CN216819846U

CN216819846U - Optical module

Info

Publication number: CN216819846U
Application number: CN202220442572.5U
Authority: CN
Inventors: 刘澍; 王玲; 石良; 吴堂猛
Original assignee: Hisense Broadband Multimedia Technology Co Ltd
Current assignee: Hisense Broadband Multimedia Technology Co Ltd
Priority date: 2022-03-02
Filing date: 2022-03-02
Publication date: 2022-06-24
Anticipated expiration: 2032-03-02

Abstract

The application discloses optical module is equipped with supply circuit and limiting amplifier. The power supply circuit comprises a voltage stabilizing circuit. The voltage stabilizing circuit is used for changing the first power supply voltage into the second power supply voltage, the first power supply voltage is unstable, and the second power supply voltage is stable. And the second input pin of the limiting amplifier is connected with a power supply circuit and comprises an SD threshold circuit and an SD comparator. The SD threshold circuit is used for providing an SD threshold for the SD comparator, and the SD threshold is kept unchanged under the first power supply voltage. And the SD comparator is connected with a forward input pin and an output pin of the SD threshold circuit, and connected with a signal amplitude detection circuit and used for comparing the voltage signal amplitude with the SD threshold so as to control the output of the SD signal. Under the combined action of the stabilizing circuit and the SD threshold circuit, the SD threshold is kept unchanged under the first power supply voltage, stable output of small optical signals is not influenced, and receiving sensitivity is improved.

Description

Optical module

Technical Field

The application relates to the technical field of communication, in particular to an optical module.

Background

With the development of data services, IPTV (Internet Protocol television) and high-definition video services are increasing exponentially, the efficiency of the transmission bandwidth of a GPON (Gigabit-Capable Passive Optical Network) Optical module is limited, and the application requirements of an XGSPON (10-Gigabit-Capable Passive Optical Network, 10 Gigabit-Capable symmetric Passive Optical Network) OLT (Optical Line Terminal) Optical module are receiving more attention.

The Combo (optical-electrical multiplexing) optical transceiver integrated module integrating the XGSON OLT and the GPON OLT, which is developed as a module meeting the coexistence requirement of smoothly upgrading the GPON to the XGSON, well solves the current requirement. The Combo optical module product transmits XGSPON downlink and GPON downlink services. But the reception sensitivity of the GPON upstream end is low.

SUMMERY OF THE UTILITY MODEL

The application provides an optical module, which improves receiving sensitivity.

A light module, comprising:

a circuit board;

the light receiving component is connected with the circuit board and used for receiving light signals;

a photoelectric detector and a trans-impedance amplifier are arranged in the light receiving assembly;

the photoelectric detector is connected with an input pin of the transimpedance amplifier and is used for converting the received optical signal into a current signal;

the trans-impedance amplifier is used for converting the current signal into a voltage signal so as to facilitate signal amplitude detection;

the circuit board is provided with a power supply circuit and a limiting amplifier;

the power supply circuit comprises a power supply and a voltage stabilizing circuit and is used for providing stable power supply voltage for the limiting amplifier;

the power supply source provides a first power supply voltage, and the first power supply voltage is unstable;

the input pin of the voltage stabilizing circuit is connected with a power supply and is used for changing the first power supply voltage into a second power supply voltage, and the second power supply voltage is stable;

the amplitude limiting amplifier is characterized in that a first input pin is in differential connection with an output pin of the trans-impedance amplifier, a second input pin is connected with the power supply circuit, and the amplitude limiting amplifier comprises an SD threshold circuit, a signal amplitude detection circuit and an SD comparator;

the SD threshold circuit is connected with the second input pin and used for providing an SD threshold for the SD comparator, wherein the SD threshold is kept unchanged under the first power supply voltage;

the signal amplitude detection circuit is connected with the first input pin in a differential mode and used for acquiring the amplitude of a voltage signal input to the first input pin of the limiting amplifier;

and the SD comparator is used for comparing the voltage signal amplitude with the SD threshold to control the output SD signal so as to close the quick discharge of the differential line on the first input pin of the limiting amplifier.

Has the advantages that: the application provides an optical module, which comprises a circuit board and an optical receiving assembly connected with the circuit board. The optical receiving component is used for receiving optical signals. The light receiving component is internally provided with a photoelectric detector and a transimpedance amplifier. And the photoelectric detector is connected with an input pin of the transimpedance amplifier and is used for converting the received optical signal into a current signal. And the trans-impedance amplifier is used for converting the current signal into a voltage signal so as to facilitate signal amplitude detection. The circuit board is provided with a power supply circuit and a limiting amplifier. And the power supply circuit comprises a power supply and a voltage stabilizing circuit and is used for providing stable power supply voltage for the limiting amplifier. Since the power supply provides the first supply voltage, the first supply voltage is unstable. Therefore, a voltage stabilizing circuit is designed in the power supply circuit. And the input pin of the voltage stabilizing circuit is connected with the power supply and used for converting the first power supply voltage into a second power supply voltage, and the second power supply voltage is stable. And the first input pin of the limiting amplifier is in differential connection with the output pin of the trans-impedance amplifier, and the second input pin of the limiting amplifier is connected with the power supply circuit and comprises an SD threshold circuit, a signal amplitude detection circuit and an SD comparator. And the input pin of the SD threshold circuit is connected with the second input pin and is used for providing an SD threshold for the SD comparator, wherein the SD threshold is kept unchanged under the first power supply voltage. And the signal amplitude detection circuit is connected with the first input pin in a differential mode and used for acquiring the amplitude of the voltage signal input to the first input pin of the limiting amplifier. And the SD comparator is connected with a forward input pin and an output pin of the SD threshold circuit, and is used for comparing the voltage signal amplitude with the SD threshold so as to control the output of the SD signal and further close the rapid discharge of a differential line on a first input pin of the limiting amplifier. And closing the rapid discharge of the differential line on the first input pin of the limiting amplifier, so that the signal input to the first input pin of the limiting amplifier is not discharged, and the limiting amplifier carries out limiting amplification. The voltage stabilizing circuit can change the first power supply voltage into a second power supply voltage to be provided for the SD threshold circuit. Under the second supply voltage, the SD threshold circuit provides an SD threshold for the SD comparator to keep unchanged under the first supply voltage. Because of the stability of the SD threshold, the stable output of the small optical signal is not influenced, and the receiving sensitivity is further improved. Under the combined action of the stabilizing circuit and the SD threshold circuit, the SD threshold is kept unchanged under the first power supply voltage, stable output of small optical signals is not influenced, and receiving sensitivity is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic diagram of electrical connections of an optical communication terminal according to some embodiments;

figure 2 is a schematic diagram of an optical network terminal structure according to some embodiments;

fig. 3 is a schematic structural diagram of an optical module according to some embodiments;

FIG. 4 is an exploded view of a light module according to some embodiments;

fig. 5 is a schematic diagram of an internal structure of a light module according to some embodiments;

FIG. 6 is a schematic diagram of a circuit board according to some embodiments;

fig. 7 is a schematic diagram of a circuit provided in accordance with some embodiments.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are only a part of the embodiments of the present disclosure, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.

In the optical communication technology, light is used to carry information to be transmitted, and an optical signal carrying the information is transmitted to information processing equipment such as a computer through information transmission equipment such as an optical fiber or an optical waveguide, so that the transmission of the information is completed. Because the optical signal has the passive transmission characteristic when being transmitted through the optical fiber or the optical waveguide, the information transmission with low cost and low loss can be realized. Further, since a signal transmitted by an information transmission device such as an optical fiber or an optical waveguide is an optical signal and a signal that can be recognized and processed by an information processing device such as a computer is an electrical signal, it is necessary to perform interconversion between the electrical signal and the optical signal in order to establish an information connection between the information transmission device such as an optical fiber or an optical waveguide and the information processing device such as a computer.

The optical module realizes the function of interconversion between the optical signal and the electrical signal in the technical field of optical fiber communication. The optical module comprises an optical port and an electrical port, the optical module realizes optical communication with information transmission equipment such as optical fibers or optical waveguides and the like through the optical port, realizes electrical connection with an optical network terminal (such as an optical modem) through the electrical port, and the electrical connection is mainly used for realizing power supply, I2C signal transmission, data signal transmission, grounding and the like; the optical network terminal transmits the electric signal to the computer and other information processing equipment through a network cable or a wireless fidelity (Wi-Fi).

Fig. 1 is a diagram of optical communication system connections according to some embodiments. As shown in fig. 1, the optical communication system mainly includes a remote server 1000, a local information processing device 2000, an optical network terminal 100, an optical module 200, an optical fiber 101, and a network cable 103;

one end of the optical fiber 101 is connected to the remote server 1000, and the other end is connected to the optical network terminal 100 through the optical module 200. The optical fiber itself can support long-distance signal transmission, for example, signal transmission of several kilometers (6 kilometers to 8 kilometers), on the basis of which if a repeater is used, ultra-long-distance transmission can be theoretically achieved. Therefore, in a typical optical communication system, the distance between the remote server 1000 and the optical network terminal 100 may be several kilometers, tens of kilometers, or hundreds of kilometers.

One end of the network cable 103 is connected to the local information processing device 2000, and the other end is connected to the optical network terminal 100. The local information processing apparatus 2000 may be any one or several of the following apparatuses: router, switch, computer, cell-phone, panel computer, TV set etc..

The physical distance between the remote server 1000 and the optical network terminal 100 is greater than the physical distance between the local information processing apparatus 2000 and the optical network terminal 100. The connection between the local information processing device 2000 and the remote server 1000 is completed by the optical fiber 101 and the network cable 103; and the connection between the optical fiber 101 and the network cable 103 is completed by the optical module 200 and the optical network terminal 100.

The optical module 200 includes an optical port and an electrical port. The optical port is configured to connect with the optical fiber 101, so that the optical module 200 establishes a bidirectional optical signal connection with the optical fiber 101; the electrical port is configured to be accessed into the optical network terminal 100, so that the optical module 200 establishes a bidirectional electrical signal connection with the optical network terminal 100. The optical module 200 converts an optical signal and an electrical signal to each other, so that a connection is established between the optical fiber 101 and the optical network terminal 100. For example, an optical signal from the optical fiber 101 is converted into an electrical signal by the optical module 200 and then input to the optical network terminal 100, and an electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module 200 and input to the optical fiber 101.

The optical network terminal 100 includes a housing (housing) having a substantially rectangular parallelepiped shape, and an optical module interface 102 and a network cable interface 104 provided on the housing. The optical module interface 102 is configured to access the optical module 200, so that the optical network terminal 100 establishes a bidirectional electrical signal connection with the optical module 200; the network cable interface 104 is configured to access the network cable 103 such that the optical network terminal 100 establishes a bi-directional electrical signal connection with the network cable 103. The optical module 200 is connected to the network cable 103 via the optical network terminal 100. For example, the optical network terminal 100 transmits an electrical signal from the optical module 200 to the network cable 103, and transmits a signal from the network cable 103 to the optical module 200, so that the optical network terminal 100 can monitor the operation of the optical module 200 as an upper computer of the optical module 200. The upper computer of the Optical module 200 may include an Optical Line Terminal (OLT) and the like in addition to the Optical network Terminal 100.

The remote server 1000 establishes a bidirectional signal transmission channel with the local information processing device 2000 through the optical fiber 101, the optical module 200, the optical network terminal 100, and the network cable 103.

Fig. 2 is a structure diagram of an optical network terminal according to some embodiments, and fig. 2 only shows the structure of the optical module 200 of the optical network terminal 100 in order to clearly show the connection relationship between the optical module 200 and the optical network terminal 100. As shown in fig. 2, the optical network terminal 100 further includes a PCB circuit board 105 disposed in the housing, a cage 106 disposed on a surface of the PCB circuit board 105, and an electrical connector disposed inside the cage 106. The electrical connector is configured to access an electrical port of the optical module 200; the heat sink 107 has a projection such as a fin that increases a heat radiation area.

The optical module 200 is inserted into a cage 106 of the optical network terminal 100, the cage 106 holds the optical module 200, and heat generated by the optical module 200 is conducted to the cage 106 and then diffused by a heat sink 107. After the optical module 200 is inserted into the cage 106, an electrical port of the optical module 200 is connected to an electrical connector inside the cage 106, and thus the optical module 200 establishes a bidirectional electrical signal connection with the optical network terminal 100. Further, the optical port of the optical module 200 is connected to the optical fiber 101, and the optical module 200 establishes bidirectional electrical signal connection with the optical fiber 100.

Fig. 3 is a schematic diagram of an optical module according to some embodiments, and fig. 4 is an exploded schematic diagram of an optical module according to some embodiments. As shown in fig. 3 and 4, the optical module 200 includes a housing, a circuit board 300 disposed in the housing, and an optical transceiver module;

the shell comprises an upper shell 201 and a lower shell 202, wherein the upper shell 201 is covered on the lower shell 202 to form the shell with two

openings

204 and 205; the outer contour of the housing generally appears square.

In some embodiments, the lower housing 202 includes a bottom plate and two lower side plates disposed at both sides of the bottom plate and perpendicular to the bottom plate; the upper housing 201 includes a cover plate, and two upper side plates disposed on two sides of the cover plate and perpendicular to the cover plate, and is combined with the two side plates by two side walls to cover the upper housing 201 on the lower housing 202.

The direction of the connecting line of the two

openings

204 and 205 may be the same as the length direction of the optical module 200, or may not be the same as the length direction of the optical module 200. For example, the opening 204 is located at an end (left end in fig. 3) of the optical module 200, and the opening 205 is also located at an end (right end in fig. 3) of the optical module 200. Alternatively, the opening 204 is located at an end of the optical module 200, and the opening 205 is located at a side of the optical module 200. Wherein, the opening 204 is an electrical port, and the gold finger of the circuit board 300 extends out of the electrical port 204 and is inserted into an upper computer (such as the optical network terminal 100); the opening 205 is an optical port configured to receive the external optical fiber 101 so that the optical fiber 101 is connected to an optical transceiver module inside the optical module 200.

The upper shell 201 and the lower shell 202 are combined to facilitate the installation of devices such as the circuit board 300 and the optical transceiver module into the shell, and the upper shell 201 and the lower shell 202 can form encapsulation protection for the devices. In addition, when the devices such as the circuit board 300 are assembled, the positioning components, the heat dissipation components and the electromagnetic shielding components of the devices are convenient to arrange, and the automatic implementation production is facilitated.

In some embodiments, the upper housing 201 and the lower housing 202 are generally made of metal materials, which is beneficial to achieve electromagnetic shielding and heat dissipation.

In some embodiments, the optical module 200 further includes an unlocking component 203 located on an outer wall of a housing thereof, and the unlocking component 203 is configured to realize a fixed connection between the optical module 200 and an upper computer or release the fixed connection between the optical module 200 and the upper computer.

Illustratively, the unlocking member 203 is located on the outer walls of the two lower side plates of the lower housing 202, and includes a snap-fit member that mates with a cage of an upper computer (e.g., the cage 106 of the optical network terminal 100). When the optical module 200 is inserted into the cage of the upper computer, the optical module 200 is fixed in the cage of the upper computer by the engaging member of the unlocking member 203; when the unlocking member 203 is pulled, the engaging member of the unlocking member 203 moves along with the unlocking member, and the connection relationship between the engaging member and the upper computer is changed, so that the engagement relationship between the optical module 200 and the upper computer is released, and the optical module 200 can be drawn out from the cage of the upper computer.

The circuit board 300 includes circuit traces, electronic components (such as capacitors, resistors, triodes, and MOS transistors), and chips (such as an MCU, a laser driver chip, a limiting amplifier, a clock data recovery CDR, a power management chip, and a data processing chip DSP).

The circuit board 300 connects the above devices in the optical module 200 together according to circuit design through circuit routing to implement functions of power supply, electrical signal transmission, grounding, and the like.

The circuit board 300 is generally a rigid circuit board, which can also perform a bearing function due to its relatively rigid material, for example, the rigid circuit board can stably bear a chip; the hard circuit board can also be inserted into an electric connector in the upper computer cage, and in some embodiments disclosed in the application, a metal pin/golden finger is formed on the surface of the tail end on one side of the hard circuit board and is used for being connected with the electric connector; these are not easily implemented with flexible circuit boards.

Flexible circuit boards are also used in some optical modules; the flexible circuit board is generally used in combination with the rigid circuit board, and for example, the rigid circuit board may be connected to the optical transceiver module by using the flexible circuit board as a supplement to the rigid circuit board.

As shown in fig. 4, in some embodiments, one end of the optical transceiver module 400 is connected to the optical fiber adapter 206, the optical transceiver module 400 generates signal light and receives signal light from outside of the optical module, and when the optical module is used, the signal light generated by the optical transceiver module 400 is transmitted to outside of the optical module through the optical fiber adapter 206, and the signal light received from outside of the optical module is transmitted to the optical transceiver module 400 through the optical fiber adapter 206.

As shown in fig. 4, in some embodiments, the optical transceiver component 400 is a unitary structure including an optical transmitter component 410 and an optical receiver component 420; the light emitting module 410 and the light receiving module 420 are electrically connected to the circuit board 300 through flexible circuit boards, respectively.

In some embodiments of the present application, the optical module shown in fig. 4 may be a Combo optical transceiver module for implementing the integration of an XGSPON OLT and a GPON OLT, an EML and DFB laser with center wavelengths of 1577nm and 1490nm are respectively used for downlink of a Combo optical module product to transmit XGSPON downlink and GPON downlink services, and a high-sensitivity APD detector with a wavelength of 1260 to 1280nm is used for uplink to support burst working modes of 9.953Gbps and 2.488 Gbps. Thus, the optical transmit component 410 is used to generate signal light at wavelengths of 1577nm and 1490nm that enable XGSPON and GPON technologies transmission; the optical receiving component 420 is used for receiving 1260-1280 nm signal light transmitted by XGSPON and GPON technologies from the outside of the optical module.

A photodetector and a transimpedance amplifier are provided in the light receiving module 420. In particular, the method comprises the following steps of,

and the photoelectric detector is electrically connected with the input pin of the transimpedance amplifier and is used for converting the received optical signal into a current signal. Specifically, the photodetector is an Avalanche Photodiode (APD). When the avalanche photodiode works normally, the received optical signal is converted into a current signal.

A trans-impedance amplifier (TIA) is used to convert a current signal into a voltage signal for signal amplitude detection. Specifically, the transimpedance amplifier includes an operational amplifier. The current signal output by the photoelectric detector is input through the reverse input pin of the operational amplifier, and the current signal is converted into a voltage signal under the action of the operational amplifier.

Fig. 5 is a schematic diagram of an internal structure of an optical module according to some embodiments. Fig. 6 is a schematic structural diagram of a circuit board according to some embodiments. Fig. 7 is a schematic diagram of a circuit provided in accordance with some embodiments. As shown in fig. 5 to 7, a limiting amplifier 301, an MCU302, and a power supply circuit 303 are provided on the circuit board 300. In particular, the method comprises the following steps of,

and a first input pin of the limiting amplifier 301 is connected with an output pin of the transimpedance amplifier in a differential manner, a second input pin of the limiting amplifier is connected with the power supply circuit 303, and a third input pin of the limiting amplifier is connected with the MCU 302.

And an MCU302 for supplying a reset pulse signal to the limiting amplifier 301.

The power supply circuit 303 includes a power supply and voltage stabilizing circuit 3031, and is configured to provide a stable power supply voltage for the limiting amplifier 301.

The power supply provides a first power supply voltage, and the first power supply voltage is unstable. The first power supply voltage provided by the power supply is between 3.1V and 3.5V.

The input pin of the voltage stabilizing circuit 3031 is connected to the power supply, and the output pin thereof is connected to the second input pin of the limiting amplifier 301, so as to change the first power supply voltage into the second power supply voltage, which is stable.

Under the action of the voltage stabilizing circuit 3031, the second power supply voltage output by the power supply circuit is 3.0V.

The voltage stabilizing circuit 3031 comprises a series adjusting tube 30311, a first sampling resistor 30312, a second sampling resistor 30313, a comparison amplifier 30314 and a diode 30315. In particular, the method comprises the following steps of,

the series adjustment tube 30311 has an input pin connected to the power supply, a control pin connected to the comparison amplifier 30314, and an output pin connected to the first pin of the first sampling resistor 30312 and the limiting amplifier 301.

A first sampling resistor 30312, and a second pin thereof is connected to a first pin of the second sampling resistor 30313.

And a second sampling resistor 30313, and a second pin is connected to the diode 30315.

And a comparison amplifier 30314, in which a forward input pin is connected to the second pin of the first sampling resistor 30312, a reverse input pin is connected to the power supply, and an output pin is connected to the control pin of the series adjusting tube 30311, and is configured to control a voltage drop of the series adjusting tube 30311 by comparing a reference voltage of the reverse input pin with a sampling voltage of the forward input pin, so that the voltage stabilizing circuit 3031 outputs a stable voltage.

The comparator 30314 compares the reference voltage of the inverting input pin with the sampling voltage of the forward input pin to obtain a difference between the reference voltage and the sampling voltage, amplifies the difference, and controls the voltage drop of the series regulator 30311, so that the voltage regulator circuit outputs a stable voltage.

When the output voltage of the voltage stabilizing circuit 3031 decreases, the difference between the reference voltage and the sampling voltage increases, the driving current output by the comparison amplifier 30314 increases, and the voltage drop of the series regulator 30311 decreases, so that the output voltage increases. Conversely, if the output voltage of the constant voltage circuit 3031 exceeds a desired set value, the front drive current outputted from the comparison amplifier decreases, and the output voltage decreases.

Diode 30315, the first pin of which is connected to the second pin of second sampling resistor 30313, and the second pin of which is connected to the power supply, is used to keep the reference voltage stable.

The stabilizing circuit 3031 also includes a current source 30316. And a current source 30316, a first pin of which is connected with a power supply, and a second pin of which is connected with an inverting input pin of the comparison amplifier 30314.

The current source 30316 is a constant current source for providing a reference voltage.

The limiting amplifier 301 includes an SD comparator 3011, a signal amplitude detection circuit 3012, an SD threshold circuit 3013, an SD logic output circuit 3014, an inversion controller 3015, a limiting amplifier 3016, an input buffer 3017, and an output buffer 3018. In particular, the method comprises the following steps of,

in the SD comparator 3011, a forward input pin is connected to an output pin of the SD threshold circuit 3013, and a reverse input pin is connected to an output pin of the signal amplitude detection circuit 3012, and the forward input pin is used to compare a voltage signal amplitude with an SD threshold to control output of an SD signal, thereby closing fast discharge of a differential line on a first input pin of the limiting amplifier.

The signal amplitude detection circuit 3012 has an input pin differentially connected to the first input pin of the limiting amplifier 301, and is configured to obtain the amplitude of the voltage signal input to the first input pin of the limiting amplifier 301.

The signal amplitude detection circuit 3012 acquires the amplitude of the voltage signal input to the first input pin of the limiting amplifier 301 and transmits the voltage signal amplitude to the SD comparator. The voltage signal is differentially output by the transimpedance amplifier.

And an SD threshold circuit 3013, an input pin of which is connected to the second input pin of the limiting amplifier 301, for providing an SD threshold to the SD comparator 3011, wherein the SD threshold is kept unchanged at the first supply voltage.

The SD threshold circuit 3013 includes a first resistor 30131 and a second resistor 30132.

The first resistor 30131 has an input pin connected to an output pin of the voltage stabilizing circuit 3031, and an output pin connected to a positive input pin of the SD comparator 3011.

The voltage at the input pin of the first resistor 30131 is V_CC-SDThe voltage at the output pin of the first resistor 30131 is V_SDLVL。

In the second resistor 30132, the input pin is a common mode voltage, and the output pin is connected to the output pin of the first resistor 30131.

The voltage at the input pin of the second resistor 30132 is V_COM。

The formula of the SD threshold is as follows:

V_SDLVL＝(V_CC-V_COM)*R₂(R₁+R₂)

wherein, V_SDLVLIs an SD threshold; v_COMIs a common mode voltage, not following V_CC-SDChange by change; v_CCIs a supply voltage; r₁Being a first resistanceResistance value; r₂Is the resistance of the second resistor.

The formula of the SD threshold is combined to know that the SD threshold follows the power supply voltage V_CCMay vary. The change of the SD threshold affects the stable output of the small optical signal, so that the optical reception sensitivity is low. In order to improve the light receiving sensitivity, the SD threshold needs to be kept constant under an unstable power supply voltage provided by the power supply.

The stabilizing circuit 3031 may change the first supply voltage to the second supply voltage. According to the formula of the SD threshold, when the power supply voltage is stable and unchanged, the SD threshold is also stable and unchanged, the stable output of small optical signals cannot be influenced, and the light receiving sensitivity is improved.

An SD logic output circuit 3014, a first input pin of which is connected to an output pin of the SD comparator 3011, and a second input pin of which is connected to the MCU302, and configured to output an SD signal according to the reset pulse signal and the comparison result output by the SD comparator.

The SD signal may be low or high.

When the SD logic output circuit 3014 receives the reset signal, the output SD signal is at a high level; when the SD logic output circuit 3014 receives the comparison result output by the SD comparator and the voltage signal amplitude is greater than the SD threshold, the output SD signal is at low level.

And an inverting controller 3015 having an input pin connected to an output pin of the SD logic output circuit 3014 and an output pin differentially connected to the first input pin of the limiting amplifier 301, and configured to control differential line discharge on the first input pin of the limiting amplifier 301 according to the SD signal.

When the SD signal is low, the inversion controller 3015 controls the differential line on the first input pin of the limiting amplifier 301 to discharge. If the fast discharge of the differential line on the first input pin of the limiting amplifier is not turned off, the signal input to the first input pin of the limiting amplifier 301 is dropped, and subsequent limiting amplification cannot be performed.

When the SD signal is at a high level, the inversion controller 3015 controls to turn off the differential line discharge on the first input pin of the limiting amplifier 301. And closing the rapid discharge of the differential line on the first input pin of the limiting amplifier, so that the signal input to the first input pin of the limiting amplifier is not discharged, and the limiting amplifier carries out limiting amplification.

A limiting amplifier 3016 has an input pin differentially connected to a first input pin of the limiting amplifier 301.

An input buffer has an input pin differentially connected to a first input pin of the limiting amplifier 301, and an output pin differentially connected to an input pin of the limiting amplifier 3016.

An output buffer has an input pin differentially connected to an output pin of the limiting amplifier 3016, and an output pin connected to an output pin of the limiting amplifier 301.

The limiting amplifier 301 further includes a first capacitor and a second capacitor. In particular, the method comprises the following steps of,

and the input pin of the first capacitor is connected with one sub-pin of the first input pin of the limiting amplifier, and the output pin of the first capacitor is connected with one sub-pin of the input buffer.

And the input pin of the second capacitor is connected with the other sub-pin of the first input pin of the limiting amplifier, and the output pin of the second capacitor is connected with the other sub-pin of the input buffer.

The application provides an optical module, which comprises a circuit board and an optical receiving assembly connected with the circuit board. The optical receiving component is used for receiving optical signals. A photoelectric detector and a trans-impedance amplifier are arranged in the light receiving component. And the photoelectric detector is connected with an input pin of the transimpedance amplifier and is used for converting the received optical signal into a current signal. And the trans-impedance amplifier is used for converting the current signal into a voltage signal so as to facilitate signal amplitude detection. The circuit board is provided with a power supply circuit and a limiting amplifier. And the power supply circuit comprises a power supply and a voltage stabilizing circuit and is used for providing stable power supply voltage for the limiting amplifier. Since the power supply provides the first supply voltage, the first supply voltage is unstable. Therefore, a voltage stabilizing circuit is designed in the power supply circuit. And the input pin of the voltage stabilizing circuit is connected with the power supply and used for converting the first power supply voltage into a second power supply voltage, and the second power supply voltage is stable. And the first input pin of the limiting amplifier is in differential connection with the output pin of the trans-impedance amplifier, and the second input pin of the limiting amplifier is connected with the power supply circuit and comprises an SD threshold circuit, a signal amplitude detection circuit and an SD comparator. And the input pin of the SD threshold circuit is connected with the second input pin and is used for providing an SD threshold for the SD comparator, wherein the SD threshold is kept unchanged under the first power supply voltage. And the signal amplitude detection circuit is connected with the first input pin in a differential mode and used for acquiring the amplitude of the voltage signal input to the first input pin of the limiting amplifier. And the SD comparator is connected with a forward input pin and an output pin of the SD threshold circuit, and is used for comparing the voltage signal amplitude with the SD threshold so as to control the output of the SD signal and further close the rapid discharge of a differential line on a first input pin of the limiting amplifier. And closing the rapid discharge of the differential line on the first input pin of the limiting amplifier, so that the signal input to the first input pin of the limiting amplifier is not discharged, and the limiting amplifier carries out limiting amplification. The voltage stabilizing circuit can change the first power supply voltage into a second power supply voltage to be provided for the SD threshold circuit. Under the second supply voltage, the SD threshold circuit provides an SD threshold for the SD comparator, which is kept unchanged under the first supply voltage. Because of the stability of the SD threshold, the stable output of the small optical signal is not influenced, and the receiving sensitivity is further improved. Under the combined action of the stabilizing circuit and the SD threshold circuit, the SD threshold is kept unchanged under the first power supply voltage, stable output of small optical signals is not influenced, and receiving sensitivity is improved.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present disclosure, not to limit it; although the present disclosure has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present disclosure.

Claims

1. A light module, comprising:

a circuit board;

a photoelectric detector and a transimpedance amplifier are arranged in the light receiving assembly;

the photoelectric detector is connected with an input pin of the transimpedance amplifier and is used for converting a received optical signal into a current signal;

the power supply provides a first power supply voltage, and the first power supply voltage is unstable;

the input pin of the voltage stabilizing circuit is connected with the power supply and is used for changing the first power supply voltage into a second power supply voltage, and the second power supply voltage is stable;

the first input pin of the limiting amplifier is in differential connection with the output pin of the trans-impedance amplifier, and the second input pin of the limiting amplifier is connected with the power supply circuit and comprises an SD threshold circuit, a signal amplitude detection circuit and an SD comparator;

the input pin of the SD threshold circuit is connected with the second input pin and is used for providing an SD threshold for the SD comparator, wherein the SD threshold is kept unchanged under the first power supply voltage;

the signal amplitude detection circuit is provided with an input pin which is connected with the first input pin in a differential mode and is used for acquiring the amplitude of a voltage signal input to the first input pin of the limiting amplifier;

and the SD comparator is connected with the output pin of the SD threshold circuit through a forward input pin, is connected with the output pin of the signal amplitude detection circuit through a reverse input pin, and is used for comparing the voltage signal amplitude with the SD threshold so as to control the output of an SD signal and further close the rapid discharge of a differential line on a first input pin of the limiting amplifier.

2. The optical module of claim 1, wherein the voltage regulation circuit comprises a series regulator, a first sampling resistor, a second sampling resistor, a comparison amplifier, and a diode;

an input pin of the series adjusting tube is connected with the power supply, a control pin of the series adjusting tube is connected with the comparison amplifier, and an output pin of the series adjusting tube is respectively connected with a first pin of the first sampling resistor and the limiting amplifier;

the second pin of the first sampling resistor is connected with the first pin of the second sampling resistor;

the second pin of the second sampling resistor is connected with the first pin of the diode;

the comparison amplifier has a forward input pin connected with the second pin of the first sampling resistor, a reverse input pin connected with a power supply, and an output pin connected with the control pin of the series adjusting tube, and is used for controlling the voltage drop of the series adjusting tube by comparing the reference voltage of the reverse input pin with the sampling voltage of the forward input pin, so that the voltage stabilizing circuit outputs a stable voltage;

and the second pin of the diode is connected with the power supply.

3. The optical module of claim 1, wherein the SD threshold circuit comprises a first resistor and a second resistor;

an input pin of the first resistor is connected with an output pin of the voltage stabilizing circuit, and the output pin of the first resistor is connected with a positive input pin of the SD comparator;

and the voltage of the input pin of the second resistor is common-mode voltage, and the output pin of the second resistor is connected with the output pin of the first resistor.

4. The optical module of claim 1, wherein the limiting amplifier further comprises an SD logic output circuit;

and the first input pin of the SD logic output circuit is connected with the output pin of the SD comparator, and the second input pin of the SD logic output circuit is connected with the MCU and used for outputting an SD signal according to the reset pulse signal and the comparison result output by the SD comparator.

5. The light module of claim 4, wherein the limiting amplifier further comprises a reverse controller;

and the input pin of the reverse controller is connected with the output pin of the SD logic output circuit, and the output pin of the reverse controller is differentially connected with the first input pin of the limiting amplifier and is used for controlling differential line discharge on the first input pin of the limiting amplifier according to the SD signal.

6. The optical module of claim 1, wherein the limiting amplifier further comprises a limiting amplifier;

and the input pin of the limiting amplifier is differentially connected with the first input pin of the limiting amplifier.

7. The optical module of claim 6, wherein the limiting amplifier further comprises an input buffer and an output buffer;

an input pin of the input buffer is in differential connection with a first input pin of the limiting amplifier, and an output pin of the input buffer is in differential connection with an input pin of the limiting amplifier;

and an input pin of the output buffer is in differential connection with an output pin of the limiting amplifier.

8. The optical module of claim 7, wherein the limiting amplifier 301 further comprises a first capacitor and a second capacitor;

the input pin of the first capacitor is connected with one sub-pin of the first input pin of the limiting amplifier, and the output pin of the first capacitor is connected with one sub-pin of the input buffer;

and an input pin of the second capacitor is connected with the other sub-pin of the first input pin of the limiting amplifier, and an output pin of the second capacitor is connected with the other sub-pin of the input pins of the input buffer.