JP3409739B2 - Automatic skew adjuster - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic skew for automatically adjusting a skew between transmission lines when serial transmission is divided into a plurality of transmission lines in high-speed parallel-serial conversion transmission. Regarding the adjusting device.

[0002]

2. Description of the Related Art In a high-speed parallel-serial conversion transmission, when an attempt is made to increase the transmission rate, either the serial transmission speed is increased, or the serial transmission speed is increased and the number of bits is increased. On the other hand, when transmitting and receiving multiple bits, either multiplexing or dividing the high-speed serial transmission line into several lines is performed. In this case, there are multiple serial transmission lines when parallel-serial conversion is performed. The skew between them becomes a problem. Usually, the transmission line is designed so that the skew of the transmission line is minimized, but it is necessary to strictly align the length of the transmission line.

As described above, in the case of the conventional high-speed serial transmission, when the serial transmission paths are plural, the skews must be aligned with a considerable accuracy, and the higher the serial transmission speed, the higher the skew becomes. There were some issues to consider.

[0004]

According to the present invention, when a plurality of serial transmission lines are used as in the above-mentioned high-speed parallel-serial conversion transmission, the transmission between the serial transmission lines is automatically adjusted by adjusting the skew between the serial transmission lines. An object of the present invention is to provide an automatic skew adjustment device that enables transmission that is not affected by the skew of a road.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 converts a parallel input signal into a plurality of serial signals and transmits them to the transmission path, and a plurality of transmitting sections. A receiving unit for converting a plurality of serial signals received via a transmission line composed of a serial transmission line into a parallel signal and outputting the parallel signal, and a test signal having a predetermined test pattern, which is provided in the transmitting unit. And a test pattern generating section for generating a test pattern generating section for receiving the predetermined test pattern,
A test pattern receiving unit that measures a transmission delay difference between the serial transmission lines of the transmission line, and one that is provided in at least one of the transmitting unit and the receiving unit, and is measured by the test pattern receiving unit. It was based on the delay difference, characterized by comprising a delay means for controlling the delay amount of the signal transmitted in each serial transmission line, further, the delay hand
Stage holds the control state of the delay amount for each transmission line.
It is characterized by having means for

Further, in the invention according to claim 2, the transmitting section has a first switching means for selecting and transmitting either one of the input normal signal and the test signal, and the receiving section. It is characterized in that the section has a second switching means for selecting whether to connect to a means for converting a received normal signal into parallel or to connect to the test pattern receiving section. According to a third aspect of the present invention, a synchronization pattern for detecting the phase of the signal is preset in the test signal, and the test signal is sent in phase to each transmission line. Is characterized by.

Further, the automatic skew adjusting device of the present invention is
As described in claim 4 , it is possible to further include a transmission line including the plurality of serial transmission lines.

According to the present invention, the skews due to the difference in the lengths of the transmission paths can be reduced by electrically aligning the skews of the transmission paths instead of physically aligning the skews. Even when the transmission line is changed, it can be adjusted, so it is effective even when the transmission line is changed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an automatic skew adjusting device according to the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an embodiment of the automatic skew adjusting apparatus of the present invention. The present embodiment is roughly divided into a transmission unit 17 that converts an input parallel signal into a serial signal and transmits the transmission signal, a transmission line 6 that transmits the serial signal transmitted from the transmission unit 17, and a transmission line 6. Receiving unit 18 that receives the sent serial signal, converts it to a parallel signal, and outputs it
It consists of

The parallel signal input from the signal transmission unit 15 of the transmission unit 17 is input to the input terminal of the serial transmission device 1. In the serial transmission device 1, the input parallel signal is parallel-serial converted into a plurality of serial signals, which are input to the skew adjusting unit 3 via the serial transmission line 2 including a plurality of serial transmission lines. The skew adjustment unit 3 is controlled by the control unit 19 described later, and performs skew adjustment between a plurality of serial signals. Then, the skew-adjusted signal passes through the transmission path 6 through the connector 4 and the connector 5 and is transmitted to the receiving unit 18 connected by the connectors 11 and 10.

On the receiving side, a plurality of serial signals pass through the switch section 9 and further through the serial transmission line 8 to the serial receiving device 7, undergo serial-parallel conversion, and then are transmitted to the signal receiving section 16. Are converted back into parallel signals and output.

The skew adjustment unit 3 shown in FIG. 1 with reference to FIG.
Will be described in detail. Skew adjustment unit 3 shown in Figure 2
Is a plurality of delay processing units 1 (reference numeral 21), 2 (2
3), ..., N (24) and (n is the number of transmission lines in the transmission line 6), and a control unit 25 for controlling each delay processing unit 1 (21), 2 (23) ,. And a test pattern generator 28.

One of the inputs from the serial transmission line 2 is input to, for example, the input side of the delay line 20 in the delay processing section 1 (21), and the delay amount is adjusted by the multiplexer 22 according to the designation from the control section 25. Done. After that, the output of the multiplexer 22 is the TTL → LVDS conversion unit 27 (TTL: Transisto
r−Transistor Logic, LVDS: Low Voltage Differential
Signaling) to LVDS level, then TTL
→ The LVDS conversion unit 27 outputs one serial signal via a pair of signal lines, and the skew adjustment unit 3 outputs one serial signal.

Details of the switch unit 9 shown in FIG. 1 will be described below with reference to FIG. The switch unit 9 includes a transmission line 6
It is composed of a plurality of switch units 1 (reference numeral 43), 2 (44), ... Each switch unit 1 (43), 2 (44), ..., n (45)
Outputs the input serial signal 1-1 'or output 2-2'
The switch 40 for switching and outputting to either one of the two, the test pattern receiving section 41 connected to the output 2-2 ′ of the switch 40, and the output 1-1 ′ of the switch 40.
It is composed of LVDS → TTL converter 42, and normally switch 40 outputs the input signal to LVDS → TTL converter 42, from each switch unit 1 (43), 2 (44), ..., n (45). Outputs a TTL level signal. Switching of each switch 40 is performed by the control unit 1 of FIG.
Done by 9. On the other hand, when measuring the skew of the transmission line, the switch 40 is connected to the test pattern receiving unit 41 side, the test pattern receiving unit 41 measures the delay amount of the transmission line, and sends it to the control unit 19 side of FIG. .

Next, the operation of the embodiment described with reference to FIGS. 1 to 3 will be described with reference to the drawings. In FIG. 1, the parallel transmission data output from the signal transmission unit 15 is input to the input side of the serial transmission device 1.
The input data width of the serial device 1 varies depending on the device used, but is, for example, 28-bit width. The serial transmission device 1 performs parallel-serial conversion. For example, a 28-bit wide parallel signal is converted into a signal on four serial data transmission lines and one serial clock transmission line. After the parallel-serial conversion, the data is transmitted through the serial transmission line 2 and input to the skew adjusting unit 3.

The skew adjusting unit 3 has a configuration as shown in FIG. 2 described above, and sets the delay amount and the L level from the TTL level.
Mainly performs conversion to VDS level. The purpose of converting to LVDS level is to increase the distance of the transmission line and to use EMC (Electrimag
This is because there are advantages such as netic Compayobility).

Here, a method of setting the delay amount will be described. In FIG. 2, when setting the delay amount, since the control unit 25 measures the difference in the delay amount due to a plurality of transmission lines, unlike the normal processing, from the test pattern generating unit 28 as a signal for skew adjustment, A test signal having a common (in-phase) measurement pattern is sent to each transmission line. A synchronization pattern is preset in the test signal so that the phase can be known. This signal is switched to the normal signal in each TTL → LVDS converter 27 and sent to the receiving side. This test signal is transmitted as a signal at the same timing among a plurality of transmission lines. On the other hand, on the receiving unit 18 side, the operation of the switch 40 in each switch unit 9 shown in FIG. 3 is switched to the test pattern receiving unit 41 side.

Each test pattern receiving section 41 receives the transmitted test signal and transmits the timing of the synchronization signal to the control section 25 via the control section 19 for each transmission path. Control unit 25
In consideration of the reception timing which is different for each transmission line, the operation of adjusting the timing of each transmission line to the most delayed timing is performed. This is performed by controlling the delay time setting of each delay line 20 of FIG. 2 by each multiplexer 22. It should be noted that the state in which all the timings are the same is held and held until the next setting. The above is the setting of the delay amount.

The data for which the delay amount has been set passes through the transmission line 6 and is connected to the receiving unit 1 by the connector 11 and the connector 10.
Entered in 8. In the receiver 18, the LVDS signal is sent to the switch 9
Is input to each switch 40 and the normal operation is LVDS → TTL
It is connected to the conversion unit 42. In each LVDS → TTL converter 42, LVD
S level signal is converted to TTL level signal. The data signal converted to the TTL level enters the serial receiving device 7 via the serial transmission line 8, is serial-parallel converted by the serial receiving device 7, and is returned to the original parallel signal in the signal receiving unit 16 Entered in.

By the above operation, the receiving side takes into account the delay difference due to the difference in the transmission paths, and it is possible to receive a plurality of serial signals at the same timing.

Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 4, the same components as those shown in FIG. 1 are designated by the same reference numerals, and the components corresponding to those shown in FIG. 1 are designated by the same reference numerals with an alphabetical letter “a” added. . The most different point of the present embodiment compared to the embodiment shown in FIG. 1 is that the skew adjusting unit 3a is arranged not on the transmitting side but on the receiving side.

The signal transmission unit 15a in the transmission unit 17a has the same configuration as the signal transmission unit 15 of FIG. 1 except that the test pattern generation unit 28 of FIG. 2 is added. A normal data signal and a test signal are switched and output according to the signal. The serial transmission device 1a has a configuration in which the same one as the TTL → LVDS conversion unit 27 of FIG. 2 is added to the serial transmission device 1 of FIG. 1, and after converting each TTL serial signal to LVDS, Output from connector 4.
The switch unit 9 has the same configuration as that shown in FIG. 3 described above, receives a plurality of LVDS serial signals from the connector 10, and normally operates via each switch 40 in response to a control signal from the control unit 19a. And outputs a plurality of TTL serial signals converted by each LVDS → TTL converter 27. Skew adjustment unit 3a
From the skew adjustment unit 3 to the test pattern generation unit 28 in FIG.
And a plurality of TTL → LVDS conversion units 27 are removed, and the delay amount of each serial signal input from the serial transmission line 8 is adjusted and output for each transmission line under the control of the control unit 19a.

With the above configuration, in the present embodiment,
When adjusting the skew, unlike the previous embodiment, the transmitter 17a
The signal transmitting unit 15a generates a test signal having a predetermined test pattern, and the test pattern receiving unit 41 in the switch unit 9 of the receiving unit 18a receives the test signal. Then, the timing of the synchronization signal is transmitted from each test pattern receiving section 41 in the switch section 9 to the signal transmitting section 15a via the control section 19a for each transmission path. The signal transmission unit 15a performs an operation of adjusting the timing of each transmission path to the timing that is the most delayed, considering the reception timing that differs for each transmission path.

The configuration of the automatic skew adjusting device according to the present invention is not limited to the configuration of each of the above-described embodiments, and, for example, the skew adjusting unit is provided on both the transmitting side and the receiving side, and the transmission is performed. Modifications such as transmitting a TTL signal on the path 6 are possible as appropriate.

[0025]

As described above, according to the present invention, the following effects can be obtained. The first effect is that the skew of the transmission path is less taken into consideration, and the degree of freedom in design is increased. The reason is that the skew of the transmission line can be adjusted and the difference in skew can be absorbed. The second effect is that stable operation is possible even when the transmission path is changed. The reason is that adjustment is possible on the transmitting and receiving sides without being influenced by the transmission path.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an automatic skew adjustment device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a skew adjustment unit 3 in FIG.

FIG. 3 is a block diagram showing the configuration of a switch unit 9 in FIG.

FIG. 4 is a block diagram showing the configuration of another embodiment of the automatic skew adjusting apparatus according to the present invention.

[Explanation of symbols]

1, 1a ... Serial transmission device, 2 ... Serial transmission line,
3, 3a ... Skew adjustment part, 4, 5, 10, 11 ... Connector, 6 ...
Transmission line, 7 ... Serial receiving device, 8 ... Serial transmission line, 9 ... Switch unit, 15, 15a ... Signal transmitting unit, 16 ... Signal receiving unit, 17, 17a ... Transmitting unit, 18, 18a ... Receiving unit, 19, 19a ...
Control unit, 20 ... Delay line, 21 ... Delay processing unit 1, 2
2 ... Multiplexer, 23 ... Delay processing section 2, 24 ... Delay processing section n, 25 ... Control section, 27 ... TTL → LVDS conversion section, 28 ...
Test pattern generator, 40 ... Switch, 41 ... Test pattern receiver, 42 ... LVDS → TTL converter, 43 ... Switch 1,
44 ... Switch section 2, 45 ... Switch section n

Claims (4)

(57) [Claims] 1. A transmission unit for converting an input parallel signal into a plurality of serial signals and transmitting the serial signals to a transmission line composed of a plurality of serial transmission lines, and a plurality of serial signals received through the transmission lines in parallel. A receiver provided for converting into a signal and outputting the signal, a test pattern generator for generating a test signal having a predetermined test pattern, and a receiver provided for the receiver. Provided in at least one of the test pattern receiving unit, which receives the predetermined test pattern and measures the delay difference in transmission between the serial transmission lines of the transmission line, and the transmitting unit or the receiving unit. A delay means for controlling a delay amount of a signal transmitted through each serial transmission line based on a delay difference measured by the test pattern receiving section, wherein the delay means is , The control state of the delay amount for each transmission line
An automatic skew adjusting device having means for holding . 2. The transmitting section has a first switching means for selecting and transmitting one of an input normal signal and a test signal, and the receiving section receives a normal signal. The automatic skew according to claim 1, further comprising: second switching means for selecting whether to connect to a means for parallel conversion of the signal or to connect to the test pattern receiving section. Adjustment device. 3. The test signal is preset with a synchronization pattern for detecting the phase of the signal,
3. The automatic skew adjusting apparatus according to claim 1, wherein the test signal is sent out in phase with each transmission line. 4. A further automatic skew adjusting apparatus according to any one of claims 1 to 3 including a transmission line consisting of the plurality of serial transmission line.