first current generation module, the second comparison module and the second current generation module is given.
  • Figure 6a shows that the first current signal indicates that the voltage values of the first sampling signal and the second sampling signal are relatively large, and the second current signal indicates that the voltage values of the first sampling signal and the second sampling signal are relatively small, the first comparison module, the first An example of how the current generation module, the second comparison module, and the second current generation module are arranged.
  • the first comparison module 10211 includes a first switch SWD1, a second switch SWR1 and a first comparator CMP1, and one end c1 of the first switch SWD1 serves as the common mode detection module 102
  • the first end (E end) of the second switch SWR1 receives the first sampling signal CANH_SEN, and the other end d1 is connected to the other end d2 of the second switch SWR1 and the first input end (such as the negative input end) of the first comparator CMP1;
  • One terminal c2 of the first comparator CMP1 is connected to the third reference voltage (reference voltage V2);
  • the second input terminal (such as the positive input terminal) of the first comparator CMP1 is connected to the first reference voltage (reference voltage V3), and the output terminal outputs the first comparison signal VC_UP;
  • the second comparison module 10221 includes a third switch SWD2, a fourth switch SWR2 and a second comparator CMP2, and one terminal c3 of the third switch SWD2 is used as the second terminal (G terminal) of the common mode detection module 102 to receive the second sampling signal CANL_SEN , the other end d3 is connected to the other end d4 of the fourth switch SWR2 and the first input end (such as the negative input end) of the second comparator CMP2; one end c4 of the fourth switch SWR2 is connected to the fourth reference voltage (reference voltage V4); A second input terminal (for example, a positive input terminal) of the second comparator CMP2 is connected to a second reference voltage (reference voltage V5 ), and an output terminal outputs a second comparison signal VC_DN.
  • the working states of the first comparator CMP1 and the second comparator CMP2 can be controlled by an enable signal from the microcontroller 1300 .
  • the microcontroller 1300 does not provide an enable signal, and the first comparator CMP1 and the second comparator CMP2 are not enabled (for example, disconnected from the power supply) to save power consumption.
  • the CAN transceiver 1100 acts as a transmitter, the microcontroller 1300 provides an enable signal, and the first comparator CMP1 and the second comparator CMP2 are enabled. Opening and closing of the first switch, the third switch, the second switch, and the fourth switch can be controlled by a control signal from the microcontroller 1300 .
  • the first sampling signal is input to the first comparator CMP1, so that the first comparator CMP1 can output the first comparison signal VC_UP;
  • the second sampling signal is input to the second comparator CMP2 so that the second comparator CMP2 can output the second comparison signal VC_DN.
  • the first switch SWD1 and the third switch SWD2 can be set to open when the control signal is not received and closed when the control signal is received; the second switch SWR1 and the fourth switch SWR2 can be set to not receive the control signal, for example. Closed when the control signal is received, and opened when the control signal is received.
  • the common mode detection module does not need to work. Since the control signal is not received, the first switch SWD1 and the third switch SWD2 are turned off, and the second switch SWR1 and the second switch SWR1 are turned off.
  • the four switches SWR2 are closed, so that the first comparator CMP1 and the second comparator CMP2 will not respond to changes in the first sampling signal and the second sampling signal.
  • the CAN transceiver 1100 acts as a transmitter and sends a dominant state signal
  • the first switch SWD1 and the third switch SWD2 are closed, and the second switch SWR1 and the fourth switch SWR2 are opened, so that the first comparator CMP1 and the second comparator CMP2 receive the first sampling signal and the second sampling signal respectively. Sampling the signal, outputting a first comparison signal associated with the first sampling signal and a second comparison signal associated with the second sampling signal.
  • the first comparison module and the second comparison module can respond to the first sampling signal and the second sampling signal, and output the first comparison signal and the second comparison signal, so that the common
  • the mode detection module can output the first current signal or the second current signal according to the first comparison signal and the second comparison signal, so that when the first current signal or the second current signal acts on the driving module, the driving module can output a reduced common mode interfering differential voltage signal.
  • the first detection sub-module detects whether there is common-mode interference caused by voltage positive jitter
  • the second detection sub-module detects whether there is common-mode interference caused by voltage negative jitter
  • the voltage values of the reference voltage V2 and the reference voltage V4 can also be set to other values, as long as the second switch SWR2 and the fourth switch SWR2 are closed, the comparison result of the first comparator and the second comparator It is sufficient that neither the first detection sub-module nor the second detection sub-module generates current. This application is not limited to this.
  • the first end (E end) of the common mode detection module 102 can be connected to the second end (B end) of the sampling module 101, and the second end (G end) of the common mode detection module 102 can be connected to the third end of the sampling module 101 ( C terminal).
  • the first comparison module and the second comparison module can respectively receive the first sampling signal and the second sampling signal, and can respectively output the first comparison signal and the second comparison signal. enabling the first current generating module and the second current generating module to respond respectively according to the first comparison signal and the second comparison signal, and generate a first current signal and a second current signal for reducing common-mode interference in the differential voltage signal , so that the common mode detection module can generate the first current signal or the second current signal.
  • the first current generating module 10212 includes a first field effect transistor MPC, the gate of the first field effect transistor MPC receives the first comparison signal VC_UP, and the first field effect transistor MPC
  • the source of the effect transistor MPC is connected to the power supply voltage VCC, and the drain is used as the third terminal (F terminal) of the common mode detection module 102.
  • the second current generation module 10222 includes a second field effect transistor MNC, and the gate of the second field effect transistor MNC receives
  • the second comparison signal VC_DN the source of the second field effect transistor MNC is connected to the ground GND, and the drain is used as the fourth terminal (H terminal) of the common mode detection module 102, and the second comparison signal VC_DN makes the second field effect transistor MNC conduction , the drain of the second field effect transistor MNC generates a second current signal, and does not generate current when the second field effect transistor MNC is not turned on (cut off).
  • the first field effect transistor MPC may be, for example, a P-type field effect transistor
  • the second field effect transistor MNC may be, for example, an N-type field effect transistor.
  • the gate of the first field effect transistor MPC is turned on when it receives a low-level signal, the first current signal is generated in the first field effect transistor MPC, and it is turned off when it receives a high-level signal, and the first field There is no current signal generated in the effect tube MPC.
  • the gate of the second field effect transistor MNC is turned on when it receives a high-level signal, the second current signal is generated in the second field effect transistor MNC, and it is cut off when it receives a low-level signal, and there is no current signal in the second field effect transistor MNC.
  • a current signal is generated. That is, in the application scenario of FIG. 6a, the first current signal is generated and the second current signal is not generated, indicating that the first comparison signal is at low level, that is, the first sampling signal is greater than the reference voltage V3, and the second comparison signal is at low level.
  • the second sampling signal is greater than the reference voltage V5
  • that is, the differential voltage signal is too large (there is common-mode interference caused by voltage positive jitter)
  • the second current signal is generated without the first current signal, indicating that the second comparison signal is High level, that is, the second sampling signal is lower than the reference voltage V5
  • the first comparison signal is high level, that is, the first sampling signal is lower than the reference voltage V3
  • the differential voltage signal is small (common mode interference caused by voltage negative jitter) .
  • the voltage jitter of the two signal lines of the CAN bus is consistent, so the common mode detection module outputs at most one current signal at the same time.
  • the first current generation module and the second current generation module can receive the first comparison signal and the second comparison signal, and generate the first current signal or the second current signal.
  • the driving module can respond according to the first current signal or the second current signal, and output a differential voltage signal with reduced common-mode interference.
  • first current generating module and the second current generating module are not limited to those shown in FIG. 6a, as long as they can generate the first The current signal or the second current signal can be generated.
  • first current signal and the second current signal by the common mode detection module, reference may be made to FIGS. 9-10 and related descriptions below.
  • Figure 6b shows that when the first current signal indicates that the voltage values of the first sampling signal and the second sampling signal are relatively small, and the second current signal indicates that the voltage values of the first sampling signal and the second sampling signal are relatively large, the first comparison module, the second sampling signal An example of the arrangement of a current generating module, a second comparing module, and a second current generating module.
  • the first detection submodule 1021 is used to detect whether there is common-mode interference caused by voltage negative jitter
  • the second detection submodule 1022 is used to detect whether there is voltage positive
  • the reference voltage V3 can be set to 2.48V
  • the reference voltage V5 can be set to 2.5V
  • the voltage value of the reference voltage V2 can be set to a voltage value greater than the reference voltage V3, for example, refer to
  • the voltage values of the reference voltage V2 and the reference voltage V4 can also be set to other values, as long as the second switch SWR2 and the fourth switch SWR2 are closed, the comparison result of the first comparator and the second comparator It is sufficient that neither the first detection sub-module nor the second detection sub-module generates current. This application is not limited to this.
  • the connection manner of the components of the first comparison module 10211 and the second comparison module 10221 reference may be made to the relevant description in FIG. 6a.
  • the first current signal indicates that the voltage values of the first sampling signal and the second sampling signal are relatively small
  • the second current signal indicates that the voltage values of the first sampling signal and the second sampling signal
  • the first current generating module 10212 includes a second field effect transistor MNC, the gate of the second field effect transistor MNC receives the first comparison signal VC_UP, and the source of the second field effect transistor MNC is connected to the ground GND , and the drain serves as the fourth terminal (H terminal) of the common mode detection module.
  • the drain of the second field effect transistor MNC generates the first current signal
  • the second field effect transistor MNC generates the first current signal.
  • the second current generation module 10222 includes a first field effect transistor MPC, the gate of the first field effect transistor MNC receives the second comparison signal VC_DN, the source of the first field effect transistor MPC is connected to the power supply voltage VCC, and the drain is used as a common mode detection
  • the third terminal (F terminal) of the module when the second comparison signal VC_DN makes the first field effect transistor MPC conduct, the drain of the first field effect transistor MPC generates a second current signal, and the first field effect transistor MPC does not conduct When on (off), no current signal is generated.
  • the first field effect transistor MPC may be, for example, a P-type field effect transistor
  • the second field effect transistor MNC may be, for example, an N-type field effect transistor.
  • the gate of the first field effect transistor MPC is turned on when it receives a low-level signal
  • the second current signal is generated in the first field effect transistor MPC, and it is cut off when it receives a high-level signal.
  • the gate of the second field effect transistor MNC is turned on when it receives a high-level signal
  • the first current signal is generated in the second field effect transistor MNC, and it is cut off when it receives a low-level signal, and there is no current signal in the second field effect transistor MNC.
  • a current signal is generated. That is, in the application scenario of Figure 6b, the generation of the first current signal indicates that the differential voltage signal is too small (there is common-mode interference caused by voltage negative jitter), and the generation of the second current signal indicates that the differential voltage signal is too large (there is voltage positive common-mode interference caused by jitter).
  • the first current generating module 10212 is used to generate a current signal when receiving a low-level signal
  • the second current generating module 10222 is used to generate a current signal when receiving a high-level signal
  • the first current generation module 10212 is used to generate a current signal when receiving a high-level signal
  • the second current generation module 10222 is used to generate a current signal when a low-level signal is received.
  • the specific structures of the first current generating module 10212 and the second current generating module 10222 are not limited to those shown in Fig. 6a and Fig. 6b, as long as they can generate The first current signal or the second current signal can be generated.
  • the present application does not limit the specific structures of the first current generating module 10212 and the second current generating module 10222 .
  • the operational amplifier may not be included in the common-mode detection module, so there is no speed limit when suppressing common-mode interference.
  • the specific structure of the common mode detection module is not limited to the above examples, for example, it can also be set so that the first sampling signal and the second sampling signal are respectively input to the positive input terminals of the first comparator and the second comparator, Correspondingly, the types of field effect transistors of the first current generating module and the second current generating module are changed, and so on. As long as it can respond to the common-mode interference in the first sampling signal and the second sampling signal, a current capable of causing the common-mode component in the output signal of the driving module to change in the opposite direction of the common-mode interference is sufficient.
  • the differential mode interference can be divided into two cases, one is the overvoltage differential mode interference caused by voltage jitter, which increases the voltage difference between the two differential voltage signals, and the other is the undervoltage differential mode interference caused by voltage jitter, which makes the two differential voltage signals
  • the voltage difference of the voltage signal decreases.
  • the ideal voltage value of the input signal at the first terminal (A terminal) of the sampling module 101 can be equal to 3.5V, and the input signal at the second terminal (B terminal) of the sampling module 101
  • the ideal voltage value can be equal to 1.5V, and the voltage difference between the two is 2V.
  • the differential voltage signal includes overvoltage differential mode interference, the voltage difference can be greater than 2V, and when including undervoltage differential mode interference, the voltage difference can be less than 2V.
  • the differential mode detection module determines whether the voltage difference between the two sampling signals corresponding to the two differential voltage signals is too large or too small, and then determines whether differential mode interference occurs in the two sampling signals, and indirectly determines the two differential voltages Whether the signal includes differential mode interference that needs to be suppressed, and when it is detected that there is differential mode interference that needs to be suppressed, a signal indicating that the voltage difference of the sampling signal is too large or too small is generated.
  • the differential mode detection module 103 includes a sampling amplifier AMP and an error amplifier EA, and the first input terminal (such as a positive input terminal) of the sampling amplifier AMP is used as the input terminal of the differential mode detection module 103.
  • the first terminal (I terminal) receives the first sampling signal
  • the second input terminal (negative input terminal) is used as the second terminal (J terminal) of the differential mode detection module 103 to receive the second sampling signal
  • the output terminal is connected to the error amplifier EA
  • the first input terminal (negative input terminal) of the error amplifier EA; the second input terminal (positive input terminal) of the error amplifier EA is connected to the fifth reference voltage (reference voltage V6), and the output terminal is used as the third terminal (K terminal) of the differential mode detection module 103 ) to output the first voltage signal VC.
  • the voltage value of the reference voltage V6 can also be set to other values, For example, when a certain deviation is allowed in the voltage difference of the differential voltage signal in the dominant state, the voltage value of the reference voltage V6 can also be set according to the ideal voltage difference of 2V and the allowable deviation, which is not limited in the present application.
  • the first end (I end) of the differential mode detection module 103 can be connected to the second end (B end) of the sampling module 101, and the second end (J end) of the differential mode detection module 103 can be connected to the third end (the J end) of the sampling module 101 C terminal).
  • the differential mode detection module can respond to the first sampling signal and the second sampling signal, and complete the function of outputting the first voltage signal.
  • the driving module can respond according to the first voltage signal, and output a differential voltage signal with reduced differential mode interference.
  • the differential mode detection module is configured to reduce the voltage value of the first voltage signal when the voltage difference between the first sampling signal and the second sampling signal is too large. When the voltage difference between the signal and the second sampling signal is relatively small, the voltage value of the first voltage signal increases.
  • FIGS. 11-12 and related descriptions below For an example of generating the first voltage signal by the differential mode detection module, reference may be made to FIGS. 11-12 and related descriptions below.
  • the differential mode detection module can output a smaller first voltage signal when the transmission signal of the CAN bus is subjected to differential mode interference caused by voltage difference overvoltage; In the case of differential mode interference caused by voltage difference and undervoltage, a first voltage signal that becomes larger is output.
  • the smaller or larger first voltage signal is input to the driving module, the accuracy of the differential voltage signal output from the driving module to the CAN bus can be improved.
  • the differential mode detection module 103 is used to output a voltage signal according to the voltage difference of the two signals received, so that when the voltage difference of the two signals received is relatively large, the voltage value of the voltage signal becomes smaller, and the voltage value of the two signals received When the voltage difference is small, the voltage value of the voltage signal becomes larger.
  • the specific structure of the differential mode detection module is not limited to the above example, as long as it can respond to the differential mode interference in the first sampling signal and the second sampling signal It is enough to generate a voltage that can make the differential mode component in the output signal of the driving module change in the opposite direction of the differential mode interference.
  • Fig. 8 shows an exemplary structural diagram of a driving module according to an embodiment of the present application.
  • the driving module 104 includes a first mirror current source I1, a second mirror current source I2 and a voltage-controlled current source VCCS, and the first mirror current source I1 and the voltage-controlled current source
  • a switch S1 is connected between VCCS, a switch S2 is connected between the second mirror current source I2 and the voltage-controlled current source VCCS, and the control end of the switch is connected to the signal line TX.
  • the CAN transceiver acts as a transmitter
  • the CAN controller 1200 outputs a logic signal 1 (recessive state) through TX
  • the switches S1 and S2 remain open, the drive module 104 has no output, and the voltage on the CAN bus is determined by the bias circuit , for example, the voltage on both buses is 2.5V.
  • the CAN controller 1200 outputs a logic signal 0 (dominant state) through TX, then the switches S1 and S2 are closed, and the voltage-controlled current source VCCS in the drive module 104 is connected to start generating current, and at the output terminal of the drive module 104 Generate a differential voltage signal.
  • the output current of the voltage-controlled current source VCSS is controlled by the output voltage of the differential mode detection module 103 .
  • the sampling module 101 samples two bus voltages (such as 2.5V and 2.5V) in the recessive state, referring to FIG.
  • the differential mode detection module 103 is in an enabled state
  • the output of the sampling amplifier AMP in the differential mode detection module 103 is 0, and the output of the error amplifier EA is the amplification result of the reference voltage V6, which is used as the initial input voltage of the voltage-controlled current source VCSS, so that the driving module 104 generates an initial output of a dominant state
  • the sampling module 101 samples the output of the driving module 104, and feeds back to the common mode detection module 102 and the differential mode detection module 103, and the output of the common mode detection module 102 and the differential mode detection module 103 generates the output of the driving module 104 Influence, to achieve the purpose of feedback correction.
  • the CAN bus includes a first CAN signal line and a second CAN signal line.
  • one end (N end) of the first mirror current source I1 obtains the first current signal, and the other end of the first mirror current source I1 is connected to the second CAN signal line;
  • one end (L end) of the second mirror current source I2 obtains the second current signal, and the other end of the second mirror current source I2 is connected to the first CAN signal line;
  • the voltage-controlled current source VCCS is connected to the first mirror current source
  • a terminal (N terminal) of I1 and a terminal (L terminal) of the second mirror current source I2 are used to receive the first voltage signal and generate current according to the first voltage signal.
  • the first current signal indicates that there is a common mode interference that makes the voltage value larger in the first sampling signal and the second sampling signal
  • the second current signal indicates that there is a common mode interference in the first sampling signal and the second sampling signal that makes the voltage value smaller.
  • Mode interference the first current signal is generated by the third terminal (F terminal) of the common mode detection module
  • the second current signal is generated by the fourth terminal (H terminal) of the common mode detection module, so as long as the second mirror current source
  • One end (L end) of I2 is connected to the fourth end (H end) of the common mode detection module to obtain the second current signal and respond, so that one end (N end) of the first mirror current source I1 is connected to the common mode detection module.
  • the third terminal (F terminal) can acquire the first current signal and make a response.
  • the drive module can adjust the current that the second CAN signal line flows into the other end of the first mirror current source, thereby adjusting the voltage value of the differential voltage signal; in response to the second current signal, the drive module can adjust the second The other end of the mirror current source flows out to the current of the first CAN signal line, so that the voltage value of the differential voltage signal can be adjusted; in response to the first voltage signal, the drive module can generate current through the voltage-controlled current source to adjust the second CAN signal line to flow into The other end of the first mirror current source and the other end of the second mirror current source flow out to the first CAN signal line, so that the voltage value of the differential voltage signal can be adjusted. In this way, the driving module can reduce the common-mode interference in the differential voltage signal according to the first current signal or the second current signal, and reduce the differential-mode interference in the differential voltage signal according to the first voltage signal.
  • the first mirror current source I1 may include a fifth field effect transistor MNB and a sixth field effect transistor MND
  • the source of the fifth field effect transistor MNB may be connected to the source of the sixth field effect transistor MND and the ground GND
  • the fifth The drain of the field effect transistor MNB can be connected to the gate of the fifth field effect transistor MNB, the gate of the sixth field effect transistor MND and the second end of the voltage-controlled current source VCCS, and serve as the first end of the driving module 104 (N Terminal), connected to the third terminal (F terminal) of the common mode detection module 102, for obtaining the first current signal.
  • the drain of the sixth field effect transistor MND can be connected to the cathode of the diode D2, and the anode of the diode D2 serves as the second terminal (O terminal) of the driving module 104 and is connected to the second CAN signal line (CANL).
  • CANL second CAN signal line
  • the second mirror current source I2 may include a third field effect transistor MPB and a fourth field effect transistor MPD, the source of the third field effect transistor MPB may be connected to the source of the fourth field effect transistor MPD and the power supply voltage terminal VCC, and the third The drain of the field effect transistor MPB can be connected to the gate of the third field effect transistor MPB, the gate of the fourth field effect transistor MPD and the first end of the voltage-controlled current source VCCS, and serves as the third end of the driving module 104 (L Terminal), connected to the fourth terminal (H terminal) of the common mode detection module 102, for obtaining the second current signal.
  • the drain of the fourth field effect transistor MPD can be connected to the anode of the diode D1, and the cathode of the diode D1 serves as the fourth terminal (M terminal) of the driving module 104 and is connected to the first CAN signal line (CANH).
  • the third terminal of the voltage-controlled current source VCCS also serves as the fifth terminal (P terminal) of the driving module 104 and is connected to the third terminal (K terminal) of the differential mode detection module 103 for receiving the first voltage signal.
  • the fifth field effect transistor MNB and the sixth field effect transistor MND can be, for example, N-type field effect transistors, and the current flowing through the sixth field effect transistor MND follows the fifth field effect transistor
  • the current flowing through MNB changes proportionally
  • the third field effect transistor MPB and the fourth field effect transistor MPD can be, for example, P-type field effect transistors, and the current flowing through the fourth field effect transistor MPD , changes in proportion to the current flowing in the third field effect transistor MPB.
  • the driving module obtains the first current signal
  • the current flowing into the driving module from the second CAN signal line increases, and the voltage values of the two differential voltage signals output by the driving module decrease
  • the driving module acquires the second current signal
  • the current flowing out of the driving module from the first CAN signal line increases, and the voltage values of the two differential voltage signals output by the driving module increase.
  • the first mirror current source I1 obtains the first current signal
  • the current flowing through the fifth field effect transistor MNB and the sixth field effect transistor MND change, so that the two differential circuits output by the driving module
  • the voltage of the voltage signal changes accordingly
  • the second mirror current source I2 obtains the second current signal
  • the current flowing in the third field effect transistor MPB and the current flowing in the fourth field effect transistor MPD change, so that the output of the driving module
  • the voltages of the two differential voltage signals change accordingly.
  • the drive module can output a differential voltage signal with a reduced voltage value, and the negative jitter of the differential voltage signal enables the drive module to obtain the second current signal.
  • the driving module can output a differential voltage signal with an increased voltage value, so as to improve the accuracy of the differential voltage signal output from the driving module to the CAN bus.
  • the current flowing into the driving module through the second CAN signal line is equal to the current flowing into the driving module through the first CAN signal line.
  • the current flowing out of the driving module decreases, and the voltage difference between the two differential voltage signals output by the driving module decreases; when the voltage value of the first voltage signal increases, when the driving module receives the first voltage signal, the second The current flowing into the driving module from the second CAN signal line and the current flowing out of the driving module from the first CAN signal line both increase, and the voltage difference between the two differential voltage signals output by the driving module increases.
  • the driving module can reduce the voltage difference of the output differential voltage signal, and when the voltage difference of the differential voltage signal is undervoltage so that When the increased first voltage signal is input to the driving module, the driving module can increase the voltage difference of the output differential voltage signal, so as to improve the accuracy of the differential voltage signal output from the driving module to the CAN bus.
  • first mirror current source and the second mirror current source are not limited thereto, as long as the mirror image change of the current at both ends of the mirror current source can be realized.
  • the function realized by the driving module 104 is to output a differential voltage signal of a dominant state when the received logic signal is 0, and the sampling module 101, the common mode detection circuit 102 and the differential mode detection circuit Under the feedback of 103, the driving module 104 can output two voltage signals according to the received first voltage signal, so that the variation trend of the voltage difference between the two voltage signals is the same as the variation trend of the voltage value of the received voltage signal, And when the common mode detection module 102 generates the first current signal, according to the first current signal, the current of the second CAN signal line flowing into the other end of the first mirror current source can be adjusted, so that the voltage value of the two differential voltage signals decreases and The degree of reduction is the same, and the second current signal can be generated in the common mode detection module 102.
  • the current flowing from the other end of the second mirror current source to the first CAN signal line can be adjusted, so that the two-way differential voltage signal The voltage value increases and increases to the same extent.
  • the first mirror current source, the second mirror current source and the switch can be implemented based on existing technology, which is not limited in this application.
  • the first current signal indicates that there is a common mode interference that makes the voltage value smaller in the first sampling signal and the second sampling signal
  • the second current signal indicates that there is a voltage in the first sampling signal and the second sampling signal.
  • one terminal (N terminal) of the first mirror current source I1 can also be set to obtain the second current signal
  • one terminal (L terminal) of the second mirror current source I2 can obtain the first current signal.
  • the function realized by the driving module 104 is to output the differential voltage signal of the dominant state when the received logic signal is 0, and in the sampling module 101, the common-mode detection circuit 102 and the differential-mode detection circuit 103 Under the action of feedback, the driving module 104 can output two voltage signals according to the received first voltage signal, so that the change trend of the voltage difference between the two voltage signals is the same as the change trend of the voltage value of the received voltage signal, and can When the common mode detection module 102 generates the first current signal, the current flowing from the other end of the second mirror current source to the first CAN signal line can be adjusted according to the first current signal, so that the voltage values of the two differential voltage signals increase and increase The magnitude is the same, and when the common mode detection module 102 generates the second current signal, the current of the second CAN signal line flowing into the other end of the first mirror current source can be adjusted according to the second current signal, so that the voltage of the two differential voltage signals decrease in value by the same amount.
  • the sending circuit receives an enable signal from the microcontroller, and when the enable signal is not received, the common-mode detection module 102 and the differential-mode detection module 103 are in a non-enabled state;
  • the common mode detection module 102 and the differential mode detection module 103 When receiving the enable signal, the common mode detection module 102 and the differential mode detection module 103 enter the enabled state from the unenabled state, and in the enabled state, the first comparator and the second comparator in the common mode detection module 102 The sampling amplifier and the error amplifier in the differential mode detection module 103 work normally.
  • the power consumption of the transmission circuit can be reduced. Further, the power consumption of the transceiver can be reduced.
  • the common-mode detection module 102 and the differential-mode detection module 103 can be set to remain disabled, and when the transceiver is used as a transmitter, the common-mode detection module 102 can be enabled again and the differential mode detection module 103 to save the power consumption of the sending circuit.
  • the enabling of the common mode detection module 102 and the differential mode detection module 103 may be triggered by an enable signal, for example.
  • the first switch SWD1, the second switch SWR1, the third switch SWD2, and the fourth switch SWR2 may remain off, and the first comparator CMP1 and the second comparator CMP2 are not enabled.
  • the comparator and the amplifier are enabled, the first switch SWD1 and the third switch SWD2 are kept open, and the second switch SWR1 and the fourth switch SWR2 can be closed.
  • the field effect transistors (MPC, MNC) of the common mode detection module are all cut off, and the common mode detection module does not generate a current signal.
  • the sending circuit 20 receives a control signal from the microcontroller 1300, and the control signal indicates that the first CAN signal line and the second CAN signal line transmit a differential voltage signal of a dominant state.
  • the first switch and the third switch in the common mode detection module are turned off, the second switch and the fourth switch are closed, and when the control signal is received, the first switch and the third switch in the common mode detection module are closed , the second switch and the fourth switch are turned off.
  • control signal is associated with the dominant state of the differential voltage signal transmitted by the transceiver to the CAN bus, so that when the transceiver transmits the differential voltage signal of this state, the common mode detection module in the sending circuit 20 can The control signal can be responded to to improve the accuracy of the output differential voltage signal. And setting the switch controlled by the control signal makes the power consumption of the transmission circuit lower than that of the dominant state when transmitting the recessive state, which can further reduce the power consumption of the transmission circuit and the transceiver.
  • the information sent according to needs such as 0101
  • the state information of the differential voltage signal output by the transceiver can be, for example, dominant state-recessive state-dominant state-recessive state
  • the enable signal and the control signal can be used to enable the common mode detection module and the differential mode detection module to respond to the sampling signal when the dominant state is transmitted, so that the transmission circuit 20 can complete the correction of the differential voltage signal.
  • the microcontroller 1300 sends an enable signal and a control signal, and in the sending circuit 20, the common mode detection module 102 receives the According to the control signal of the controller 1300, the first switch SWD1 can be closed and the second switch SWR1 can be opened according to the control signal, so that the first sampling signal can be input to the negative input terminal of the first comparator CMP1.
  • the first comparator CMP1 has been enabled, so that the first comparator CMP1 can compare the voltage value of the first sampling signal with the voltage value of the reference voltage V3, and output the first comparison signal VC_UP to control the conduction of the first field effect transistor MPC On and off; when the first field effect transistor MPC is turned on, the common mode detection module 102 generates a first current signal.
  • the common mode detection module 102 can close the third switch SWD2 and open the fourth switch SWR2 according to the control signal, so that the second sampling signal can be input to the negative input terminal of the second comparator CMP2.
  • the second comparator CMP2 has been enabled, so that the second comparator CMP2 can compare the voltage value of the second sampling signal with the voltage value of the reference voltage V5, and output the second comparison signal VC_DN to control the conduction of the second field effect transistor MNC.
  • the common mode detection module 102 When the second field effect transistor MNC is turned on, the common mode detection module 102 generates a second current signal.
  • the sampling amplifier AMP and the error amplifier EA are enabled, and the sampling amplifier AMP enables the difference between the first sampling signal and the second sampling signal to be amplified in the sampling amplifier AMP.
  • the error amplifier EA enables the voltage value output by the output terminal of the sampling amplifier AMP and the voltage value of the reference voltage V6 to be differenced and amplified in the error amplifier EA to output a first voltage signal.
  • the first comparator CMP1 , the second comparator CMP2 , the sampling amplifier AMP and the error amplifier EA can also work autonomously without being controlled by the control signal.
  • the embodiment of the present application does not limit this.
  • the voltage of the differential voltage signal in the recessive state is not controlled by the driving module.
  • the embodiment of the present application controls the voltage of the differential voltage signal through the sampling module, the common mode detection module, the differential mode detection module, and the driving module, which is aimed at the differential voltage signal in the dominant state.
  • the differential voltage signal of the CAN bus is in a dominant state, and the first current signal indicates that there is common-mode interference in the first sampling signal and the second sampling signal that makes the voltage value larger, and the second current signal indicates the first sampling signal and the second sampling signal.
  • An application scenario where there is common-mode interference in the second sampled signal that causes the voltage value to be small is taken as an example. With reference to FIGS.
  • the differential voltage signal transmitted by the CAN bus is in the normal operating range (the voltage of the first CAN signal line (CANH) can be, for example, 3.5V, the second CAN The voltage of the signal line (CANL) can be, for example, 1.5V).
  • the current (sink current) flowing through the fourth field effect transistor MPD is equal to the current (source current) flowing through the MND, so that the first drive module 104
  • the four terminals (M terminal) and the second terminal (O terminal) output an ideal differential voltage signal (the voltage of the first CAN signal line (CANH) is 3.5V, and the voltage of the second CAN signal line (CANL) is 1.5V , the voltage difference between the first CAN signal line (CANH) and the second CAN signal line (CANL) is 2V).
  • the CAN transmitter sends a differential voltage signal in a dominant state
  • the first switch SWD1 and the third switch SWD2 are in a closed state
  • the switch SWR2 is in the off state
  • the first comparator CMP1 , the second comparator CMP2 , the sampling amplifier AMP and the error amplifier EA are in the enable state.
  • the first field effect transistor MPC can be, for example, a P-type field effect transistor, and the conduction condition of the first field effect transistor MPC can be, for example, low-level conduction;
  • the second field effect transistor MNC can be, for example, an N-type field effect transistor.
  • the conduction condition of the second field effect transistor MNC can be, for example, high level conduction.
  • the first comparison signal VC_UP and the second comparison signal VC_DN can be respectively input to the first field effect transistor MPC and the second field effect transistor MNC, so that the first field effect transistor MPC and the second field effect transistor MNC One generates a current signal.
  • the first CAN signal line (CANH) and the second CAN signal line (CANL) may momentarily appear jitter voltage (up to ⁇ 40V).
  • the jitter voltage of the disturbed first CAN signal line (CANH) may be 23.5V
  • the jitter voltage of the disturbed second CAN signal line (CANL) may be 21.5V.
  • the jittering voltage of the first CAN signal line (CANH) and the jittering voltage of the second CAN signal line (CANL) both have positive direction and the same degree of jittering (both increased by 20V), which can be considered as external low frequency
  • Large-scale interference has common-mode interference caused by voltage positive jitter on the signal transmitted on the CAN bus.
  • the positive voltage jitter of the CAN bus can be suppressed through cooperation of the sampling module, the common mode detection module and the driving module, so as to ensure that the sending circuit works normally.
  • the output first sampling signal CANH_SEN and the second sampling signal CANL_SEN It also increases rapidly and is output to the first terminal (E terminal) and the second terminal (G terminal) of the common mode detection module 102 respectively.
  • the voltage values of the first comparison signal VC_UP output by the first comparator CMP1 and the second comparison signal VC_DN output by the second comparator CMP2 both become smaller, so that the second field effect transistor MNC is not turned on (off), the first field effect transistor MPC is turned on, and the third terminal (F terminal) of the common mode detection module 102 outputs the first current signal to the driving module 104 .
  • the direction of the output current of the voltage-controlled current source VCCS can be, for example, flow from the drain of the third field effect transistor MPB to the drain of the fifth field effect transistor MNB, and the first current signal is added to the voltage-controlled current source
  • the output current of VCCS makes the current flowing through the fifth field effect transistor MNB larger, and the current flowing through the fifth field effect transistor MNB is proportional to the current flowing through the sixth field effect transistor MND, so the current flowing through the sixth field effect transistor MNB
  • the source current of the field effect transistor MND also increases accordingly, so that the voltage signal output by the second terminal (O terminal) of the driving module 104 becomes low. That is, the voltage of the second CAN signal line (CANL) of the CAN bus is made low.
  • CANL second CAN signal line
  • the second CAN signal line (CANL) is connected to the first CAN signal line (CANH) through the terminal resistor R5, so the voltage of the first CAN signal line (CANH) also becomes lower.
  • the voltages of the first CAN signal line (CANH) and the second CAN signal line (CANL) can be quickly pulled down, and the influence of forward jitter is suppressed, so that the first CAN signal line (CANH) and the second CAN signal line ( CANL) quickly returns to the normal working range (the voltage of the first CAN signal line (CANH) can be close to 3.5V, and the voltage of the second CAN signal line (CANL) can be close to 1.5V).
  • the transmission signal of the CAN bus is subject to common-mode interference caused by positive voltage jitter, and the large positive jitter of the transmission signal of the CAN bus can be suppressed, so that the differential voltage signal output by the CAN bus can be corrected.
  • Common mode interference is suppressed to improve the accuracy of the differential voltage signal output from the sending circuit to the CAN bus.
  • external low-frequency large-scale interference may also cause common-mode interference caused by voltage negative jitter to signals transmitted on the CAN bus.
  • the jitter voltage of the disturbed first CAN signal line (CANH) may be -21.5V
  • the jitter voltage of the disturbed second CAN signal line (CANL) may be -23.5V.
  • the jitter voltage of the first CAN signal line (CANH) and the jitter voltage of the second CAN signal line (CANL) are both negative in direction and the degree of jitter is the same (reduced by 25V), it can be considered that the external low frequency has a large amplitude Interference
  • the negative voltage jitter of the CAN bus can be suppressed through cooperation of the sampling module, the common mode detection module and the driving module, so as to ensure the normal operation of the sending circuit.
  • the output first sampling signal CANH_SEN and the second The two-sampling signal CANL_SEN also decreases rapidly, and is respectively output to the first terminal (E terminal) and the second terminal (G terminal) of the common mode detection module 102 .
  • the voltage values of the first comparison signal VC_UP output by the first comparator CMP1 and the second comparison signal VC_DN output by the second comparator CMP2 both become larger, so that the first field effect transistor MPC is not turned on (off), the second field effect transistor MNC is turned on, and the driving module 104 inputs the second current signal to the fourth terminal (H terminal) of the common mode detection module 102 .
  • the direction of the output current of the voltage-controlled current source VCCS can be, for example, flow from the drain of the third field effect transistor MPB to the drain of the fifth field effect transistor MNB, and the second current signal is added to the voltage-controlled current source
  • the output current of VCCS makes the current flowing through the third field effect transistor MPB larger, and the current flowing through the third field effect transistor MPB is proportional to the current flowing through the fourth field effect transistor MPD, so the current flowing through the fourth field effect transistor MPB
  • the sink current of the field effect transistor MPD also increases accordingly, so that the voltage signal output by the fourth terminal (M terminal) of the driving module 104 becomes high. That is, the voltage of the first CAN signal line (CANH) is made high.
  • the first CAN signal line (CANH) is connected to the second CAN signal line (CANL) through the terminal resistor R5, so the voltage of the second CAN signal line (CANL) also becomes higher. Therefore, the voltages of the first CAN signal line (CANH) and the second CAN signal line (CANL) can be quickly pulled up, and the influence of negative jitter is suppressed, so that the first CAN signal line (CANH) and the second CAN signal line ( CANL) quickly returns to the normal working range (the voltage of the first CAN signal line (CANH) can be close to 3.5V, and the voltage of the second CAN signal line (CANL) can be close to 1.5V).
  • the transmission signal of the CAN bus is subject to common-mode interference caused by voltage negative jitter, and the large negative jitter of the transmission signal of the CAN bus can be suppressed, so that the differential voltage signal output by the CAN bus can be corrected.
  • Common mode interference is suppressed to improve the accuracy of the differential voltage signal output from the sending circuit to the CAN bus.
  • the first CAN signal line (CANH) and the second CAN signal line (CANL) may momentarily appear jittering voltage. If the jitter voltage of the first CAN signal line (CANH) is different from the jitter voltage of the second CAN signal line (CANL), it can be considered that there is a difference caused by voltage jitter on the signal transmitted by the external low-frequency large-scale interference.
  • Mode interference Taking the differential voltage signal of the CAN bus in the dominant state as an example, the working process of the transmission circuit in the embodiment of the present application to reduce the differential mode interference is exemplarily described in conjunction with FIGS. 11-12 .
  • the differential mode interference can be divided into two situations: voltage difference overvoltage and voltage difference undervoltage.
  • the jitter voltage of the disturbed first CAN signal line (CANH) can be, for example, 5.5V
  • the jitter voltage of the disturbed second CAN signal line (CANL) can be, for example, 2.5V
  • the first CAN signal after being disturbed The voltage of the line (CANH) increases by 2V
  • the voltage of the second CAN signal line (CANL) increases by 1V
  • the jitter voltage of the first CAN signal line (CANH) and the jitter voltage of the second CAN signal line (CANL) are different
  • the voltage difference after being disturbed is 3V, which is greater than the ideal voltage difference (for example, 2V). Therefore, the signal transmitted on the CAN bus has overvoltage differential mode interference caused by voltage jitter.
  • the voltage jitter of the CAN bus can be suppressed through cooperation of the sampling module, the differential mode detection module and the driving module, so as to ensure that the sending circuit works normally.
  • the differential mode detection module 103 In the differential mode detection module 103, the voltage difference between the signals input by the first input terminal (positive input terminal) and the second input terminal (negative input terminal) of the sampling amplifier AMP becomes larger, and the output voltage value of the output terminal of the sampling amplifier AMP becomes larger, that is, the voltage value of the signal input by the second input terminal (negative input terminal) of the error amplifier EA becomes larger, and the voltage value of the signal input by the first input terminal (positive input terminal) of the error amplifier EA remains unchanged, then the error amplifier The first voltage signal VC output by the EA becomes smaller, so that the third terminal (K terminal) of the differential mode detection module 103 outputs the first voltage signal which becomes smaller to the driving module 104 .
  • the direction of the output current of the voltage-controlled current source VCCS can be, for example, flow from the drain of the third field effect transistor MPB to the drain of the fifth field effect transistor MNB, and the reduced first voltage signal is input to the voltage control
  • the current source VCCS makes the output current of the voltage-controlled current source VCCS smaller, and the current flowing through the fourth field effect transistor MPD and the current flowing through the sixth field effect transistor MND also decrease accordingly, so that the second field effect transistor MND can be quickly pulled down.
  • the voltage difference between the CAN signal line (CANL) and the first CAN signal line (CANH) suppresses the impact of voltage jitter, so that the difference between the output of the fourth end (M end) and the second end (O end) of the drive module 104
  • the voltage difference of the voltage signal is close to the ideal voltage difference (2V) and remains stable.
  • the sending circuit can suppress the voltage jitter of the transmission signal of the CAN bus when the transmission signal of the CAN bus is subjected to overvoltage differential mode interference caused by voltage jitter, so as to control the differential voltage signal output by the CAN bus
  • the differential mode interference is suppressed, and the accuracy of the differential voltage signal output from the sending circuit to the CAN bus is improved.
  • the jitter voltage of the disturbed first CAN signal line (CANH) can be, for example, 4.5V
  • the jitter voltage of the disturbed second CAN signal line (CANL) can be, for example, 3.5V
  • the voltage of the first CAN signal line (CANH) increases by 1V
  • the voltage of the second CAN signal line (CANL) increases by 2V
  • the jittering degree of the jittering voltage is different, and the voltage difference after being disturbed is 1V, which is smaller than the ideal voltage difference. Therefore, the signal transmitted on the CAN bus has undervoltage differential mode interference caused by voltage jittering.
  • the voltage jitter of the CAN bus can be suppressed through cooperation of the sampling module, the differential mode detection module and the driving module, so as to ensure that the sending circuit works normally.
  • the differential mode detection module 103 In the differential mode detection module 103, the voltage difference between the signals input by the first input terminal (positive input terminal) and the second input terminal (negative input terminal) of the sampling amplifier AMP becomes smaller, and the output voltage value of the output terminal of the sampling amplifier AMP becomes smaller, that is, the voltage value of the signal input to the second input terminal (negative input terminal) of the error amplifier EA becomes smaller, and the voltage value of the signal input to the first input terminal (positive input terminal) of the error amplifier EA remains unchanged, then the error amplifier The first voltage signal VC output by the EA becomes larger, so that the third terminal (K terminal) of the differential mode detection module 103 outputs the first voltage signal which becomes larger to the driving module 104 .
  • the direction of the output current of the voltage-controlled current source VCCS can be, for example, flow from the drain of the third field effect transistor MPB to the drain of the fifth field effect transistor MNB, and the enlarged first voltage signal is input to the voltage control
  • the current source VCCS makes the output current of the voltage-controlled current source VCCS also increase, and the current flowing through the fourth field effect transistor MPD and the current flowing through the sixth field effect transistor MND also increase accordingly, so that the second
  • the voltage difference between the CAN signal line (CANL) and the first CAN signal line (CANH) suppresses the impact of voltage jitter, so that the difference between the output of the fourth end (M end) and the second end (O end) of the drive module 104
  • the voltage difference of the voltage signal is close to the ideal voltage difference (2V) and remains stable.
  • the sending circuit can suppress the voltage jitter of the transmission signal of the CAN bus when the transmission signal of the CAN bus is subjected to the undervoltage differential mode interference caused by voltage jitter, so as to control the differential voltage signal output by the CAN bus
  • the differential mode interference is suppressed, and the accuracy of the differential voltage signal output from the sending circuit to the CAN bus is improved.
  • the jitter voltage of the disturbed first CAN signal line can be, for example, 22.5V
  • the jitter voltage of the disturbed second CAN signal line can be, for example, 19.5V.
  • the first CAN signal line (CANH) and the second CAN signal line (CANL) are subjected to common-mode interference so that both voltages increase by 18V, and the differential-mode interference makes the first CAN signal Line (CANH) and then increased by 1V.
  • the sampling module 101, the common-mode detection module 102, the differential-mode detection module 103, and the driving module 104 can cooperate to suppress the voltage jitter of the CAN bus to ensure that the sending circuit works normally.
  • the microcontroller 1300 makes the CAN controller 1200 send a logic signal representing "0" to the drive module 104 of the CAN transceiver 1100 to control the switch of the drive module 104 (see S1, S2 in Figure 8) closure.
  • the microcontroller 1300 sends a control signal to the common-mode detection module 102 and the differential-mode detection module 103 of the transmitting circuit 20 to control the state of the switches (SWD1, SWD2, SWR1, SWR2) in the common-mode detection module 102 and the differential-mode detection module 103 .
  • the driving module 104 in the sending circuit 20 first outputs a differential voltage signal, and the differential voltage signal is received by the sampling module 101 .
  • the differential voltage signal received by the sampling module 101 is a signal with common-mode interference and overvoltage differential-mode interference caused by negative jitter
  • the first sample obtained by sampling is due to common-mode interference and differential-mode interference.
  • the signal CANH_SEN and the second sampling signal CANL_SEN have a decrease in voltage value and an increase in voltage difference.
  • the common mode detection module 102 In response to the reduction of the voltage values of the first sampling signal CANH_SEN and the second sampling signal CANL_SEN, in the common mode detection module 102, the output signals of the first comparator CMP1 and the second comparator CMP2 are both high level, and the first field effect transistor The MPC is turned off, the second field effect transistor MNC is turned on, and the common mode detection module 102 can receive the second current signal output by the driving module 104; in response to the rise of the voltage difference between the first sampling signal CANH_SEN and the second sampling signal CANL_SEN, the difference In the mode detection module 103, the output signal of the sampling amplifier AMP becomes larger, and the first voltage signal VC output by the error amplifier EA becomes smaller.
  • the driving module 104 acquiring the second current signal and receiving the first voltage signal are performed simultaneously.
  • the driving module 104 obtains the second current signal
  • the current flowing through the fourth field effect transistor MPD in the driving module 104 becomes larger, so that the fourth terminal (M terminal) of the driving module 104 and the second The output voltage of terminal (O terminal) becomes higher, so it is realized to reduce the common-mode interference caused by negative jitter;
  • the driver module 104 receives the first voltage signal that becomes smaller, the driver module 104 is made to flow through the fourth field effect transistor MPD
  • the current of the current and the current flowing through the sixth field effect transistor MND are both reduced, so that the voltage difference between the output voltages of the fourth end (M end) and the second end (O end) of the driving module 104 becomes smaller, thus reducing the Overvoltage differential mode interference caused by small jitter.
  • reducing common-mode interference can be completed prior to reducing differential-mode interference.
  • the reason is that the signals output by the first comparator CMP1 and the second comparator CMP2 are relatively large, and the signal output by the error amplifier EA is relatively small. Therefore, the influence of the second current signal on the driving module can be stronger than that of the first voltage signal on the driving module. module impact. That is to say, in the embodiment shown in FIG. 13 , before the common mode interference is reduced, the second current signal always exists, and the driving module 104 responds to the second current signal, so that the current flowing through the fourth field effect transistor MPD changes is large, and cannot be equal to the current flowing through the sixth field effect transistor MND.
  • the driving module 104 also responds to the first voltage signal, the current of the fourth field effect transistor MPD decreases, but the fourth field effect transistor MPD
  • the current reduction degree of the MPD is weaker than that of the fourth field effect transistor MPD, so the effect of reducing the differential mode interference is not obvious; after the common mode interference is reduced, the common mode detection module 102 no longer generates With the second current signal, the current of the fourth field effect transistor MPD no longer increases.
  • the differential mode interference is reduced, so that the driving module 104 outputs a differential voltage signal with a stable voltage value and voltage difference.
  • the common-mode interference and differential-mode interference in the differential voltage signal can also be combined in different types, for example, the differential voltage signal can also have negative jitter Signals of common-mode interference and under-voltage differential-mode interference caused by positive jitter; or signals of common-mode interference and overvoltage differential-mode interference caused by positive jitter; interfering signal. Only common-mode interference or differential-mode interference may exist in the differential voltage signal.
  • the embodiment of the present application can perform adaptive processing on the differential voltage signal according to different values of the differential voltage signal received by the sampling module. Taking the circuit structure of FIG.
  • the sending circuit 20 can generate different signals.
  • the sending circuit 20 when the sending circuit 20 only generates the first current signal, the common-mode interference caused by voltage forward jitter in the differential voltage signal can be reduced according to the first current signal; when the sending circuit 20 only generates the second current signal, according to the second The current signal can reduce the common-mode interference caused by negative voltage jitter in the differential voltage signal; when the sending circuit 20 only generates the first voltage signal, the overvoltage caused by the voltage jitter in the differential voltage signal can be reduced according to the first voltage signal or undervoltage differential mode interference; when the transmitting circuit 20 generates the first current signal and the first voltage signal, according to the first current signal and the first voltage signal, the common mode interference caused by the positive voltage jitter in the differential voltage signal can be reduced And the resulting overvoltage or undervoltage differential mode interference; when the sending circuit 20 generates the second current signal and the first voltage signal, according to the second current signal and the first voltage signal,
  • the sending circuit can adapt to the correction work of the differential voltage signal under various disturbances, and the processing ability of the sending circuit to the differential voltage signal is improved.
  • the above figures 9-13 show that the first current signal indicates that there is common mode interference in the first sampling signal and the second sampling signal that causes the voltage value to be too large, and the second current signal indicates that there is a common mode interference in the first sampling signal and the second sampling signal that causes An exemplary method for reducing the interference in the differential voltage signal in the application scenario of common-mode interference with a small voltage value, those skilled in the art should understand that the first current signal indicates that the first sampling signal and the second sampling signal exist in the In the application scenario where there is common-mode interference with a relatively small voltage value and the second current signal indicates that there is common-mode interference with a relatively large voltage value in the first sampling signal and the second sampling signal, the transmission circuit of the embodiment of the present application can also reduce the interference with differential voltage signals.
  • the embodiment of the present application also proposes a CAN transceiver, including the above-mentioned sending circuit.
  • the transceiver includes a sending circuit and a receiving circuit
  • the receiving circuit includes the sampling module
  • the drive module receives the logic signal output by the CAN controller and converts it into a differential voltage signal
  • the sending circuit When the common-mode detection module and the differential-mode detection module are enabled and the common-mode detection module receives the control signal, the sending circuit outputs two differential voltage signals through the driving module.
  • transceiver as a transmitter and a receiver, reference may be made to the description related to FIG. 2 above, and details are not repeated here.
  • the sending circuit can be used in combination with the receiving circuit in the transceiver, so as to reduce the hardware cost of the sending circuit and further reduce the hardware cost of the transceiver.
  • the common-mode detection module and differential-mode detection module of the transmitting circuit can be arranged inside the transceiver, and the voltage-controlled current source can be embedded in the drive module, which does not occupy the space of the plate connected to the transceiver, and can reduce the area of the plate.
  • the sending circuit in the embodiment of the present application can also be applied to communication protocols based on low-voltage differential signaling (LVDS) physical layer transmission characteristics, such as mobile industry processor interface (mobile industry processor interface, MIPI) and the like.
  • LVDS low-voltage differential signaling

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Abstract

La présente demande porte sur un circuit d'envoi d'un émetteur-récepteur de réseau de zone de commande (CAN) et d'un émetteur-récepteur CAN. Le circuit d'envoi comprend un module d'échantillonnage, un module de détection de mode commun, un module de détection de mode différentiel et un module d'entraînement. Le module de détection de mode commun génère, selon un signal échantillonné et obtenu par le module d'échantillonnage, un premier signal de courant ou un second signal de courant ; le module de détection de mode différentiel génère un premier signal de tension en fonction du signal échantillonné et obtenu par le module d'échantillonnage ; le module de pilotage génère deux signaux de tension différentielle, réduit l'interférence de mode commun dans les signaux de tension différentielle au moyen du premier signal de courant ou du second signal de courant, et réduit l'interférence de mode différentiel dans les signaux de tension différentielle au moyen du premier signal de tension. Selon le circuit d'envoi des modes de réalisation de la présente invention, le brouillage en mode commun et l'interférence en mode différentiel peuvent être efficacement supprimés, un signal différentiel ayant une précision relativement élevée peut être délivré, et lorsque le circuit d'envoi est appliqué à un émetteur-récepteur CAN, la capacité anti-interférence de l'émetteur-récepteur peut être améliorée tout en régulant les coûts.
PCT/CN2021/095794 2021-05-25 2021-05-25 Circuit d'envoi d'émetteur-récepteur de réseau de zone de commande (can) et émetteur-récepteur de can WO2022246645A1 (fr)

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CN202180088442.4A CN116783830A (zh) 2021-05-25 2021-05-25 控制器局域网络can收发器的发送电路及can收发器
PCT/CN2021/095794 WO2022246645A1 (fr) 2021-05-25 2021-05-25 Circuit d'envoi d'émetteur-récepteur de réseau de zone de commande (can) et émetteur-récepteur de can

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CN105244841A (zh) * 2015-11-12 2016-01-13 杭州电子科技大学 一种基于can的电气火灾监控装置
CN109779765A (zh) * 2018-12-15 2019-05-21 华南理工大学 一种模块化电子节气门可靠驱动器
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