WO2004025866A1

WO2004025866A1 - Signal transmission device

Info

Publication number: WO2004025866A1
Application number: PCT/JP2003/011495
Authority: WO
Inventors: Nobuhide Yoshida
Original assignee: Nec Corporation
Priority date: 2002-09-13
Filing date: 2003-09-09
Publication date: 2004-03-25
Also published as: JP2004112059A

Abstract

A transmission/reception device for signal transmission includes a test signal generation circuit (11) for generating a test signal in a process of waveform adjustment, a comparison potential generation circuit (16) for generating a voltage value of a test signal before passing through a transmission path (14) as a reference potential, a comparison circuit (17) for comparing the voltage value of a reflected signal to the reference potential so as to obtain a potential difference, a controller (18) for calculating a distortion amount attributed to attenuation characteristic of the transmission path (14) from the potential difference and controlling an output adjustment circuit (12) so as to compensate the transmission signal according to the distortion amount, the output adjustment circuit (12) controlled by the controller so as to compensate the test signal and the normal transmission signal, and a transmission drive circuit (13) for amplifying the signal compensated by the output adjustment circuit (12) and transmitting the signal via the transmission path (14) to a reception device (2). Thus, it is possible to easily perform level adjustment for mitigating the waveform distortion and inter-code interference caused by high frequency attenuation generated in the signal transmitted via the signal transmission path.

Description

Description Signal transmission device Background of the invention

The present invention relates to a transmission / reception device for signal transmission, and particularly to a signal transmission / reception device used for signal transmission between LSI (Large Scale Integrated Circuit) chips or signal transmission between elements in a chip or between circuit blocks. It relates to a transmitting / receiving device.

In recent years, the revitalization of the Internet market, the spread and expansion of networks, and the high performance of processors and storage devices have been remarkable. For example, in recent years, the performance of dynamic random access memory (DRAM) and processors has been significantly improved, and even personal computers have Gbps-class performance. In addition, the number of cases where images and videos are frequently exchanged outdoors, not only through home personal computers but also through mobile phones, has been increasing.

In order to realize these, in recent years, high performance and high speed operation of LSI have been promoted. With the high performance and high speed operation of the LSI, there is a need for higher speed signal transmission between LSI chips, between elements in a chip, and between circuit blocks.

For example, high-speed signal transmission between processors and signal transmission between processors and memory are required. In addition, high-speed signal transmission is also required for connections between chassis for configuring multiprocessor servers and for connections between servers and storage devices and other peripheral devices.

As described above, the performance of systems and networks is determined by the signal transmission speed between servers, chassis, and LSI chips, and the signal transmission speed between elements in a chip and between circuit blocks. I have. Therefore, speeding up these signal transmissions is an important issue.

Against this background, in recent years, high-speed signal transmission technologies exceeding Gbps have been actively developed. Conventionally, in signal transmission and reception circuits, the impedance of signal transmission The output impedance of the transmission circuit is optimally adjusted according to the frequency (see Japanese Patent Application Laid-Open No. H10-261948).

According to Japanese Patent Application Laid-Open No. H10-2619648, an initial amplitude voltage value generated from a signal transmission transmitting circuit connected to a signal transmission line is detected, and the output impedance is controlled by the voltage value. I do. Therefore, even if the impedance changes due to a change in the connection of the signal transmission line, the optimum output impedance is always automatically obtained. However, when signal transmission speeds up significantly, signal waveform distortion occurs in transmission paths such as cables and pack boards due to high-frequency attenuation caused by skin effects and dielectric loss.

FIGS. 7A, 7B, and 7C are diagrams showing waveform distortion caused by high-speed signal transmission. The signal transmission / reception device 100 shown in FIG. 7A that performs high-speed signal transmission of Gbps transmits a signal at a very high speed. Therefore, in the process of transmitting a signal from the transmission circuit 101 through a transmission path such as a transmission transmission line 102 such as a cable or a board including a connector or the like, a high-frequency component caused by a skin effect and a dielectric loss. As shown in Fig. 7C, the waveform is distorted at the receiving end due to the attenuation. For this reason, it becomes difficult for the receiving circuit 103 to receive accurately.

Conventionally, a response method has been proposed. According to an example of the conventional method, the transmission circuit for transmission transmission compensates for waveform distortion by adjusting the level of the signal output by the amount of distortion of the waveform due to attenuation. Since the higher the frequency, the lower the level is, the signal is processed to emphasize the edge of the waveform. This processing is called emphasis processing.

FIG. 8 is a block diagram schematically showing a configuration example of a conventional signal transmission transmitting apparatus. Referring to FIG. 8, the signal transmission transmitter includes a former-stage driver 94, a level adjustment circuit 95, and an output-stage driver 91. Then, the transmission device for signal transmission transmits a signal to the receiver 92 of the reception device for signal transmission via the signal transmission line 93. The signal transmission line 93 is formed of a thin copper wire such as AWG (American Wireless Gauge) 30 to 28 and has a length of about several meters. Further, the signal transmission / reception device 110 is constituted by the signal transmission transmission device, the signal transmission line 93, and the signal transmission reception device. The pre-stage driver 94 compensates for attenuation of the high frequency component of the transmission signal. The level adjustment circuit 95 gives an adjustment level to the preceding driver 94. The output stage driver 91 transmits the signal output from the pre-stage driver 94 to the signal transmission line 93.

The level of the signal A input to the pre-stage driver 94 is adjusted by the level adjustment circuit 95 and the pre-stage driver 94. At this time, the high frequency component is emphasized in order to compensate for the attenuation of the high frequency component by the signal transmission line 93. Generally, the amount of attenuation of the high-frequency component varies depending on the length and structure of the signal transmission line 93. Therefore, the level adjustment circuit 95 needs to change the adjustment level according to the amount of attenuation in the signal transmission line 93.

The signal B whose level has been adjusted is amplified by the output stage driver 91 and transmitted to the signal transmission line 93. Signal B is distorted on signal transmission line 93. The signal C distorted by the signal transmission line 93 is received by the receiver 92 of the signal transmission receiver. The signal C distorted by the signal transmission line 93 can be normally received by the receiver 92 because the distortion of the signal C is compensated in advance by the pre-driver 94.

The conventional transmission device for signal transmission as shown in FIG. 8 is designed so that even if the length or structure of the signal transmission line 93 changes and the amount of attenuation of high-frequency components changes, the receiver 92 can receive signals normally. Level adjustment is possible. However, in such emphasis processing, for example, the user manually adjusts the waveform while monitoring the waveform at the receiving end.

As another example, the user calculates the amount of attenuation from the length of the transmission path and the like, and manually sets the attenuation based on the calculated amount. In the example shown in FIG. 8, the signal level of the pre-stage driver 94 was manually adjusted by operating the level adjustment circuit 95 in accordance with the length and structure of the signal transmission line 93. For example, in a multi-channel device having a communication interface of 100 ch to 100 ch, the length and structure of the transmission medium for each channel are different. It was necessary to make adjustments so as to obtain the optimal reception waveform, which required a great deal of effort for the user.

In the conventional signal transmission transmitter shown in FIG. 8, when the length, structure, characteristics, and the like of the signal transmission line 93 are unknown, the user performs trial and experiment until an optimum reception waveform is obtained. It was necessary to repeat the adjustment by mistake, and the user was forced to work with difficulty and great effort. Further, when changing the connection of the cable, in the conventional transmission device for signal transmission, it is necessary for the user to manually set the adjustment level once set again, which is cumbersome. Summary of the Invention

An object of the present invention is to provide a signal transmission / reception device capable of easily performing level adjustment for mitigating waveform distortion and intersymbol interference caused by high-frequency attenuation generated in a signal transmitted through a signal transmission line. Is to do. In order to achieve the above object, a signal transmission device according to the present invention includes: a reception device that opens a receiving end in a waveform adjustment process; and a test signal transmitted to a reception device via a transmission line in a waveform adjustment process. The voltage value of the reflected signal reflected at the receiving end of the receiver is compared with the reference potential obtained from the voltage value of the test signal before passing through the transmission line, and the distortion caused by the attenuation characteristics of the transmission line is calculated from the potential difference. And a transmission device that detects the amount and compensates the transmission signal according to the detected distortion amount.

Also, the transmitting device sends a test signal again after compensating the transmitting signal, and calculates the voltage value of the reflected signal reflected at the receiving end of the receiving device and the voltage value of the test signal before passing through the transmission line. The comparison may be used to confirm whether or not the transmission signal is properly compensated.

A transmitting device according to the present invention is a transmitting device connected via a transmission line to a receiving device that opens a receiving end in a process of adjusting a waveform, and a test signal that generates a test signal in a process of adjusting the waveform. A generation circuit, an output adjustment circuit for compensating the test signal and the transmission signal, a voltage value of a signal reflected by a receiving end of the test signal output from the output adjustment circuit and sent to the receiving device via the transmission line, and a transmission line A comparison circuit for comparing the reference potential obtained from the voltage value of the test signal before passing through the comparator with a reference potential to obtain a potential difference, and obtaining a distortion amount due to the attenuation characteristic of the transmission line from the potential difference obtained by the comparison circuit, A controller for controlling the output adjustment circuit to compensate the transmission signal based on the amount. Further, the test signal generation circuit generates a test signal again after the output adjustment circuit compensates the transmission signal, and the comparison circuit generates the test signal voltage value and the reference potential of the reflected signal by the receiving end of the transmitted test signal again. A comparison unit for comparing the transmission signal and a judgment unit for confirming whether or not the compensation of the transmission signal is appropriately performed.

FIG. 1 is a schematic circuit diagram showing a configuration of a signal transmission / reception device according to a first embodiment of the present invention.

FIG. 2A is a diagram illustrating a signal transmission / reception device according to the first embodiment of the present invention. FIG. 2B, FIG. 2C, FIG. 2D, and FIG. 2E are diagrams illustrating signal transmission by the signal transmission / reception device of the first embodiment of the present invention.

FIG. 3 is a schematic circuit diagram showing the configuration of the signal transmission / reception device according to the second embodiment of the present invention.

FIG. 4 is a flowchart showing a waveform adjusting operation of the signal transmission / reception device according to the second embodiment of the present invention.

FIG. 5 is a schematic circuit diagram showing the configuration of the signal transmission / reception device according to the third embodiment of the present invention.

FIG. 6 is an example of a specific circuit diagram of an analog / digital converter according to the third embodiment of the present invention.

FIG. 7A is a diagram showing a signal transmission / reception device.

FIGS. 7B and 7C are diagrams showing waveform distortions due to high-speed signal transmission. FIG. 8 is a block diagram schematically showing a configuration example of a conventional signal transmission transmitting apparatus. Detailed description of the embodiment

Embodiments of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, a signal transmission transmitter 1 and a signal transmission receiver 2 are connected via a signal transmission line 14. The signal transmission line 14 is a thin copper wire such as AWG 28 to 30 and is several meters long. 03 011495

6 The signal transmission transmitter 1 is composed of a test signal generation circuit 11, an output intensity adjustment circuit 12 connected to the test signal generation circuit 11, and a transmission drive circuit connected to the output intensity adjustment circuit 12. 13 、 Comparison potential generation circuit 16 、 Comparison circuit 17 connected to comparison potential generation circuit 16 、 Comparator 17 、 Controller 18 connected to output intensity adjustment circuit 12 . The comparison circuit 17 is connected to the signal transmission line 14. The signal transmission receiving device 2 includes a receiving circuit 15. °

The test signal generation circuit 11 generates, for example, a test signal of a step pulse in an initial training sequence of signal transmission. The initial training sequence is a series of processes that are performed before starting normal operation, such as when the device is started or restarted, and that initializes or optimizes the state of each unit. Here, a process of automatically adjusting the output waveform of the signal transmission transmitter 1 is included in the initial training sequence so that signal transmission can be performed normally.

The output intensity adjustment circuit 12 adjusts the waveform of the signal generated from the test signal generation circuit 11 according to the control from the controller 18. At this time, the output intensity adjusting circuit 12 adjusts the waveform by emphasizing the harmonic components of the signal with an emphasis degree (emphasis intensity) according to the control from the controller 18.

The transmission drive circuit 13 amplifies the signal whose waveform has been adjusted by the output intensity adjustment circuit 12 and transmits the amplified signal to the signal transmission line 14.

The comparison potential generation circuit 16 generates a comparison potential which is a reference for waveform adjustment. The comparison potential is a voltage value of the test signal before passing through the signal transmission line 14 or a value obtained from the voltage value.

The signal reflected at the receiving end of the receiving circuit 15 from the transmission driving circuit 13 via the signal transmission line 14 is input to the comparison circuit 17 via the signal transmission line 14. The comparison potential generated by the comparison potential generation circuit 16 is input to the comparison circuit 17. Then, the comparison circuit 17 compares the signal reflected at the reception end of the reception circuit 15 with the comparison potential to determine the waveform distortion due to the high-frequency attenuation in the signal transmission line 14.

The controller 18 generates a control signal for adjusting the output waveform according to the waveform distortion obtained by the comparison circuit 17. 2003/011495 The signal transmission receiver 2 includes a reception circuit 15 connected to the signal transmission line 14. The receiving circuit 15 includes a receiver circuit and a termination circuit. The signal transmission receiver 2 receives the signal transmitted from the signal transmission transmitter 1 by the reception circuit 15. Also, in the initial training sequence, the signal transmission receiver 2 sets the end of the receiving end to an open state, and totally reflects the signal from the signal transmission transmitter 1.

If the length or structure of the signal transmission line 14 changes, the attenuation of the high-frequency component of the transmitted signal also changes. Therefore, the adjustment range in the output intensity adjustment circuit 12 may be variable.

As described above, the transmission device for signal transmission 1 is configured to pre-emphasize the high-frequency component by the output intensity adjustment circuit 12 so as to compensate for the attenuation of the high-frequency component in the signal transmission line 14. As a result, the signal that has passed through the signal transmission line 14 and attenuated in the high-frequency component and arrived at the receiving end of the receiving circuit 15 has an excellent waveform without distortion or intersymbol interference.

Next, signal transmission by the signal transmission / reception device of the first embodiment of the present invention will be described. FIG. 2A shows a transmission / reception device for signal transmission, FIG. 2B shows a waveform of a transmission signal from the transmission drive circuit 13 when waveform adjustment is not performed, and FIG. 2C shows a reception circuit 15 via a transmission line 14. 5 is a waveform of a signal received by the control unit. FIG. 2D shows the waveform of the transmission signal from the transmission drive circuit 13 when the waveform is adjusted, and FIG. 2E shows the waveform of the signal received by the reception circuit 15 via the transmission line 14. is there.

When a signal having a waveform as shown in FIG. 2B is transmitted from the transmission-side drive circuit 13 without adjusting the waveform in the output intensity adjustment circuit 12, the reception circuit is affected by the high-frequency attenuation caused by the signal transmission line 14. The waveform at the receiving end of 15 is a waveform with large intersymbol interference and distortion as shown in Fig. 2C.

On the other hand, when the waveform is adjusted in advance by the output intensity adjusting circuit 12 and a signal having a waveform as shown in FIG. 2D is transmitted from the transmitting side driving circuit 13, the receiving end of the receiving circuit 15 receives the signal. As shown in Fig. 2E, the waveform of Fig. 2E is a good waveform without distortion and intersymbol interference, with attenuation of high-frequency components compensated.

During the initial training sequence of the device, the signal transmission receiving device 2 sets the receiving end of the receiving circuit 15 to the open state. And the signal transmission transmitter 1 Five

8 The signal generation circuit 11 generates, for example, a test signal of a step pulse. This test signal passes through the signal transmission line 14 and reaches the receiving end of the receiving circuit 15. Since the receiving end of the receiving circuit 15 is set to the open state, the test signal is totally reflected. The signal that has been totally reflected and returned (hereinafter, referred to as a reflected signal) is input to the comparison circuit 17. The comparison circuit 17 compares the potential of the reflected signal with the comparison potential generated by the comparison potential generation circuit 16 to determine a potential difference.

The controller 18 determines the magnitude of the high-frequency attenuation based on the potential difference obtained by the comparison circuit 17. At this time, if the potential difference is large, the controller 18 judges that the high-frequency attenuation is large. Then, when determining that the high-frequency attenuation is large, the controller 18 sends a control signal to the output intensity adjustment circuit 12 to control the high-frequency component in accordance with the magnitude of the high-frequency attenuation. The output intensity adjusting circuit 12 emphasizes the signal waveform under the control of the controller 18.

Thus, the signal transmitted from the signal transmission transmission circuit 1 by the initial training sequence has a waveform in which high-frequency components are automatically emphasized according to the characteristics of the signal transmission line 14.

As a result, even when the length and structure of the signal transmission line 14 are unknown, the user does not need to manually adjust the waveform of the transmission signal, and the waveform is automatically and easily adjusted, and good signal transmission is possible. It becomes.

In the transmission and reception device for signal transmission according to the present embodiment, the process of generating a test signal from the test signal generation circuit 11 and adjusting the transmission waveform is included in the initial training sequence, so that when the device is started up, Although the waveform adjustment is automatically performed at this time, the present invention is not limited to this. For example, the process of adjusting the transmission waveform may be started by any user.

Next, a transmitting / receiving apparatus for signal transmission according to a second embodiment of the present invention will be described.

The signal transmission / reception device of the second embodiment adjusts the waveform of a transmission signal through two processes, an adjustment mode for adjusting the waveform and a check mode for checking the adjustment result. Referring to FIG. 3, a signal transmission transmitter 3 and a signal transmission receiver 2 are connected via a signal transmission line 14. The signal transmission receiver 2 and the signal transmission line 14 are the same as those in the first embodiment shown in FIG. The signal transmission transmitter 3 includes a test signal generation circuit 21, an output intensity adjustment circuit 12 connected to the test signal generation circuit 21, and a transmission drive circuit 1 connected to the output intensity adjustment circuit 12. 3, comparison potential generation circuit 22 connected to test signal generation circuit 21, comparison circuit 23 connected to test signal generation circuit 21 and comparison potential generation circuit 22, output adjustment circuit 12, and comparison It has a controller 18 connected to the circuit 23. The comparison circuit 23 is connected to the signal transmission line 14.

The output intensity adjustment circuit 12, the transmission drive circuit 13, and the controller 18 are the same as those in the first embodiment shown in FIG.

When the test signal generation circuit 21 generates, for example, a step pulse test signal, it transmits a signal 24 to that effect to the comparison potential generation circuit 22. When the test signal generation circuit 21 receives the comparison end notification signal 25 from the comparison circuit 23 after generating the first test signal, the test signal generation circuit 21 generates the second test signal and enters the check mode. The signal 26 indicating the switching of the signal is transmitted to the comparison circuit 23.

The comparison potential generation circuit 22 generates a comparison potential when receiving the signal 21 indicating that the test signal has been generated from the test signal generation circuit 21.

The comparison circuit 23 includes a comparison unit 23a and a determination unit 23b. When comparing the potential of the reflected signal due to the first test signal with the comparison potential, the comparison unit 23a notifies the controller 18 of the result and also outputs the signal 25 notifying that the first comparison has been completed. Send to test signal generation circuit 21

After receiving the signal 26 indicating the switch to the check mode from the test signal generation circuit 21, the comparison section 23 a of the comparison circuit 23 compares the potential of the reflected signal by the second test signal. Compare with the potential. Then, the determination unit 23 b of the comparison circuit 23 determines whether or not the waveform of the output signal has been appropriately adjusted based on the comparison result, and outputs a signal 27 indicating the result. The judgment result output to the signal 27 is displayed to a user, for example. For example, by providing a notifying unit 28 connected to the comparing circuit 23, the user is notified when the compensation of the transmission signal is not properly performed.

Confirmation of whether or not the waveform has been properly adjusted can be performed, for example, based on whether or not the potential difference of the comparison result has been improved to such an extent that no adjustment is necessary.

In the confirmation mode, the determination unit 23 b of the comparison circuit 23 compares the potential of the reflected signal with the comparison voltage. P2003 / 011495

If no adjustment is necessary compared to the 10th place, it is determined that the adjustment has been made appropriately. If further adjustment is required, it is determined that adjustment has not been performed properly. Next, the waveform adjustment operation of the signal transmission / reception device according to the second embodiment of the present invention will be described. According to FIG. 4, first, a test signal is generated from the test signal generation circuit 21 and the adjustment operation is started (step S 1). The test signal is transmitted to the signal transmission line 14 via the output intensity adjustment circuit 12 and the transmission drive circuit 13. The test signal that has reached the receiving circuit 15 from the signal transmission line 14 is totally reflected since the receiving end of the receiving circuit 15 is open, and is input to the comparing circuit 23. Further, the comparison potential generation circuit 22 that has learned that the test signal has been generated by the signal 24 from the test signal generation circuit 21 generates a comparison potential.

The reflected signal totally reflected at the receiving end of the receiving circuit 15 is detected by the comparing circuit 23 (step S 2). Upon detecting the reflected signal, the comparison circuit 23 compares the reflected signal with a comparison potential to determine whether it is necessary to switch the emphasis intensity of the waveform (step S3).

If there is no need to switch the intensity of the emphasis, the signal transmission / reception circuit ends the adjustment operation (step S7).

If the intensity of emphasis needs to be switched, the controller 18 generates a control signal according to the comparison result of the comparison circuit 23 and sends it to the output intensity adjustment circuit 12. The output intensity adjusting circuit 12 switches the emphasis intensity according to the control signal (step S4).

The comparison circuit 23 that has completed the comparison between the reflected signal and the comparison potential notifies the test signal generation circuit 21 of that fact. The test signal generating circuit 21 receiving the signal generates a second test signal (step S5).

When the reflected signal due to the second test signal is detected, the comparison circuit 23 compares the reflected signal with the comparison potential and determines whether or not the waveform adjustment is properly performed (Step S6).

If the waveform adjustment has been properly performed, the comparison circuit 23 outputs a signal 27 to that effect, and the signal transmission / reception device completes the adjustment operation (step S7). If the waveform adjustment has not been properly performed, the comparison circuit 23 outputs a signal 27 to that effect for signal transmission. 11 The transmitting / receiving device ends the adjusting operation with an error (step S8).

As described above, according to the present embodiment, the user can know from the signal 27 whether or not the waveform adjustment of the output signal has been appropriately performed. It is possible to determine whether or not to perform automatic waveform adjustment again, or to perform the waveform adjustment by other methods, such as manually, and so on, which makes the waveform adjustment easier.

Next, a transmitting / receiving apparatus for signal transmission according to a third embodiment of the present invention will be described. The transmitting and receiving apparatus for signal transmission according to the third embodiment is a device that performs a Z-to-digital conversion of a comparison result between a comparison potential and a potential of a reflected signal, and adjusts the intensity of emphasis using a control signal of digital data. .

Referring to FIG. 5, a signal transmission transmitter 4 and a signal transmission receiver 2 are connected via a signal transmission line 14. The signal transmission receiver 2 and the signal transmission line 14 are the same as those in the second embodiment shown in FIG.

The signal transmission transmitter 4 includes a test signal generation circuit 21, an output intensity adjustment circuit 12 connected to the test signal generation circuit 21, and a transmission drive circuit 1 connected to the output intensity adjustment circuit 12. 3. A comparison potential generation circuit 22 connected to the test signal generation circuit 21; an analog Z digital comparator 31 connected to the test signal generation circuit 21 and the comparison potential generation circuit 22; Further, the analog / digital converter 31 is connected to the output intensity adjusting circuit 12 and the signal transmission line 14. The analog Z digital converter 31 includes a comparison circuit 31a and a transmission signal compensation circuit 31b.

The test signal generation circuit 21, the output intensity adjustment circuit 12, the transmission drive circuit 13, and the comparison potential generation circuit 22 are the same as those in the second embodiment shown in FIG.

In this embodiment, an analog / digital converter (AZD converter) 31 is provided in place of the comparison circuit 23 and the controller 18 in the second embodiment. The comparison circuit 3 la compares the input comparison potential with the potential of the reflected signal. The transmission signal compensating circuit 31b converts the comparison result input from the comparing circuit 31a into an analog Z-digital signal, and adjusts the emphasis intensity using the digital signal control signal. The analog Z-to-digital converter 31 includes an analog-to-digital converter, and when a reflected signal is detected, calculates the difference between the potential and the comparison potential, converts the potential difference to analog-to-digital, and outputs a digital-to-digital control signal. It is a digital controller input to the intensity adjustment circuit 12.

For example, if the analog Z-digital converter included in the analog-to-digital converter 31 has a 2-bit output, the emphasis intensity can be switched between four levels (00, 01, 10, 11). If the analog / digital conversion circuit has a 3-bit output, the emphasis intensity can be switched between eight levels (000, 001, 010, 011, 100, 101, 110, 111). If it is a 1-bit output, it can be switched to two stages (0, 1).

Therefore, according to the present embodiment, the intensity of emphasis can be switched to a plurality of levels, and thus highly accurate waveform adjustment can be performed. Also, by selecting the number of output bits of the analog Z digital conversion circuit, it is possible to select the switching range and accuracy of the emphasis intensity. For example, the number of output bits may be determined by selecting the switching range and the precision according to the expected length, structure, and characteristics of the signal transmission line.

Next, an example of the analog Z-to-digital converter 31 used in the signal transmission / reception device of the third embodiment of the present invention will be described. Referring to FIG. 6, a 1-bit analog-to-digital converter 40 is used. The comparison potential is input to one comparison potential input terminal 42 of the differential circuit, and the reflection signal is input to the other reflection signal input terminal 43 of the differential circuit. The input comparison potential is compared with the reflected signal, and the comparison result is latched by FF (flip flop) 41.

According to the above-described embodiment, the transmitting device detects the amount of distortion based on the reflected signal at the receiving end of the receiving device, and automatically compensates the amount of distortion for the transmission signal. Therefore, even when connecting multi-channel transmission lines with different lengths and configurations, or when the transmission line length is unknown, there is no need to manually adjust each transmission line, and the waveform of the transmission signal can be easily adjusted. Can be automatically adjusted so that a good waveform is obtained at the receiving end of the receiving apparatus.

Further, according to the above-described embodiment, the transmitting apparatus performs the distortion calculation based on the reflected signal. High-frequency components are emphasized with the degree of emphasis according to the amount. Therefore, even if waveform distortion due to high-frequency attenuation occurs in high-speed signal transmission, the high-frequency component of the transmission signal is emphasized, and a good waveform can be obtained at the receiving end, facilitating high-speed signal transmission at Gbps. Thus, signal transmission with good performance can be obtained.

In addition, according to the above-described embodiment, after compensating the transmission signal, the transmission device transmits the test signal again to check whether the transmission signal is properly compensated. Therefore, the user can easily know whether or not the compensation has been properly performed.

Further, according to the above-described embodiment, the waveform adjustment is performed in the initial training sequence. For this reason, the waveform is always adjusted at the start-up of the device, even if the user is not particularly aware, and a good waveform is obtained at the receiving end of the receiving device.

As described above, the transmission / reception device according to the present invention is suitable for use in a signal transmission / reception device used for signal transmission between LSI chips or between elements in a chip or between circuit blocks. I have.

Claims

The scope of the claims

1. A receiving device that opens the receiving end in the process of waveform adjustment,

In the process of waveform adjustment, a test signal is sent to the receiving device via a transmission line, and a voltage value of a reflected signal reflected at a receiving end of the receiving device and a voltage value of the test signal before passing through the transmission line are calculated. A transmission device that compares the obtained reference potential with the reference potential, detects the amount of distortion due to the attenuation characteristic of the transmission line from the potential difference, and compensates the transmission signal according to the detected amount of distortion.

A signal transmission device comprising:

2. The signal transmission device according to claim 1, wherein the transmission device compensates a transmission signal by emphasizing a high-frequency component with an emphasis degree corresponding to a distortion amount.

3. The signal transmission device according to claim 1, wherein a waveform adjustment process is incorporated as a part of an initial training sequence for setting the transmission device and the reception device to an initial state before the operation starts. .

4. The transmitting device sends a test signal again after compensating the transmitting signal, and calculates the voltage value of the reflected signal reflected at the receiving end of the receiving device and the voltage value of the test signal before passing through the transmission line. 2. The signal transmission device according to claim 1, wherein it is confirmed whether or not the compensation of the transmission signal is appropriately performed by comparing.

5. The transmitting device normally ends the waveform adjustment process if the transmission signal is properly compensated, and notifies the user if the compensation is not properly performed. The signal transmission device according to claim 4.

6. A transmitting device connected via a transmission line to a receiving device that opens the receiving end in the process of waveform adjustment, A test signal generation circuit for generating a test signal in the process of waveform adjustment, an output adjustment circuit for compensating the test signal and the transmission signal,

It is obtained from the voltage value of the reflected signal at the receiving end of the test signal output from the output adjustment circuit and sent to the receiving device via the transmission line, and the voltage value of the test signal before passing through the transmission line. A comparison circuit for obtaining a potential difference by comparing the

A controller that obtains a distortion amount due to the attenuation characteristic of the transmission line from the potential difference obtained by the comparison circuit, and controls the output adjustment circuit to compensate for a transmission signal based on the distortion amount.

A transmission device comprising:

7. The transmission device according to claim 6, wherein the controller controls the output adjustment circuit so as to emphasize a high-frequency component with a degree of enhancement corresponding to a distortion amount.

8. The test signal generation circuit generates a test signal again after the output adjustment circuit compensates the transmission signal,

The comparison circuit includes:

A comparing unit for comparing the voltage value of the reflected signal by the receiving end of the retransmitted test signal with the reference potential;

A judgment unit for checking whether the transmission signal is compensated properly;

7. The transmitting device according to claim 6, comprising:

9. The determination unit terminates the waveform adjustment process normally if the transmission signal is properly compensated, and notifies the user if the compensation is not properly performed. The transmitting device according to 8.

10. A transmission signal compensating circuit for controlling the output adjusting circuit so as to perform analog-to-digital conversion of the potential difference output from the comparison circuit and compensate the transmission signal in accordance with the digital data obtained thereby. Claims comprising: 7. The transmitting device according to 6.

11. The transmitting apparatus according to claim 10, wherein the comparing circuit and the transmission signal compensating circuit form an analog / digital converter.

12. The transmission device according to claim 11, wherein the analog / digital converter controls the output adjustment circuit so as to emphasize a high-frequency component at an intensity corresponding to digital data.

13. The test signal generation circuit generates a test signal again after the output adjustment circuit compensates for the transmission signal,

The analog / digital converter compares the voltage value of the signal reflected by the receiving end of the retransmitted test signal with a reference potential to confirm whether or not the transmission signal has been properly compensated. The transmission device according to claim 10, characterized in that:

1 4. The analog / digital converter terminates the waveform adjustment process normally if the transmission signal is properly compensated, and notifies the user if it is not properly compensated. 13. The transmission device according to claim 13, wherein

15. The transmitting apparatus according to claim 14, further comprising a notifying unit for notifying that the transmission signal is not properly compensated.

16. The transmission device according to claim 6, further comprising a comparison potential generation circuit that generates a voltage value of the test signal before passing through the transmission line as a reference potential.

17. The transmission circuit according to claim 6, further comprising a transmission drive circuit that amplifies the signal compensated by the output adjustment circuit and sends the amplified signal to the reception device via the transmission line.

18. The test signal generation circuit according to claim 6, wherein a waveform adjustment process is incorporated as part of an initial training sequence process for setting an initial state before operation starts. Transmission device.

1 9. In the process of waveform adjustment, the step of sending a test signal to the receiver via the transmission line,

Comparing the voltage value of the reflected signal reflected at the receiving end of the receiving device with a reference potential obtained from the voltage value of the test signal before passing through the transmission line, based on the result of the comparison The step of detecting the amount of distortion due to the attenuation characteristics of the transmission line;

Compensating the transmission signal according to the distortion amount;

A signal transmission method comprising: