JP5461963B2 - Deskew circuit and error measuring device - Google Patents

Description

  The present invention relates to a deskew circuit that detects and corrects a skew, and an error measurement device including the deskew circuit.

  There has been proposed a communication system that detects and corrects skew in a high-speed data transmission path that generates skew in a transmission system or reception system (see, for example, Patent Document 1). When transmitting and receiving data through such a high-speed data transmission path, a pattern that can detect and correct skew is held in the frame, and skew is detected and corrected using the pattern. .

JP-T-2002-533020

    When developing a device or device used in a high-speed data transmission line that generates skew in a transmission system or a reception system, first, detection and correction of a skew such as a PRBS (Pseudo Random Binary Sequence) signal is performed. The quality of the transmission line is evaluated using continuous signals that have no function.

  At this time, if the skew is not detected and corrected, the pattern synchronization of the continuous signals cannot be obtained due to the occurrence of skew or the order mismatch of DEMUX.

  Even if a pattern capable of detecting and correcting the skew is inserted into the continuous signal, the characteristics of the continuous signal may be deteriorated or it may be impossible to connect to a general-purpose BERT (Bit Error Rate Tester) system.

  Therefore, in order to solve the above problems, the present invention evaluates a high-speed data transmission path that generates skew in a transmission system or reception system using a continuous signal that does not have a function of detecting and correcting skew. It is an object of the present invention to provide a deskew circuit and an error measurement device that enable the above.

In order to achieve the above object, the deskew circuit of the present invention provides:
In order to enable evaluation of a high-speed data transmission path that generates skew in a transmission system or reception system using a continuous signal that does not have a function of detecting and correcting skew,
A test signal generation circuit (31) for generating and outputting a test signal with a lane number attached after a certain bit of a predetermined specific code string for a plurality of lane numbers ;
A continuous signal is input to each lane and the test signal is input from the test signal generation circuit, the continuous signal of the lane number attached to the test signal is replaced with the test signal, and the continuous signal is input from each lane. A selector circuit (32) for outputting a signal or the test signal;
A test signal detection circuit (35) for detecting the specific code string and outputting the lane number and the detection time of the lane number that are attached after a certain bit of the specific code string;
A skew correction circuit (36) for detecting and correcting skew in the lane of the lane number by comparing the detection time point from the test signal detection circuit with a predetermined time point;
Equipped with a,
The predetermined time point is a detection time point of another lane number output from the test signal detection circuit, or an absolute reference time point that repeats at a time difference greater than or equal to the maximum time difference generated in each lane .

  By comparing the test signal detection time points, it is possible to detect how much skew is generated in the signal output from which lane number. Thereby, the skew of each lane can be corrected. Therefore, the deskew circuit of the present invention enables evaluation of a high-speed data transmission path that generates skew in a transmission system or reception system using a continuous signal that does not have a function of detecting and correcting skew. Can do.

In the deskew circuit according to the present invention, the test signal generation circuit generates and outputs the test signal for a plurality of lane numbers, and the predetermined time point corresponds to another lane number output by the test signal detection circuit. It can be set as the structure which is a detection time.
The skew of each lane can be detected by comparing the detection points of each lane with each other. Thereby, the skew of each lane can be corrected.

In the deskew circuit according to the present invention, the predetermined time point may be an absolute reference time point that repeats at a time difference greater than or equal to a maximum time generated in each lane.
The skew of each lane can be detected by comparing the detection time of each lane with the absolute reference time. Thereby, the skew of each lane can be corrected.

In the deskew circuit of the present invention, the test signal has a predetermined frame length, and a sequence number indicating the order of the frames in the same lane is attached after a certain bit of the lane number, and the test signal The signal detection circuit further outputs the sequence number given after a certain bit of the lane number, and the skew correction circuit outputs a reference number determined by the predetermined time point and a sequence output by the test signal detection circuit The time difference between the reference number and the sequence number is calculated as the time difference between the predetermined time point and the detection time point of the lane number output from the test signal detection circuit. It can be set as the structure shortened only.
By attaching a sequence number to the test signal, the test signal can be transmitted over a plurality of frames to detect the skew. Thereby, the skew of each lane can be detected using a common counter.

An error measurement apparatus according to the present invention includes a deskew circuit (100) according to the present invention, a signal generation unit that generates a plurality of columns of the continuous signals and outputs the signals to each lane of the deskew circuit, and an output signal from the deskew circuit And an error detection circuit (23) for detecting an error included in the display, and a display for outputting that skew is being corrected .

  By providing the deskew circuit according to the present invention, the skew of each lane can be corrected. Therefore, the error measurement device of the present invention enables evaluation of a high-speed data transmission line that generates skew in a transmission system or reception system using a continuous signal that does not have a function of detecting and correcting skew. be able to.

In the error measurement device of the present invention, when the skew correction circuit completes the correction of the skew of each lane, the skew correction circuit outputs a lock signal instructing to stop switching to the selector circuit, and the selector circuit receives the lock signal. Then, the replacement with the test signal is stopped, and the continuous signal can be output from each lane.
After the correction of the skew of each lane is completed, a continuous signal can be continuously output from each lane. This makes it possible to evaluate a high-speed data transmission path that generates skew using a continuous signal that does not have a function of detecting and correcting skew.

In the error measurement device of the present invention, the error detection circuit outputs an operation instruction signal to the selector circuit when an error rate to be detected exceeds a certain value, and the operation signal is input to the selector circuit. The continuous signal of at least one lane among the input continuous signals can be replaced with the test signal.
If any lane has a skew, the error rate detected by the error detection circuit increases. Therefore, by setting such an error rate to a constant value, it is possible to maintain a state in which no skew occurs in each lane. As a result, it is possible to appropriately evaluate the quality of the transmission path using a continuous signal that does not have a function of detecting and correcting skew.

The error measuring device according to the present invention further includes a changeover switch (34) for switching the continuous signal from the continuous signal in the selector circuit to the test signal to automatic or manual, and when the changeover switch is automatic, the selector circuit includes: When the operation instruction signal is input, the continuous signal of at least one lane of the input continuous signals is replaced with the test signal, and when the changeover switch is manual, the selector circuit Even if a signal is input, it can be configured to output a continuous signal from each lane.
Depending on the high-speed data transmission line to be measured, if any lane has skew, the error rate detected by the error detection circuit may exceed a certain value, or no lane has skew. However, the error rate may exceed a certain value. Therefore, when the object to be measured is the former, the changeover switch is set to automatic, and when the object to be measured is the latter, the changeover switch is set to manual. As a result, it is possible to appropriately evaluate the quality of the transmission path using a continuous signal that does not have a function of detecting and correcting skew.

  The above inventions can be combined as much as possible.

  According to the present invention, it is possible to provide a deskew circuit and an error measurement device that enable quality evaluation of a transmission path using a continuous signal that does not have a function of detecting and correcting skew.

1 shows an example of an error measurement device according to a first embodiment. It is an example of a continuous signal, (a) shows the continuous signal from a continuous signal generation circuit, (b) shows the parallel signal from a serial-parallel conversion circuit. 4A and 4B are examples of input / output signals of a deskew circuit, in which FIG. 4A shows a signal input to each lane of the test signal insertion unit, and FIG. 4B shows a signal output from lane number # 0 of the test signal insertion unit. , (C) shows a signal output from lane number # 1 of the test signal insertion unit, and (d) shows a signal output from lane number # 9 of the test signal insertion unit. An example of a test signal insertion part and a signal generation part is shown. An example of a test signal is shown. An example of a skew correction | amendment part and an error detection part is shown. It is an example of the operation of the skew correction circuit, (a) shows the absolute reference time, (b) shows the detection time of lane number # 0, (c) shows the detection time of lane number # 1, (D) shows the detection time of lane number # 9. The structural example in case a to-be-measured object transmits a parallel signal in Embodiment 1 is shown. An example of the error measuring device which concerns on Embodiment 2 is shown. 4 shows another form of the signal generator according to the second embodiment. The structural example in case the to-be-measured object transmits a parallel signal in Embodiment 2 is shown.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
In the present embodiment, a deskew circuit according to the present invention and an error measuring apparatus including the same will be described. FIG. 1 shows an example of an error measurement device according to the present embodiment. The error measurement apparatus 101 according to the present embodiment includes a deskew circuit 100, a signal generation unit 11, and an error detection unit 14. Further, the deskew circuit 100 includes a test signal insertion unit 12 and a skew correction unit 13.

  The error measuring apparatus 101 detects and corrects a skew generated in the measurement target 91. During this time, the error measuring apparatus 101 outputs a message indicating that the skew is being corrected to the display. When the correction of the skew is completed, the error measurement apparatus 101 evaluates the measurement target 91 using a continuous signal that does not have a function of detecting and correcting the skew.

  The signal generator 11 shown in FIG. 1 generates a plurality of columns of continuous signals and outputs them to each lane of the deskew circuit 100. For example, a continuous signal generation circuit 21 and a serial / parallel conversion circuit 22 are provided. 2A and 2B are examples of continuous signals. FIG. 2A shows a continuous signal from the continuous signal generation circuit 21, and FIG. 2B shows a parallel signal from the serial / parallel conversion circuit 22. The continuous signal generation circuit 21 generates a 512-bit continuous signal. The serial-parallel conversion circuit 22 separates the 512-bit continuous signal into 128-bit signals and converts them into 10 columns of parallel signals.

  Here, the continuous signal is a signal that does not have a function of detecting and correcting a skew such as a PRBS signal. The continuous signal is not limited to the PRBS signal, but may be a user-defined signal. Further, in the present embodiment, a case where the signal generation unit 11 generates 10 columns of continuous signals of lane number # 0, lane number # 1,... Lane number # 9 is described. .

  The test signal insertion unit 12 shown in FIG. 1 outputs a test signal to the measurement target 91 instead of the input continuous signal. The test signal has a predetermined frame length FL that is the same as the frame length FL of the continuous signal from the signal generator 11. For example, if the continuous signal is 128 bits, the test signal is also 128 bits. The measurement target 91 transmits the input continuous signal and outputs it to each lane of the deskew circuit 100.

  3A and 3B are examples of input / output signals of the deskew circuit 100. FIG. 3A shows signals input to the lanes of the test signal insertion unit 12, and FIG. 3B shows lane numbers # 0 of the test signal insertion unit 12. (C) shows the signal output from lane number # 1 of the test signal insertion unit 12, and (d) shows the signal output from lane number # 9 of the test signal insertion unit 12. Show.

  As shown in FIG. 3A, the deskew circuit 100 is input with a continuous signal P1, a continuous signal P2, a continuous signal P3, a continuous signal P4, and a continuous signal P5 in order of sequence numbers indicating the order of frames. . Here, the continuous signal P1 of each lane is set to a different code string in consideration of being converted into a serial signal by the measurement target 91. The same applies to other continuous signals.

  In the signal output from the lane number # 0 of the deskew circuit, the frame of sequence number 2 is the test signal T2, as shown in FIG. 3B. In the signal output from the lane number # 1 of the deskew circuit, the frame of sequence number 2 is the test signal T2, as shown in FIG. As shown in FIG. 3D, the signal output from the lane number # 9 of the deskew circuit 100 has a frame of sequence number 4 as the test signal T4.

  The skew correction unit 13 detects and corrects the skew generated in the continuous signal of each lane. For example, the skew is detected using test signals output from the lanes of lane number # 0, lane number # 1, and lane number # 9. Based on this detection result, the skews in the lanes of lane number # 0, lane number # 1, and lane number # 9 are corrected.

  When the correction of the skew of each lane is completed, the skew correction unit 13 outputs a lock signal instructing to stop switching to the test signal insertion unit 12. In this case, when the lock signal is input, the test signal insertion unit 12 stops the replacement with the test signal and outputs a continuous signal from each lane. Since the correction of the skew of each lane has been completed, the skew correction unit 13 can output a continuous signal in which the skew is corrected to the error detection unit 14.

  The error detection unit 14 detects an error included in the output signal from the deskew circuit 100. For example, the error detection unit 14 determines whether or not the signal output from the skew correction unit 13 matches the continuous signal generated by the continuous signal generation circuit 21. At this time, the error detection unit 14 can acquire a continuous signal in which the skew is corrected. As a result, the quality of the measurement object 91 can be evaluated using a continuous signal that does not have a function of detecting and correcting skew.

  The error detection unit 14 outputs an operation instruction signal to the test signal insertion unit 12 when the detected error rate exceeds a certain value. When the operation instruction signal is input, the deskew circuit 100 starts skew detection and correction. Here, the constant value is an error rate generated when a skew occurs. When detecting skew and starting correction, the test signal insertion unit 12 replaces the continuous signal of at least one lane among the input continuous signals with the test signal. Thereby, when the skew cannot be corrected with the correction value in the skew correction unit 13, the skew can be detected and corrected again.

Next, details of the deskew circuit 100 will be described.
FIG. 4 shows an example of the test signal insertion unit 12 and the signal generation unit 11. The test signal insertion unit 12 includes a test signal generation circuit 31, a selector circuit 32, a timing generator 33, and a changeover switch 34.

  The test signal generation circuit 31 generates a test signal. The test signal for each lane may have the same sequence number or may be different. For example, the test signal generation circuit 31 generates a test signal with sequence number 2 for lane number # 0 and lane number # 1, and generates a test signal with sequence number 4 for lane number # 9. Thus, the test signal generation circuit 31 may generate test signals for a plurality of lane numbers. Further, the sequence numbers of the test signals may be different from each other.

  In the selector circuit 32, a continuous signal is input to each lane and a test signal is input from the test signal generation circuit 31, and the continuous signal of the lane number attached to the test signal is replaced with the test signal, and the continuous signal is input from each lane. Output signal or test signal. For example, when outputting the continuous signal of lane number # 0 and lane number # 1 to sequence number 2, the selector circuit 32 replaces the continuous signal of lane number # 0 and lane number # 1 with a test signal. At this time, the selector circuit 32 replaces the continuous signal of sequence number 2 with the test signal according to the timing of the output signal of the timing generator 33.

  FIG. 5 shows an example of the test signal. The test signal includes a predetermined specific code string, a first bit string, a lane number, a second bit string, and a sequence number in order. The predetermined specific code string is a code string that can be identified as a test signal. The lane number is given after the first bit string of the specific code string. The first bit string can be arbitrarily set. For example, the lane number may be added immediately after the specific code string. The sequence number indicates the order of frames in the same lane, and is attached after the second bit string of the lane number. The second bit string can be arbitrarily set. For example, the sequence number may be added immediately after the lane number.

  The changeover switch 34 switches the replacement from the continuous signal to the test signal in the selector circuit 32 automatically or manually. When the changeover switch 34 is automatic, when the operation instruction signal is input, the selector circuit 32 replaces the continuous signal of at least one lane among the input continuous signals with the test signal and transmits the test signal. On the other hand, when the changeover switch 34 is manually operated, the selector circuit 32 continues to output a continuous signal from each lane even when an operation instruction signal is input. As a result, it is possible to perform a test with a fixed value in which the error rate detected by the error detection circuit 23 is arbitrarily set, and a test irrespective of the error rate detected by the error detection circuit 23.

  FIG. 6 shows an example of the skew correction unit 13 and the error detection unit 14. The skew correction unit 13 includes a test signal detection circuit 35 and a skew correction circuit 36. The test signal detection circuit 35 detects the specific code string and outputs the lane number given after a certain bit of the specific code string and the detection time of the lane number. When the sequence number is attached to the test signal, the test signal detection circuit 35 outputs the sequence number together with the lane number and the detection time of the lane number.

  For example, when a test signal of lane number # 0 is detected, a flag F0 is output at the time when lane number # 0 is detected, and lane number # 0 and sequence number 2 are output. When the test signal of lane number # 1 is detected, flag F1 is output at the time when lane number # 1 is detected, and lane number # 1 and sequence number 2 are output. When the test signal with the lane number # 9 is detected, the flag F9 is output at the time when the lane number # 9 is detected, and the lane number # 9 and the sequence number 4 are output.

  The skew correction circuit 36 detects and corrects the skew in the lane of the lane number by comparing the detection time point from the test signal detection circuit 35 with a predetermined time point. FIG. 7 shows an example of the operation of the skew correction circuit. (A) shows the absolute reference time, (b) shows the detection time of lane number # 0, and (c) shows the detection of lane number # 1. (D) shows the detection time of lane number # 9.

  The predetermined time is, for example, the time when another lane number output from the test signal detection circuit 35 is detected. In this case, the time point S1R between the flag F0 and the flag F1 is detected by comparing the output time point of the flag F0 and the output time point of the flag F1. As a result, the skew between lane number # 0 and lane number # 1 can be corrected. Similarly, the corrected lane number # 1 is compared with the lane number # 2 before correction, the corrected lane number # 2 is compared with the lane number # 3 before correction, and the corrected lane number # 8 is compared with lane number # 9 before correction, and each correction is performed. Thereby, the skew of each lane can be corrected.

  In the skew correction between the lane number # 0 and the lane number # 1, the common sequence number 2 is used. However, the sequence numbers of the test signals may be different. For example, the output time point of the flag F0 may be compared with the output time point of the flag F9. In this case, the skew correction circuit 36 calculates the difference between the reference number 2 determined by a predetermined flag F0 and the sequence number 4 output from the test signal detection circuit 35. Then, a time difference S9R between a predetermined time point of the flag F0 and a detection time point of the flag F9 of the lane number # 9 output from the test signal detection circuit 35 is set as a frame length (2FL) of the difference between the reference number 2 and the sequence number 4 ). As a result, the skew between lane number # 0 and lane number # 9 can be corrected.

  In the correction of the skew between the lane number # 0 and the lane number # 1, the predetermined time point is a relative time point, but the predetermined time point may be an absolute time point. For example, the predetermined time point is an absolute reference time point that is greater than or equal to the maximum time difference occurring in each lane. In this case, the flag FA2, the flag FA3, and the flag FA4 are output at an absolute reference time. The absolute reference time is defined for each frame sequence number. For example, flag FA2, flag FA3, and flag FA4 repeat at an interval LA, flag FA2 corresponds to test signal sequence number 2, flag FA3 corresponds to test signal sequence number 3, and flag FA4 corresponds to test signal sequence number. Corresponding to 4. By detecting the time difference S0A between the flag F0 and the flag FA2, the skew of the lane number # 0 is corrected. The skew of lane number # 1 is corrected by detecting the time difference S1A between the flag F1 and the flag FA2. By detecting the time difference S9A between the flag F9 and the flag FA4, the skew of the lane number # 1 is corrected. As a result, the skew between lane number # 0 and lane number # 9 can be corrected.

  Although FIG. 1 illustrates an example in which the measurement target 91 converts a parallel signal into a serial signal and transmits the serial signal, the present invention is not limited to this. Even when the measurement target 91 transmits as a parallel signal, skew occurs, so the error measurement apparatus 101 according to the present embodiment can be used.

  FIG. 8 shows a configuration example when the object to be measured transmits a parallel signal. The measurement target 92 transmits the parallel signal output from the test signal insertion unit 12 as the parallel signal. The error measurement apparatus 101 according to the present embodiment outputs a test signal with a lane number attached thereto from each lane. For this reason, by checking the lane number of the test signal input to the skew correction unit 13 and the output port of the measured object 92, the correspondence between the input port and the output port of the measured object 92 can be easily grasped. Can do. Therefore, even if the measurement object 92 has a large number of input ports and output ports, it can be easily connected to the measurement object 92.

(Embodiment 2)
FIG. 9 shows an example of an error measurement device according to this embodiment. The error measurement device 102 according to the present embodiment is different from the error measurement device 101 shown in FIG. 1 in the signal generation unit 11 and the error detection unit 14. Specifically, the signal generation unit 11 illustrated in FIG. 1 generates a plurality of columns of continuous signals using the continuous signal generation circuit 21 and the serial-parallel conversion circuit 22, but the signal generation unit 11 according to the present embodiment. Includes a continuous signal generating circuit 21-0, a continuous signal generating circuit 21-1, ..., a continuous signal generating circuit 21-9. Further, the error detection unit 14 includes an error detection circuit 23-0, an error detection circuit 23-1, ..., an error detection circuit 23-9.

  The continuous signal generation circuit 21-0, the continuous signal generation circuit 21-1,..., The continuous signal generation circuit 21-9, use a separate continuous signal generation circuit for each lane, respectively, A continuous signal that can be recovered is generated. The error detection circuit 23-0 determines whether or not it matches the continuous signal generated by the corresponding continuous signal generation circuit 21-0. The same applies to the error detection circuit 23-1, ..., the error detection circuit 23-9.

  At this time, since the skew correction unit 13 corrects the skew, the continuous signal generated by the continuous signal generation circuit 21-0 is input to the error detection circuit 23-0, and the continuous signal generation circuit is input to the error detection circuit 23-1. The continuous signal generated by the continuous signal generating circuit 21-9 is input to the error detecting circuit 23-9. As a result, the error detection circuit 23-0, the error detection circuit 23-1,..., The error detection circuit 23-9 each determine whether or not they match the continuous signal generated by the corresponding continuous signal generation circuit. be able to.

  FIG. 10 shows another form of the signal generator 11. In FIG. 9, 10 continuous signal generation circuits and error detection circuits are used for 10 lane continuous signals. However, as shown in FIG. 10, 20 continuous signal generation circuits and error detection circuits may be used. . In this case, the continuous signal generation circuit 21-0 includes a continuous signal generation circuit 21-0-1, a continuous signal generation circuit 21-0-2, and a Mux 25-0. The Mux 25-0 multiplexes and outputs the continuous signal from the continuous signal generation circuit 21-0-1 and the continuous signal from the continuous signal generation circuit 21-0-2. Thus, the continuous signal generation circuit 21-0 can generate a high-speed continuous signal using the low-speed continuous signal generation circuit 21-0-1 and the continuous signal generation circuit 21-0-2.

  The error detection circuit 23-0 includes an error detection circuit 23-0-1, an error detection circuit 23-0-2, and DeMux 26-0. The DeMux 26-0 separates the signal output from the skew correction unit 13 to the lane number # 0 and outputs the signal to the error detection circuit 23-0-1 and the error detection circuit 23-0-2. As a result, the error detection circuit 23-0 can perform high-speed continuous signal error detection using the low-speed error detection circuit 23-0-1 and the error detection circuit 23-0-2.

  FIG. 11 shows a configuration example when the object to be measured transmits a parallel signal. The measurement target 92 transmits the parallel signal output from the test signal insertion unit 12 as the parallel signal. The error measurement device 102 according to the present embodiment outputs a test signal with a lane number attached thereto from each lane. For this reason, by checking the lane number of the test signal input to the skew correction unit 13 and the output port of the measured object 92, the correspondence between the input port and the output port of the measured object 92 can be easily grasped. Can do. Therefore, even if the measurement object 92 has a large number of input ports and output ports, it can be easily connected to the measurement object 92.

  Since the present invention can be used for testing a high-speed data transmission path that generates skew, it can be applied to the information and communication industry.

11: Signal generation unit 12: Test signal insertion unit 13: Skew correction unit 14: Error detection unit 21, 21-0, 21-1, 21-9, 21-0-1, 21-0-2, 21-9 -21, 21-9-2: continuous signal generation circuit 22: serial / parallel conversion circuit 23, 23-0, 23-1, 23-9, 23-0-1, 23-0-2, 23-9- 1, 23-9-2: Error detection circuit 24: Parallel-serial conversion circuit 25-0, 25-9: Mux
26-0, 26-9: DeMux
31: Test signal generation circuit 32: Selector circuit 33: Timing generator 34: Changeover switch 35: Test signal detection circuit 36: Skew correction circuit 81: Multiplexing unit 82: EO conversion unit 83: OE conversion unit 84: Separation unit 91 92: Measurement object 100: Deskew circuit 101, 102: Error measuring device

Claims (6)

In order to enable evaluation of a high-speed data transmission path that generates skew in a transmission system or reception system using a continuous signal that does not have a function of detecting and correcting skew,
A test signal generation circuit (31) for generating and outputting a test signal with a lane number attached after a certain bit of a predetermined specific code string for a plurality of lane numbers ;
A continuous signal is input to each lane and the test signal is input from the test signal generation circuit, the continuous signal of the lane number attached to the test signal is replaced with the test signal, and the continuous signal is input from each lane. A selector circuit (32) for outputting a signal or the test signal;
A test signal detection circuit (35) for detecting the specific code string and outputting the lane number and the detection time of the lane number that are attached after a certain bit of the specific code string;
A skew correction circuit (36) for detecting and correcting skew in the lane of the lane number by comparing the detection time point from the test signal detection circuit with a predetermined time point;
Equipped with a,
The deskew circuit is a deskew circuit that is a detection time of another lane number output from the test signal detection circuit or an absolute reference time point that repeats at a time difference greater than or equal to a maximum time difference generated in each lane . The test signal has a predetermined frame length, and a sequence number indicating the order of the frames in the same lane is attached after a certain bit of the lane number,
The test signal detection circuit further outputs the sequence number attached after a certain bit of the lane number,
The skew correction circuit calculates a difference between a reference number determined by the predetermined time point and a sequence number output from the test signal detection circuit, and outputs a lane output from the predetermined time point and the test signal detection circuit. deskew circuit of claim 1, the time difference between the detection time of the numbers, characterized by shortened by the reference number and the sequence number and time corresponding to the frame length difference. A deskew circuit (100) according to claim 1 or 2 ,
A signal generator that generates the continuous signals of a plurality of columns and outputs the continuous signals to each lane of the deskew circuit;
An error detection circuit (23) for detecting an error included in the output signal from the deskew circuit;
A display that outputs that skew is being corrected;
An error measuring device comprising: When the skew correction circuit completes the correction of the skew of each lane, the skew correction circuit outputs a lock signal instructing to stop switching to the selector circuit,
The error measuring device according to claim 3 , wherein when the lock signal is input, the selector circuit stops replacement with the test signal and outputs the continuous signal from each lane. The error detection circuit outputs an operation instruction signal to the selector circuit when an error rate to be detected exceeds a certain value.
5. The error measurement device according to claim 4 , wherein when the operation instruction signal is input, the selector circuit replaces the continuous signal of at least one lane among the input continuous signals with the test signal. A changeover switch (34) for switching the replacement from the continuous signal to the test signal in the selector circuit between automatic and manual;
When the changeover switch is automatic, when the operation instruction signal is input, the selector circuit replaces the continuous signal of at least one lane of the input continuous signals with the test signal,
The error measuring device according to claim 5 , wherein when the changeover switch is manual, the selector circuit outputs a continuous signal from each lane even when the operation instruction signal is input.

Images