KR102665188B1 - Active Optical Cable Device for Two-way optical communication - Google Patents

Abstract

The present invention provides an AOC device for short-distance optical communication. The AOC device of the present invention is configured to further include an electric conductor between the transmitting end and the receiving end to feed back the monitoring signal of the receiving end. The receiving end controls the high-frequency component compensation of the equalization filter, acquires the received signal size determination result and the high-frequency component compensation result of the equalization filter as a monitoring signal, and feeds back the acquired monitoring signal to the transmitting end through the electric conductor. A monitoring means is further included, and the transmitting end receives a monitoring signal from the receiving end fed back through the electric conductor, and based on the received monitoring signal, a high frequency component control code of the high frequency component control circuit, and the optical element driving circuit. It is characterized in that it further includes a transmitting end control means for controlling the optical signal output size control code.

Description

Active Optical Cable Device for Two-way optical communication}

The present invention relates to an AOC device and a method for controlling its operation, and more specifically, to an AOC device implemented as an adaptive system dedicated to AOC (Active Optical Cable) that can reduce power consumption and reduce cost, and to a method for controlling its operation.

Optical communication is widely used to build a broadband communication network by utilizing the broadband, low-loss characteristics of optical fiber cables and the high transmission speed and long-distance transmission characteristics. In this way, optical communication was mainly used for long-distance communication, and electrical communication using electric cables was mainly used for short-distance communication.

However, recently, with the development of ICT technology, the transmission speed of data communication has increased, and due to the increase in transmission speed, the attenuation of high frequencies in electric conductors has increased, making telecommunication transmission distances shorter.

In order to overcome the transmission distance limitations of telecommunication cables as described above, this product is equipped with optical elements and optical communication ICs in the form of modules on both ends of the optical fiber cable that transmits optical signals. AOC (Active Optical Cable) ('short-distance optical cable') is used for short-distance optical communication. 'Optical communication cable device') is used. It is equipped with the same connector as the electric cable, allowing immediate replacement of the electric cable.

Short-distance optical communication is used for transmission distances of 1 to 100 m in intra-building communication, inter-rack communication, and intra-device communication, and requires low cost and low power consumption compared to long-distance optical communication. Fiber optic cables use SMF (Single-Mode Fiber) for long-distance optical communication and are relatively expensive. For short-distance optical communication, MMF (Multi-Mode Fiber) is used and are relatively inexpensive. As a light source, DFB Laser is used for long-distance optical communication. Vertical-cavity surface-emitting laser (VCSEL) is used in short-distance optical communications. Compared to DFB Laser, VCSEL is cheaper and consumes less power.

The main application field of AOC for short-distance optical communication is as a communication connection cable within a data center. Data centers are rapidly expanding with the advent of cloud computing and big data. Data centers consist of thousands to tens of thousands of server computers, and to share data between servers, much more communication connections are required than the number of servers.

Compared to long-distance optical communication cables, short-distance optical communication cables are used in large quantities. These short-distance optical communication cables are used in large quantities in large-scale computer facilities such as data centers.

A data center is divided into multiple server rooms, and a large number of racks are installed in each server room. In each rack, communication equipment, servers, and storage are stacked. Within each rack within a data center, servers, storage, and communication equipment are connected using DAC (Direct-Attach Cable), a data center communication cable connected with electrical conductors (0 to 3 m), and the rack and Racks are connected using AOC cables (3 to 30 m), and server rooms are connected via transceiver cables (30 to 100 m).

However, the DAC and AOC used as connection cables in data centers do not differ in appearance, and the transceiver is a structure inherited from existing long-distance communication (long-distance/short-distance product). Because AOC is treated the same as DAC, there are no standards for its internal structure, but since the transceiver uses optical fibers, the performance of the optical unit is standardized.

As the power consumption of data centers continues to increase, power consumption must be reduced to lower operating costs. In other words, the demand for technology to reduce power consumption in terms of hardware and software is highlighted. Additionally, data center hardware typically has a lifespan of 5 to 6 years, but as operating costs continue to increase, it is most efficient to replace it every three years, taking into account the superior performance and power efficiency of new hardware.

AOC products currently used in data centers consume a constant amount of power regardless of the transmission distance. Since most AOC manufacturers provide AOC products that support up to 100m instead of 30m, the power consumption of transceiver products using MMF and the power consumption of AOC are the same. In other words, the power consumption of 1m AOC, 100m AOC and Transceiver products is the same at 3.5W. The reason is that the optical communication IC for the transceiver is used in the AOC and the AOC is manufactured by fixing the optical fiber cable to the transceiver product.

The reason why power consumption is the same regardless of transmission distance is because it is designed taking margins due to tolerances in the manufacturing process into consideration. Since all components used in the system have tolerances, the design must accommodate the worst case scenario.

The only variable that can be selected by the AOC module manufacturer is the optical transmitter output current. Ultimately, the optical output must be set to a certain level so that it operates normally even if only the worst parts are used. For example, assuming that the optical transmitter output current requires 1.53 mA when using the best components, 3.063 mA when using the intermediate components, and 7.144 mA when using the worst components, considering yield, the worst You must select 7.144mA, which satisfies the use of components. More than twice the output current is consumed for stable operation.

In addition, the VCSEL driving current, which is the light source of a normally operating optical transmitter, is inevitably designed with excessive performance. Due to the temperature dependence of the VCSEL device, the current-to-light conversion efficiency of the VCSEL device decreases as the temperature increases. The current required to create an optical signal of the same size increases as the temperature increases. Therefore, the VCSEL driving current must be selected to be large according to the maximum operating temperature limit, resulting in excessive performance.

In order to maintain the driving current of the VCSEL in an optimal state rather than an excessive state, monitoring to compensate for high-frequency components is required. Optical fiber has a very wide bandwidth, but optical devices and integrated circuits have bandwidth limitations. The wider the bandwidth of optical devices, the higher the price. If integrated circuits compensate for the bandwidth limitations of optical devices, the use of low-cost optical devices will become possible.

The bandwidth compensation method of the integrated circuit is to strengthen the high-frequency component in the VCSEL driving current by applying a pre-emphasis technique to the optical transmitter, and to compensate for the high-frequency component in the restored current signal by applying an equalizer circuit to the optical receiver to produce an attenuated high-frequency signal. must be compensated appropriately. If it is insufficient or excessive, signal distortion occurs.

Therefore, the results of monitoring the reduction in optical output and high-frequency components at the receiving end must be transmitted to the transmitting end, and the transmitting end compensates for the high-frequency components and always outputs only the optical signal in the required sequence, thereby reducing power consumption. This allows low-cost optical sources to be used. You can now use rulers.

Existing analog monitoring methods include a method that detects the current output of a photodetector, a method that converts the current output of the photodetector into a voltage signal and then measures the size, but this has the problem of making it difficult to monitor high-frequency signals. there is. As an existing monitoring method, the digital method converts optical signals into electrical signals and then restores the data, or digitally converts them to observe signal quality. The method of converting to electrical signals uses a clock data recovery circuit, so it consumes less power. And the circuit area is large, and the digital conversion method uses large digital logic for the analog-to-digital converter and cue-factor determination, so it has the disadvantage of large power consumption and large circuit area.

The existing feedback circuit is a method of transmitting monitoring results between data to be sent in two-way communication between side A and side B. As the protocol becomes more complex, the overall circuit area increases, and the final data transmission efficiency decreases. The disadvantage is that it cannot be used for AOC, which is one-way transmission.

Another existing feedback method is to monitor the output of the optical transmitter and apply it to the optical transmitter. It is mainly used for long-distance communication, and requires optical elements and optical components to create a dedicated monitoring circuit, and observes the signal at the receiving end. Strictly speaking, it does not completely monitor the transmission signal.

Another existing feedback method is to add a feedback-only optical communication channel, which has the disadvantage of adding one channel's worth of Guam fiber cables, optical devices, and optical components.

The present invention was proposed to solve the above-described conventional problems, and is an AOC device that reduces power consumption and can be implemented as a low-cost product by feeding back the monitoring signal from the receiving end to the transmitting end and controlling it with an optimized optical output current. It is intended to provide a method for controlling its operation.

In addition, the present invention is intended to enable low-cost implementation by feeding back the monitoring signal without adding an optical channel by constructing an integrated circuit of the transmitting end and the receiving end so that an electric conductor can be used as a signal line for feeding back the monitoring signal.

In addition, the present invention configures an adaptive equalizer at the receiving end, monitors the input signal size determination result and high-frequency component compensation result from the adaptive equalizer, and transmits them to the transmitting end, making it possible to control optical communication with optimal transmission power in real time. It is intended to be so.

The present invention to achieve the above object,

In the AOC device that communicates optically by connecting an optical fiber cable between the transmitting end and the receiving end,

Between the transmitting end and the receiving end, an electric conductor is further included to feed back the monitoring signal from the receiving end to the transmitting end,

At the receiving end,

An optical receiver integrated circuit including an equalization filter that compensates and equalizes the high-frequency components of the received signal is included,

Monitoring means controls the high-frequency component compensation of the equalization filter, acquires the received signal size determination result and the high-frequency component compensation result of the equalization filter as a monitoring signal, and feeds back the acquired monitoring signal to the transmitting end through the electric conductor. Includes more,

At the transmitting end,

It includes an optical transmitter integrated circuit including a high-frequency component control circuit that controls the high-frequency component of the input signal and an optical element driving circuit that drives the optical element,

A transmitting end that receives the monitoring signal from the receiving end fed back through the electric conductor and controls the high frequency component control code of the high frequency component control circuit and the optical signal output size control code of the optical element driving circuit based on the received monitoring signal. It is characterized by further including control means.

In an embodiment of the present invention, in a configuration where an MCU is included in a unidirectional AOC device and a bidirectional AOC device, the functions of the transmitting end control means and the monitoring means can be included in each MCU.

In another embodiment of the present invention, the one-way AOC device and the two-way AOC device each include an optical signal reception and high-frequency component monitoring circuit in the optical receiver integrated circuit, and an optical signal output and high-frequency component control circuit in the optical transmitter integrated circuit. It can be configured by including more circuits.

The one-way AOC device according to an embodiment of the present invention,

An optical transmitter integrated circuit that controls the high frequency component of the input electrical signal and generates an optical device driving signal in response to the electrical signal, and is driven by the optical device driving signal of the optical transmitter integrated circuit to generate an optical signal, thereby creating an optical fiber cable. A first connector unit including an optical element for optical output that transmits to,

It includes an optical element for receiving light that receives an optical signal transmitted through the optical fiber cable, and an optical receiver integrated circuit that converts the output current of the optical element for receiving light into voltage, compensates for the high frequency component of the received signal, and outputs it as an electric signal. A second connector portion,

Consisting of one or more optical fiber cables coupled between the first connector and the second connector to transmit optical signals,

A transmitter MCU included in the first connector unit and including optical signal output control and high-frequency component control functions of the optical transmitter integrated circuit,

A receiving end MCU included in the second connector unit and including optical signal reception control and high frequency component control functions of the optical receiver integrated circuit,

It includes an electrical conductor for monitoring signal feedback connected between the receiving end MCU and the transmitting end MCU,

The receiving end MCU monitors the size determination result and high frequency component compensation result information of the received signal of the receiving end integrated circuit and feeds them back to the transmitting end MCU through the electrical conductor, and the transmitting end MCU integrates the transmitting end by the monitoring signal fed back. It is characterized by being configured to control the optical signal output and high-frequency component compensation signal of the circuit.

The optical transmitter integrated circuit,

An electrical signal input circuit that receives an electrical signal, a high-frequency component control circuit that controls to emphasize the high-frequency component of the current signal for driving the optical device, and an optical device for optical output based on the electrical signal with the high-frequency component controlled ( An optical device driving circuit that drives the VCSEL) and the monitoring signal fed back by the transmitting terminal MCU are interfaced with the high frequency component control code of the high frequency component control circuit and the optical signal output size control code of the optical device driving circuit for optical output to the transmitting terminal. It is characterized by including an internal memory and an interface circuit at the transmitting end that controls the output current of.

The optical receiver integrated circuit,

A TIA (Trans-Impedance Amplifier) that converts the photoelectrically converted current signal into a voltage signal through the light receiving optical device (PD), and an equalization filter are used to filter the received signal to compensate for the high-frequency component, and to adjust the size of the input signal and An adaptive equalizer that continuously monitors high-frequency components and uses this to optimally compensate for the high-frequency components of the equalization filter, and an electrical signal driving circuit that outputs a received signal with compensated high-frequency components from the adaptive equalizer as an electrical signal; It is characterized by comprising an internal memory and an interface circuit at the receiving end that transmits the input signal size determination result of the adaptive equalizer and the high frequency component compensation result information to the receiving end MCU.

The adaptive equalizer,

a first equalization filter that compensates for and outputs high-frequency components of the received signal according to an equalizer control code;

a second equalization filter that receives the received signal in parallel with the first equalization filter, compensates for high-frequency components using an equalizer monitoring code, and outputs it as a monitoring signal;

a magnitude comparator that compares the magnitude of the monitoring signal of the second equalization filter with a reference voltage set by a reference voltage code;

By changing the equalizer monitoring code to be provided to the second equalization filter and the reference signal of the magnitude comparator, the comparator output of the magnitude comparator is sampled and converted into digital data, and the optimal equalizer control code is found based on the digital data. a digital control unit that controls an equalizer control code of the first equalization filter; It is characterized by including.

A two-way AOC device according to another embodiment of the present invention,

an optical transmitter integrated circuit that emphasizes and controls high-frequency components of an input electrical signal and drives an optical element in response to the electrical signal; An optical device for optical output that converts an electrical signal into an optical signal under the control of the optical transmitter integrated circuit and transmits it through an optical fiber cable; An optical element for receiving light that receives an optical signal received through an optical fiber cable; an optical receiver integrated circuit that converts the current signal of the optical element for light reception into a voltage signal, compensates for the high-frequency component of the received signal converted into a voltage signal, and outputs it as an electric signal; An MCU for integrated circuit control including optical signal output control and high frequency component control functions of the optical transmitter integrated circuit and the optical receiver integrated circuit; First and second connector parts including;

a plurality of optical fiber cables having first and second connectors coupled at both ends to transmit and receive optical signals;

First and second electrical conductors for monitoring signal feedback arranged and connected with the optical fiber cables between the integrated circuit control MCUs of the first and second connector parts; It is composed including,

The integrated circuit control MCU feeds back the received signal size determination result and high-frequency component compensation result information of the optical receiver integrated circuit to the corresponding communication counterpart integrated circuit control MCU through the first and second electrical conductors for the monitoring signal feedback,

The integrated circuit control MCU is configured to control optical signal output and high-frequency component compensation of the optical transmitter integrated circuit based on a feedback monitoring signal.

A one-way AOC device according to another embodiment of the present invention,

An optical transmitter integrated circuit that controls the high frequency component of the input electrical signal and generates an optical device driving signal in response to the electrical signal, and is driven by the optical device driving signal of the optical transmitter integrated circuit to generate an optical signal, thereby creating an optical fiber cable. A first connector unit including an optical element for optical output that transmits to;

It includes an optical element for receiving light that receives an optical signal transmitted through the optical fiber cable, and an optical receiver integrated circuit that converts the output current of the optical element for receiving light into voltage, compensates for the high frequency component of the received signal, and outputs it as an electric signal. a second connector unit;

Consists of one or more optical fiber cables coupled between the first connector and the second connector to transmit optical signals,

It includes an electrical conductor for monitoring signal feedback connected between the optical receiver integrated circuit and the optical transmitter integrated circuit to transmit the monitoring signal from the receiving end to the transmitting end;

The optical receiver integrated circuit further includes an optical signal output and high frequency component monitoring circuit that monitors the magnitude determination result and high frequency component compensation result information of the received signal and feeds them back to the optical transmitter integrated circuit through the electrical conductor,

The optical transmitter integrated circuit includes a high frequency component control code of the optical transmitter integrated circuit and an optical signal output size control code based on a monitoring signal fed back from the optical signal output and high frequency component monitoring circuit. It is characterized in that it further includes a circuit.

A two-way AOC device according to another embodiment of the present invention,

an optical transmitter integrated circuit that emphasizes and controls high-frequency components of an input electrical signal and drives an optical element in response to the electrical signal; An optical device for optical output that converts an electrical signal into an optical signal under the control of the optical transmitter integrated circuit and transmits it through an optical fiber cable; An optical element for receiving light that receives an optical signal received through an optical fiber cable; an optical receiver integrated circuit that converts the current signal of the optical element for light reception into a voltage signal, compensates for the high-frequency component of the received signal converted into a voltage signal, and outputs it as an electric signal; first and second connector units comprising a;

a plurality of optical fiber cables having first and second connectors coupled at both ends to transmit and receive optical signals;

It further includes first and second electrical conductors for monitoring signal feedback, which are connected between the optical receiver integrated circuit and the optical transmitter integrated circuit of each of the first and second connector parts and transmit the monitoring signal from the receiving end to the transmitting end.

The optical receiver integrated circuit monitors the magnitude determination result and high frequency component compensation result information of the received signal, and outputs an optical signal and high frequency component to be fed back to the optical transmitter integrated circuit on the communication counterpart through the first or second electric conductor. A monitoring circuit is further included,

The optical transmitter integrated circuit includes an optical signal output and high frequency signal that controls a high frequency component control code of the optical transmitter integrated circuit and an optical signal output size control code based on the monitoring signal fed back from the optical signal output and high frequency component monitoring circuit of the communication counterpart. It is characterized in that it further includes a component control circuit.

Meanwhile, the operation control method of the AOC device according to the embodiment of the present invention is:

In the operation control method of the AOC device, which monitors the signal transmitted from the transmitting end at the receiving end and feeds back the monitoring signal,

The receiving end is,

An input signal size determination step of comparing the range of the input signal with the range of the reference signal and adjusting the size of the input signal to fit within the range of the reference signal;

When the input signal is adjusted within the reference signal range, an equalization filter monitoring step to find the optimal high-frequency band gain by monitoring the equalization characteristics of the equalization filter at the receiving end;

collecting the input signal size determination result of the input signal determination step and the high frequency component compensation result information of the equalization filter monitoring step and feeding them back to the transmitter;

In the input signal size determination step, if the input signal is smaller than the reference signal range, it is determined that there is no input signal and the equalization filter is terminated for a certain period of time. In the equalization filter monitoring step, the optimal high-frequency band gain is found and applied to the equalization filter. , terminating the equalizer monitoring for a certain period of time, and when the predetermined time elapses, turning on the equalizer monitoring and equalization filter to cycle to the input signal size determination step; performing a waiting step;

The transmitting end is,

A transmitting end adjustment step of controlling the high frequency component of the transmitting end and the optical signal output size based on the monitoring signal fed back from the receiving end; It is characterized by including.

According to the present invention with this configuration, the monitoring signal from the receiving end is fed back to the transmitting end through a low-cost electric conductor, so that the transmitting end can control the optimal high-frequency component control code and optical signal output size. As a result, optical output optical devices and their driving circuits can be implemented at low cost and power consumption can be reduced. Therefore, it has the effect of reducing the overall manufacturing cost of short-distance AOC devices and reducing power consumption in large-capacity facilities such as data centers where numerous short-distance AOC devices must be installed.

1 is a configuration diagram of a one-way one-way AOC device according to the present invention.
Figure 2 is a configuration diagram of a two-way AOC device showing another embodiment of the present invention.
Figure 3 is a detailed configuration diagram for explaining the monitoring signal feedback of the AOC device equipped with the MCU of Figures 1 and 2.
Figure 4 is a configuration diagram of a one-way AOC device showing another embodiment according to the present invention.
Figure 5 is a configuration diagram of a two-way AOC device showing another embodiment of the present invention.
FIG. 6 is a detailed configuration diagram for explaining the monitoring signal feedback of the AOC device without the MCU of FIGS. 4 and 5.
Figure 7 is an explanatory diagram of monitoring signal feedback of an AOC device without MCU according to the present invention.
Figure 8 is an explanatory diagram of the high-frequency component control circuit of the optical transmitter integrated circuit according to the present invention.
Figure 9 is a configuration diagram of an adaptive equalizer of an optical receiver integrated circuit according to the present invention.
Figure 10 is a diagram that can be used to explain the size comparator of the adaptive equalizer according to the present invention.
Figure 11 is an explanatory diagram of the operation sequence of the AOC device according to an embodiment of the present invention.
Figure 12 is an explanatory diagram for calibrating an input signal by adjusting the amplification gain of the present invention.
Figure 13 is an explanatory diagram of input signal calibration by reference signal adjustment according to the present invention.
Figure 14 is a diagram for explaining the step of observing equalization filter characteristics according to the present invention.
Figure 15 is a flow chart to explain the adaptive equalization control according to the present invention.
Figure 16 is a characteristic diagram for explaining the adaptive equalization method according to the present invention.
Figure 17 is an explanatory diagram of the transmitting end adjustment step according to the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but are not intended to indicate the presence of one or more other features. It should be understood that it does not exclude in advance the possibility of the existence or addition of elements, numbers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted in an ideal or excessively formal sense unless explicitly defined in the present application. No.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings. In order to facilitate overall understanding when describing the present invention, the same reference numerals are used for the same components in the drawings, and duplicate descriptions for the same components are omitted. In addition, the first and second connector units, the optical transmitter integrated circuit, and the optical receiver integrated circuit will be described by assigning the same reference numeral to each embodiment for convenience, regardless of unidirectional optical communication, bidirectional optical communication, and the presence or absence of an MCU.

1 is a configuration diagram of a one-way AOC device according to the present invention.

As shown, it consists of an optical fiber cable 10 made of a cable bundle, and first and second connector parts 100 and 200 installed at both ends of the optical fiber cable 10.

In a unidirectional AOC device, the first connector unit 100 is described as a transmitting end (TX), and the second connector unit 200 is described as a receiving end (RX).

The first connector unit 100 includes electrical components 101 for connecting computer devices and electrical signals, an optical transmitter integrated circuit 110, a VCSEL 120, which is an optical element for optical output, and an optical fiber cable 10 for transmitting optical signals. It includes connecting optical components 103 and includes a transmitter MCU 130 for controlling the optical signal integrated circuit 110.

The second connector unit 200 includes electrical components 201 for connecting computer devices and electrical signals, an optical receiver integrated circuit 210, a PD (Photo-Diode) 220, which is an optical element for receiving light, and an optical fiber cable 10. ) and includes an optical component 203 for receiving an optical signal from the optical signal, and a transmitter MCU 130 for controlling the optical signal integrated circuit 110.

The optical transmitter integrated circuit 110 controls (emphasizes) the high-frequency component of the input electrical signal and drives the optical element 120 in response to the electrical signal. The optical device 120 uses VCSEL, which is used as a short-distance optical communication light source.

The optical receiver integrated circuit 210 receives a received signal from the optical element 220 for light reception, converts it into a voltage signal, compensates for the high frequency component of the received signal, and outputs it as an electrical signal.

The number of optical fiber cables 10 is determined according to the number of communication channels, and is composed of a bundle of cables. The electrical conductor 20 for the feedback signal is packaged together with an optical fiber cable in the cable bundle.

The transmitting terminal MCU 130 of the first connector unit 100 controls a high-frequency component control code for controlling the high-frequency component of the optical transmitter integrated circuit 110 and an optical signal output size control code of the optical device driving circuit.

The receiving end MCU 230 of the second connector unit 200 receives the received signal size determination result and high frequency component compensation result information from the optical receiver integrated circuit 210 and transmits the transmitting end MCU ( 130).

Accordingly, in the present invention, the transmitting end MCU 130 receives monitoring signal feedback from the receiving end MCU 230. The high-frequency component control code and the optical signal output size control code are controlled based on the monitored signal being fed back.

In this way, by controlling the emphasis of high-frequency components at the transmitting end and controlling the size of the optical output signal based on the monitoring signal from the receiving end, the optimal output can be set. Therefore, in the conventional AOC, the output current of the VCSEL was set to the maximum current among the settable currents, but in the present invention, power consumption can be reduced by setting the output current to the optimal current. Additionally, because it uses feedback signals in real time, it can actively respond to changes in the communication environment.

Figure 2 is a configuration diagram of a two-way AOC device showing another embodiment of the present invention.

As shown, first connector parts 100 and second connector parts 200 are connected and installed at both ends of the plurality of optical fiber cables 10, respectively, and first and second connector parts 100 and 200 are connected to each other. ), the first and second electric conductors 20 for monitoring signal feedback are connected and installed between them.

The first and second connector units 100 and 200 each include a transmitting end (TX) and a receiving end (RX) and are configured to enable two-way communication. For convenience of explanation, the same symbols in the drawings are assigned to the same configuration of the transmitting terminals (TX) of the first and second connector parts 100 and 200, and the same symbols are used for the transmission terminals (TX) of the first and second connector parts 100 and 200. The same configuration of the receiving end (RX) is assigned the same symbol.

The first connector unit 100 is equipped with an integrated circuit control MCU 130 that controls the transmitting end (TX) and the receiving end (RX), and the second connector unit 200 also has a transmitting end (TX) and a receiving end (RX). An MCU 230 for controlling the integrated circuit is included.

The transmitting end (TX) includes an electrical component 101, an optical transmitter integrated circuit 110, a VCSEL 120, which is an optical element for optical output, and an optical component 103. The receiving end (RX) includes an optical component 203, a PD 220 that is an optical element for receiving light, an optical receiver integrated circuit 210, and an electrical component 101.

In the bidirectional AOC device of FIG. 2, the integrated circuit control MCUs 130 and 230 installed in the first and second connectors 100 receive signals from the optical receiver integrated circuit 210 of each receiving end (RX). It is monitored and fed back to the MCU on the other side of the communication. Monitoring signal feedback is achieved through two-way communication through the first and second electrical conductors (20). The integrated circuit control MCU (130) (230) that receives the monitoring signal as feedback controls the optical transmitter integrated circuit (110) (210) of each transmitter (TX) to optimally control high frequency component control and optical output current.

Figure 3 is a detailed configuration diagram for explaining the monitoring signal feedback of the AOC device equipped with the MCU of Figures 1 and 2.

The optical transmitter integrated circuit #1 (110) is composed of an electrical signal input circuit (111), a high frequency component control circuit (112), a VCSEL driving circuit (113), and a transmitter internal memory and interface circuit (114). The optical receiver integrated circuit 210 is composed of a TIA 211, an adaptive equalizer 212, an electric signal driving circuit 213, and an internal memory and interface circuit 214 at the receiving end.

The transmitting end MCU 130 controls the high frequency component control circuit 112 and the VCSEL driving circuit 113 of the transmitting end through the transmitting end internal memory and interface circuit 114. The receiving end MCU 230 receives the received signal size determination result and high frequency component compensation result as a monitoring signal from the adaptive equalizer 212 of the receiving end through the internal memory and interface circuit 114 of the receiving end.

The receiving end MCU 230 feeds back the monitoring signal to the transmitting end MCU 130 through the electrical conductor 20. The transmitter MCU 130 generates a high-frequency component control code and an optical signal output size control code based on the monitored signal fed back. The transmitting end MCU 130 controls the high frequency component control code of the high frequency component control circuit 112 and the optical signal output size control code of the VCSEL driving circuit 113 through the transmitting end internal memory and interface circuit 114.

Ultimately, when data is transmitted from the first connector unit 100 to the second connector unit 200, the monitoring signal of the second connector unit 200 is fed back to the first connector unit 100, and the first connector unit ( The transmitting terminal MCU (130) of 100 controls the optical transmitter integrated circuit #1 (110). It controls the high frequency component control code of the high frequency component control circuit 112 and the optical signal output size control code of the VCSEL driving circuit 113. This is controlled by receiving feedback from the monitoring signal at the receiving end. Therefore, the transmission output of the transmitter can be controlled by applying the received signal monitoring results in real time.

Meanwhile, the AOC device does not include an MCU and can be implemented directly inside the optical transmitter integrated circuit #2 and the optical receiver integrated circuit #2. For the configuration, refer to FIGS. 4, 5, and 6.

Figure 4 is a configuration diagram of a one-way AOC device showing another embodiment of the present invention, and Figure 5 is a configuration diagram of a two-way AOC device showing another embodiment of the present invention.

Referring to FIG. 3, in the configuration of FIG. 1, there is no transmitting end MCU and receiving end MCU. It is configured by including the functions of the MCU in optical transmitter integrated circuit #2 (110) and optical receiver integrated circuit #2 (210), respectively.

Likewise, referring to FIG. 4, the configuration of FIG. 2 does not have an MCU for integrated circuit control. It is configured by including the functions of the integrated circuit control MCU in the optical transmitter integrated circuit #2 (110) and the optical receiver integrated circuit #2 (210), respectively.

Figure 6 is a detailed configuration diagram to explain the monitoring signal feedback of the AOC device without the MCU of Figures 4 and 5. The optical transmitter integrated circuit #2 (110) of FIGS. 4 to 6 includes an optical signal output and high frequency component control circuit (1140). The optical receiver integrated circuit #2 (210) further includes an optical signal reception and high-frequency component monitoring circuit (2140).

The first and second electrical conductors 20 are connected to the optical transmitter integrated circuit #2 (110) and the optical receiver integrated circuit #2 (210) corresponding to each other between the first connector unit 100 and the second connector unit 200. are connected to each other. Monitoring signal feedback between the corresponding optical signal output and high-frequency component control circuit 1140 and the optical signal reception and high-frequency component monitoring circuit 2140 is possible through the first and second electrical conductors 200.

The optical transmitter integrated circuit #1 and optical receiver integrated circuit #1 of FIGS. 1 to 3 and the optical receiver integrated circuit #2 and optical receiver integrated circuit #2 of FIGS. 4 to 5 have different configurations in some parts, but as described in the description For convenience, the same symbol is given.

Figure 7 is an explanatory diagram of monitoring signal feedback of an AOC device without MCU according to the present invention.

The optical signal reception and high-frequency component monitoring circuit 2140 included in the optical receiver integrated circuit #2 (210) at the receiving end converts the input signal size determination result and the high-frequency component compensation result from the adaptive equalizer 212 into a monitoring signal. Collect. The monitoring signal is transmitted to the transmitting end through the electric conductor 20.

The optical signal and high frequency component control circuit 1140 included in the optical transmitter integrated circuit #2 (110) of the transmitting end receives the monitoring signal fed back through the electrical conductor 20. Based on the fed-back monitoring signal, the high-frequency component control code and the optical signal output size control code are input as control signals to the high-frequency component control circuit 112 and the VCSEL driving circuit 113, respectively.

In the present invention, a VCSEL element is used as the optical element 120 for light output. In short-distance optical communication, VCSEL is used, and the driving circuit is simple due to the direct modulation method. The manufacturing cost is low and power consumption is low (1/3 of that of the DFB Laser). It has a forward connection structure and outputs an optical signal in proportion to the current.

A PD device is used as the optical device 220 for light reception. PD can secure bandwidth relatively easily compared to VCSEL. It has a reverse connection structure and outputs a current proportional to the optical signal. Since it is a small current, a TIA (Trans-impedance Amplifier) 211 that converts it into a voltage signal is required.

The optical fiber cable 10 uses MMF (Multi-Mode Fiber) in short-distance optical communication using VCSEL. It is manufactured by wrapping a bundle of cables with a single sheath.

The optical components 103 and 203 stably guide and protect the optical path along which the optical signal travels between the optical element and the optical fiber.

As for the electrical components 101 and 201, the AOC integrates all optical elements, optical components, and electronic components in the connector portion, and has a structure for connecting cables to terminals. The integrated PCB itself can also be connected to the terminal as is.

MCU (Micro-Control Unit) 130 (230) is an integrated circuit for digital signal processing. It is used for purposes such as inputting the initial setting value of the optical transmitter integrated circuit and the optical receiver integrated circuit, and as in the present invention, it is obtained by further including a function of controlling the monitoring signal from the receiving end by feeding it back to the transmitting end.

The high-frequency component control circuit 112 of the optical transmitter integrated circuits #1 and #2 controls the emphasis of the high-frequency component of the input signal input from the electric signal input unit 111 and outputs it as an output signal.

Figure 8 is an explanatory diagram of the high-frequency component control circuit of the optical transmitter integrated circuit according to the present invention.

As shown in (A) of Figure 8, as the signal transmitted from the transmitter (TX) passes through the channel, the high-frequency component is attenuated and distorted. The receiving end (RX) receives a signal lacking high-frequency components. In order to compensate for this attenuation of high-frequency components, distortion that emphasizes high-frequency components is created at the transmitting end (TX), as shown in (B) of FIG. 8. At the receiving end (RX), distortion is reduced at the transmitting end (TX), allowing the signal to be received close to the original signal.

Therefore, the high-frequency component control circuit 110 at the transmitting end forcibly creates and transmits distortion that emphasizes the high-frequency component.

The VCSEL driving circuit 120 drives current so that the electrical signal inside the integrated circuit can be converted into an optical signal through the VCSEL. As a control signal, there is basically an average current control that controls the amount of current flowing at all times and a modulation current control that controls the amount of current whose size is controlled in response to the signal.

In the present invention, the above-described average current control and modulation current control are performed by setting an optical signal output size control code based on the result of determining the input signal size of the monitoring signal.

Another way to configure the optical transmitter integrated circuit is to configure the VCSEL driving circuit by including all of the high-frequency component emphasis control function, average current control, and modulation current control function without configuring the high-frequency component control circuit separately. The high-frequency component control circuit is omitted.

Meanwhile, the photoelectric conversion is performed in the optical device (PD) for light reception and output as a microcurrent signal. The TIA (211) receives the microcurrent output from the PD as an input signal and converts it into a voltage signal.

The adaptive equalizer 212 continuously monitors the size and high-frequency components of the input signal and uses this to optimally compensate for the high-frequency components of the equalization filter at the receiving end. In the present invention, the adaptive algorithm outputs the result of determining the size of the input signal. Additionally, the optimal equalization filter control code found in the adaptation algorithm is output as a high-frequency component compensation result.

Figure 9 is a configuration diagram of an adaptive equalizer of an optical receiver integrated circuit according to the present invention.

The adaptive equalizer 212 includes a first equalization filter 2121 that compensates for and outputs high-frequency components of the received signal using an equalizer control code; a second equalization filter (2122) that receives the received signal in parallel with the first equalization filter (2121), compensates for high-frequency components using an equalizer monitoring code, and outputs it as a monitoring signal; a magnitude comparator 2123 that compares the magnitude of the monitoring signal of the second equalization filter 2122 with a reference voltage set by a reference voltage code; By changing the equalizer monitoring code to be provided to the second equalization filter 2122 and the reference signal of the magnitude comparator 2123, the comparator output of the magnitude comparator 2123 is sampled and converted into digital data, and based on the digital data a digital control unit 2124 that finds the optimal equalizer control code and controls the equalizer control code of the first equalization filter 2121; It is characterized by including.

The first equalization filter 2121 can compensate and output the components of the high frequency band of the received signal. The first equalization filter 2121 receives an equalizer control code from the digital control unit 2124. The first equalization filter 2121 may select an equalization coefficient in response to an equalizer control code and perform equalization with an equalization gain corresponding to the selected equalization coefficient.

The second equalization filter 2122 is installed in parallel with the first equalization filter 2121 at the receiving signal end.

Like the first equalization filter 2121, the second equalization filter 2122 has the function of compensating for and outputting the components of the high frequency band of the received signal, so the second equalization filter 2122 is similar to the first equalization filter 2121. It can be said that they have the same operating characteristics.

Meanwhile, the second equalization filter 2122 can be said to be an equalization filter dedicated to signal monitoring. The second equalization filter 2122 performs monitoring to find the optimal equalizer control code that can optimally compensate the received signal according to the equalizer monitoring code of the digital controller 2124.

That is, the second equalization filter 2122 can compensate and output the received signal according to the equalizer monitoring code of the digital controller 2124 in order to find the optimal equalizer control code in the digital controller 2124. . And, the signal output from the second equalization filter 2122 can be called a monitoring signal.

The above-described first equalization filter 2121 and second equalization filter 2122 may include an input signal stage, an output signal stage, a low-frequency gain control stage, and a high-frequency gain control stage, respectively. Here, the low-frequency gain control stage receives a signal that controls the amplification amount of the low-frequency band of the signal, and the high-frequency gain control stage receives a signal that controls the amplification amount of the high-frequency band of the signal. Low-frequency gain control can control the size of the input signal and thus can control the amplification gain. High-frequency gain control can control the transition speed of an input signal and change the waveform of the signal itself.

The equalizer control code of the digital controller 2124 is input to the low frequency gain control stage or the high frequency gain control stage of the first equalization filter 2121 depending on the situation. And, the equalizer monitoring code of the digital controller 2124 is input to the low-frequency gain control stage or the high-frequency gain control stage of the second equalization filter 2122 depending on the situation. That is, in order to amplify the input signal of the second equalization filter 2122, a predetermined equalizer monitoring code will be input to the low-pi gain control stage. When it is desired to change the waveform of the input signal of the second equalization filter 2122 (to control the transition speed of the signal), a predetermined equalizer monitoring code will be input to the high frequency gain control stage.

The magnitude comparator 2123 receives a predetermined clock signal (e.g., asynchronous clock), a monitoring signal from the second equalization filter 2122, and a reference signal control code from the digital controller 2124.

Accordingly, the magnitude comparator 2123 measures (samples) the magnitude of the input signal (monitoring signal) from the second equalization filter 2122 every cycle of the input clock signal (asynchronous clock). In other words, the magnitude comparator 2123 can sample the input signal every cycle of the clock signal (asynchronous clock) and compare it with a digitally controlled reference voltage to digitally output high/low.

The digital controller 2124 provides an equalizer control code to the first equalization filter 2121, an equalizer monitoring code (also known as a high-frequency band gain control code) to the second equalization filter 2122, and controls the reference signal. Code can be provided to size comparator 2123.

The digital controller 2124 collects comparison data from the magnitude comparator 2123 by changing the equalizer monitoring code to be provided to the second equalization filter 2122 and the reference signal of the magnitude comparator 2123, and Based on this, activities to find the optimal equalizer control code are continuously performed. The optimal equalizer control code found is applied to the first equalization filter (2121).

That is, the digital controller 2124 provides an equalizer monitoring code to be provided to the second equalization filter 2122 (for example, it can be said to be a high-frequency band gain code input to the high-frequency gain control stage) and the magnitude comparator 2123. As the reference signal control code to be provided is changed, the number of highs in the comparison data is counted each time. In addition, the digital controller 2124 calculates the difference between the current counting value and the previous counting value, determines the value with the largest peak in the probability density function (PDF) as optimal, and sends the corresponding equalizer control code to the first equalization filter (2121). ) can be provided to.

In other words, the digital controller 2124 adjusts the size of the input signal received from the adaptive equalization device, and based on this, the code for the optimal high-frequency band gain found by observing the characteristics of the second equalization filter 2122 ( That is, the equalizer control code) can be applied to the first equalization filter (2121).

Figure 10 is a diagram that can be used to explain the size comparator of the adaptive equalizer according to the present invention.

The magnitude comparator 2123 may include a reference signal generator 31, an analog comparator 32, and a sampling circuit 33.

The reference signal generator 31 generates a reference signal (also referred to as a reference voltage) of an analog component corresponding to the reference signal control code from the digital controller 2124. Here, the reference signal control code is a code that determines the level of the reference voltage, and may be, for example, any one of about 16 codes having different levels.

Accordingly, the reference signal control code applied to the reference signal generator 31 may be any one of about 16 codes having different levels. Additionally, the reference signal output from the reference signal generator 31 varies depending on the reference signal control code.

The analog comparator 32 obtains the difference between the input signal (i.e., the monitoring signal from the second equalization filter 2122) and the reference signal from the reference signal generator 31 and outputs it as an analog signal.

The sampling circuit 33 samples and digitizes the output from the analog comparator 32 at every cycle of the input clock signal (eg, asynchronous clock). Accordingly, the sampling circuit 33 outputs predetermined digital data (eg, high or low).

Here, the clock signal is a signal that provides a point in time to perform comparison, and generally can use a rising edge or falling edge.

The reference signal generator 31, analog comparator 32, and sampling circuit 33 are each configured separately, but can be integrated if necessary.

The magnitude comparator 2123 configured as described above compares the magnitude of the input signal with an internally generated reference signal. Then, the size comparator 2123 samples the clock signal for each cycle, determines the size, and outputs digital data corresponding to it. The reference signal to be compared varies depending on the control.

Meanwhile, the magnitude comparator 2123 can be implemented by creating a signal by subtracting the difference from the input signal by the amount of the reference signal and comparing it based on 0 (zero).

The magnitude comparator 2123 described above can randomly sample an input signal when it receives an asynchronous clock. In this case, the probability that the input signal is high/low is 50:50. Since each input signal bit is not sampled at a specific point in time, the sampling value at a random point in time can be obtained. Although there is no data at the time of sampling, data on the distribution of the sampled voltage (i.e., allowing counting the number of highs and lows in the comparison data) can be obtained.

If the clock is asynchronous, random sampling occurs, so a low-speed clock can be used. Using a low-speed asynchronous clock reduces the burden of operating speed, so power consumption and circuit size can be reduced.

Figure 11 is an explanatory diagram of the operation sequence of the AOC device according to an embodiment of the present invention.

The present invention performs the steps of determining the size of the input signal in the adaptive equalizer at the receiving end (S100) and observing the characteristics of the equalization filter (S200), and feeds back the equalization filter characteristic observation information to the transmitting end as a monitoring signal. It includes a transmitter adjustment step (S300) to make adjustments and a waiting step (S400) to reduce power consumption, but has a cyclical structure.

The adaptive equalization method according to an embodiment of the present invention is performed in the adaptive equalization device described with reference to FIGS. 9 and 10.

The input signal size determination step (S100) is a size calibration step of the input signal. After comparing the range of the signal (monitoring signal) input to the size comparator 2123 with the range of the internally generated reference signal, the size of the input signal is adjusted so that the input signal is approximately 1/2 of the reference signal range. After adjusting the size of the input signal, the process moves to the equalization filter characteristic observation step (S200), and if the input signal is too small, it is assumed that there is no signal and moves to the standby step (S400).

The reason why the size of the input signal is adjusted so that the input signal is approximately 1/2 of the reference signal range (i.e., between the maximum and minimum values of the reference signal) in the input signal size determination step (S100) is because the input signal is too large. This is because if it is too small, the accuracy in the equalization filter characteristic observation step (S200) decreases. In other words, if the input signal is approximately 1/2 of the reference signal range, the characteristics of the second equalization filter 30, which is the monitoring target, can be better observed, and the optimal equalizer control code can be set to the first equalization filter 2121. can be provided to.

As described above, input signal amplification calibration (Ampitude Calibration) is required to adjust the input signal to approximately 1/2 of the reference signal range.

As an input signal calibration method, a method of gradually increasing the amplification gain of the second equalization filter 2122 or a method of reducing the range of the reference signal can be adopted.

First, the case of using a method of gradually increasing the amplification gain of the second equalization filter 2122 to find a gain that is greater than the reference signal will be described with reference to FIG. 12.

Figure 12 is an explanatory diagram of calibrating an input signal by adjusting the amplification gain of the present invention.

Referring to FIG. 12, first, the digital controller 2124 sets the amplification gain of the second equalization filter 2122 to the minimum (S101), sets "reference signal = -reference signal middle", and then sets the magnitude comparator 2123. Collect N-time sampling results from (S102). If the sampling results (i.e., comparison values of the magnitude comparator 2123) in step S102 are not all high, the digital controller 2124 moves to the equalization filter characteristic observation step S200.

If the sampling results (i.e., comparison values of the size comparator 2123) in step S102 are all high (“Yes” in S103), the digital controller 2124 sets “reference signal = + reference signal middle”. After setting, the N-time sampling results from the size comparator 2123 are collected (S104). If the sampling results (i.e., comparison values of the magnitude comparator 2123) in step S104 are all low (“Yes” in S105), the digital controller 2124 determines whether the current amplification gain is maximum (S106) ). If the current amplification gain is not the maximum, the digital controller 2124 increases the current amplification gain (S107) and then returns to the above-described step S102 and repeats the operation from the corresponding step.

If the sampling results (i.e., comparison values of the size comparator 2123) in step S105 are not all low, the digital controller 2124 moves to the equalization filter characteristic observation step (S200), and determines the amplification gain in step S106. If this is the maximum, move to the waiting stage (S300).

In this way, the magnitude of the input signal can be compared by gradually increasing the amplification gain of the second equalization filter 2122 and finding a gain that is greater than the reference signal.

Meanwhile, there is a method of adjusting the reference signal for input signal calibration.

Figure 13 is an explanatory diagram of input signal calibration by reference signal adjustment according to the present invention.

Referring to FIG. 13, the digital controller 2124 first sets the reference signal range in the magnitude comparator 2123 to the maximum (S111), sets it to "reference signal = -reference signal middle", and then sets the magnitude comparator 2123 to the maximum. Collect N-time sampling results from (S112). If the sampling results (i.e., comparison values of the size comparator 2123) in step S112 are not all high, the digital controller 2124 moves to the equalization filter characteristic observation step S200.

If the sampling results (i.e., comparison values of the size comparator 2123) in step S112 are all high (“Yes” in S113), the digital controller 2124 sets “reference signal = + middle of reference signal”. After setting, the N-time sampling results from the size comparator 2123 are collected (S114). If the sampling results (i.e., comparison values of the magnitude comparator 2123) in step S114 are all low (“Yes” in S115), the digital controller 2124 determines whether the range of the current reference signal is minimum. (S116). If the range of the current reference signal is not the minimum, the digital controller 2124 reduces the range of the current reference signal (S117), returns to the above-described step S112, and repeats the operation from the corresponding step.

If the sampling results (i.e., comparison values of the size comparator 2123) in step S115 are not all low, the digital controller 2124 moves to the equalization filter characteristic observation step (S200), and returns the reference signal in step S116. If the range is minimum, move to the waiting step (S300).

In this way, by adjusting the reference signal range of the size comparator 2123 and allowing the input signal to be larger than the reference signal range, the size of the input signal can be compared.

As described above, the input signal is adjusted to fall within 1/2 of the reference signal range through input signal calibration. Once the input signal calibration is completed, the equalization filter characteristic observation step can be performed.

In the equalization filter characteristic observation step (S200), the peak value of the histogram is calculated by changing the high frequency band gain or reference signal of the second equalization filter (2122), and the optimal value found using the second equalization filter (2122) is calculated. A code for the high frequency band gain (i.e., equalizer control code) is applied to the first equalization filter 2121. Afterwards, a flag indicating that adaptation of the adaptive equalizer has been completed is raised and the process moves to the waiting stage (S400). Here, the equalization filter characteristic observation step (S200) can be said to be an equalizer control code application step.

In the transmitting end adjustment step (S300), the operation result of the adaptive equalizer of the receiver is converted into a required form and transmitted to the transmitter. The transmitter controls the VCSEL driver circuit output and high-frequency component emphasis level based on the operation results. Once adjustment is completed, the process moves to the waiting stage.

In the standby step (S400) (i.e., standby mode), the power to the second equalization filter 2122 and the size comparator 2123 is turned off to reduce power consumption after the equalization filter characteristic observation step (S200). Additionally, if it is determined that there is no signal in the input signal size determination step (S100), the power of the first equalization filter 2121 is also turned off. After a certain period of time has elapsed, the process moves to the input signal size determination step (S100).

The above-described input signal size determination step (S100), equalization filter characteristic observation step (S200), and monitoring signal feedback and waiting step (S300) of the transmitting end adjusting step (S300) can be sufficiently performed under the supervision of the digital controller 2124.

Figure 14 is a diagram for explaining the step of observing equalization filter characteristics according to the present invention. Since the first equalization filter 2121 and the second equalization filter 2122 have the same characteristics, it is possible to observe the characteristics of the first equalization filter 2121 just by observing the characteristics of the second equalization filter 2122. It can be something.

Referring to FIG. 14, when the reference signal (i.e., reference voltage (Vref)) is below the input signal range, everything is Low, so the count value is 0 (zero), and when the reference voltage is within the input signal range, the corresponding comparison data is By counting, the count value increases little by little. If the reference voltage is above the input signal range, everything is high, so the count value becomes the number of sampling times. The counted value takes the form of a cumulative density function (CDF), and when the difference with adjacent count values is calculated, it is expressed in the form of a probability density function (PDF). Cumulative density function (CDF) and probability density function (PDF) can be expressed as a histogram.

The probability density function (PDF) represents the probability that the input signal stays between each reference voltage. Basically, the digital data of the magnitude comparator 2123 has a high or low value, so there is a high probability that it will remain at a high or low voltage. As a result, the probability density function (PDF) has a peak value as shown in FIG. 14.

Here, the size of the peak in the probability density function (PDF) varies depending on the excess/deficiency of the high-frequency component. Figure 14 shows how the adaptive equalization device finds the most optimal state depending on whether the data transition speed is slow, too fast, or optimal. Here, when the data transition speed is slow, it is under-equalized in FIG. 14, and when the data transition speed is too fast, it is over-equalized in FIG. 14, and when the data transition speed is optimal (appropriate). is the case of Optimum-equalized in FIG. 14.

For example, if the high-frequency component is insufficient (i.e., in the case of under-equalized), the data transition moves more slowly than in the optimal state (i.e., in the case of optimal-equalized), so the probability of staying at the intermediate value increases. As the probability density function (PDF) between high and low increases, the peak decreases. Conversely, if the high-frequency component is excessive (i.e., in the case of over-equalized), it protrudes more than High/Low during data transition than in the optimal state (i.e., in the case of Optimum-equalized), resulting in high ) and the probability density function (PDF) outside the low increases, the peak decreases.

In this way, by changing the high-frequency band gain of the second equalization filter 2122, the largest peak value on the probability density function (PDF) becomes optimal.

According to the equalization filter characteristic observation step (S200) in the present invention, the amount of stored data can be significantly reduced. This is because, in the embodiment of the present invention, after each round of sampling, the difference with the previous counting value is calculated, if it is the maximum, it is stored (recorded), and if it is not the maximum, it is immediately discarded.

Additionally, in the embodiment of the present invention, it was changed to continuously circulate. In an embodiment of the present invention, continuous equalization filter adaptation is possible by adding a second equalization filter 2122 dedicated to monitoring.

Next, the above-described equalization filter characteristic observation step (S200) will be described in more detail with reference to FIGS. 15 and 16.

Figure 15 is a flow chart for explaining the adaptive equalization control according to the present invention, and Figure 16 is a characteristic diagram for explaining the adaptive equalization method according to the present invention.

First, the digital controller 2124 sets K = 0 (zero), S = 0 (zero), maximum peak = 0 (zero), and optimal code = 0 (zero) (S201), and the second equalization filter 2122 ) Enter the Kth equalization filter high frequency band gain code (S202). Here, K may be the equalization filter high-frequency band gain code (i.e., the equalizer monitoring code applied to the second equalization filter 2122), and S may be the reference signal control code.

Afterwards, the digital controller 2124 inputs the S reference signal control code to the magnitude comparator 2123 (S203). Accordingly, the magnitude comparator 2123 will generate a reference signal (reference voltage) corresponding to the S reference signal control code (i.e., the 0th reference signal control code).

Then, the digital controller 2124 collects the X number of sampling results from the size comparator 2123, counts the high number of the collected sampling results, and temporarily stores the corresponding counting value (S204). For example, when the 0th reference signal control code is applied to the size comparator 2123, the counting value for the data that has been compared with the input signal and the reference signal corresponding to the 0th reference signal control code in the size comparator 2123 (The high number counting value) will be temporarily stored in the corresponding digital controller 2124.

Next, the digital controller 2124 determines whether the absolute value of the difference between the current counting value and the previous counting value is greater than the maximum peak (S205).

If the absolute value of the difference between the current counting value and the previous counting value is greater than the maximum peak, the digital controller 2124 replaces the maximum peak with the absolute value of the difference between the current counting value and the previous counting value. (S206).

Then, the digital controller 2124 sets the optimal code as the current K (S207) and sets the previous counting value as the current counting value (S208).

Meanwhile, as a result of the determination in step S205, if the absolute value of the difference between the current counting value and the previous counting value is not greater than the maximum peak, the digital controller 2124 moves to step S208. In other words, after sampling X times, the difference from before is calculated, and if it is the maximum, the temporarily stored counting value is recorded. If it is not the maximum, it is immediately discarded.

Afterwards, the digital controller 2124 determines whether “S = N” (S209). Here, N means the maximum value of the reference signal control code. For example, N may be preset to “16”.

If “S = N”, the digital controller 2124 performs “S = S + 1” (S210) and then returns to step S203 and repeats the operation from the corresponding step. If the reference signal control code increases sequentially, the magnitude comparator 2123 will generate a reference signal (reference voltage) that increases sequentially.

Conversely, if “S = N”, the digital controller 2124 determines whether “K = M” (S211). Here, M means the maximum value of the equalization filter high frequency band gain code. For example, M may be preset to “8”.

If not “K = M”, the digital controller 2124 performs “K = K + 1” (S212) and then returns to step S202 and repeats the operation from the corresponding step.

Conversely, if "K = M", the digital controller 2124 uses the optimal code as the equalizer control code most optimal for the current state of the first equalization filter 2121 and reflects it in the first equalization filter 2121 (S213) . Therefore, when the corresponding equalizer control code is applied to the first equalization filter 2121, the adaptive equalization device according to an embodiment of the present invention can be controlled to have an optimal equalization gain in real time.

Figure 16 is a characteristic diagram for explaining the adaptive equalization method according to the present invention. Referring to FIG. 16, the equalizer monitoring code (A) is varied step by step from levels 1 to 8. At this time, the equalizer control code of the first equalization filter is set to the initial state (level 1). It goes through an amplitude calibration step to adjust the size of the input signal. Adjust the input signal to be 1/2 of the standard voltage signal range.

When calibration is completed, the reference voltage (C) is sequentially varied to preset levels. The size of the input signal for each reference voltage (C) is compared and sampled. In this case, an asynchronous clock is used. The result of comparing the magnitude of the input signal and the reference voltage is counted. The difference between neighboring size comparison values is obtained and detected using a cumulative and degree function (CDF), and the cumulative density function (CDF) is converted to a probability density function (PDF) to generate a histogram (D).

Afterwards, the equalizer monitoring code (A) is changed to the next level 2, and the reference voltage level is gradually varied again to generate a probability density function (PDF) histogram.

By repeating the above process, the equalizer monitoring code (A) progresses from level 1 to level 8, and then the histograms at each level are compared to find the maximum peak value. In Figure 16, the histogram of the probability density function (PDF) at equalizer monitoring code level 6 shows the maximum peak value. Therefore, we find the optimal equalizer control code level 6. The equalizer monitoring code level 6 is set as the equalizer control code of the first equalization filter.

In this way, by varying the monitoring control code and reference voltage, the equalizer monitoring code that can obtain the optimal equalizer output is found and set as the equalizer control code.

Accordingly, the adaptive equalizer of the present invention can continue to output normally without a calibration section of the output signal even when the equalizer control code is varied. This is because the optimal equalizer control code is found and set while calibrating and monitoring the monitoring signal.

Figure 17 is an explanatory diagram of the transmitting end adjustment step according to the present invention.

The monitoring signal found in the optical receiver integrated circuit 210 is fed back to the transmitter. The amplification gain or reference signal range found in the input signal determination step (S100) and the optimal equalizer control code found in the equalization filter characteristic observation step (S200) are collected as monitoring signals (301). The monitoring signal is converted into a form suitable for transmission in the optical receiver integrated circuit and transmitted to the optical receiver integrated circuit (S302). In other words, the monitoring signal is fed back to the transmitting end. A monitoring signal is received from the optical transmitter integrated circuit of the transmitting end (S302). The optical transmitter integrated circuit controls the average current and modulation current based on the received data (S304).

In this way, in the AOC device of the present invention, the receiving end feeds back the monitoring signal to the transmitting end. At the transmitting end, the attenuated high-frequency signal can be appropriately compensated in real time based on the monitored signal fed back. It receives feedback from monitoring signals in real time and adjusts optical transmission output appropriately. Power consumption can be reduced by always sending out only the necessary level of optical signal output. Additionally, by compensating for high-frequency components, low-cost optical devices can be used. Additionally, the present invention can use an adaptive equalizer to feed back the monitoring signal from the receiving end to the transmitting end through an electric conductor. Therefore, the monitoring signal at the receiving end can be fed back without adding a separate optical channel. By adopting a structure in which the monitoring signal is fed back through electric conductors, signal transmission efficiency is better than the method of transmitting by inserting the monitoring signal between the signals to be transmitted. Ultimately, the present invention enables low-cost manufacturing of short-distance AOC devices and has the effect of reducing power consumption. Using the AOC device of the present invention has the effect of reducing overall power consumption and maintenance costs in large-scale facilities such as data centers that require numerous short-distance AOC devices.

As described above, the optimal embodiment has been disclosed in the drawings and specifications. Although specific terms are used here, they are used only for the purpose of describing the present invention and are not used to limit the meaning or scope of the present invention described in the claims. Therefore, those skilled in the art will understand that various modifications and other equivalent embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the attached claims.

10: fiber optic cable
20: electrical conductor
100: first connector part
101, 201: Electrical parts
103, 203: Optical parts
110: Optical transmitter integrated circuit
111: Electrical signal input circuit
112: High frequency component control circuit
113: VCSEL driving circuit
114: Transmitter internal memory and interface circuit
120: Optical element for optical signal output (VCSEL)
130, 230: MCU
210: Optical receiver integrated circuit
211:TIA
212: Adaptive equalizer
213: Electrical signal driving circuit
220: Optical device (PD) for receiving optical signals
1140: Optical signal output and high frequency component control circuit
2140: Optical signal reception and high-frequency component monitoring circuit

Claims (6)

In a two-way AOC device that performs optical communication by connecting an optical fiber cable between the transmitting end and the receiving end,
an optical transmitter integrated circuit that emphasizes and controls high-frequency components of an input electrical signal and drives an optical element in response to the electrical signal; An optical device for optical output that converts an electrical signal into an optical signal under the control of the optical transmitter integrated circuit and transmits it through an optical fiber cable; An optical element for receiving light that receives an optical signal received through an optical fiber cable; an optical receiver integrated circuit that converts the current signal of the optical element for light reception into a voltage signal, compensates for the high-frequency component of the received signal converted into a voltage signal, and outputs it as an electric signal; An MCU for integrated circuit control including optical signal output control and high frequency component control functions of the optical transmitter integrated circuit and the optical receiver integrated circuit; First and second connector parts including;
a plurality of optical fiber cables having first and second connectors coupled at both ends to transmit and receive optical signals;
First and second electrical conductors for monitoring signal feedback arranged and connected with the optical fiber cables between the integrated circuit control MCUs of the first and second connector parts; It is composed including,
The integrated circuit control MCU feeds back the received signal size determination result and high-frequency component compensation result information of the corresponding optical receiver integrated circuit to the corresponding communication counterpart integrated circuit control MCU through the first and second electrical conductors for the monitoring signal feedback,
The integrated circuit control MCU is configured to control optical signal output and high-frequency component compensation of the optical transmitter integrated circuit based on the feedback monitoring signal,
The optical receiver integrated circuit,
A TIA (Trans-Impedance Amplifier) that converts the photoelectrically converted current signal into a voltage signal through the light receiving optical device (PD), and an equalization filter are used to filter the received signal to compensate for the high-frequency component, and to adjust the size of the input signal and An adaptive equalizer that continuously monitors high-frequency components and uses this to optimally compensate for the high-frequency components of the equalization filter, and an electrical signal driving circuit that outputs a received signal with high-frequency components compensated from the adaptive equalizer as an electrical signal; It includes an internal memory and an interface circuit at a receiving end that transmits the input signal size determination result of the adaptive equalizer and high-frequency component compensation result information to the integrated circuit control MCU,
The adaptive equalizer,
a first equalization filter that compensates for and outputs high-frequency components of the received signal according to an equalizer control code;
a second equalization filter that receives the received signal in parallel with the first equalization filter, compensates for high-frequency components using an equalizer monitoring code, and outputs it as a monitoring signal;
a magnitude comparator that compares the magnitude of the monitoring signal of the second equalization filter with a reference voltage set by a reference voltage code;
By changing the equalizer monitoring code to be provided to the second equalization filter and the reference signal of the magnitude comparator, the comparator output of the magnitude comparator is sampled and converted into digital data, and the optimal equalizer control code is found based on the digital data. a digital control unit that controls an equalizer control code of the first equalization filter; A two-way AOC device comprising:
According to paragraph 1,
The optical transmitter integrated circuit,
An electrical signal input circuit that receives an electrical signal, a high-frequency component control circuit that controls to emphasize the high-frequency component of the current signal for driving the optical device, and an optical device for optical output based on the electrical signal with the high-frequency component controlled ( The optical device driving circuit that drives the VCSEL) and the monitoring signal fed back by the integrated circuit control MCU are interfaced with the high frequency component control code of the high frequency component control circuit and the optical signal output size control code of the optical device driving circuit for optical output. A bi-directional AOC device comprising an internal memory and an interface circuit at the transmitting end to control the output current of the transmitting end.
delete delete According to paragraph 1,
The size comparator is,
a reference signal generation unit that generates a reference signal of an analog component corresponding to the reference signal control code from the digital control unit;
an analog comparator that obtains the difference between the monitoring signal from the second equalization filter and the reference signal from the reference signal generator and outputs the difference as an analog signal; and
A bi-directional AOC device comprising a sampling circuit unit that samples and digitizes the output from the analog comparator at every cycle of the input asynchronous clock signal.
According to paragraph 1,
The digital control unit,
The size of the input signal is adjusted so that the input signal received by the size comparator is within a specific reference signal range, and after the adjustment is completed, the equalizer monitoring code of the second equalization filter or the reference signal of the size comparator is changed to determine the peak of the histogram ( A bi-directional AOC device characterized in that it calculates a peak value and applies the optimal equalizer control code found based on the calculated peak value to the first equalization filter.

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