Patent Description:
<NUM> passive optical network (Passive Optical Network, PON) technologies and products have been ready and enter a large-scale deployment stage. In a <NUM> PON, costs of an optical network unit (Optical Network Unit, ONU) become a key problem in massive deployment in the future, and costs reduction is a key requirement of the <NUM> PON. A bi-directional optical sub-assembly on board (Bi-directional Optical Sub-Assembly On Board, BOB) technology that is widely used in a gigabit passive optical network (Gigabit Passive Optical Network, GPON) can also be used in the <NUM> PON, to reduce packaging costs. Therefore, component costs reduction is key to further costs reduction.

In the ONU of the <NUM> PON, a <NUM> avalanche photodiode (Avalanche Photodiode, APD) is a highest-rate optical component, and accounts for a largest proportion of costs. Therefore, reduction of costs of the APD is key to reduction of the costs of the ONU of the <NUM> PON. <CIT> discloses a high-speed optical receiver, which is configured to receive an optical signal having a higher transmission rate than that received using a general avalanche photo diode (APD) by expanding a frequency bandwidth using a receiver circuit configured together with an APD in the optical receiver including the APD, an APD bias control circuit, a transimpedance amplifier (TIA) for amplifying a signal received from the APD to have low noise, and a post amplifier. <CIT> discloses an optical receiver including a light receiving element for converting an optical signal to an electrical signal having a first bandwidth and an amplifier for amplifying the electrical signal. The amplifier has a first gain response that yields a second bandwidth that is less than the first bandwidth. The optical receiver also includes an equalizing circuit operationally coupled to the amplifier. The equalizing circuit has a second gain response that compensates for the first gain response of the amplifier so that a substantially constant net gain is imparted by the amplifier and the equalizing circuit to the electrical signal over the first bandwidth. <CIT> discloses an amplifier circuit and a compensation circuit. The amplifier circuit comprises a light detector and a transimpedance amplifier. The transimpedance amplifier generates an amplified signal. The compensation circuit includes at least one pole compensation stage that performs pole compensation on the amplified signal.

Embodiments of this application provide an optical receiver, to receive a high-rate signal by using a low-rate APD, thereby resolving a problem that costs of an overall component are excessively high due to excessively high costs of a high-rate APD.

According to a first aspect, an optical receiver is provided, including an optoelectronic detector, a transimpedance amplification circuit, a single-ended-to-differential converter, an I/O interface, and a controller, where the optoelectronic detector is configured to convert a received optical signal into a current signal, where bandwidth of the optoelectronic detector is lower than a system transmission bandwidth requirement; the transimpedance amplification circuit is configured to: receive the current signal and a first control signal, and perform transimpedance gain on the current signal based on the first control signal, to obtain a voltage signal, where a frequency response value of the current signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector; the single-ended-to-differential converter is configured to: convert the voltage signal into a differential voltage signal, and send the differential voltage signal to the I/O interface and the controller; the I/O interface is configured to output the differential voltage signal; and the controller is configured to: generate a second control signal based on the differential voltage signal, and send the second control signal to the transimpedance amplification circuit, where the second control signal is used to control the transimpedance amplification circuit to perform transimpedance gain on the current signal.

According to the optical receiver provided in this embodiment of this application, the optoelectronic detector whose bandwidth is lower than the system transmission bandwidth requirement is used, to greatly reduce costs of the optical receiver; and the transimpedance amplification circuit is used, to remedy received signal deterioration caused by bandwidth insufficiency, so that component costs are reduced while received signal quality is ensured.

With reference to the first aspect, in a first possible implementation of the first aspect, the controller is specifically configured to: perform a plurality of times of sampling processing, and perform the following process in each time of sampling processing: sending a control signal to the transimpedance amplification circuit; sampling an upper level and a lower level of the received differential voltage signal, to obtain a value of a sampling point; and modifying the control signal based on a preset modification amount; and after performing the plurality of times of sampling processing, the controller is specifically configured to use, as the second control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of sampling processing.

With reference to the first aspect, in a second possible implementation of the first aspect, the controller is specifically configured to: perform a plurality of times of detection processing, and perform the following process in each time of detection processing: sending a control signal to the transimpedance amplification circuit; using a first frequency as a boundary, and separately detecting energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal; and modifying the control signal based on a preset modification amount; and after performing the plurality of times of detection processing, the controller is specifically configured to use, as the second control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of detection processing.

The foregoing two embodiments are two implementations in which the controller selects an optimal control signal. The optimal control signal can enable the transimpedance amplification circuit to perform, for the optoelectronic detector, optimal compensation that can be implemented by the transimpedance amplification circuit. Further, gain compensation by the transimpedance amplification circuit is implemented inside the transimpedance amplification circuit, so that no additional noise is introduced.

With reference to the first aspect, in a third possible implementation of the first aspect, the optical receiver further includes an equalizer, where the equalizer is configured to: receive the differential voltage signal and a third control signal, perform gain on the differential voltage signal based on the third control signal, and send a differential voltage signal obtained after the gain to the controller and the I/O interface, where a frequency response value of the differential voltage signal within second bandwidth is greater than that within the first bandwidth, and any frequency in the second bandwidth is higher than any frequency in the first bandwidth; and the controller is further configured to: generate a fourth control signal based on the differential voltage signal, and send the fourth control signal to the equalizer, where the fourth control signal is used to control the equalizer to perform gain on the differential voltage signal.

In this embodiment of this application, the equalizer is used, so that a range of compensation for the optoelectronic detector is extended, and gain compensation can be performed for a higher frequency compared with the transimpedance amplification circuit.

With reference to the third possible implementation of the first aspect, in a fourth possible implementation of the first aspect, the controller is specifically configured to: perform a plurality of times of first sampling processing, and perform the following process in each time of first sampling processing: sending a control signal to the transimpedance amplification circuit; sampling an upper level and a lower level of the received differential voltage signal, to obtain a value of a sampling point; and modifying the control signal based on a preset modification amount; and after performing the plurality of times of first sampling processing, the controller is specifically configured to use, as the second control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of first sampling processing; and
after sending the second control signal to the transimpedance amplification circuit, the controller further performs a plurality of times of second sampling processing, and performs the following process in each time of second sampling processing: sending a control signal to the equalizer; sampling an upper level and a lower level of the received differential voltage signal, to obtain a value of a sampling point; and modifying the control signal based on the preset modification amount; and after performing the plurality of times of second sampling processing, the controller is specifically configured to use, as the fourth control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of second sampling processing.

With reference to the third possible implementation of the first aspect, in a fifth possible implementation of the first aspect, the controller is specifically configured to: perform a plurality of times of first detection processing, and perform the following process in each time of first detection processing: sending a control signal to the transimpedance amplification circuit; using a first frequency as a boundary, and separately detecting energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal; and modifying the control signal based on a preset modification amount; and after performing the plurality of times of first detection processing, the controller is specifically configured to use, as the second control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of first detection processing; and
after sending the second control signal to the transimpedance amplification circuit, the controller further performs a plurality of times of second detection processing, and performs the following process in each time of second detection processing: sending a control signal to the equalizer; using the first frequency as a boundary, and separately detecting energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal; and modifying the control signal based on the preset modification amount; and after performing the plurality of times of second detection processing, the controller is specifically configured to use, as the fourth control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of second detection processing.

The foregoing two embodiments are two manners in which the controller selects an optimal control signal when the optical receiver includes the equalizer. The transimpedance amplification circuit is first used to perform gain compensation without introducing additional noise; and if gain compensation is not enough, the equalizer is then used to perform gain compensation, so that an optimal compensation effect is achieved at a minimum noise cost.

According to a second aspect, an optical receiver is provided, including an optoelectronic detector, a first transimpedance amplification circuit, a single-ended-to-differential converter, an equalizer, an I/O interface, and a controller, where the optoelectronic detector is configured to convert a received optical signal into a current signal, where bandwidth of the optoelectronic detector is lower than a system transmission bandwidth requirement; the first transimpedance amplification circuit is configured to: receive the current signal, and perform transimpedance gain on the current signal, to obtain a voltage signal; the single-ended-to-differential converter is configured to: convert the voltage signal into a differential voltage signal, and send the differential voltage signal to the equalizer; the equalizer is configured to: receive the differential voltage signal and a first control signal, perform gain on the differential voltage signal based on the first control signal, and send a differential voltage signal obtained after the gain to the I/O interface and the controller, where a frequency response value of the differential voltage signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector, and any frequency in the first bandwidth is higher than an upper cut-off frequency of the optoelectronic detector; the I/O interface is configured to output the differential voltage signal obtained after the gain; and the controller is configured to: generate a second control signal based on the differential voltage signal obtained after the gain, and send the second control signal to the equalizer, where the second control signal is used to control the equalizer to perform gain on the differential voltage signal.

In this embodiment of this application, the equalizer is used to implement gain compensation for a high frequency. According to a feature of a wide compensation range of the equalizer, the equalizer is enabled to perform compensation for the optoelectronic detector, to achieve an optimal effect. Compared with the embodiment provided in the first aspect, this embodiment has an advantage of a wider range of compensation for the optoelectronic detector, and has a disadvantage that more noise is introduced because gain compensation for the high frequency is completely implemented by the equalizer.

With reference to the second aspect, in a first possible implementation of the second aspect, the controller is specifically configured to: perform a plurality of times of sampling processing, and perform the following process in each time of sampling processing: sending a control signal to the equalizer; sampling an upper level and a lower level of the received differential voltage signal, to obtain a value of a sampling point; and modifying the control signal based on a preset modification amount; and after performing the plurality of times of sampling processing, the controller is specifically configured to use, as the second control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of sampling processing.

With reference to the second aspect, in a second possible implementation of the second aspect, the controller is specifically configured to: perform a plurality of times of detection processing, and perform the following process in each time of detection processing: sending a control signal to the equalizer; using a first frequency as a boundary, and separately detecting energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal; and modifying the control signal based on a preset modification amount; and after performing the plurality of times of detection processing, the controller is specifically configured to use, as the second control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of detection processing.

According to a third aspect, a receiving method is provided, including: converting, by an optical receiver, a received optical signal into a current signal by using an optoelectronic detector, where bandwidth of the optoelectronic detector is lower than a system transmission bandwidth requirement; performing, by the optical receiver, transimpedance gain on the current signal based on a first control signal, to obtain a voltage signal, where a frequency response value of the current signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector, and any frequency in the first bandwidth is not lower than an upper cut-off frequency of the optoelectronic detector; and converting, by the optical receiver, the voltage signal into a differential voltage signal, and generating a second control signal based on the differential voltage signal, where the second control signal is used to control the optical receiver to perform transimpedance gain on the current signal.

With reference to the third aspect, in a first possible implementation of the third aspect, the generating a second control signal based on the differential voltage signal specifically includes: performing a plurality of times of sampling processing, and using, as the second control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of sampling processing, where the following process is performed in each time of sampling processing: performing transimpedance gain on the current signal based on a control signal, to obtain the voltage signal, and converting the voltage signal into the differential voltage signal; sampling an upper level and a lower level of the differential voltage signal, to obtain a value of a sampling point; and modifying the control signal based on a preset modification amount.

With reference to the third aspect, in a second possible implementation of the third aspect, the generating a second control signal based on the differential voltage signal specifically includes: performing a plurality of times of detection processing, and using, as the second control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of detection processing, where the following process is performed in each time of detection processing: performing transimpedance gain on the current signal based on a control signal, to obtain the voltage signal, and converting the voltage signal into the differential voltage signal; using a first frequency as a boundary, and separately detecting energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal; and modifying the control signal based on a preset modification amount.

With reference to the third aspect, in a third possible implementation of the third aspect, after the converting, by the optical receiver, the voltage signal into a differential voltage signal, the method further includes: performing gain on the differential voltage signal based on a third control signal, where a frequency response value of the differential voltage signal within second bandwidth is greater than that within the first bandwidth, and any frequency in the second bandwidth is higher than any frequency in the first bandwidth; and after the generating a second control signal, the method further includes: generating a fourth control signal based on a differential voltage signal obtained after the gain, where the fourth control signal is used to control the optical receiver to perform gain on the differential voltage signal.

With reference to the third possible implementation of the third aspect, in a fourth possible implementation of the third aspect, the generating a second control signal based on the differential voltage signal specifically includes: performing a plurality of times of first sampling processing, and using, as the second control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of first sampling processing, where the following process is performed in each time of first sampling processing: performing transimpedance gain on the current signal based on a control signal, to obtain the voltage signal, and converting the voltage signal into the differential voltage signal; sampling an upper level and a lower level of the differential voltage signal, to obtain a value of a sampling point; and modifying the control signal based on a preset modification amount; and the generating a fourth control signal based on the differential voltage signal specifically includes: performing a plurality of times of second sampling processing, and using, as the fourth control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of second sampling processing, where the following process is performed in each time of second sampling processing: performing gain on the differential voltage signal based on a control signal, to obtain the differential voltage signal obtained after the gain; sampling an upper level and a lower level of the differential voltage signal obtained after the gain, to obtain a value of a sampling point; and modifying the control signal based on the preset modification amount.

With reference to the third possible implementation of the third aspect, in a fifth possible implementation of the third aspect, the generating a second control signal based on the differential voltage signal specifically includes: performing a plurality of times of first detection processing, and using, as the second control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of first detection processing, where the following process is performed in each time of first detection processing: performing transimpedance gain on the current signal based on a control signal, to obtain the voltage signal, and converting the voltage signal into the differential voltage signal; sampling an upper level and a lower level of the differential voltage signal, to obtain a value of a sampling point; and modifying the control signal based on a preset modification amount; and the generating a fourth control signal based on the differential voltage signal specifically includes: performing a plurality of times of second detection processing, and using, as the fourth control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of second sampling processing, where the following process is performed in each time of second detection processing: performing gain on the differential voltage signal based on a control signal, to obtain the differential voltage signal obtained after the gain; using a first frequency as a boundary, and separately detecting energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal; and modifying the control signal based on the preset modification amount.

The embodiment in the third aspect is a receiving method corresponding to the optical receiver in the first aspect, beneficial effects are the same as those of the first aspect, and details are not described herein again.

According to a fourth aspect, a receiving method is provided, comprising: converting, by an optical receiver, a received optical signal into a current signal by using an optoelectronic detector, where bandwidth of the optoelectronic detector is lower than a system transmission bandwidth requirement; performing, by the optical receiver, transimpedance gain on the current signal, to obtain a voltage signal, and converting the voltage signal into a differential voltage signal; performing, by the optical receiver, gain on the differential voltage signal based on a first control signal, to obtain a differential voltage signal obtained after the gain, where a frequency response value of the differential voltage signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector, and any frequency in the first bandwidth is higher than an upper cut-off frequency of the optoelectronic detector; and generating, by the optical receiver, a second control signal based on the differential voltage signal obtained after the gain, where the second control signal is used to control the optical receiver to perform gain on the differential voltage signal.

With reference to the fourth aspect, in a first possible implementation of the fourth aspect, the generating a second control signal based on the differential voltage signal obtained after the gain specifically includes: performing a plurality of times of sampling processing, and using, as the second control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of sampling processing, where the following process is performed in each time of sampling processing: performing gain on the differential voltage signal based on a control signal, to obtain the differential voltage signal obtained after the gain; sampling an upper level and a lower level of the differential voltage signal obtained after the gain, to obtain a value of a sampling point; and modifying the control signal based on a preset modification amount.

With reference to the fourth aspect, in a second possible implementation of the fourth aspect, the generating a second control signal based on the differential voltage signal obtained after the gain specifically includes: performing a plurality of times of detection processing, and using, as the second control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of detection processing, where the following process is performed in each time of detection processing: performing gain on the differential voltage signal based on a control signal, to obtain the differential voltage signal obtained after the gain; using a first frequency as a boundary, and separately detecting energy that is of the differential voltage signal obtained after the gain and that is higher than the first frequency and energy that is of the differential voltage signal obtained after the gain and that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal; and modifying the control signal based on a preset modification amount.

The embodiment in the fourth aspect is a receiving method corresponding to the optical receiver in the second aspect, beneficial effects are the same as those of the second aspect, and details are not described herein again.

According to a fifth aspect, a transimpedance amplification circuit is provided, including a fixed resistor, a first transistor, a second transistor, a variable resistance circuit, and an output port, where the fixed resistor includes two ports, where one port is grounded, and the other port is connected to an emitter of the first transistor; a base of the first transistor is configured to receive an input signal, and a collector of the first transistor is connected to an emitter of the second transistor; a base of the second transistor is configured to receive a bias voltage signal, and a collector of the second transistor is connected to a first port of the variable resistance circuit, where the bias voltage signal is used to adjust a gain for the input signal; the output port is located on a connecting line between the collector of the second transistor and the first port of the variable resistance circuit; and the variable resistance circuit includes three ports, where a second port of the variable resistance circuit is configured to receive a control signal, a third port of the variable resistance circuit is grounded, and the control signal is used to control a resistance value of the variable resistance circuit.

In conclusion, according to the optical receiver provided in the embodiments of this application, the optoelectronic detector whose bandwidth is lower than the system transmission bandwidth requirement is used, to greatly reduce costs of the optical receiver; and the transimpedance amplification circuit is used, to remedy received signal deterioration caused by bandwidth insufficiency, so that component costs are reduced while received signal quality is ensured.

Referring to <FIG> is a schematic structural diagram of a <NUM> PON system to which an ONU or an Optical Line Terminal (OLT) that has an optical receiver provided in the embodiments of this application is applicable. A <NUM> PON system <NUM> includes at least one OLT <NUM>, a plurality of ONUs <NUM>, and one optical distribution network (Optical Distribution Network, ODN) <NUM>. The OLT <NUM> is connected to the plurality of ONUs <NUM> by using the ODN <NUM> in a point-to-multipoint manner. A direction from the OLT <NUM> to the ONU <NUM> is defined as a downlink direction, and a direction from the ONU <NUM> to the OLT <NUM> is defined as an uplink direction.

An embodiment of this application provides an optical receiver <NUM>, and the optical receiver <NUM> may be applied to an ONU of a <NUM> PON system or a higher-rate PON system. As shown in <FIG>, the optical receiver <NUM> includes an optoelectronic detector <NUM>, a transimpedance amplification circuit <NUM>, a single-ended-to-differential converter <NUM>, an I/O interface <NUM>, and a controller <NUM>.

The optoelectronic detector <NUM> is configured to convert a received optical signal into a current signal, where bandwidth of the optoelectronic detector <NUM> is lower than a system transmission bandwidth requirement.

Specifically, the optoelectronic detector <NUM> accounts for a largest proportion of costs in the optical receiver <NUM>, and therefore component costs can be greatly reduced by using the low-bandwidth optoelectronic detector <NUM>. Correspondingly, there is a problem that a high-frequency signal cannot be detected.

The transimpedance amplification circuit <NUM> is configured to: receive the current signal and a first control signal, and perform transimpedance gain on the current signal based on the first control signal, to obtain a voltage signal, where a frequency response value of the current signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector <NUM>, and any frequency in the first bandwidth is not lower than an upper cut-off frequency of the optoelectronic detector <NUM>.

Optionally, the transimpedance amplification circuit <NUM> may be an underdamped transimpedance amplification circuit. This application provides a possible implementation. A structure of the underdamped transimpedance amplification circuit is shown in <FIG>, and includes a fixed resistor <NUM>, a first transistor <NUM>, a second transistor <NUM>, a variable resistance circuit <NUM>, and an output port <NUM>.

The fixed resistor <NUM> includes two ports. One port is grounded, and the other port is connected to an emitter of the first transistor <NUM>. A base of the first transistor <NUM> is configured to receive an input signal, and a collector of the first transistor <NUM> is connected to an emitter of the second transistor <NUM>. A base of the second transistor <NUM> is configured to receive a bias voltage signal, and a collector of the second transistor <NUM> is connected to a first port of the variable resistance circuit <NUM>. The bias voltage signal is used to adjust a gain for the input signal. The output port <NUM> is located on a connecting line between the collector of the second transistor <NUM> and the first port of the variable resistance circuit <NUM>. The variable resistance circuit <NUM> includes three ports. A second port of the variable resistance circuit <NUM> is configured to receive a control signal, a third port of the variable resistance circuit <NUM> is grounded, and the control signal is used to control a resistance value of the variable resistance circuit <NUM>.

It should be understood that <NUM> in <FIG> shows a specific implementation solution of the variable resistance circuit, and there are still many similar implementation solutions. This is not limited in this application.

In this embodiment of this application, the resistance value of the variable resistance circuit <NUM> is adjusted, to change a damping factor of the transimpedance amplification circuit <NUM>. A smaller damping factor brings a greater additional gain for a high frequency. A frequency response curve of the transimpedance amplification circuit <NUM> is shown in <FIG>, and ζ in <FIG> is a damping factor. The high frequency herein is a frequency higher than the upper cut-off frequency of the optoelectronic detector <NUM>.

It should be noted that the first bandwidth of the transimpedance amplification circuit <NUM> may be controlled by using an existing technical solution. This is not limited in this application. In addition, the damping factor cannot be excessively small because a smaller damping factor causes severer system oscillation. Due to a value limitation of the damping factor, there is a value range of an additional gain for the high frequency by the transimpedance amplification circuit <NUM>. As shown in <FIG>, a solid line represents a frequency response curve of the optoelectronic detector <NUM>, and a dashed line is a combined frequency response curve of the transimpedance amplification circuit <NUM> and the optoelectronic detector <NUM>. For example, at a location a, a to-be-compensated difference does not exceed the range of the additional gain for the high frequency by the transimpedance amplification circuit <NUM>, and therefore compensation may be performed by using the transimpedance amplification circuit <NUM>; and at a location b, a to-be-compensated difference exceeds the range of the additional gain for the high frequency by the transimpedance amplification circuit <NUM>, and therefore complete compensation cannot be implemented solely by using the transimpedance amplification circuit <NUM>. In this case, next-order compensation is needed.

The single-ended-to-differential converter <NUM> is configured to: convert the voltage signal into a differential voltage signal, and send the differential voltage signal to the I/O interface <NUM> and the controller <NUM>.

The I/O interface <NUM> is configured to output the differential voltage signal.

The controller <NUM> is configured to: generate a second control signal based on the differential voltage signal, and send the second control signal to the transimpedance amplification circuit <NUM>, where the second control signal is used to control the transimpedance amplification circuit <NUM> to perform transimpedance gain on the current signal.

Specifically, a signal processing process of the optical receiver <NUM> is as follows:.

An optical signal detected by the optical receiver <NUM> first passes through the optoelectronic detector <NUM> for optoelectronic detection, to generate a current signal, and the current signal is converted into a voltage signal after passing through the transimpedance amplification circuit <NUM>. The transimpedance amplification circuit can provide a first-order high frequency gain, and the gain is implemented inside the transimpedance amplification circuit <NUM>. As shown in <FIG>, the resistance value of the variable resistance circuit <NUM> is adjusted, to generate a peak gain at a gain frequency to compensate for insufficiency of the bandwidth of the optoelectronic detector <NUM> (that is, provide a higher gain at a high frequency in a passband range of the transimpedance amplification circuit <NUM>). Because the gain is implemented inside the transimpedance amplification circuit <NUM> without introducing additional noise, noise-free gain compensation can be implemented for the high frequency. The high frequency herein is also a frequency that is higher than the upper cut-off frequency of the optoelectronic detector <NUM>.

The signal for which gain compensation is performed by the transimpedance amplification circuit <NUM> is converted into a differential signal by the single-ended-to-differential converter <NUM>, and the differential signal is output by using the I/O interface <NUM>.

Further, the controller <NUM> is configured to: adaptively generate the second control signal, and control the transimpedance amplification circuit <NUM> to perform transimpedance gain on the received current signal, to enable the transimpedance amplification circuit <NUM> to perform current-stage optimal compensation for the optoelectronic detector <NUM>. Three compensation possibilities: under-compensation, optimal compensation, and over-compensation are shown in <FIG>.

Optionally, the second control signal that enables the transimpedance amplification circuit <NUM> to perform the current-stage optimal compensation is mainly generated in the following two manners:.

In this case, the transimpedance amplification circuit <NUM> generates, for the current signal, a transimpedance gain determined by the control signal, to obtain a voltage signal; and the voltage signal passes through the single-ended-to-differential converter <NUM>, to obtain a differential voltage signal.

Then, the controller <NUM> samples an upper level and a lower level of the received differential voltage signal, to obtain a value of a sampling point.

Finally, the controller <NUM> modifies the control signal based on a preset modification amount.

In other words, each time of sampling processing is performed for a signal that is obtained after different transimpedance gain, to obtain a different sampling point. A sampling point with a maximum value is selected from obtained sampling points, and a control signal corresponding to the sampling point can enable the transimpedance amplification circuit <NUM> to perform the current-stage optimal compensation.

Therefore, after performing the plurality of times of sampling processing, the controller <NUM> is specifically configured to use, as the second control signal, the control signal corresponding to the sampling point with the maximum value in the plurality of sampling points obtained after the plurality of times of sampling processing.

(<NUM>) The controller <NUM> performs a plurality of times of detection processing, and performs the following process in each time of detection processing:
First, the controller <NUM> sends a control signal to the transimpedance amplification circuit <NUM>.

Then, the controller <NUM> uses a first frequency as a boundary, and separately detects energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the received differential voltage signal.

In other words, each time of detection processing is performed for a signal that is obtained after different transimpedance gain, to obtain a different energy difference. A minimum energy difference is selected from obtained energy differences, and a control signal corresponding to the energy difference can enable the transimpedance amplification circuit <NUM> to perform the current-stage optimal compensation.

Therefore, after performing the plurality of times of detection processing, the controller <NUM> is specifically configured to use, as the second control signal, the control signal corresponding to the minimum energy difference in the plurality of energy differences obtained after the plurality of times of detection processing.

It should be understood that the second control signal may be selected at intervals. Because an execution time of the foregoing selection process is very short compared with an interval time, service transmission is not affected. In addition, a compensation effect of the transimpedance amplification circuit <NUM> varies with an environmental change, and the environmental change (such as a temperature change) is a gradual process. Therefore, a control signal used during current execution may be modified for several times only in a relatively small range, and an optimal control signal is selected by using one of the foregoing methods (<NUM>) and (<NUM>). In this way, the execution time of the selection process can be effectively reduced.

Optionally, the optical receiver <NUM> further includes an equalizer <NUM>. As shown in <FIG>, the equalizer <NUM> is configured to: receive the differential voltage signal and a third control signal, perform gain on the differential voltage signal based on the third control signal, and send a differential voltage signal obtained after the gain to the controller and the I/O interface, where a frequency response value of the differential voltage signal within second bandwidth is greater than that within the first bandwidth, and any frequency in the second bandwidth is higher than any frequency in the first bandwidth.

In this case, the controller <NUM> is further configured to: generate a fourth control signal based on the differential voltage signal, and send the fourth control signal to the equalizer <NUM>, where the fourth control signal is used to control the equalizer <NUM> to perform gain on the differential voltage signal.

Specifically, in this embodiment of this application, the differential voltage signal output by the single-ended-to-differential converter <NUM> first passes through the equalizer <NUM>. If gain compensation needs to be further optimized, the equalizer <NUM> performs further gain on the differential voltage signal; and if gain compensation is optimal, the equalizer <NUM> does not perform processing on the signal, and is equivalent to a transmission circuit.

Further, the controller <NUM> is configured to: adaptively generate the fourth control signal, and control the equalizer <NUM> to perform gain on the received differential voltage signal, to enable the equalizer <NUM> to perform optimal compensation for the optoelectronic detector <NUM>. The equalizer <NUM> may be an analog equalizer or a digital equalizer.

Optionally, the second control signal that enables the transimpedance amplification circuit <NUM> to perform the optimal compensation and the fourth control signal that enables the equalizer <NUM> to perform the optimal compensation are mainly generated in the following two manners:.

After performing the plurality of times of first sampling processing, the controller <NUM> uses, as the second control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of first sampling processing.

After sending the second control signal to the transimpedance amplification circuit <NUM>, the controller <NUM> further performs a plurality of times of second sampling processing, and performs the following process in each time of second sampling processing:.

After performing the plurality of times of second sampling processing, the controller <NUM> uses, as the fourth control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of second sampling processing.

(<NUM>) The controller <NUM> performs a plurality of times of first detection processing, and performs the following process in each time of first detection processing:.

After performing the plurality of times of first detection processing, the controller <NUM> uses, as the second control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of first detection processing.

After sending the second control signal to the transimpedance amplification circuit <NUM>, the controller <NUM> further performs a plurality of times of second detection processing, and performs the following process in each time of second detection processing:.

After performing the plurality of times of second detection processing, the controller <NUM> uses, as the fourth control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of second detection processing.

It should be noted that if the obtained value of the sampling point is maximum or the obtained energy difference is minimum when the equalizer <NUM> does not perform gain on the differential voltage signal, it indicates that the transimpedance amplification circuit <NUM> has already performed optimal compensation for the optoelectronic detector <NUM>, and the equalizer <NUM> does not need to function; otherwise, it indicates that the equalizer <NUM> needs to function.

In addition, gain compensation by the transimpedance amplification circuit <NUM> is implemented inside the transimpedance amplification circuit <NUM> without introducing additional noise, but the equalizer <NUM> introduces additional noise during compensation. Therefore, the transimpedance amplification circuit <NUM> is adjusted preferentially. However, the equalizer <NUM> has an advantage of a wide compensation range, and can perform compensation for a higher frequency compared with the transimpedance amplification circuit <NUM>. If the transimpedance amplification circuit <NUM> cannot implement optimal compensation, the equalizer <NUM> may perform further compensation, to achieve an optimal compensation effect.

Further, the second control signal and the fourth control signal may be selected at intervals. Because an execution time of the foregoing selection process is very short compared with an interval time, service transmission is not affected. In addition, compensation effects of the transimpedance amplification circuit <NUM> and the equalizer <NUM> vary with an environmental change, and the environmental change (such as a temperature change) is a gradual process. Therefore, only a control signal used during current execution may be modified for several times in a relatively small range, and an optimal control signal is selected by using one of the foregoing methods (<NUM>) and (<NUM>). In this way, the execution time of the selection process can be effectively reduced.

Another embodiment of this application provides a receiving method. As shown in <FIG>, the method includes the following steps:.

Optionally, solutions in which the optical receiver generates the second control signal based on the differential voltage signal are as follows:.

In short, in both the foregoing two solutions, the control signal is modified, so that the received signal is in different statuses, and a relatively optimal control signal is selected by comparing these statuses.

Optionally, after the converting, by the optical receiver, the voltage signal into a differential voltage signal, the method further includes: performing gain on the differential voltage signal based on a third control signal, where a frequency response value of the differential voltage signal within second bandwidth is greater than that within the first bandwidth, and any frequency in the second bandwidth is higher than any frequency in the first bandwidth. After the generating a second control signal, the method further includes: generating a fourth control signal based on a differential voltage signal obtained after the gain, where the fourth control signal is used to control the optical receiver to perform gain on the differential voltage signal.

In this case, solutions in which the optical receiver generates the second control signal and the fourth control signal based on the differential voltage signal are as follows:.

After generating the second control signal, the optical receiver performs a plurality of times of second sampling processing, and uses, as the fourth control signal, a control signal corresponding to a sampling point with a maximum value in a plurality of sampling points obtained after the plurality of times of second sampling processing, where the following process is performed in each time of second sampling processing:
performing gain on the differential voltage signal based on a control signal, to obtain the differential voltage signal obtained after the gain; sampling an upper level and a lower level of the differential voltage signal obtained after the gain, to obtain a value of a sampling point; and modifying the control signal based on the preset modification amount.

(<NUM>) Perform a plurality of times of first detection processing, and use, as the second control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of first detection processing, where the following process is performed in each time of first detection processing:
performing transimpedance gain on the current signal based on a control signal, to obtain the voltage signal, and converting the voltage signal into the differential voltage signal; sampling an upper level and a lower level of the differential voltage signal, to obtain a value of a sampling point; and modifying the control signal based on a preset modification amount.

After generating the second control signal, the optical receiver performs a plurality of times of second detection processing, and uses, as the fourth control signal, a control signal corresponding to a minimum energy difference in a plurality of energy differences obtained after the plurality of times of second sampling processing, where the following process is performed in each time of second detection processing: performing gain on the differential voltage signal based on a control signal, to obtain the differential voltage signal obtained after the gain; using a first frequency as a boundary, and separately detecting energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal; and modifying the control signal based on the preset modification amount.

This embodiment of this application is a method embodiment corresponding to the foregoing apparatus embodiment, implementation principles and achieved effects have been described in the foregoing embodiment, and details are not described in this embodiment of this application again.

Another embodiment of this application provides an optical receiver <NUM>, and the optical receiver <NUM> may be applied to an ONU of a <NUM> PON system or a higher-rate PON system. As shown in <FIG>, the optical receiver <NUM> includes an optoelectronic detector <NUM>, a first transimpedance amplification circuit <NUM>, a single-ended-to-differential converter <NUM>, an equalizer <NUM>, an I/O interface <NUM>, and a controller <NUM>.

The first transimpedance amplification circuit <NUM> is configured to: receive the current signal, and perform transimpedance gain on the current signal, to obtain a voltage signal.

The single-ended-to-differential converter <NUM> is configured to: convert the voltage signal into a differential voltage signal, and send the differential voltage signal to the equalizer <NUM>.

The equalizer <NUM> is configured to: receive the differential voltage signal and a first control signal, perform gain on the differential voltage signal based on the first control signal, and send a differential voltage signal obtained after the gain to the I/O interface <NUM> and the controller <NUM>, where a frequency response value of the differential voltage signal within first bandwidth is greater than that within the bandwidth of the optoelectronic detector <NUM>, and any frequency in the first bandwidth is higher than an upper cut-off frequency of the optoelectronic detector <NUM>.

The equalizer <NUM> herein may be an analog equalizer or a digital equalizer.

The I/O interface <NUM> is configured to output the differential voltage signal obtained after the gain.

The controller <NUM> is configured to: generate a second control signal based on the differential voltage signal obtained after the gain, and send the second control signal to the equalizer <NUM>, where the second control signal is used to control the equalizer <NUM> to perform gain on the differential voltage signal.

In this embodiment of this application, the equalizer <NUM> is used to implement gain compensation for a high frequency. According to a feature of a wide compensation range of the equalizer <NUM>, the equalizer <NUM> is enabled to perform compensation for the optoelectronic detector <NUM>, to achieve an optimal effect. Compared with the previous embodiment without the equalizer, this embodiment has an advantage of a wider range of compensation for the optoelectronic detector <NUM>, and has a disadvantage that more noise is introduced because gain compensation for the high frequency is completely implemented by the equalizer.

Optionally, the second control signal that enables the equalizer <NUM> to perform current-stage optimal compensation for the optoelectronic detector <NUM> is mainly generated in the following two manners:.

In this case, the equalizer <NUM> generates, for the differential voltage signal, a gain determined by the control signal, to obtain the differential voltage signal obtained after the gain.

Then, the controller <NUM> samples an upper level and a lower level of the differential voltage signal obtained after the gain, to obtain a value of a sampling point.

In other words, each time of sampling processing is performed for a signal that is obtained after different gain, to obtain a different sampling point. A sampling point with a maximum value is selected from obtained sampling points, and a control signal corresponding to the sampling point can enable the equalizer <NUM> to perform optimal compensation.

(<NUM>) The controller <NUM> performs a plurality of times of detection processing, and performs the following process in each time of detection processing:
First, the controller <NUM> sends a control signal to the equalizer <NUM>.

Then, the controller <NUM> uses a first frequency as a boundary, and separately detects energy of the differential voltage signal that is higher than the first frequency and energy of the differential voltage signal that is lower than the first frequency, to obtain an energy difference, where the first frequency is <NUM>/Tb, and Tb is duration of each bit of the differential voltage signal.

In other words, each time of detection processing is performed for a signal that is obtained after different gain, to obtain a different energy difference. A minimum energy difference is selected from obtained energy differences, and a control signal corresponding to the energy difference can enable the equalizer <NUM> to perform optimal compensation.

Optionally, generating a control signal with a relatively best compensation effect based on the differential voltage signal obtained after the gain is mainly performed in the following two methods:.

The control methods in the foregoing plurality of embodiments are all adaptive feedback control manners. This application provides a plurality of possible implementations, and any similar control solution shall fall within the protection scope of this application.

Further, in addition to the adaptive feedback control manners, equalization adjustment may further be controlled and implemented in a programmable analog or digital manner. An optical receiver in this solution may include components similar to those included in any optical receiver shown in <FIG>, <FIG>, or <FIG>. Functions of an optoelectronic detector, a transimpedance amplification circuit, a single-ended-to-differential converter, an equalizer, and an I/O interface are all the same as those in the foregoing embodiments, and an only difference lies in that a controller does not need to receive a differential voltage signal, and therefore does not perform sampling processing or detection processing on the differential voltage signal. A correspondence between an external environmental change and a control signal, such as a relationship between a temperature and a control signal, is estimated based on related information such as a simulation result in a product design stage, and a corresponding control signal is directly selected based on an external temperature value. For reference, <FIG> is a schematic structural diagram of an optical receiver including components the same as those included in the optical receiver shown in <FIG>.

It should be understood that the relationship between an external environmental change and a control signal may be pre-stored inside the controller; or may be stored in another driving component, where the driving component controls the controller to work; or may be printed, where operating personnel control, based on the correspondence, the controller to work. This is not limited in this application.

According to the optical receiver provided in the plurality of embodiments of this application, the optoelectronic detector whose bandwidth is lower than the system transmission bandwidth requirement is used, to greatly reduce costs of the optical receiver; and the transimpedance amplification circuit and/or the equalizer are/is used, to remedy received signal deterioration caused by bandwidth insufficiency, so that component costs are reduced while received signal quality is ensured.

Claim 1:
An optical receiver, comprising an optoelectronic detector (<NUM>), a transimpedance amplification circuit (<NUM>), a single-ended-to-differential converter (<NUM>) and an I/O interface (<NUM>), wherein:
the optoelectronic detector (<NUM>), configured to convert a received optical signal into a current signal, wherein bandwidth of the optoelectronic detector is lower than a system transmission bandwidth requirement;
the transimpedance amplification circuit (<NUM>), configured to:
receive the current signal and a first control signal; and
perform transimpedance gain compensation for the current signal based on the first control signal to obtain a voltage signal, wherein a frequency response value of the current signal within first bandwidth of the transimpedance amplification circuit (<NUM>) is higher than that within the bandwidth of the optoelectronic detector (<NUM>), and wherein any frequency in the first bandwidth is not lower than an upper cut-off frequency of the optoelectronic detector (<NUM>), wherein the first control signal is received from a controller (<NUM>);
the single-ended-to-differential converter (<NUM>), configured to:
convert the voltage signal into a differential voltage signal; and,
send the differential voltage signal to the I/O interface (<NUM>) and the controller (<NUM>), wherein the first
control signal is generated based on the differential voltage signal; and,
the I/O interface (<NUM>), configured to output the differential voltage signal.