JP2000312238A - Optical transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology to reduce a data transmission skew between data channels. SOLUTION: The optical transmission system is provided with transmitter side 1st pins SP1, SP3 connected to a transmission means by a 1st wire, transmitter side 2nd pins SP2, SP4 connected to the transmission means by a 2nd wire shorter than the 1st wire, receiver side 1st pins RP1, RP3 connected to a reception means by a 3rd wire, and receiver side 2nd pins RP2, RP4 connected to the reception means by a 4th wire longer than the 3rd wire. A data transmission skew between a plurality of data channels can be reduced by setting data channels so that the transmitter side 1st pins SP1, SP3 correspond to the receiver side 1st pins RP1, RP3 and the transmitter side 2nd pins SP2, SP4 correspond to the receiver side 2nd pins RP2, RP4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission technology, and for example, relates to a technology effective when applied to an optical interconnection device.

[0002]

2. Description of the Related Art In advanced information processing apparatuses such as large-capacity exchanges and massively parallel computers, electrical wiring has become a bottleneck for improving performance. The technology of transmitting and receiving signals between devices or boards by light is called optical interconnection, and research and development are active as a key technology for realizing high-speed and high-density wiring.

[0003] The optical interconnection technology has a wide range of application depending on the hierarchy of the information processing device.
Various system and device technologies are required. In recent years, broadband, low loss, light weight, small diameter, and EM resistant
Utilizing characteristics that are excellent in I property and suitable for ground-free wiring,
Research and development of a connection distance of about 10 to 100 m, a fixed connection, and an optical interconnect between spatial multiplexing devices / boards have been actively conducted in order to achieve high performance, compactness, and smartness of an information processing device.

Examples of documents describing the optical interconnect technology include the IEICE, IEICE Technical Report,
95-58, OPE95-30, LQE95-34 (1995-07).

[0005]

FIG. 3 shows a device to be compared with the optical interconnection device according to the present invention. The optical interconnection device 400 illustrated in FIG. 3 has four data channels as indicated by ch1 to ch4, and includes a transmission module 10 as a transmission device, a reception module 30 as a reception device, and the transmission module. An optical fiber array 20 that enables transmission of optical information by coupling the receiving module 10 with the receiving module 30. Transmission module 10
Includes an LD (laser diode) array 6 for converting an electric signal into an optical signal, and a transmission IC 5 for driving the signal according to input data. A plurality of pins SP1 to SP4 that can be fitted to a first external device (not shown) are arranged. The plurality of pins SP1 to SP4 and the transmission IC 5
They are connected by the corresponding printed wirings SP1 to SP4. The receiving module 30 includes a PD (photodiode) array 7 for converting an optical signal transmitted via the optical fiber array 20 into an electric signal,
And a receiving IC 8 for receiving the electric signal output from the PD array 7. A plurality of pins RP1 to RP4 that can be fitted with a second external device (not shown) are arranged. The plurality of pins RP1 to RP4 and the receiving IC 8 are connected by the corresponding printed wirings RL1 to RL4, respectively.

In the transmitting module 10 and the receiving module 30, a plurality of pins are alternately shifted to minimize the dimension in the channel arrangement direction as much as possible.
For example, in the transmission module 10, the pin SP
1 and SP3 are arranged near the end of the module 10, and pins SP2 and SP4 are arranged close to the transmission IC5. In the receiving module 30, the pins RP1 and RP3 are arranged near the end of the module 30, and the pins RP2 and RP4 are arranged close to the transmitting IC 5. As a result, in the transmission module 10, the printed wiring S corresponding to the data channels ch1 and ch3
L1 and SL3 are longer than the printed wirings SL2 and SL4 corresponding to the data channels ch2 and ch4. The same applies to the receiving-side module 30. That is, in the receiving module 30, the printed wirings RL1 and RL3 corresponding to the data channels ch1 and ch3 are provided.
Is longer than the print wirings RL2 and RL4 corresponding to the data channels ch2 and ch4.

The inventors of the present invention have examined the transmission module 10 and the reception module 30. As a result, the pin arrangement of the data channel is the same for the transmission module 10 and the reception module 30, which reduces the data transmission skew. It was found to be a factor that makes it bigger.

That is, as described above, the transmission module 1
At 0, the print lines SL1 and SL3 corresponding to the data channels ch1 and ch3 are
2 and ch4 are longer than the printed wirings SL2 and SL4 corresponding to ch4.
In, the data delay of the data channels ch1 and ch3 is longer than that of the data channels ch2 and ch4 due to the longer printed wiring. Similarly, in the receiving module 30, the data channels ch1, ch3
Are printed wiring lines RL1 and RL3 corresponding to data channels ch2 and ch4.
Since the length is longer than L4, at least in the receiving module 30, the data channels ch1 and ch3 are
As compared with the data channels ch2 and ch4, the printed wiring is longer and the signal delay time there is longer.

That is, for the data channels ch1 and ch3, the transmission module 10 and the reception module 30
In both cases, the signal delay time is longer than in the data channels ch2 and ch4. Therefore, in the optical interconnection device 400, the data channel ch
The data transmission skew between the data channels 1 and 3 and the data channels ch2 and ch4 cannot be ignored. To extend the data transmission distance by the optical interconnection device,
It is necessary to reduce the data transmission skew between the data channels as much as possible. For this purpose, a flip-flop for retiming may be arranged for each data channel in the transmission IC 5 or the reception IC 8. However, if a flip-flop for retiming is provided, the chip size of the transmission IC 5 or the reception IC 8 increases accordingly. Further, since a clock signal for operating the flip-flop for retiming must be supplied to the flip-flop, a clock signal transmission system must be provided separately from the data channels ch1 to ch4.

An object of the present invention is to provide a technique for reducing data transmission skew between data channels without providing a flip-flop for retiming.

[0011]

The following is a brief description of an outline of a typical invention among the inventions disclosed in the present application.

That is, transmitting means for converting an electric signal into an optical signal and transmitting the same, a transmitting first pin coupled to the transmitting means by a first wiring, and a second pin shorter than the first wiring. A transmission module comprising: a transmission-side second pin coupled to the transmission means by the wiring of
A receiving means for receiving the optical signal output from the transmitting means and converting it into an electric signal; a first receiving-side pin coupled to the receiving means by a third wiring; and a third wiring. An optical fiber for transmitting an optical signal output from the transmitting module to the receiving means, the receiving module comprising: a receiving side second pin coupled to the receiving means by a long fourth wiring. An array is provided, and a data channel is set such that the transmission-side first pin corresponds to the reception-side first pin and the transmission-side second pin corresponds to the reception-side second pin.

According to the above means, the data channel is set such that the first pin on the transmitting side corresponds to the first pin on the receiving side and the second pin on the transmitting side corresponds to the second pin on the receiving side. Thus, the signal delay difference between the plurality of data channels is reduced, which achieves a reduction in data transmission skew between the plurality of data channels.

[0014] Further, there is provided a transmission module including transmission means for converting an electric signal into an optical signal and transmitting the signal, and a transmission-side pin coupled to the transmission means, wherein an optical signal output from the transmission means is provided. Receiving means for receiving and converting the signal into an electric signal, and a receiving module comprising a receiving pin coupled to the receiving means, further comprising: an optical signal output from the transmitting module to the receiving means. An optical fiber array for transmission is provided, and an added value of a signal wiring length from the transmitting pin to the transmitting means and a signal wiring length from the receiving means to the receiving pin is set between a plurality of data channels. The data channels are set to be substantially equal to each other.

According to the above-described means, the sum of the signal wiring length from the transmitting pin to the transmitting means and the signal wiring length from the receiving means to the receiving pin is determined between a plurality of data channels. Since they are adjusted to be substantially equal to each other, the signal delay difference between the plurality of data channels is reduced, which means that data transmission between the plurality of data channels can be performed without providing a flip-flop for retiming. Achieve skew reduction.

At this time, the transmitting means includes a transmitting IC for amplifying the received electric signal, and an optical signal transmitted to the receiving module via the optical fiber based on an output signal of the transmitting IC. And a light-emitting element array for generating light.

The receiving means includes a photodiode array for converting an optical signal transmitted via the optical fiber into an electric signal, and a receiving means for amplifying the electric signal output from the photodiode array. It can be configured to include an IC.

[0018]

FIG. 1 shows an example of the overall configuration of an optical interconnection device according to the present invention.

As shown in FIG. 1, the optical interconnection device 500 allows, although not particularly limited, data communication by light between two devices (not shown), a transmission module 10 as a transmission device, and a transmission module 10 as a reception device. , And an optical fiber array 20 that enables transmission of optical information by coupling the transmission module 10 and the reception module 30. Although not particularly limited, the number of channels for data transmission is four as indicated by ch1 to ch4.

The transmitting module 10 includes the transmitting module 1
0 includes an LD (laser diode) array 6 for converting an electric signal into an optical signal, and a transmission IC 5 for driving the optical signal according to input data. A plurality of pins SP1 to SP4 that can be fitted to a first external device (not shown) are arranged. The plurality of pins SP1 to SP4 and the transmission IC 5 are connected by the corresponding printed wirings SL1 to SL4, respectively.

Here, since the pins SP1 and SP3 are arranged near the end of the transmitting module 10, the printed wiring S connecting the pins SP1 and SP3 and the transmitting IC 5 is formed.
L1 and SL3 are relatively long wirings. On the other hand, the pins SP2 and SP4 are provided at a position closer to the transmission IC 5 than the pins SP1 and SP3.
Printed wiring S connecting P2, SP4 and transmission IC5
L2 and SL4 are relatively short wirings.

The receiving module 30 includes a PD array 7 for converting an optical signal transmitted via the optical fiber array 20 into an electric signal, and a receiving IC 8 for receiving the electric signal output from the PD array 7. including. A plurality of pins RP1 to R that can be fitted to a second external device (not shown)
P4 is arranged. The plurality of pins RP1 to RP4 and the receiving IC 8 correspond to the corresponding printed wirings RL1 to RL1.
Combined by RL4.

Here, since the pins RP2 and RP4 are arranged near the end of the receiving module 30, the pins RP2 and RP4
2, a printed wiring RL that couples the RP4 and the receiving IC 8
2, RL4 is relatively long. On the other hand, the pin RP
1, RP3 is the receiving IC 8 compared to the pins RP2, RP4.
RP1, R2
Printed wiring lines RL1 and R connecting the P3 and the receiving IC 8
L3 is a relatively short wiring.

The pins SP1 to SP4 of the transmitting module 10 are connected to the pin R of the receiving module 30.
Data channels are set to correspond to P1 to RP4. That is, the pin SP1 coupled to the transmission IC 5 by the relatively long printed wiring SL1 corresponds to the pin RP1 coupled to the receiving IC 8 by the relatively short printed wiring RL1, and is coupled to the transmission IC 5 by the relatively short printed wiring SL2. Pin SP2 corresponds to pin RP2 coupled to receiving IC 8 by a relatively long printed wiring RL2, and pin SP3 coupled to transmitting IC 5 by a relatively long printed wiring SL3 is connected to receiving IC 8 by a relatively short printed wiring RL3. The pin SP4 coupled to the transmitting IC5 by the relatively short printed wiring SL4 corresponds to the pin RP4 coupled to the receiving IC 8 by the relatively long printed wiring RL4. In other words, the pins SP1 to SP4
The sum of the printed wiring length from the receiving IC 8 to the transmitting IC 5 and the printed wiring length from the receiving IC 8 to the pins RP1 to RP4 is adjusted to be substantially equal among the plurality of data channels ch1 to ch4. As a result, the signal delay between the data channels becomes equal to each other, and the data transmission skew can be reduced. By reducing the data transmission skew as described above, the transmission distance by the optical interconnection device can be extended. Hereinafter, the reason will be described.

When data is transmitted at 1 Gb / s, the time per data bit is 1 ns. If the total value of the rise and fall times is 100 ps,
The effective data width is 1 ns-100 ps = 900 ps. In the optical interconnection module, since a plurality of data are transmitted in parallel, the data transmission skew narrows the effective data range. For example, if the skew generated in the transmission IC 5 and the reception IC 8 is 50 ps, the skew generated due to the difference in the light emission timing of the laser diodes LD1 to LD4 is 300 ps, and the skew generated due to the input sensitivity of the reception circuit is 300 ps, the remaining skew (= “Intra-module wiring skew” + “optical fiber skew”) is shown by Expression 1.

[0026]

[Equation 1] 900ps-50ps-300ps-300p
s = 250 ps When the optical fiber skew is set to 1 ps / m, the transmission distance is expressed by Expression 2.

[0027]

## EQU2 ## (250-wire skew in module [p
s]) × 1 [m] When the effective permittivity εr of the wiring in the module is set to 6.8, the transmission time of the wiring in the module is about 0.1 mm / s, which causes the transmission distance to be shortened by 100 m.

Therefore, by reducing the skew,
The transmission distance can be extended.

Here, as shown in FIG. 2, the printed wiring length SL from the transmitting IC 5 to each pin SP in the transmitting module 10 is made equal to each other, and similarly the printed wiring length from the receiving IC to each pin in the receiving module. Are equal to each other, the skew can be reduced as in the case described above. However, in that case, the dimension in the pin arrangement direction (the direction of arrow 9) becomes undesirably long. On the other hand, in the configuration shown in FIG. 1, the pins SP1 to SP4 and the pins RP1 to RP4 can be arranged alternately in the transmission module 10 and the reception module 30, so that the dimension in the pin arrangement direction is undesirably long. It will not be.

FIG. 4 shows a configuration example of the transmission module 10.

The LD array 6 has data channels ch1 to ch1.
Laser diode LD1 arranged corresponding to ch4
~ LD4.

The transmission IC 5 includes a driving circuit 110- for driving the plurality of laser diodes LD1 to LD4.
1 to 110-4. The drive circuit 110-1 for driving the laser diode LD1 is not particularly limited, but an input buffer 111-1 for taking in input data from an input terminal, and an npn-type bipolar transistor 112-1 arranged at a subsequent stage. , 113-1.
The emitters of the transistors 112-1 and 113-1 are differentially coupled by being coupled to the low potential power supply VEE via the constant current source 114-1. Transistor 112-
The output signal from the non-inverting output terminal of the input buffer 111-1 is input to the base electrode
The output signal from the inverted output terminal of the input buffer 111-1 is input to the base electrode 3-1. The collector electrode of the transistor 112-1 is connected to the high potential side power supply VCC, and the collector electrode of the transistor 113-1 is connected to the cathode electrode of the laser diode LD1. In order to speed up the lighting of the laser diode LD1, a constant current source 115-1 for supplying a predetermined bias current to the laser diode LD1 is provided.

Note that another laser diode LD2 to LD
4 is also configured in the same manner as the circuit 110-1, and a detailed description thereof will be omitted.

FIG. 5 shows a detailed configuration of the receiving module 30.

The PD array 7 includes four photodiodes PD1 to PD4 corresponding to the number of data channels. Although not particularly limited, the receiving IC 8 is configured as follows by a known semiconductor integrated circuit manufacturing technique.

The receiving module 30 is provided with photodiodes PD1 to PD4 corresponding to the four optical fibers in the optical fiber array 20.

Four receiving circuits 310-1 for amplifying electric signals obtained by the photodiodes PD1 to PD4, respectively, corresponding to the photodiodes PD1 to PD4.
To 310-4. The receiving circuits have the same configuration.

The receiving circuit 310-1 corresponding to the photodiode PD1, although not particularly limited, generates an input circuit 311-1 for converting a current signal obtained by the photodiode PD1 into a current-voltage signal, and generates a predetermined threshold value. A threshold value generating circuit 316-1, an amplifying circuit 313-1 for amplifying the generated threshold value and an output signal of the input circuit 311-1, and a comparator 314-1 for performing a logical judgment on an output signal of the amplifying circuit 313-1 And an npn-type bipolar transistor 315-1 for driving an external load based on the output signal of the comparator 314-1. The amplifier circuit 313-1 is a differential amplifier circuit having a differential input terminal and a differential output terminal. The comparator 314-1 at the subsequent stage also has a differential input terminal, and the differential output signal of the differential circuit 313-1 is transmitted to the differential input terminal. When the output signal level of the input circuit 311-1 exceeds the threshold value Vref, the comparison circuit 313-1
Output logic is inverted.

According to the above example, the following functions and effects can be obtained.

(1) The pin SP1 coupled to the transmitting IC 5 by the relatively long printed wiring SL1 corresponds to the pin RP1 coupled to the receiving IC 8 by the relatively short printed wiring RL1, and the transmission is performed by the relatively short printed wiring SL2. Pin SP2 coupled to IC5 corresponds to pin RP2 coupled to receiving IC 8 by relatively long printed wiring RL2, and relatively long printed wiring SL3.
The pin SP3 coupled to the transmission IC 5 by the corresponding pin RP3 coupled to the reception IC 8 by the relatively short printed wiring RL3, and the relatively short printed wiring SL
4 corresponds to pin RP4 which is coupled to receiving IC 8 by relatively long printed wiring RL4. That is, the pins SP1 to SP
Printed wiring length from P4 to transmission IC5 and reception IC
8 is adjusted so that the value added to the length of the printed wiring from the pins RP1 to RP4 becomes substantially equal to each other among the plurality of data channels ch1 to ch4. Transmission skew can be reduced.

(2) Since the data transmission skew can be reduced by the operation and effect of (1), the transmission distance by the optical interconnection device can be extended.

(3) In the long-distance transmission, a repeater including a receiving module and a transmitting module is interposed, but the effect of the above (2) can extend the transmission distance by the optical interconnection device. Therefore, the number of repeaters can be reduced, and the cost can be reduced.

(4) As described above, the signal delays between the data channels are equal to each other, and the data transmission skew can be reduced. Therefore, in the transmission module 10 or the reception module 30, a flip-flop for retiming is used. Since there is no need to provide them, an increase in the circuit scale can be suppressed, and an increase in the cost of the device can be suppressed.

Although the invention made by the present inventor has been specifically described above, the present invention is not limited to this, and it goes without saying that various modifications can be made without departing from the gist of the invention.

For example, the number of pins (the number of data channels) can be further increased.

In the above description, the case where the invention made by the present inventor is mainly applied to an optical interconnection device which is the background of use has been described. However, the present invention is not limited to this. It can be widely applied to data transmission devices.

The present invention can be applied on condition that at least parallel data transmission is performed.

[0048]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, the first transmitting pin connected to the transmitting means by relatively long wiring, the second transmitting pin connected to the transmitting means by relatively short wiring, and the receiving means by relatively short wiring. A first pin on the receiving side and a second pin on the receiving side coupled to the receiving means by relatively long wiring are provided. By setting the data channels so as to correspond to the pins, it is possible to reduce data transmission skew between a plurality of data channels without providing a flip-flop for retiming.

Further, the sum of the signal wiring length from the transmitting pin to the transmitting means and the signal wiring length from the receiving means to the receiving pin is adjusted so that the plurality of data channels are substantially equal to each other. Therefore, the signal delay difference between the plurality of data channels is reduced, and the skew of data transmission between the plurality of data channels can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an overall configuration example of an optical interconnection device according to the present invention.

FIG. 2 is an explanatory diagram of a configuration example of a device to be compared with the optical interconnection device.

FIG. 3 is an explanatory diagram of another configuration example of a device to be compared with the optical interconnection device.

FIG. 4 is a circuit diagram illustrating a configuration example of a transmission module included in the optical interconnection device.

FIG. 5 is a circuit diagram illustrating a configuration example of a receiving module included in the optical interconnection device.

[Explanation of symbols]

 Reference Signs List 5 transmission IC 6 LD array 7 PD array 8 reception IC 10 transmission module 20 optical fiber SP1 to SP4, RP1 to RP4 pin SL1 to SL4, RL1 to RL4 print wiring 500 optical interconnection device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K002 AA01 AA03 BA07 BA13 BA31 CA01 DA05 FA01 5K034 AA05 EE01 HH01 HH02 JJ11 KK04

Claims (4)

[Claims] A transmitting means for converting an electric signal into an optical signal and transmitting the optical signal; a transmitting first pin coupled to the transmitting means by a first wiring; and a second pin shorter than the first wiring. The transmitting side second connected to the transmitting means by wiring
A transmitting module comprising: a transmitting module, a receiving module configured to receive an optical signal output from the transmitting module and converting the optical signal into an electric signal; and a first receiving-side pin coupled to the receiving module by a third wiring. A receiving module comprising: a receiving-side second pin coupled to the receiving means by a fourth wiring longer than the third wiring; and transmitting an optical signal output from the transmitting module to the receiving means. Wherein the data channel is set such that the first pin on the transmitting side corresponds to the first pin on the receiving side, and the second pin on the transmitting side corresponds to the second pin on the receiving side. An optical transmission device, comprising: 2. A transmitting module comprising: transmitting means for converting an electric signal into an optical signal for transmission; a transmitting module including a transmitting pin coupled to the transmitting means; and an optical signal output from the transmitting means. A receiving module including receiving means for receiving and converting to an electric signal, a receiving-side first pin coupled to the receiving means, and transmitting an optical signal output from the transmitting module to the receiving means An optical fiber array for: and the sum of the signal wiring length from the transmitting pin to the transmitting means and the signal wiring length from the receiving means to the receiving pin, between a plurality of data channels An optical transmission device characterized by being adjusted to be substantially equal to each other. 3. The transmitting means includes: a transmitting IC for amplifying a captured electric signal; and an optical signal transmitted to the receiving module via the optical fiber based on an output signal of the transmitting IC. 3. The optical transmission device according to claim 1, further comprising a light emitting element array for generating light. 4. The receiving means comprises: a photodiode array for converting an optical signal transmitted via the optical fiber into an electric signal; and a receiving means for amplifying the electric signal output from the photodiode array. 4. The optical transmission device according to claim 1, further comprising an IC.