JP6652156B2 - Transmission device - Google Patents

Description

  The present disclosure relates to a transmission device that transmits a signal.

  2. Description of the Related Art In recent years, various devices such as semiconductor chips, sensors, and display devices are mounted on electronic devices as electronic devices become more sophisticated and multifunctional. A large amount of data is exchanged between these devices, and the amount of data is increasing as electronic devices become more sophisticated and multifunctional. Therefore, data is often exchanged using, for example, a high-speed interface capable of transmitting and receiving data at several Gbps.

  In order to improve communication performance in a high-speed interface, emphasis (pre-emphasis, de-emphasis) and an equalizer are often used. The pre-emphasis is to emphasize the high-frequency component of the signal before transmission (for example, Patent Document 1), and the de-emphasis is to reduce the low-frequency component of the signal before transmission. The equalizer increases the high-frequency component of a signal during reception. Thereby, in the communication system, the influence of signal attenuation due to the transmission path can be suppressed, and the communication performance can be improved.

JP 2011-142382 A

  As described above, in the communication system, improvement in communication performance is desired, and further improvement in communication performance is expected.

  The present disclosure has been made in view of such a problem, and an object of the present disclosure is to provide a transmission device capable of improving communication performance.

  A transmission device according to the present disclosure includes a transmission unit and a control unit. The transmitting unit generates three transmission signals based on a data signal indicating a sequence of transmission symbols. The control unit controls the transmission unit to adjust the voltage level of the transmission signal based on two consecutive transmission symbols in the data signal. Each transmission signal transitions between three or more voltage states.

  In the transmission device of the present disclosure, three transmission signals are generated based on the data signals. At that time, in the data signal, the voltage level of the transmission signal is adjusted based on two consecutive transmission symbols.

  According to the transmission device of the present disclosure, the voltage level of the transmission signal is adjusted based on two consecutive transmission symbols, so that communication performance can be improved. The effects described here are not necessarily limited, and any effects described in the present disclosure may be provided.

1 is a block diagram illustrating a configuration example of a communication system according to an embodiment of the present disclosure. FIG. 2 is an explanatory diagram illustrating voltage states of signals transmitted and received by the communication system illustrated in FIG. 1. FIG. 2 is a block diagram illustrating a configuration example of a transmission device according to a first embodiment. FIG. 2 is an explanatory diagram illustrating transition of symbols transmitted and received by the communication system illustrated in FIG. 1. FIG. 4 is a circuit diagram illustrating a configuration example of a transmission section illustrated in FIG. 3. FIG. 2 is a block diagram illustrating a configuration example of a receiving device according to the first embodiment. FIG. 7 is an explanatory diagram illustrating an example of a receiving operation of the receiving device illustrated in FIG. 6. 4 is a table illustrating an operation example of the signal generation unit illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating an operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 4 is a waveform chart illustrating another operation example of the transmission device illustrated in FIG. 3. FIG. 9 is a waveform diagram illustrating an operation example of a transmission device according to a comparative example. FIG. 11 is a waveform chart illustrating another operation example of the transmission device according to the comparative example. 9 is a table illustrating an operation example of a signal generation unit according to a modification of the first embodiment. FIG. 13 is a block diagram illustrating a configuration example of a transmission device according to another modification of the first embodiment. 21 is a table illustrating an operation example of the signal generation unit illustrated in FIG. 20. FIG. 13 is a block diagram illustrating a configuration example of a signal generation section according to another modification of the first embodiment. 9 is a table illustrating an operation example of a signal generation unit according to another modification of the first embodiment. FIG. 14 is a waveform chart illustrating an operation example of a transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 14 is a block diagram illustrating a configuration example of a communication system according to another modification of the first embodiment. 27 is a block diagram illustrating a configuration example of a receiving device illustrated in FIG. 26. FIG. 27 is a block diagram illustrating a configuration example of a transmission device illustrated in FIG. 26. FIG. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 13 is a waveform chart illustrating another operation example of the transmission device according to another modification of the first embodiment. FIG. 14 is a block diagram illustrating a configuration example of a transmission device according to a second embodiment. FIG. 32 is a circuit diagram illustrating a configuration example of a transmission section illustrated in FIG. 31. FIG. 14 is a block diagram illustrating a configuration example of a receiving device according to a second embodiment. 34 is a waveform chart illustrating an operation example of the receiving device illustrated in FIG. 33. 34 is a waveform chart illustrating another operation example of the receiving device illustrated in FIG. 33. 34 is a waveform chart illustrating another operation example of the receiving device illustrated in FIG. 33. 34 is a waveform chart illustrating another operation example of the receiving device illustrated in FIG. 33. 1 is a perspective view illustrating an external configuration of a smartphone to which a communication system according to an embodiment is applied. 1 is a block diagram illustrating a configuration example of an application processor to which a communication system according to an embodiment has been applied. 1 is a block diagram illustrating a configuration example of an image sensor to which a communication system according to an embodiment is applied.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order.
1. First embodiment (example using emphasis)
2. Second embodiment (example using an equalizer)
3. Application example

<1. First Embodiment>
[Configuration example]
FIG. 1 illustrates a configuration example of a communication system to which the transmission device according to the first embodiment is applied. The communication system 1 aims at improving communication quality by pre-emphasis.

  The communication system 1 includes a transmitting device 10 and a receiving device 30. In the communication system 1, the transmitting device 10 transmits signals SIGA, SIGB, and SIGC to the receiving device 30 via the transmission paths 9A, 9B, and 9C, respectively. Signals SIGA, SIGB, and SIGC transition between three voltage states SH, SM, and SL, respectively. Here, the voltage state SH is a state corresponding to the high-level voltage VH. That is, the voltage indicated by the voltage state SH includes not only the high-level voltage VH but also a voltage when pre-emphasis is performed on the high-level voltage VH, as described later. Similarly, voltage state SM is a state corresponding to middle level voltage VM, and voltage state SL is a state corresponding to low level voltage VL.

  FIG. 2 shows voltage states of the signals SIGA, SIGB, and SIGC. The transmitting device 10 transmits six symbols “+ x”, “−x”, “+ y”, “−y”, “+ z”, and “−z” using three signals SIGA, SIGB, and SIGC. For example, when transmitting the symbol “+ x”, the transmitting apparatus 10 sets the signal SIGA to the voltage state SH (for example, the high-level voltage VH), sets the signal SIGB to the voltage state SL (for example, the low-level voltage VL), and sets the signal SIGC To a voltage state SM (for example, a medium level voltage VM). When transmitting the symbol “−x”, the transmitting apparatus 10 sets the signal SIGA to the voltage state SL, sets the signal SIGB to the voltage state SH, and sets the signal SIGC to the voltage state SM. When transmitting the symbol “+ y”, the transmitting apparatus 10 sets the signal SIGA to the voltage state SM, sets the signal SIGB to the voltage state SH, and sets the signal SIGC to the voltage state SL. When transmitting the symbol “−y”, the transmitting apparatus 10 sets the signal SIGA to the voltage state SM, sets the signal SIGB to the voltage state SL, and sets the signal SIGC to the voltage state SH. When transmitting the symbol “+ z”, the transmitting device 10 sets the signal SIGA to the voltage state SL, sets the signal SIGB to the voltage state SM, and sets the signal SIGC to the voltage state SH. When transmitting the symbol “−z”, the transmitting apparatus 10 sets the signal SIGA to the voltage state SH, sets the signal SIGB to the voltage state SM, and sets the signal SIGC to the voltage state SL.

  FIG. 3 illustrates a configuration example of the transmission device 10. The transmission device 10 includes a signal generation unit 11, a register 12, flip-flops (F / F) 13 to 15, and a transmission unit 20.

  The signal generator 11 obtains a symbol NS based on the symbol CS, the signals TxF, TxR, TxP, and the clock TxCK. Here, the symbols CS and NS indicate one of the six symbols “+ x”, “−x”, “+ y”, “−y”, “+ z”, “−z”, respectively. It is. The symbol CS is a symbol currently being transmitted (current symbol), and the symbol NS is a symbol to be transmitted next (next symbol).

  FIG. 4 illustrates the operation of the signal generation unit 11. FIG. 4 shows six symbols “+ x”, “−x”, “+ y”, “−y”, “+ z”, “−z” and transitions between them.

  The signal TxF causes a symbol to transition between “+ x” and “−x”, a symbol to transition between “+ y” and “−y”, and a signal to transition between “+ z” and “−z”. The symbol is changed. Specifically, when the signal TxF is “1”, a transition is made so as to change the symbol polarity (for example, from “+ x” to “−x”), and when the signal TxF is “0”, Does not perform such a transition.

  When the signal TxF is “0”, the signals TxR and TxP are between “+ x” and “+ x”, between “+ y” and “+ y”, and “+ z” and “+ z”. The symbol transitions between. More specifically, when the signal TxR is "1" and the signal TxP is "0", the symbol is kept clockwise in FIG. 4 (for example, from "+ x" to "+ y") while maintaining the polarity of the symbol. If the signal TxR is “1” and the signal TxP is “1”, the polarity of the symbol is changed, and clockwise in FIG. 4 (for example, from “+ x” to “−y”). To "). When the signal TxR is “0” and the signal TxP is “0”, the signal transits counterclockwise in FIG. 4 (for example, from “+ x” to “+ z”) while maintaining the polarity of the symbol. When the signal TxR is “0” and the signal TxP is “1”, the polarity of the symbol is changed and the symbol is turned counterclockwise in FIG. 4 (for example, from “+ x” to “−z”). Transition.

  As described above, in the signal generation unit 11, the direction of symbol transition is specified by the signals TxF, TxR, and TxP. Therefore, the signal generation unit 11 can obtain the next symbol NS based on the current symbol CS and these signals TxF, TxR, and TxP. Then, the signal generator 11 supplies the symbol NS to the flip-flop 13 using the 3-bit signal S1 in this example.

  The signal generation unit 11 also has a function of generating signals EA, EB, and EC based on an LUT (Look Up Table) 19 supplied from the register 12. The signal EA indicates whether or not to perform pre-emphasis on the signal SIGA. The signal generation unit 11 controls the signal SIGA to perform pre-emphasis by activating the signal EA. Similarly, the signal EB indicates whether or not to perform pre-emphasis on the signal SIGB, and the signal generation unit 11 controls the signal SIGB to perform pre-emphasis on the signal SIGB by activating the signal EB. I do. The signal EC indicates whether or not to perform the pre-emphasis on the signal SIGC. The signal generation unit 11 controls the signal SIGC to perform the pre-emphasis by activating the signal EC. . The LUT 19 shows the relationship between the current symbol CS, the signals TxF, TxR, TxP, and the signals EA, EB, EC. The signal generator 11 generates signals EA, EB, and EC by referring to the LUT 19 based on the current symbol CS and the signals TxF, TxR, and TxP. In other words, the signal generation unit 11 generates the signals EA, EB, and EC according to two temporally adjacent symbols (the current symbol CS and the next symbol NS), that is, two consecutive symbols. Has become.

  With this configuration, for example, the signal generation unit 11 can selectively perform pre-emphasis on some transitions among the transitions between the voltage states SH, SM, and SL, and also generate the signals SIGA, SIGB, and Pre-emphasis can be selectively performed on some signals of the SIGC.

  The register 12 stores the LUT 19. The LUT 19 is written in the register 12 from an application processor (not shown) when the power of the transmitting apparatus 10 is turned on, for example.

  The flip-flop 13 delays the signal S1 by one clock of the clock TxCK and outputs it as a 3-bit signal S2. That is, the flip-flop 13 generates the current symbol CS by delaying the next symbol NS indicated by the signal S1 by one clock of the clock TxCK. Then, the flip-flop 13 supplies the signal S2 to the signal generator 11 and the transmitter 20.

  The flip-flop 14 delays the signals EA, EB, and EC by one clock of the clock TxCK and outputs each. The flip-flop 15 delays three output signals of the flip-flop 14 by one clock of the clock TxCK and outputs the signals as signals EA2, EB2, and EC2, respectively. Then, the flip-flop 15 supplies the signals EA2, EB2, EC2 to the transmitting unit 20.

  The transmission unit 20 generates signals SIGA, SIGB, and SIGC based on the signal S2 and the signals EA2, EB2, and EC2.

  FIG. 5 illustrates a configuration example of the transmission unit 20. The transmission unit 20 includes an output control unit 21, output units 22A, 22B, 22C, an emphasis control unit 23, and output units 24A, 24B, 24C.

  The output control unit 21 supplies a control signal to the output units 22A, 22B, 22C based on the signal S2, and controls the operation of the output units 22A, 22B, 22C.

  The output unit 22A sets the voltage state of the signal SIGA to one of the voltage states SH, SM, and SL based on the control signal supplied from the output control unit 21. The output unit 22B sets the voltage state of the signal SIGB to one of the voltage states SH, SM, and SL based on the control signal supplied from the output control unit 21. The output unit 22C sets the voltage state of the signal SIGC to one of the voltage states SH, SM, and SL based on the control signal supplied from the output control unit 21.

  With this configuration, transmitting section 20 sets signals SIGA, SIGB, and SIGC to voltage states SH, SM, and SL corresponding to symbol CS, as shown in FIG. 2, based on symbol CS indicated by signal S2. You can do it.

  Hereinafter, the output unit 22A of the transmission unit 20 will be described in more detail. The same applies to the output units 22B and 22C.

  The output unit 22A has transistors 25 and 26 and resistance elements 27 and 28. In this example, the transistors 25 and 26 are N-channel MOS (Metal Oxide Semiconductor) type FETs (Field Effect Transistors). The control signal is supplied from the output control unit 21 to the gate of the transistor 25, the voltage V 1 is supplied to the drain, and the source is connected to one end of the resistance element 27. A control signal is supplied from the output control unit 21 to the gate of the transistor 26, the drain is connected to one end of the resistance element 28, and the source is grounded. The resistance elements 27 and 28 function as termination resistors in the communication system 1. One end of the resistance element 27 is connected to the source of the transistor 25, and the other end is connected to the other end of the resistance element 28 and to the output terminal ToutA. One end of the resistance element 28 is connected to the drain of the transistor 26, and the other end is connected to the other end of the resistance element 27 and to the output terminal ToutA.

  For example, when setting the signal SIGA to the voltage state SH, the output control unit 21 supplies a high-level control signal to the transistor 25 and supplies a low-level control signal to the transistor 26. Accordingly, transistor 25 is turned on and transistor 26 is turned off, an output current flows through transistor 25, and signal SIGA is set to voltage state SH. For example, when setting the signal SIGA to the voltage state SL, the output control unit 21 supplies a low-level control signal to the transistor 25 and supplies a high-level control signal to the transistor 26. As a result, the transistor 25 is turned off and the transistor 26 is turned on, an output current flows through the transistor 26, and the signal SIGA is set to the voltage state SL. For example, when setting the signal SIGA to the voltage state SM, the output control unit 21 supplies a low-level control signal to the transistors 25 and 26. As a result, the transistors 25 and 26 are turned off, and the signal SIGA is set to the voltage state SM by the resistance elements 31A, 31B and 31C (described later) of the receiving device 30.

  The emphasis control unit 23 controls the operation of the output units 24A, 24B, 24C based on the signal S2 and the signals EA2, EB2, EC2. Specifically, the emphasis control unit 23 supplies a control signal to the output unit 24A based on the signal S2 and the signal EA2, and supplies a control signal to the output unit 24B based on the signal S2 and the signal EB2. The control signal is supplied to the output unit 24C based on the signal S2 and the signal EC2.

  The output unit 24A performs pre-emphasis on the signal SIGA based on the control signal supplied from the emphasis control unit 23. The output unit 24B performs pre-emphasis on the signal SIGB based on the control signal supplied from the emphasis control unit 23. The output unit 24C performs pre-emphasis on the signal SIGC based on the control signal supplied from the emphasis control unit 23. The configurations of the output units 24A, 24B, 24C are the same as those of the output units 22A, 22B, 22C.

  With this configuration, the transmitting unit 20 performs pre-emphasis on the signal SIGA when the signal EA2 is active, performs pre-emphasis on the signal SIGB when the signal EB2 is active, and outputs the signal EC2. When active, pre-emphasis is performed on the signal SIGC.

  The transmitting unit 20 is not limited to this configuration, and various other configurations can be applied.

  FIG. 6 illustrates a configuration example of the receiving device 30. The receiving device 30 includes resistance elements 31A, 31B, 31C, amplifiers 32A, 32B, 32C, a clock generator 33, flip-flops (F / F) 34, 35, and a signal generator 36. .

  The resistance elements 31A, 31B, and 31C function as termination resistors in the communication system 1. One end of the resistance element 31A is connected to the input terminal TinA and the signal SIGA is supplied, and the other end is connected to the other ends of the resistance elements 31B and 31C. One end of the resistance element 31B is connected to the input terminal TinB and supplied with the signal SIGB, and the other end is connected to the other ends of the resistance elements 31A and 31C. One end of the resistance element 31C is connected to the input terminal TinC and supplied with the signal SIGC, and the other end is connected to the other ends of the resistance elements 31A and 31B.

  Each of the amplifiers 32A, 32B, and 32C outputs a signal corresponding to a difference between a signal at the positive input terminal and a signal at the negative input terminal. The positive input terminal of the amplifier 32A is connected to the negative input terminal of the amplifier 32C and one end of the resistance element 31A, and is supplied with the signal SIGA. The negative input terminal is connected to the positive input terminal of the amplifier 32B and one end of the resistance element 31B. And the signal SIGB is supplied. The positive input terminal of the amplifier 32B is connected to the negative input terminal of the amplifier 32A and one end of the resistance element 31B, and is supplied with the signal SIGB. The negative input terminal is connected to the positive input terminal of the amplifier 32C and one end of the resistance element 31C. And the signal SIGC is supplied. The positive input terminal of the amplifier 32C is connected to the negative input terminal of the amplifier 32B and one end of the resistance element 31C, and is supplied with the signal SIGC. The negative input terminal is connected to the positive input terminal of the amplifier 32A and one end of the resistance element 31A. And a signal SIGA is supplied.

  With this configuration, the amplifier 32A outputs a signal corresponding to the difference AB (SIGA-SIGB) between the signal SIGA and the signal SIGB, and the amplifier 32B responds to the difference BC (SIGB-SIGC) between the signal SIGB and the signal SIGC. The amplifier 32C outputs a signal corresponding to a difference CA (SIGC-SIGA) between the signal SIGC and the signal SIGA.

  FIG. 7 illustrates an operation example of the amplifiers 32A, 32B, and 32C. In this example, signal SIGA is at high level voltage VH, signal SIGB is at low level voltage VL, and signal SIGC is at medium level voltage VM. In this case, the current Iin flows in the order of the input terminal TinA, the resistance element 31A, the resistance element 31B, and the input terminal TinB. The high level voltage VH is supplied to the positive input terminal of the amplifier 32A and the low level voltage VL is supplied to the negative input terminal, and the difference AB becomes positive (AB> 0). Is output. Further, the low level voltage VL is supplied to the positive input terminal of the amplifier 32B and the middle level voltage VM is supplied to the negative input terminal, and the difference BC becomes negative (BC <0). Is output. Further, the medium level voltage VM is supplied to the positive input terminal of the amplifier 32C and the high level voltage VH is supplied to the negative input terminal, and the difference CA becomes negative (CA <0). "Is output.

  The clock generator 33 generates a clock RxCK based on output signals of the amplifiers 32A, 32B, and 32C.

  The flip-flop 34 delays the output signals of the amplifiers 32A, 32B, and 32C by one clock of the clock RxCK and outputs each. That is, the output signal of the flip-flop 34 indicates the current symbol CS2. Here, like the symbols CS and NS, the current symbol CS2 is any one of the six symbols “+ x”, “−x”, “+ y”, “−y”, “+ z”, and “−z”. Or one of them.

  The flip-flop 35 delays the three output signals of the flip-flop 34 by one clock of the clock RxCK, and outputs each of them. That is, the flip-flop 35 generates the symbol PS2 by delaying the current symbol CS2 by one clock of the clock RxCK. This symbol PS2 is a previously received symbol (previous symbol), and like the symbols CS, NS, CS2, six symbols “+ x”, “−x”, “+ y”, “−y”, “ + Z "or" -z ".

  The signal generator 36 generates signals RxF, RxR, and RxP based on the output signals of the flip-flops 34 and 35 and the clock RxCK. The signals RxF, RxR, and RxP correspond to the signals TxF, TxR, and TxP in the transmitting device 10, respectively, and represent symbol transitions. The signal generation unit 36 specifies a symbol transition (FIG. 4) based on the current symbol CS2 indicated by the output signal of the flip-flop 34 and the previous symbol PS2 indicated by the output signal of the flip-flop 35, and specifies the signal RxF, RxR and RxP are generated.

  Here, the signals S1 and S2 correspond to a specific example of “data signal” in the present disclosure. Signals SIGA, SIGB, and SIGC correspond to a specific example of “three transmission signals” in the present disclosure. The signal generation unit 11 corresponds to a specific example of “control unit” in the present disclosure.

[Operation and Action]
Subsequently, an operation and an operation of the communication system 1 according to the present embodiment will be described.

(Overview of overall operation)
First, an overall operation outline of the communication system 1 will be described with reference to FIG. In transmitting apparatus 10, signal generation section 11 finds the next symbol NS based on current symbol CS and signals TxF, TxR, TxP, and outputs it as signal S1. Further, the signal generator 11 generates and outputs signals EA, EB, and EC with reference to the LUT 19 based on the current symbol CS and the signals TxF, TxR, and TxP. The flip-flop 13 delays the signal S1 by one clock of the clock TxCK and outputs it as a signal S2. The flip-flop 14 delays the signals EA, EB, and EC by one clock of the clock TxCK and outputs each. The flip-flop 15 delays the three output signals of the flip-flop 14 by one clock of the clock TxCK and outputs them as signals EA2, EB2, and EC2, respectively. The transmitting unit 20 generates signals SIGA, SIGB, and SIGC based on the signal S2 and the signals EA2, EB2, and EC2.

  In the receiving device 30, the amplifier 32A outputs a signal corresponding to the difference AB between the signal SIGA and the signal SIGB, the amplifier 32B outputs a signal corresponding to the difference BC between the signal SIGB and the signal SIGC, and the amplifier 32C , And outputs a signal corresponding to the difference CA between the signal SIGC and the signal SIGA. The clock generator 33 generates a clock RxCK based on the output signals of the amplifiers 32A, 32B, 32C. The flip-flop 34 delays the output signals of the amplifiers 32A, 32B, 32C by one clock RxCK, and outputs each. The flip-flop 35 delays the three output signals of the flip-flop 34 by one clock of the clock RxCK and outputs each. The signal generator 36 generates signals RxF, RxR, and RxP based on the output signals of the flip-flops 34 and 35 and the clock RxCK.

(Detailed operation)
The signal generator 11 determines the next symbol NS based on the current symbol CS and the signals TxF, TxR, and TxP, and refers to the LUT 19 to determine whether to perform pre-emphasis on the signals SIGA, SIGB, and SIGC. EA, EB, and EC shown in FIG.

  FIG. 8 illustrates an example of the LUT 19, and illustrates a relationship among the current symbol CS, the signals TxF, TxR, TxP, and the signals EA, EB, and EC. Note that FIG. 8 also shows the next symbol NS for convenience of description.

  The signal generator 11 generates signals EA, EB, and EC by referring to the LUT 19 based on the current symbol CS and the signals TxF, TxR, and TxP. Then, the flip-flops 14 and 15 delay the signals EA, EB and EC to generate the signals EA2, EB2 and EC2. , SIGC are pre-emphasized. Hereinafter, a case where the current symbol CS is “+ x” and a case where the current symbol CS is “−x” will be described in detail.

  9A to 9E and 10A to 10E show an operation when a symbol changes from “+ x” to other than “+ x”, and FIGS. 9A to 9E show waveforms of signals SIGA, SIGB, and SIGC. 10A to 10E show waveforms of the differences AB, BC, and CA. 9A and 10A show a transition from “+ x” to “−x”, FIGS. 9B and 10B show a transition from “+ x” to “+ y”, and FIGS. 9C and 10C show a transition from “+ x” to “−y”. 9D and 10D show a transition from “+ x” to “+ z”, and FIGS. 9E and 10E show a transition from “+ x” to “−z”. 9A to 9E and 10A to 10E, a thin line indicates a case where pre-emphasis is not performed, and a thick line indicates a case where pre-emphasis is performed. In this example, the lengths of the transmission lines 9A to 9C are sufficiently short.

  When the symbol transits from “+ x” to “−x”, the signal generation unit 11 changes the signals EA, EB, and EC to “1”, “1”, and “0” as shown in FIG. I do. As a result, the transmission unit 20 performs pre-emphasis on the signal SIGA as shown in FIG. 9A, transitions from the high-level voltage VH to a voltage lower than the low-level voltage VL, and also transmits the signal SIGB. Pre-emphasis is performed to make a transition from the low level voltage VL to a voltage higher than the high level voltage VH. At this time, the transmission unit 20 does not perform the pre-emphasis on the signal SIGC, and maintains the intermediate level voltage VM. As a result, as shown in FIG. 10A, the difference AB makes a quicker transition from a positive voltage to a negative voltage as compared with the case where pre-emphasis is not performed, and the differences BC and CA correspond to the case where pre-emphasis is not performed. The transition from negative to positive is faster than.

  When the symbol transits from “+ x” to “+ y”, the signal generator 11 changes the signals EA, EB, and EC to “0”, “1”, and “1”, as shown in FIG. . Thus, as shown in FIG. 9B, the transmission unit 20 performs pre-emphasis on the signal SIGB, transitions from the low level voltage VL to a voltage higher than the high level voltage VH, and The pre-emphasis is performed to make a transition from the medium level voltage VM to a voltage lower than the low level voltage VL. At this time, the transmission unit 20 does not perform pre-emphasis on the signal SIGA, and makes a transition from the high-level voltage VH to the middle-level voltage VM. That is, the signal SIGA transitions from the voltage state SH to the voltage state SM, but the transmitting unit 20 does not perform pre-emphasis on the signal SIGA. As a result, as shown in FIG. 10B, the difference AB makes a quicker transition from positive to negative as compared to the case without pre-emphasis, and the difference BC becomes more negative than with no pre-emphasis. Transition faster than positive. The difference CA maintains a negative state.

  When the symbol transits from “+ x” to “−y”, the signal generation unit 11 changes the signals EA, EB, and EC to “0”, “1”, and “1” as shown in FIG. I do. As a result, the transmission unit 20 performs pre-emphasis on the signal SIGB, as shown in FIG. 9C, transitions from the low-level voltage VL to a voltage lower than the low-level voltage VL, and The pre-emphasis is performed to make a transition from the middle level voltage VM to a voltage higher than the high level voltage VH. That is, signal SIGB maintains voltage state SL, but transmitting section 20 performs pre-emphasis on signal SIGB. At this time, the transmission unit 20 does not perform pre-emphasis on the signal SIGA, and makes a transition from the high-level voltage VH to the middle-level voltage VM. That is, the signal SIGA transitions from the voltage state SH to the voltage state SM, but the transmitting unit 20 does not perform pre-emphasis on the signal SIGA. As a result, as shown in FIG. 10C, the difference CA changes earlier from negative pressure to positive pressure as compared to the case where pre-emphasis is not performed. Further, the difference AB maintains a positive state, and the difference BC maintains a negative state.

  When the symbol transitions from “+ x” to “+ z”, the signal generation unit 11 changes the signals EA, EB, and EC to “1”, “0”, and “1” as shown in FIG. . As a result, the transmission unit 20 performs pre-emphasis on the signal SIGA as shown in FIG. 9D, transitions from the high-level voltage VH to a voltage lower than the low-level voltage VL, and also transmits the signal SIGC. The pre-emphasis is performed to make a transition from the middle level voltage VM to a voltage higher than the high level voltage VH. At this time, the transmission unit 20 does not perform pre-emphasis on the signal SIGB, and makes a transition from the low level voltage VL to the middle level voltage VM. That is, signal SIGB changes from voltage state SL to voltage state SM, but transmitting section 20 does not perform pre-emphasis on signal SIGB. As a result, as shown in FIG. 10D, the difference AB changes from positive to negative earlier than in the case without pre-emphasis, and the difference CA changes from negative to negative in comparison with the case without pre-emphasis. Transition faster than positive. The difference BC maintains a negative state.

  When the symbol transitions from “+ x” to “−z”, the signal generation unit 11 changes the signals EA, EB, and EC to “1”, “0”, and “1” as shown in FIG. I do. As a result, the transmission unit 20 performs pre-emphasis on the signal SIGA as shown in FIG. 9E, transitions from the high-level voltage VH to a voltage higher than the high-level voltage VH, and also transmits the signal SIGC. The pre-emphasis is performed to make a transition from the medium level voltage VM to a voltage lower than the low level voltage VL. That is, the signal SIGA maintains the voltage state SH, but the transmission unit 20 performs pre-emphasis on the signal SIGA. At this time, the transmission unit 20 does not perform pre-emphasis on the signal SIGB, and makes a transition from the low level voltage VL to the middle level voltage VM. That is, signal SIGB changes from voltage state SL to voltage state SM, but transmitting section 20 does not perform pre-emphasis on signal SIGB. As a result, as shown in FIG. 10E, the difference BC changes earlier from negative to positive as compared to the case where pre-emphasis is not performed. Further, the difference AB maintains a positive state, and the difference CA maintains a negative state.

  11A to 11E and 12A to 12E show the operation when the symbol changes from "-x" to other than "-x", and FIGS. 11A to 11E show the waveforms of the signals SIGA, SIGB, and SIGC. 12A to 12E show waveforms of the differences AB, BC, and CA. 11A and 12A show the transition from “−x” to “+ x”, FIGS. 11B and 12B show the transition from “−x” to “+ y”, and FIGS. 11C and 12C show the transition from “−x” to “−x”. 11D and 12D show a transition from “−x” to “+ z”, and FIGS. 11E and 12E show a transition from “−x” to “−z”.

  When the symbol transits from “−x” to “+ x”, the signal generator 11 changes the signals EA, EB, EC to “1”, “1”, “0” as shown in FIG. I do. As a result, the transmission unit 20 performs pre-emphasis on the signal SIGA as shown in FIG. 11A, transitions from the low-level voltage VL to a voltage higher than the high-level voltage VH, and also transmits the signal SIGB. Pre-emphasis is performed to make a transition from the high level voltage VH to a voltage lower than the low level voltage VL. At this time, the transmission unit 20 does not perform the pre-emphasis on the signal SIGC, and maintains the intermediate level voltage VM. As a result, as shown in FIG. 12A, the difference AB transitions from negative to positive earlier than when no pre-emphasis is performed, and the differences BC and CA differ as compared with the case without pre-emphasis. Transition from positive to negative faster.

  When the symbol transits from “−x” to “+ y”, the signal generator 11 changes the signals EA, EB, EC to “0”, “1”, “1” as shown in FIG. I do. As a result, as shown in FIG. 11B, the transmission unit 20 performs pre-emphasis on the signal SIGB, transitions from the high-level voltage VH to a voltage higher than the high-level voltage VH, and also transmits the signal SIGC. The pre-emphasis is performed to make a transition from the medium level voltage VM to a voltage lower than the low level voltage VL. That is, signal SIGB maintains voltage state SH, but transmitting section 20 performs pre-emphasis on signal SIGB. At this time, the transmission unit 20 does not perform the pre-emphasis on the signal SIGA, and makes a transition from the low level voltage VL to the middle level voltage VM. That is, the signal SIGA transitions from the voltage state SL to the voltage state SM, but the transmitting unit 20 does not perform pre-emphasis on the signal SIGA. As a result, as shown in FIG. 12B, the difference CA changes from positive to negative earlier than in the case where pre-emphasis is not performed. Further, the difference BC maintains a positive state, and the difference AB maintains a negative state.

  When the symbol transits from “−x” to “−y”, the signal generator 11 changes the signals EA, EB, EC to “0”, “1”, “1” as shown in FIG. To As a result, the transmission unit 20 performs pre-emphasis on the signal SIGB, as shown in FIG. 11C, and makes a transition from the high-level voltage VH to a voltage lower than the low-level voltage VL. The pre-emphasis is performed to make a transition from the middle level voltage VM to a voltage higher than the high level voltage VH. At this time, the transmission unit 20 does not perform pre-emphasis on the signal SIGA, and makes a transition from the low level voltage VL to the middle level voltage VM. That is, the signal SIGA transitions from the voltage state SL to the voltage state SM, but the transmitting unit 20 does not perform pre-emphasis on the signal SIGA. As a result, as shown in FIG. 12C, the difference AB transitions from negative to positive earlier than when no pre-emphasis is performed, and the difference BC is more positive than when no pre-emphasis is performed. Transition faster to negative. The difference CA maintains a positive state.

  When the symbol transits from “−x” to “+ z”, the signal generation unit 11 changes the signals EA, EB, EC to “1”, “0”, “1” as shown in FIG. I do. As a result, the transmission unit 20 performs pre-emphasis on the signal SIGA as shown in FIG. 11D, transitions from the low level voltage VL to a voltage lower than the low level voltage VL, and The pre-emphasis is performed to make a transition from the middle level voltage VM to a voltage higher than the high level voltage VH. That is, signal SIGA maintains voltage state SL, but transmitter 20 performs pre-emphasis on signal SIGA. At this time, the transmission unit 20 does not perform the pre-emphasis on the signal SIGB, and makes a transition from the high-level voltage VH to the middle-level voltage VM. That is, signal SIGB transitions from voltage state SH to voltage state SM, but transmitter 20 does not perform pre-emphasis on signal SIGB. As a result, as shown in FIG. 12D, the difference BC changes from positive to negative earlier than in the case where pre-emphasis is not performed. Further, the difference AB maintains a negative state, and the difference CA maintains a positive state.

  When the symbol transitions from “−x” to “−z”, the signal generation unit 11 changes the signals EA, EB, EC to “1”, “0”, “1” as shown in FIG. To As a result, as shown in FIG. 11E, the transmission unit 20 performs pre-emphasis on the signal SIGA, transitions from the low-level voltage VL to a voltage higher than the high-level voltage VH, and also transmits the signal SIGC. The pre-emphasis is performed to make a transition from the medium level voltage VM to a voltage lower than the low level voltage VL. At this time, the transmission unit 20 does not perform the pre-emphasis on the signal SIGB, and makes a transition from the high-level voltage VH to the middle-level voltage VM. That is, signal SIGB transitions from voltage state SH to voltage state SM, but transmitter 20 does not perform pre-emphasis on signal SIGB. As a result, as shown in FIG. 12E, the difference AB transitions from negative to positive earlier than when no pre-emphasis is performed, and the difference CA is more positive than when no pre-emphasis is performed. Transition faster to negative. The difference BC maintains a positive state.

  As described above, the transmission device 10 performs pre-emphasis on the signal that transitions from the voltage state SL, SM to the voltage state SH among the signals SIGA to SIGC, and transitions from the voltage state SH, SM to the voltage state SL. Perform pre-emphasis on the signal. Further, transmitting apparatus 10 also performs pre-emphasis on signals that maintain voltage states SL and SH among signals SIGA to SIGC. On the other hand, the transmission device 10 does not perform pre-emphasis on the signals that transition from the voltage states SL and SH to the voltage state SM among the signals SIGA to SIGC, and also performs the signal maintenance on the signals that maintain the voltage state SM. Do not perform pre-emphasis.

  The amplifiers 32A to 32C generate and output signals according to whether the differences AB, BC, and CA are positive or negative. Therefore, in the communication system 1, as shown in FIGS. 10A to 10E and FIGS. 12A to 12E, the jitter TJ is defined by the shift width of the timing at which the differences AB, BC, and CA cross “0”. In the communication system 1, since the pre-emphasis is performed on the signals SIGA to SIGC, the signal transition becomes steep, so that the jitter TJ can be reduced. In particular, when the symbol “+ x” transitions to “+ y” (FIG. 10B) or the symbol “+ x” transitions to “+ z” (FIG. 10D), two of the differences AB, BC, and CA are “ In the case of straddling 0 ", the jitter TJ can be effectively improved.

  Next, some of the symbol transitions will be described in more detail with examples.

  First, a case where a symbol transitions from “+ x” to “+ y” will be described. In this case, as shown in FIG. 9B, signal SIGA changes from voltage state SH (for example, high-level voltage VH) to voltage state SM (for example, medium-level voltage VM), and signal SIGB changes to voltage state SL (for example, low level). Level signal VL) to the voltage state SH, and the signal SIGC changes from the voltage state SM to the voltage state SL. In this case, as shown in FIG. 10B, for example, the transition time of the difference AB becomes longer. The first cause is that the signal SIGA transitions to the middle level voltage VM. That is, when the signal SIGA is set to the medium level voltage VM, the output unit 22A of the transmission unit 20 turns off both the transistors 25 and 26. That is, the signal SIGA is set to the voltage state SM by the resistance elements 31A to 31C of the reception device 30. As a result, the transition time of the signal SIGA becomes longer, and the transition time of the difference AB also becomes longer. The second cause is that the voltage change amount of the difference AB is large.

  Such a case also occurs, for example, when the symbol transitions from “+ x” to “+ z” (FIGS. 9D and 10D). In this case, as shown in FIG. 9D, signal SIGA changes from voltage state SH (for example, high level voltage VH) to voltage state SL (for example, low level voltage VL), and signal SIGB changes from voltage state SL to voltage state SL. The signal SIGC changes from the voltage state SM to the voltage state SH. In addition, this also occurs when the symbol transitions from “−x” to “−y” (FIGS. 11C and 12C), or when the symbol transitions from “−x” to “−z” (FIGS. 11E and 12E).

  FIGS. 13 and 14 show the operation when the symbol transitions from "+ x" to "+ y". FIGS. 13A to 13C show the waveforms of the signals SIGA, SIGB, and SIGC, respectively. 14A to 14C show waveforms of the differences AB, BC, and CA, respectively. FIG. 13 corresponds to FIG. 9B, and FIG. 14 corresponds to FIG. 10B. FIG. 14 also shows an eye mask EM indicating the reference of the eye opening.

  When the symbol transitions from “+ x” to “+ y”, the transmission unit 20 emphasizes the transition of the signal SIGB by the voltage ΔV and the transition of the signal SIGC by the voltage ΔV, as shown in FIG. At this time, the difference AB becomes a waveform W1 in FIG. 14, and the difference BC becomes a waveform W3 in FIG. As described above, in the communication system 1, the pre-emphasis is performed, and the transition of the waveform is sharpened, so that the eye can be widened. If pre-emphasis is not performed on the signals SIGA to SIGC, for example, the difference AB becomes a waveform W2 in FIG. 14, and the difference BC becomes a waveform W4 in FIG. That is, in such a case, since the transition of the waveform becomes dull and the amplitude of the difference becomes small, the eye may be narrowed. On the other hand, in the communication system 1, pre-emphasis is performed on the signals SIGA to SIGC, so that the eyes can be widened and the communication quality can be improved.

  Next, a case where a symbol transits from “+ x” to “−z” will be described.

  FIGS. 15 and 16 show the operation when the symbol transitions from “+ x” to “−z”. FIGS. 15A to 15C show the waveforms of the signals SIGA, SIGB, and SIGC, respectively. 16A to 16C show waveforms of the differences AB, BC, and CA, respectively. FIG. 15 corresponds to FIG. 9E, and FIG. 16 corresponds to FIG. 10E.

  When the symbol transitions from “+ x” to “−z”, the transmission unit 20 sets the voltage of the signal SIGA to a voltage higher by the voltage ΔV and changes the transition of the signal SIGC to the voltage ΔV as shown in FIG. Just emphasize. In other words, transmitting section 20 performs pre-emphasis on signal SIGA despite signal SIGA maintaining voltage state SH, and transmits signal SIGB despite transition from voltage state SL to voltage state SM. , And does not perform pre-emphasis on the signal SIGB. In other words, the transmission device 10 selects the signals SIGA and SIGC and performs pre-emphasis on them. At this time, the difference AB becomes a waveform W11 in FIG. 16, and the difference BC becomes a waveform W13 in FIG. As described above, in the communication system 1, the pre-emphasis is performed, and the transition of the waveform is sharpened, so that the eye can be widened. If pre-emphasis is not performed on the signals SIGA to SIGC, for example, the difference AB becomes a waveform W12 in FIG. 16 and the difference BC becomes a waveform W14 in FIG. That is, in such a case, since the transition of the waveform becomes dull and the amplitude of the difference becomes small, the eye may be narrowed. On the other hand, in the communication system 1, pre-emphasis is performed on the signals SIGA to SIGC, so that the eyes can be widened and the communication quality can be improved.

[Comparative example]
Here, as a comparative example, a case where pre-emphasis is performed on a signal whose voltage state changes among signals SIGA to SIGC, and pre-emphasis is not performed on a signal whose voltage state does not change will be considered.

  17 and 18 show the operation when the symbol transitions from "+ x" to "-z". FIGS. 17A to 17C show the waveforms of the signals SIGA, SIGB, and SIGC, respectively. 18 (A) to 18 (C) show waveforms of the differences AB, BC and CA, respectively.

  When the symbol transitions from “+ x” to “−z”, the transmission device 10R according to the comparative example emphasizes the transition of the signal SIGB by the voltage ΔV and changes the transition of the signal SIGC by the voltage as shown in FIG. Emphasize by ΔV. That is, pre-emphasis is performed on the signals SIGB and SIGC whose voltage state changes, and no pre-emphasis is performed on the signal SIGA whose voltage state does not change. At this time, the difference AB becomes as shown in FIG. 18A, and the eye may be narrowed.

  On the other hand, in the communication system 1, a signal for performing pre-emphasis is selected from the signals SIGA to SIGC. Specifically, as shown in FIG. 15, transmitting apparatus 10 according to the present embodiment sets the voltage of signal SIGA to a voltage higher by voltage ΔV and emphasizes the transition of signal SIGC by voltage ΔV. That is, transmitting apparatus 10 performs pre-emphasis on signal SIGA despite signal SIGA maintaining voltage state SH, and also transmits signal SIGB from voltage state SL to voltage state SM. , The signal SIGB is not pre-emphasized. Thereby, in the communication system 1, the possibility that the eye becomes narrow can be reduced, and the communication quality can be improved.

  As described above, in the communication system 1, the pre-emphasis is selectively performed on the signals SIGA to SIGC. For example, when the transition is a large jitter, the pre-emphasis is performed. If the transition is such that becomes narrower, pre-emphasis can not be performed. Thereby, in the communication system 1, communication quality can be improved.

[effect]
As described above, in the present embodiment, pre-emphasis is selectively performed on signals SIGA to SIGC, so that communication quality can be improved.

[Modification 1-1]
In the above embodiment, as shown in FIG. 8, at every transition between the six symbols, pre-emphasis is performed on at least one of the signals SIGA, SIGB, and SIGC. It is not something to be done. Alternatively, for example, pre-emphasis may be performed only for a part of transitions between six symbols. Hereinafter, the communication system 1A according to the present modification will be described in detail.

  FIG. 19 illustrates an example of the LUT 19A according to the present modification. The signal generator 11A according to the present modification generates signals EA, EB, and EC based on the LUT 19A. For example, the signal generation unit 11 </ b> A converts the symbol from “+ x” to “−x”, the symbol from “+ x” to “−y”, and the symbol from “+ x” to “−z”. When making a transition, all of the signals EA, EB, and EC are set to “0”. That is, in these cases, the transmission unit 20 does not perform pre-emphasis on any of the signals SIGA, SIGB, and SIGC. For example, when the symbol transits from “+ x” to “−z”, if pre-emphasis is performed as shown in FIGS. 17 and 18, for example, the eye becomes narrow. Does not perform pre-emphasis. On the other hand, for example, when the symbol transitions from “+ x” to “+ y”, the signal generation unit 11A sets the signals EA, EB, EC to “0”, “1”, “1”, and sets the symbol to “ When transitioning from “+ x” to “+ z”, the signals EA, EB, and EC are set to “1”, “0”, and “1”. That is, in these cases, as shown in FIGS. 10B and 10D, the transition time of the difference AB becomes longer, so that the transmission unit 20 performs pre-emphasis. There are two types of cases where pre-emphasis is performed in this way. That is, one of the signals SIGA, SIGB, and SIGC is such that the first signal transits from the voltage state SH (for example, the high-level voltage VH) to the voltage state SM (for example, the medium-level voltage VM), and the second signal Transitions from the voltage state SL (for example, the low-level voltage VL) to the voltage state SH, and the third signal transitions from the voltage state SM to the voltage state SL. The other is that, of the signals SIGA, SIGB, and SIGC, the first signal changes from the voltage state SL to the voltage state SM, and the second signal changes from the voltage state SH to the voltage state SL. This is the case where the signal No. 3 changes from the voltage state SM to the voltage state SH. In other words, this is a case where any of the voltage state of the signal SIGA, the voltage state of the signal SIGB, and the voltage state of the signal SIGC change. As described above, in the communication system 1A, the pre-emphasis is performed only when one of the transition times of the differences AB, BC, and CA becomes long, and the pre-emphasis is not performed in other cases. Even with such a configuration, the same effects as those of the communication system 1 according to the above-described embodiment can be obtained.

  Note that, among the transitions between the six symbols, the transition for performing the pre-emphasis is not limited to the example of FIG. 19, and it is possible to arbitrarily set which transition to perform the pre-emphasis.

[Modification 1-2]
In the above embodiment, the signal generation unit 11 generates the three signals EA, EB, and EC and independently controls the pre-emphasis for the signals SIGA to SIGC, but is not limited to this. Absent. Hereinafter, the transmitting device 10B according to the present modification will be described in detail.

  FIG. 20 illustrates a configuration example of the transmission device 10B. The transmission device 10B includes a signal generation unit 11B, flip-flops 14B and 15B, and a transmission unit 20B. The signal generation unit 11B obtains the next symbol NS based on the current symbol CS and the signals TxF, TxR, and TxP, and generates the signal EE by referring to the LUT 19B. The flip-flop 14B delays the signal EE by one clock of the clock TxCK and outputs it. The flip-flop 15B delays the output signal of the flip-flop 14 by one clock of the clock TxCK and outputs it as a signal EE2. The transmission unit 20B generates signals SIGA, SIGB, and SIGC based on the signal S2 and the signal EE2. At this time, when the signal EE2 is active, the transmission unit 20B performs pre-emphasis on the signals SIGA, SIGB, and SIGC. With this configuration, in the transmission device 10B, the signal generation unit 11B collectively controls the pre-emphasis for the signals SIGA to SIGC.

  FIG. 21 illustrates an example of the LUT 19B according to the present modification. The signal generation unit 11B, for example, when the symbol transitions from “+ x” to “−x”, when the symbol transitions from “+ x” to “−y”, and when the symbol transitions from “+ x” to “−z” When making a transition, the signal EE is set to “0”. That is, in these cases, the transmitting unit 20B does not perform pre-emphasis on the signals SIGA, SIGB, and SIGC. On the other hand, the signal generation unit 11B sets the signal EE to “1” when, for example, the symbol changes from “+ x” to “+ y” and when the symbol changes from “+ x” to “+ z”. That is, in these cases, as in the case of the above-described modified example 1-1, the transition time of the difference AB becomes long, so that the transmission unit 20B performs pre-emphasis on the signals SIGA, SIGB, and SIGC. As described above, the transmitting device 10B operates so as to perform the pre-emphasis only when one of the transition times of the differences AB, BC, and CA becomes longer, and not to perform the pre-emphasis in other cases. Even with such a configuration, the same effects as those of the communication system 1 according to the above-described embodiment can be obtained.

  Note that, among the transitions between the six symbols, the transition for performing the pre-emphasis is not limited to the example of FIG. 21, and it is possible to arbitrarily set which transition to perform the pre-emphasis. For example, pre-emphasis may be performed only when any two of the differences AB, BC, and CA transit across “0”. Also, for example, pre-emphasis may be performed only when all of the differences AB, BC, and CA transit across “0”.

[Modification 1-3]
The operation of the signal generation unit 11 to generate the signals EA, EB, and EC with reference to the LUT 19 may be realized by software or hardware. Hereinafter, an example of a method realized by hardware will be described. Here, an example in which this modification is applied to the signal generation unit 11B according to Modification 1-2 will be described.

  FIG. 22 illustrates a configuration example of a portion that generates the signal EE in the signal generation section 11C according to the present modification. In this example, the signal generator 11C generates the signal EE based on the current symbol CS, the next symbol NS, and the LUT 19B. The signal generation unit 11C includes symbol determination units 100 and 110, logic circuits 120, 130, 140, 150, 160, and 170, and an OR circuit 180.

  The symbol determination unit 100 determines which of the six symbols “+ x”, “−x”, “+ y”, “−y”, “+ z”, “−z” is the current symbol CS. Is what you do. The symbol determination unit 100 includes comparison units 101 to 106. The comparing section 101 outputs “1” when the current symbol CS is the symbol “+ x”. The comparing section 102 outputs “1” when the current symbol CS is the symbol “−x”. The comparing section 103 outputs “1” when the current symbol CS is the symbol “+ y”. The comparing section 104 outputs “1” when the current symbol CS is the symbol “−y”. The comparing section 105 outputs “1” when the current symbol CS is the symbol “+ z”. The comparing section 106 outputs “1” when the current symbol CS is the symbol “−z”.

  The symbol determination unit 110 determines whether the next symbol NS is one of the six symbols “+ x”, “−x”, “+ y”, “−y”, “+ z”, “−z”. Is what you do. The symbol determination unit 110 includes comparison units 111 to 116. The comparing unit 111 outputs “1” when the next symbol NS is the symbol “+ x”. The comparing section 112 outputs “1” when the next symbol NS is the symbol “−x”. The comparing unit 113 outputs “1” when the next symbol NS is the symbol “+ y”. The comparing section 114 outputs “1” when the next symbol NS is the symbol “−y”. The comparing section 115 outputs “1” when the next symbol NS is the symbol “+ z”. The comparing section 116 outputs “1” when the next symbol NS is the symbol “−z”.

  The logic circuit 120 generates a signal based on the output signal of the comparison unit 101, the output signals of the comparison units 112 to 116, and the setting of pre-emphasis in the LUT 19B.

  The logic circuit 120 has AND circuits 121 to 125. An output signal of the comparison unit 101 is supplied to a first input terminal of the AND circuit 121, an output signal of the comparison unit 112 is supplied to a second input terminal, and a third input terminal is included in the LUT 19B. The value of the signal EE (“0” in this example) corresponding to the symbol CS = “+ x” and the symbol NS = “− x” is supplied. That is, the comparing section 101 outputs “1” when the current symbol CS is the symbol “+ x”, and the comparing section 112 outputs “1” when the next symbol NS is the symbol “−x”. Since it outputs “1”, the value of the signal EE corresponding to the symbol CS = “+ x” and the symbol NS = “− x” is supplied to the third input terminal. Similarly, the output signal of the comparison unit 101 is supplied to the first input terminal of the AND circuit 122, the output signal of the comparison unit 113 is supplied to the second input terminal, and the third input terminal is supplied to the third input terminal. The value of the signal EE (“1” in this example) corresponding to the symbol CS = “+ x” and the symbol NS = “+ y” included in the LUT 19B is supplied. The output signal of the comparison unit 101 is supplied to the first input terminal of the AND circuit 123, the output signal of the comparison unit 114 is supplied to the second input terminal, and the third input terminal is included in the LUT 19B. , The value of the signal EE (“0” in this example) corresponding to the symbol CS = “+ x” and the symbol NS = “− y”. The output signal of the comparison unit 101 is supplied to the first input terminal of the AND circuit 124, the output signal of the comparison unit 115 is supplied to the second input terminal, and the third input terminal is included in the LUT 19B. , The value of the signal EE (“1” in this example) corresponding to the symbol CS = “+ x” and the symbol NS = “+ z”. The output signal of the comparator 101 is supplied to a first input terminal of the AND circuit 125, the output signal of the comparator 116 is supplied to a second input terminal, and the LUT 19B is included in a third input terminal. Of the signal EE (“0” in this example) corresponding to the symbol CS = “+ x” and the symbol NS = “− z”.

  As a result, when the symbol CS = “+ x” and the symbol NS = “+ y” as shown in FIG. 21, the logical product circuit 122 outputs “1”, and the symbol CS = “+ x” and the symbol CS = “+ x”. When the symbol NS = “+ z”, the AND circuit 124 outputs “1”.

  Similarly, the logic circuit 130 generates a signal based on the output signal of the comparison unit 102, the output signals of the comparison units 111 and 113 to 116, and the setting of pre-emphasis in the LUT 19B. The logic circuit 140 generates a signal based on the output signal of the comparison unit 103, the output signals of the comparison units 111, 112, 114 to 116, and the setting of pre-emphasis in the LUT 19B. The logic circuit 150 generates a signal based on the output signal of the comparison unit 104, the output signals of the comparison units 111 to 113, 115, and 116, and the setting of pre-emphasis in the LUT 19B. The logic circuit 160 generates a signal based on the output signal of the comparison unit 105, the output signals of the comparison units 111 to 114 and 116, and the setting of the pre-emphasis in the LUT 19B. The logic circuit 170 generates a signal based on the output signal of the comparison unit 106, the output signals of the comparison units 111 to 116, and the setting of pre-emphasis in the LUT 19B. The logic circuits 130, 140, 150, 160, 170 have the same configuration as the logic circuit 120.

  The logical sum circuit 180 calculates the logical sum of the output signals of all the logical product circuits in the logical circuits 120, 130, 140, 150, 160, and 170.

  Even with such a configuration, the same effects as those of the communication system 1 according to the above-described embodiment can be obtained.

[Modification 1-4]
In the above embodiment, the transmitting apparatus 10 performs the pre-emphasis on the signals SIGA, SIGB, and SIGC. However, the present invention is not limited to this. For example, the transmitting apparatus 10 may perform the de-emphasis on the signals. You may. Hereinafter, the transmitting device 10D according to the present modification will be described in detail.

  FIG. 23 illustrates an example of the LUT 19D according to the present modification. The signal generation unit 11D of the transmission device 10D generates signals EA, EB, and EC by referring to the LUT 19D based on the current symbol CS and the signals TxF, TxR, and TxP. Then, the transmission unit 20D of the transmission device 10D performs de-emphasis on the signals SIGA, SIGB, and SIGC based on the signals EA2, EB2, and EC2. Hereinafter, an example in which the current symbol CS is “+ x” will be described in detail.

  FIGS. 24A to 24E and 25A to 25E show an operation when a symbol changes from “+ x” to other than “+ x”, and FIGS. 24A to 24E show waveforms of signals SIGA, SIGB, and SIGC. 25A to 25E show waveforms of the differences AB, BC, and CA. In this example, the lengths of the transmission lines 9A to 9C are sufficiently short.

  When the symbol transits from “+ x” to “−x”, the signal generation unit 11D changes the signals EA, EB, EC to “0”, “0”, “0” as shown in FIG. I do. As a result, the transmission unit 20D does not perform de-emphasis on the signals SIGA to SIGC, as illustrated in FIG. 24A. As a result, the differences AB, BC, and CA have waveforms as shown in FIG. 25A.

  When the symbol transits from "+ x" to "+ y", the signal generation unit 11D sets the signals EA, EB, EC to "0", "0", "0" as shown in FIG. . As a result, the transmission unit 20D does not perform de-emphasis on the signals SIGA to SIGC, as shown in FIG. 24B. As a result, the differences AB, BC, and CA have waveforms as shown in FIG. 25B.

  When the symbol transits from “+ x” to “−y”, the signal generation unit 11D changes the signals EA, EB, EC to “0”, “1”, “0” as shown in FIG. I do. Accordingly, as illustrated in FIG. 24C, the transmission unit 20D performs de-emphasis on the signal SIGB, and makes a transition from the low level voltage VL to a voltage higher than the low level voltage VL. At this time, the transmission unit 20D does not perform de-emphasis on the signals SIGA and SIGC. As a result, the differences AB, BC, and CA have waveforms as shown in FIG. 25C. That is, in this example, the difference CA that transits across “0” is not affected by de-emphasis.

  When the symbol transitions from "+ x" to "+ z", the signal generation unit 11D sets the signals EA, EB, and EC to "0", "0", and "0" as shown in FIG. . As a result, the transmission unit 20D does not perform de-emphasis on the signals SIGA to SIGC, as shown in FIG. 24D. As a result, the differences AB, BC, and CA have waveforms as shown in FIG. 25D.

  When the symbol transitions from “+ x” to “−z”, the signal generation unit 11D changes the signals EA, EB, EC to “1”, “0”, “0” as shown in FIG. I do. Accordingly, as illustrated in FIG. 24E, the transmission unit 20D performs de-emphasis on the signal SIGA, and makes a transition from the high-level voltage VH to a voltage lower than the high-level voltage VH. At this time, the transmission unit 20D does not perform de-emphasis on the signals SIGA and SIGB. As a result, the differences AB, BC, and CA have waveforms as shown in FIG. 25E. That is, in this example, the difference BC that transits across “0” is not affected by de-emphasis.

  As described above, the transmitting device 10D performs de-emphasis so that the one that transits across “0” among the differences AB, BC, and CA is not affected. Even with such a configuration, the same effects as those of the communication system 1 according to the above-described embodiment can be obtained.

  Note that, among the transitions between the six symbols, the transition for performing de-emphasis is not limited to the example of FIG. 23, and it is possible to arbitrarily set which transition to perform de-emphasis.

[Modification 1-5]
In the above embodiment, the signal generation unit 11 generates the signals EA, EB, and EC using the LUT 19 stored in the register 12. At this time, the LUT 19 may be configured so that the setting of the pre-emphasis can be changed. Hereinafter, the communication system 1E according to the present modification will be described in detail.

  FIG. 26 illustrates a configuration example of a communication system 1E. The communication system 1E includes a receiving device 30E and a transmitting device 10E. The communication system 1E changes the pre-emphasis setting based on the result of transmitting and receiving a predetermined pattern for calibration.

  FIG. 27 illustrates a configuration example of the receiving device 30E. The receiving device 30E has a signal generation unit 36E. The signal generator 36E has a pattern detector 37E. In the calibration mode, the pattern detection unit 37E compares the pattern of the signal received by the reception device 30E with a predetermined calibration pattern, and supplies the comparison result to the transmission device 10E as a signal DET.

  FIG. 28 illustrates a configuration example of the transmission device 10E. The transmission device 10E has an LUT generation unit 16E. The LUT generator 16E generates the LUT 19 based on the signal DET and stores the LUT 19 in the register 12.

  In the communication system 1E, in the calibration mode, the setting of the pre-emphasis is changed so that the bit error rate is reduced, for example. Specifically, first, the transmission device 10E transmits signals SIGA to SIGC having a predetermined pattern for calibration. The receiving device 30E receives the signals SIGA to SIGC, the pattern detecting unit 37E compares the received signal pattern with a predetermined calibration pattern, and notifies the transmitting device 10E of the comparison result. I do. Then, the LUT generation unit 16E of the transmission device 10E changes the pre-emphasis setting based on the comparison result. In the communication system 1E, the pre-emphasis setting is changed by such an operation so that, for example, the bit error rate decreases. Then, after the pre-emphasis setting is completed, the calibration mode is ended and normal data transmission is performed. Such calibration may be performed, for example, when the power is turned on, may be performed periodically, or may be performed when the amount of exchanged data is small.

[Modification 1-6]
In the above embodiment, the LUT 19 indicating the relationship between the current symbol CS, the signals TxF, TxR, TxP, and the signals EA, EB, EC is used. However, the present invention is not limited to this. For example, an LUT indicating the relationship between the next symbol NS, the signals TxF, TxR, TxP, and the signals EA, EB, and EC may be used. For example, the current symbol CS and the next symbol NS may be used. And a LUT indicating the relationship between the signals EA, EB, and EC.

[Modification 1-7]
In the above embodiment, pre-emphasis is performed over a period of transmitting one symbol as shown in FIG. 13 and the like. However, the present invention is not limited to this. Instead, for example, FIG. , 30, pre-emphasis may be performed only for a predetermined period after transition of signals SIGA, SIGB, and SIGC. FIGS. 29 and 30 show a case where the symbol transitions from “+ x” to “+ y”. As shown in FIG. 29, transmitting section 20 performs pre-emphasis only for a predetermined period after the transition of signals SIGA, SIGB, and SIGC. At this time, the difference AB becomes a waveform W21 in FIG. 30, and the difference BC becomes a waveform W23 in FIG. If pre-emphasis is not performed on the signals SIGA to SIGC, for example, the difference AB becomes a waveform W22 in FIG. 30, and the difference BC becomes a waveform W24 in FIG. That is, in such a case, since the transition of the waveform is slowed down, the eye may be narrowed. On the other hand, in this modification, pre-emphasis is performed only for a predetermined period after the transition of the signals SIGA, SIGB, and SIGC, so that the eye can be widened and the communication quality can be improved.

[Other Modifications]
Further, two or more of these modifications may be combined.

<2. Second Embodiment>
Next, a communication system 2 according to a second embodiment will be described. The communication system 2 aims to improve communication quality by using an equalizer. That is, in the communication system 1 according to the first embodiment, the transmitting device 10 performs the pre-emphasis on the signals SIGA to SIGC. However, in the communication system 2, the receiving device transmits the signals SIGA to SIGC. This is to perform equalization. That is, the same components as those of the communication system 1 according to the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

  As shown in FIG. 1, the communication system 2 includes a transmitting device 40 and a receiving device 60. In the communication system 2, the transmitting device 40 does not perform pre-emphasis on the signals SIGA to SIGC, and the receiving device 60 performs equalization on the signals SIGA to SIGC.

  FIG. 31 illustrates a configuration example of the transmission device 40. The transmission device 40 has a signal generation unit 41 and a transmission unit 50. The signal generation unit 41 obtains the next symbol NS based on the current symbol CS, the signals TxF, TxR, TxP, and the clock TxCK, similarly to the signal generation unit 11 according to the first embodiment, and obtains the signal S1. Is output. That is, the signal generation unit 41 does not include the function of generating the signals EA, EB, and EC from the signal generation unit 11. The transmitting unit 50 generates signals SIGA, SIGB, and SIGC based on the signal S2.

  FIG. 32 illustrates a configuration example of the transmission section 50. The transmission unit 50 has an output control unit 21 and output units 22A, 22B, and 22C. That is, the transmission unit 50 is obtained by omitting the emphasis control unit 23 and the output units 24A to 24C from the transmission unit 20 according to the first embodiment.

  FIG. 33 illustrates a configuration example of the receiving device 60. The receiving device 60 includes an equalizer 61, receiving units 62 and 63, FIFO (First In First Out) memories 66 and 67, and a selector 68.

  The equalizer 61 increases the high-frequency component of the signal SIGA and outputs the signal SIGA2, increases the high-frequency component of the signal SIGB and outputs the signal SIGB2, and increases the high-frequency component of the signal SIGC and outputs the signal SIGC2. is there.

  The receiving unit 62 generates signals RxF1, RxR1, RxP1 and a clock RxCK1 based on the equalized signals SIGA2, SIGB2, and SIGC2. The receiving section 62 includes amplifiers 32A, 32B, 32C, a clock generating section 33, flip-flops 34, 35, and a signal generating section 36. That is, the receiving unit 62 has the same configuration as the receiving device 30 according to the first embodiment.

  The receiving section 63 generates signals RxF2, RxR2, RxP2 and a clock RxCK2 based on the non-equalized signals SIGA, SIGB, SIGC. The receiving unit 63 includes amplifiers 32A, 32B, 32C, a clock generating unit 33, flip-flops 34 and 35, a signal generating unit 65, and a register 64. That is, the receiving unit 63 is obtained by replacing the signal generating unit 36 with the signal generating unit 65 in the receiving unit 62 and adding the register 64.

  The signal generation unit 65 generates the signals RxF2, RxR2, and RxP2 based on the output signals of the flip-flops 34 and 35 and the clock RxCK2, similarly to the signal generation unit 36. Further, the signal generation section 65 has a function of generating a signal SEL based on the LUT 59 supplied from the register 64. Signal SEL includes signals RxF1, RxR1, RxP1 generated based on equalized signals SIGA2, SIGB2, SIGC2 and signals RxF2, RxR2, RxP2 generated based on non-equalized signals SIGA, SIGB, SIGC2. It indicates which one to select. The LUT 59 shows, for example, the relationship between the current symbol CS2, the signals RxF2, RxR2, RxP2, and the signal SEL, and is, for example, similar to the LUT 19 and the like according to the first embodiment. The signal generation unit 65 generates and outputs a signal SEL by referring to the LUT 59 based on the current symbol CS2 and the signals RxF2, RxR2, and RxP2.

  The register 64 stores the LUT 59. The LUT 59 is written into the register 64 by an application processor (not shown) when the power of the receiving device 60 is turned on, for example.

  The FIFO memory 66 is a buffer memory that temporarily stores the signals RxF1, RxR1, and RxP1 supplied from the receiving unit 62. In this example, the FIFO memory 66 writes and reads data using the clock RxCK1.

  The FIFO memory 67 is a buffer memory that temporarily stores the signals RxF2, RxR2, RxP2 and the signal SEL supplied from the receiving unit 63. In this example, the FIFO memory 67 writes data using the clock RxCK2 and reads data using the clock RxCK1.

  The selector 68 selects the signal RxF1, RxR1, RxP1 read from the FIFO memory 66 or the signal RxF2, RxR2, RxP2 read from the FIFO memory 67 based on the signal SEL read from the FIFO memory 67, The signals are output as signals RxF, RxR, and RxP.

  Next, some of the symbol transitions will be described in detail with examples.

  FIGS. 34 and 35 show the operation when the symbol transitions from "+ x" to "+ y". FIGS. 34 (A) to 34 (C) show the waveforms of the equalized signals SIGA2, SIGB2 and SIGC2. 35A to 35C show waveforms of a difference AB2 between the signals SIGA2 and SIGB2, a difference BC2 between the signals SIGB2 and SIGC2, and a difference CA2 between the signals SIGC2 and SIGA2, respectively. In this example, the lengths of the transmission lines 9A to 9C are sufficiently short.

  When the symbol transitions from “+ x” to “+ y”, the equalizer 61 generates the signals SIGA2 to SIGC2 by emphasizing the transitions in the signals SIGA to SIGC, as shown in FIG. At this time, the differences AB2, BC2, and CA2 are as shown in FIG. As described above, in the communication system 2, by performing equalization and making the transition of the waveform sharp, the eye can be widened. Therefore, in such a transition, the selector 68 selects the signals RxF1, RxR1, RxP1 generated based on the equalized signals SIGA2, SIGB2, SIGC2, and outputs the selected signals as signals RxF, RxR, RxP.

  FIGS. 36 and 37 show the operation when the symbol transitions from “+ x” to “−z”. FIGS. 36A to 36C show waveforms of the equalized signals SIGA2, SIGB2, and SIGC2. 37A to 37C show waveforms of the differences AB2, BC2, and CA2, respectively.

  Even when the symbol transitions from "+ x" to "-z", the equalizer 61 generates the signals SIGA2 to SIGC2 by emphasizing the transitions in the signals SIGA to SIGC, as shown in FIG. At this time, the differences AB2, BC2, and CA2 are as shown in FIG. As described above, in the waveform of the difference AB2, as shown in FIG. 37A, an undershoot occurs at the time of transition, and the eye may be narrowed. Therefore, in such a transition, the selector 68 selects the signals RxF2, RxR2, and RxP2 generated based on the non-equalized signals SIGA, SIGB, and SICC, and outputs them as the signals RxF, RxR, and RxP.

  As described above, in the communication system 2, equalization is selectively performed on the signals SIGA, SIGB, and SIGC. Therefore, for example, when the transition is such that the eye becomes narrower when the equalization is performed, the equalization is performed. Can not be. Thereby, in the communication system 2, communication quality can be improved.

As described above, in the present embodiment, equalization is selectively performed on signals SIGA to SIGC, so that communication quality can be improved.

[Modification 2-1]
In the above embodiment, the signal generation unit 65 of the reception unit 63 generates the signal SEL. However, the present invention is not limited to this. For example, the signal generation unit 36 of the reception unit 62 may The signal SEL may be generated. Alternatively, the signal generation unit 36 of the reception unit 62 and the signal generation unit 65 of the reception unit 63 may generate the signals SEL, and the selector 68 may perform the selection operation based on these signals SEL.

[Modification 2-2]
Further, a communication system may be configured by combining transmitting apparatus 10 according to the first embodiment and receiving apparatus 60 according to the present embodiment. In this case, since the transmitting device 10 performs pre-emphasis on the signals SIGA, SIGB, and SIGC, and the receiving device 60 performs equalization on the signals SIGA, SIGB, and SIGC, longer transmission paths 9A, 9B, and 9C are used. Can be transmitted and received via the.

<3. Application example>
Next, an application example of the communication system described in the above embodiment and the modified example will be described.

  FIG. 38 illustrates an appearance of a smartphone 300 (multifunctional mobile phone) to which the communication system according to any of the above embodiments and the like is applied. Various devices are mounted on the smartphone 300, and the communication system according to the above-described embodiment and the like is applied to a communication system for exchanging data between the devices.

  FIG. 39 illustrates a configuration example of an application processor 310 used in the smartphone 300. The application processor 310 includes a CPU (Central Processing Unit) 311, a memory control unit 312, a power control unit 313, an external interface 314, a GPU (Graphics Processing Unit) 315, a media processing unit 316, and a display control unit 317. And a MIPI (Mobile Industry Processor Interface) interface 318. In this example, the CPU 311, the memory control unit 312, the power supply control unit 313, the external interface 314, the GPU 315, the media processing unit 316, and the display control unit 317 are connected to a system bus 319. Can be exchanged.

  The CPU 311 processes various information handled by the smartphone 300 according to a program. The memory control unit 312 controls the memory 501 used when the CPU 311 performs information processing. The power control unit 313 controls the power of the smartphone 300.

  The external interface 314 is an interface for communicating with an external device, and in this example, is connected to the wireless communication unit 502 and the image sensor 503. The wireless communication unit 502 performs wireless communication with a base station of a mobile phone, and includes, for example, a baseband unit, an RF (Radio Frequency) front end unit, and the like. The image sensor 503 acquires an image, and includes, for example, a CMOS sensor.

  The GPU 315 performs image processing. The media processing unit 316 processes information such as voice, characters, and graphics. The display control unit 317 controls the display 504 via the MIPI interface 318. The MIPI interface 318 transmits an image signal to the display 504. As the image signal, for example, a signal in a YUV format, an RGB format, or the like can be used. As the communication system between the MIPI interface 318 and the display 504, for example, the communication system according to the above-described embodiment or the like is applied.

FIG. 40 illustrates a configuration example of the image sensor 410. The image sensor 410 includes a sensor unit 411, an ISP (Image Signal Processor) 412, a JPEG (Joint Photographic Experts Group) encoder 413, a CPU 414, a RAM (Random Access Memory) 415, and a ROM (Read Only Memory) 416. , A power control unit 417, an I ² C (Inter-Integrated Circuit) interface 418, and a MIPI interface 419. Each of these blocks is connected to a system bus 420 in this example, and can exchange data with each other via the system bus 420.

The sensor unit 411 acquires an image, and is configured by, for example, a CMOS sensor. The ISP 412 performs a predetermined process on an image acquired by the sensor unit 411. The JPEG encoder 413 encodes an image processed by the ISP 412 to generate a JPEG image. The CPU 414 controls each block of the image sensor 410 according to a program. The RAM 415 is a memory used when the CPU 414 performs information processing. The ROM 416 stores a program executed by the CPU 414. The power control unit 417 controls the power of the image sensor 410. The I ² C interface 418 receives a control signal from the application processor 310. Although not shown, the image sensor 410 receives a clock signal from the application processor 310 in addition to a control signal. Specifically, the image sensor 410 is configured to operate based on clock signals of various frequencies. The MIPI interface 419 transmits an image signal to the application processor 310. As the image signal, for example, a signal in a YUV format, an RGB format, or the like can be used. As the communication system between the MIPI interface 419 and the application processor 310, for example, the communication system of the above-described embodiment and the like is applied.

  As described above, the present technology has been described with reference to some embodiments and modifications, and application examples to electronic devices. However, the present technology is not limited to these embodiments and the like, and various modifications are possible. is there.

  For example, in each of the above embodiments, the signals SIGA, SIGB, and SIGC transition between the three voltage states SH, SM, and SL, respectively. However, the present invention is not limited to this. Thus, for example, a transition may be made between two voltage states, or between four or more voltage states.

  Further, for example, in each of the above embodiments, communication was performed using three signals SIGA, SIGB, and SIGC. However, the present invention is not limited to this, and instead, for example, using two signals Communication may be performed, or communication may be performed using four or more signals.

  It should be noted that the effects described in the present specification are merely examples, are not limited, and may have other effects.

  1, 1E, 2 communication system, 9A to 9C transmission line, 10, 10B, 10E, 40 transmission device, 11 and 11B signal generator, 12 register, 13 to 15, 14B, 15B flip-flop, 16E: LUT generation unit, 19, 19B, 59: LUT, 20, 20B, 50: Transmission unit, 21: Output control unit, 22A to 22C: Output unit, 23: Emphasis control unit, 24A to 24C: Output unit, 25 , 26 ... transistor, 27, 28 ... resistor, 30, 30E, 60 ... receiver, 31A-31C ... resistor, 32A-32C ... amplifier, 33 ... clock generator, 34, 35 ... flip-flop, 36, 36E ... Signal generation unit, 37E ... Pattern detection unit, 61 ... Equalizer, 62,63 ... Reception unit, 64 ... Register, 65 ... Signal generation unit, 66,67 ... FIFO Mori, 68 selector, 100, 110 symbol determination section, 120, 130, 140, 150, 160, 170 logic circuit, 121 to 125 logical product circuit, 180 logical sum circuit, AB, BC, CA, AB2 , BC2, CA2... Difference, CS, CS2, NS, PS2... Symbol, EA to EC, EE, EA2 to EC2, EE2, SEL, SIGA to SIGC, SIGA2 to SIGC2, S1, S2, RxF, RxR, RxP, RxF1 , RxR1, RxP1, RxF2, RxR2, RxP2, TxF, TxR, TxP ... signal, DET ... signal, EM ... eye mask, SH, SL, SM ... voltage state, RxCK, RxCK1, RxCK2, TxCK ... clock, TinA, TinB , TinC: input terminal, TJ: jitter, ToutA, ToutB, ToutC: output terminal, VH High-level voltage, VL ... low-level voltage, VM ... mid-level voltage, V1 ... voltage.

Claims (16)

A transmitting unit that generates three transmission signals based on a data signal indicating a sequence of transmission symbols;
A control unit that controls the transmission unit to adjust a voltage level of the transmission signal based on two consecutive transmission symbols in the data signal,
A transmission device where each transmission signal transitions between three or more voltage states. The control unit has a look-up table indicating a relationship between a transition pattern of the data signal and a flag indicating whether to adjust the voltage level, and adjusts the voltage level based on the look-up table. Judge whether to do
The transmission device according to claim 1 . The lookup table is configured to be programmable
The transmission device according to claim 2 . The transmission device according to any one of claims 1 to 3 , wherein the transmission unit adjusts the voltage level so as to increase a high-frequency component of the transmission signal. The three or more voltage states include a first voltage state, a second voltage state, and a voltage level between the voltage level of the first voltage state and the voltage level of the second voltage state. 3 voltage states;
The control unit adjusts the voltage level with respect to the transmission signal in some transitions among the first voltage state, the second voltage state, and the third voltage state. Judge to do
The transmission device according to claim 4 . The control unit includes:
Among the three transmission signals, it is determined that the voltage level should be adjusted for the transmission signals that transition from the first voltage state and the third voltage state to the second voltage state,
Among the three transmission signals, it is determined that the voltage level should be adjusted for a transmission signal that transits from the second voltage state and the third voltage state to the first voltage state.
The transmission device according to claim 5 . The control unit determines that the voltage level should be adjusted for a transmission signal that maintains the first voltage state and the second voltage state among the three transmission signals.
The transmission device according to claim 6 . The control unit includes:
Among the three transmission signals, it is determined that the voltage level should not be adjusted for a transmission signal that transitions from the first voltage state and the second voltage state to the third voltage state,
It is determined that the voltage level should not be adjusted for a transmission signal that maintains the third voltage state among the three transmission signals.
The transmission device according to claim 6 . The three transmission signals include a first transmission signal, a second transmission signal, and a third transmission signal,
The control unit changes the first transmission signal from the first voltage state to the third voltage state, and changes the second transmission signal from the second voltage state to the first voltage state. And when the third transmission signal changes from the third voltage state to the second voltage state, adjusts the voltage level for the second transmission signal and the third transmission signal. Judge to do
The transmission device according to claim 5 . The three transmission signals include a first transmission signal, a second transmission signal, and a third transmission signal,
The control unit may include a difference signal between the first transmission signal and the second transmission signal, a difference signal between the second transmission signal and the third transmission signal, and a difference signal between the first transmission signal and the third transmission signal. It is determined that the voltage level should be adjusted when any of the difference signals from the transmission signal of No. 3 changes the polarity.
The transmitting device according to claim 4 . The transmission device according to any one of claims 1 to 3 , wherein the transmission unit adjusts the voltage level so as to reduce a low frequency component of the transmission signal. The three or more voltage states have a first voltage state, a second voltage state, and a voltage level between the voltage level of the first voltage state and the voltage level of the second voltage state. 3 voltage states;
The control unit, when each transmission signal maintains a voltage state of the first voltage state, the second voltage state, and a part of the third voltage state, for the transmission signal To adjust the voltage level
The transmission device according to claim 11 . The control unit determines that the voltage level should be adjusted for a transmission signal that maintains the first voltage state and the second voltage state among the three transmission signals.
The transmission device according to claim 12 . The control unit determines that the voltage level should not be adjusted for a transmission signal that maintains the third voltage state among the three transmission signals.
The transmission device according to claim 13 . The transmission device according to any one of claims 1 to 14 , wherein the control unit determines whether to adjust the voltage level for the three transmission signals. The transmission device according to any one of claims 1 to 14 , wherein the control unit determines whether to adjust the voltage level for the three transmission signals in a lump.

Images