Bias voltage providing circuit of avalanche photodiode and PON gateway

Abstract

The invention provides a bias voltage providing circuit of an avalanche photodiode and a PON gateway, and relates to the technical field of optical communication. The bias voltage providing circuit of the avalanche photodiode comprises a bias voltage input unit, a bias voltage control input processing unit and an avalanche photodiode protection unit. When the illumination intensity of the target avalanche photodiode exceeds the preset illumination intensity, the photo-generated current of the target avalanche photodiode exceeds the preset current, and the avalanche photodiode protection unit responds to the situation that the photo-generated current of the target avalanche photodiode exceeds the preset current. The diode bias voltage applied to the target avalanche photodiode is reduced, so that the photo-generated current of the target avalanche photodiode is reduced, and overload protection of the target avalanche photodiode is completed. Based on the above content, the problem that the target avalanche photodiode is easy to damage due to overload in the prior art can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of optical communication, and more particularly, to a bias voltage providing circuit for an avalanche photodiode and a PON gateway. Background Art

[0002] In the existing access network optical module & optical modem applications, the optoelectronic signal conversion device commonly used in 10G PON (Passive Optical Network) modules is an avalanche photodiode (APD, Avalanche Photodiode). Among them, when using the APD for optoelectronic conversion, a relatively high bias voltage needs to be applied to one end of the APD. Thus, when the input optical signal is a large or strong light (i.e., the light intensity is relatively high), a large photocurrent will be generated on the APD. Therefore, when the photocurrent exceeds the maximum current allowed by the APD die, it will cause the APD to be damaged. Summary of the Invention

[0003] In view of this, the purpose of the present application is to provide a bias voltage providing circuit for an avalanche photodiode and a PON gateway to improve the problem that the target avalanche photodiode in the existing technology is easily damaged due to overload.

[0004] To achieve the above purpose, the present application adopts the following technical solutions:

[0005] A bias voltage providing circuit for an avalanche photodiode, comprising:

[0006] A bias voltage input unit, wherein the bias voltage input unit is used to output a diode bias voltage;

[0007] A bias voltage control input processing unit, wherein the first end of the bias voltage control input processing unit is connected to the output end of the bias voltage input unit, and is used to obtain and output the diode bias voltage;

[0008] An avalanche photodiode protection unit, wherein the first end of the avalanche photodiode protection unit is connected to the second end of the bias voltage control input processing unit, the second end of the avalanche photodiode protection unit is connected to the target avalanche photodiode, and the avalanche photodiode protection unit is used to apply the diode bias voltage to the target avalanche photodiode so that the target avalanche photodiode performs optoelectronic conversion;

[0009] Moreover, the third terminal of the avalanche photodiode protection unit is connected to the output terminal of the bias voltage input unit. When the light intensity of the target avalanche photodiode exceeds the preset light intensity, the photocurrent of the target avalanche photodiode exceeds the preset current. In response to the photocurrent of the target avalanche photodiode exceeding the preset current, the avalanche photodiode protection unit reduces the diode bias voltage applied to the target avalanche photodiode, so that the photocurrent of the target avalanche photodiode is reduced, thereby completing the overload protection of the target avalanche photodiode.

[0010] In a preferred selection of the present application, in the bias voltage supply circuit of the above avalanche photodiode, the avalanche photodiode protection unit includes:

[0011] A first resistor, wherein the first end of the first resistor serves as the first end of the avalanche photodiode protection unit and is connected to the second end of the bias voltage control input processing unit, and the second end of the first resistor serves as the second end of the avalanche photodiode protection unit and is connected to the target avalanche photodiode;

[0012] A first triode, wherein the first triode is a PNP type triode, and the emitter of the first triode is connected to the first end of the first resistor;

[0013] A second resistor, wherein the first end of the second resistor is connected to the second end of the first resistor, and the second end of the second resistor is connected to the base of the first triode;

[0014] A third resistor, wherein the first end of the third resistor is connected to the collector of the first triode;

[0015] A fourth resistor, wherein the first end of the fourth resistor is connected to the second end of the third resistor, and the second end of the fourth resistor is grounded;

[0016] A fifth resistor, wherein the first end of the fifth resistor is connected to the second end of the third resistor, and the second end of the fifth resistor serves as the third end of the avalanche photodiode protection unit and is connected to the output terminal of the bias voltage input unit;

[0017] Moreover, when the light intensity of the target avalanche photodiode exceeds the preset light intensity, the photocurrent of the target avalanche photodiode exceeds the preset current. In response to the photocurrent of the target avalanche photodiode exceeding the preset current, the first triode conducts the emitter and collector of the first triode to reduce the diode bias voltage applied to the target avalanche photodiode, so that the photocurrent of the target avalanche photodiode is reduced, thereby completing the overload protection of the target avalanche photodiode;

[0018] Wherein, the voltage of the connection node of the third resistor and the fourth resistor is used as the feedback voltage, and through the feedback regulation of the avalanche photodiode protection unit, the diode bias voltage output by the bias voltage input unit is V FB *(1 + R5 / R4), where V FB is the feedback voltage, R5 is the resistance value of the fifth resistor, and R4 is the resistance value of the fourth resistor.

[0019] In a preferred selection of the present application, in the bias voltage providing circuit of the above-mentioned avalanche photodiode, the avalanche photodiode protection unit further includes:

[0020] A sixth resistor, wherein the first end of the sixth resistor is connected to the second end of the first resistor;

[0021] A first inductive element, wherein the first end of the first inductive element is connected to the second end of the sixth resistor, and the second end of the first inductive element serves as the second end of the avalanche photodiode protection unit and is connected to the target avalanche photodiode;

[0022] A first capacitor, wherein the first end of the first capacitor is connected to the second end of the first inductive element, and the second end of the first capacitor is grounded.

[0023] In a preferred selection of the present application, in the bias voltage providing circuit of the above-mentioned avalanche photodiode, the avalanche photodiode protection unit further includes:

[0024] A second capacitor, wherein the first end of the second capacitor is connected to the first end of the fifth resistor, and the second end of the second capacitor is connected to the second end of the fifth resistor.

[0025] In a preferred selection of the present application, in the bias voltage providing circuit of the above-mentioned avalanche photodiode, the bias voltage providing circuit of the avalanche photodiode further includes:

[0026] A control unit, wherein the control unit is connected to the target internal connection node of the avalanche photodiode protection unit. The control unit is used to collect the voltage of the target internal connection node, and this voltage is used as the feedback voltage. There is a correlation between this feedback voltage and the diode bias voltage applied to the target avalanche photodiode, so that the control unit can determine whether the target avalanche photodiode is overvoltage based on this feedback voltage;

[0027] A discharge unit, wherein the first end of the discharge unit is connected to the target internal connection node, the second end of the discharge unit is connected to the output end of the bias voltage input unit, and the third end of the discharge unit is grounded;

[0028] Moreover, when the control unit determines that there is an overvoltage in the target avalanche photodiode, by controlling the voltage of the target internal connection node, the second end and the third end of the discharge unit are made conductive, so as to discharge the output end of the bias voltage input unit.

[0029] In a preferred selection of the present application, in the bias voltage providing circuit of the above avalanche photodiode, the discharge unit includes:

[0030] A seventh resistor, wherein the first end of the seventh resistor serves as the first end of the discharge unit and is connected to the target internal connection node;

[0031] An eighth resistor, wherein the first end of the eighth resistor is connected to the second end of the seventh resistor, and the second end of the eighth resistor is grounded;

[0032] A first MOS transistor, wherein the first MOS transistor belongs to an N-type MOS transistor, and the gate of the first MOS transistor is connected to the second end of the seventh resistor;

[0033] A ninth resistor, wherein the first end of the ninth resistor is connected to the drain of the first MOS transistor, and the second end of the ninth resistor serves as the second end of the discharge unit and is connected to the output end of the bias voltage input unit;

[0034] A discharge diode, wherein the anode of the discharge diode is connected to the source of the first MOS transistor, and the cathode of the discharge diode is grounded.

[0035] In a preferred selection of the present application, in the bias voltage providing circuit of the above avalanche photodiode, the bias voltage input unit includes:

[0036] A second MOS transistor, wherein the second MOS transistor belongs to an N-type MOS transistor, the source of the second MOS transistor is grounded, and the gate of the second MOS transistor serves as the control end of the bias voltage input unit and is connected to the control unit included in the bias voltage providing circuit of the avalanche photodiode to control whether the drain and the source are conductive based on the pulse width modulation signal output by the control unit;

[0037] A tenth resistor, wherein the first end of the tenth resistor is connected to the gate of the second MOS transistor, and the second end of the tenth resistor is grounded;

[0038] A second inductive element, wherein the first end of the second inductive element serves as the input end of the bias voltage input unit and is connected to an external power supply, and the second end of the second inductive element is connected to the drain of the second MOS transistor;

[0039] A Schottky diode, wherein the anode of the Schottky diode is connected to the second end of the second inductive element, and the cathode of the Schottky diode serves as the output end of the bias input unit and is connected to the first end of the bias control input processing unit.

[0040] In a preferred selection of the present application, in the bias voltage supply circuit of the above-mentioned avalanche photodiode, the bias input unit further includes:

[0041] A third capacitor, wherein the first end of the third capacitor is connected to the first end of the second inductive element, and the second end of the third capacitor is grounded;

[0042] A fourth capacitor, wherein the first end of the fourth capacitor is connected to the first end of the second inductive element, and the second end of the fourth capacitor is grounded;

[0043] A fifth capacitor, wherein the first end of the fifth capacitor is connected to the first end of the second inductive element, and the second end of the fifth capacitor is grounded;

[0044] A sixth capacitor, wherein the first end of the sixth capacitor is connected to the cathode of the Schottky diode, and the second end of the sixth capacitor is grounded;

[0045] A seventh capacitor, wherein the first end of the seventh capacitor is connected to the cathode of the Schottky diode, and the second end of the seventh capacitor is grounded.

[0046] In a preferred selection of the present application, in the bias voltage supply circuit of the above-mentioned avalanche photodiode, the bias control input processing unit includes:

[0047] A second triode, wherein the second triode belongs to a PNP type triode, and the collector of the second triode serves as the second end of the bias control input processing unit and is connected to the first end of the avalanche photodiode protection unit;

[0048] A third triode, wherein the third triode belongs to a PNP type triode, and the base of the third triode is connected to the collector of the third triode, and the base of the third triode is connected to the base of the second triode;

[0049] A fourth triode, wherein the fourth triode belongs to a PNP type triode, and the base of the fourth triode is connected to the collector of the second triode, and the emitter of the fourth triode is connected to the collector of the third triode;

[0050] The eleventh resistor, wherein the first end of the eleventh resistor serves as the first end of the bias voltage control input processing unit and is connected to the output end of the bias voltage input unit, and the second end of the eleventh resistor is connected to the emitter of the second triode;

[0051] The twelfth resistor, wherein the first end of the twelfth resistor is connected to the first end of the eleventh resistor, and the second end of the twelfth resistor is connected to the emitter of the third triode;

[0052] The thirteenth resistor, wherein the first end of the thirteenth resistor is connected to the collector of the fourth triode, and the second end of the thirteenth resistor is used to output a target RSSI current, and the target RSSI current is used to reflect the light intensity of the target avalanche photodiode;

[0053] The eighth capacitor, wherein the first end of the eighth capacitor is connected to the second end of the thirteenth resistor, and the second end of the eighth capacitor is grounded.

[0054] On the above basis, the present application further provides a PON gateway, including:

[0055] A target avalanche photodiode;

[0056] The above-mentioned bias voltage supply circuit of the avalanche photodiode, wherein the bias voltage supply circuit of the avalanche photodiode is used to provide a diode bias voltage to the target avalanche photodiode and perform corresponding overcurrent protection.

[0057] The bias voltage supply circuit of the avalanche photodiode and the PON gateway provided by the present application include a bias voltage input unit, a bias voltage control input processing unit, and an avalanche photodiode protection unit. When the light intensity of the target avalanche photodiode exceeds the preset light intensity, the photocurrent of the target avalanche photodiode exceeds the preset current. The avalanche photodiode protection unit responds to the photocurrent of the target avalanche photodiode exceeding the preset current and reduces the diode bias voltage applied to the target avalanche photodiode, so that the photocurrent of the target avalanche photodiode is reduced to complete the overcurrent protection of the target avalanche photodiode. Based on the above content, since the avalanche photodiode protection unit can not only apply the diode bias voltage to the target avalanche photodiode so that the target avalanche photodiode can perform photoelectric conversion, but also respond to the photocurrent of the target avalanche photodiode exceeding the preset current and reduce the diode bias voltage applied to the target avalanche photodiode, so that the photocurrent of the target avalanche photodiode is reduced to complete the overcurrent protection of the target avalanche photodiode, so that the target avalanche photodiode will not be damaged due to overcurrent, therefore, the problem that the target avalanche photodiode in the prior art is easily damaged due to overcurrent can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] To make the above objects, features, and advantages of the present application more obvious and understandable, the following specifically provides preferred embodiments and, in conjunction with the accompanying drawings, detailed descriptions are as follows.

[0059] Figure 1 It is a block diagram of the PON gateway provided by an embodiment of the present application.

[0060] Figure 2 It is a block diagram of a circuit for providing a bias voltage for an avalanche photodiode provided by an embodiment of the present application.

[0061] Figure 3 It is a circuit schematic diagram of a circuit for providing a bias voltage for an avalanche photodiode provided by an embodiment of the present application.

[0062] Figure 4 It is a schematic diagram of the bias voltage stabilization time when accessing a large optical signal provided by an embodiment of the present application.

[0063] Icon: APD - target avalanche photodiode; R1 - first resistor; Q1 - first triode; R2 - second resistor; R3 - third resistor; R4 - fourth resistor; R5 - fifth resistor; R6 - sixth resistor; L1 - first inductive element; C1 - first capacitor; C2 - second capacitor; R7 - seventh resistor; R8 - eighth resistor; K1 - first MOS transistor; R9 - ninth resistor; D1 - discharge diode; K2 - second MOS transistor; R10 - tenth resistor; L2 - second inductive element; D2 - Schottky diode; C3 - third capacitor; C4 - fourth capacitor; C5 - fifth capacitor; C6 - sixth capacitor; C7 - seventh capacitor; Q2 - second triode; Q3 - third triode; Q4 - fourth triode; R11 - eleventh resistor; R12 - twelfth resistor; R13 - thirteenth resistor; C8 - eighth capacitor. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Usually, the components of the embodiments of the present application described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0065] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application to be protected, but merely represents the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0066] As Figure 1 shown, an embodiment of the present application provides a PON gateway. Among them, the PON gateway may include a target avalanche photodiode and a bias voltage providing circuit for the avalanche photodiode. The bias voltage providing circuit for the avalanche photodiode is used to provide a diode bias voltage to the target avalanche photodiode and perform corresponding overcurrent protection. Exemplarily, the PON network can be used as a government-enterprise gateway, a converged gateway, etc., and can be applied to scenarios such as FTTR.

[0067] Combined with Figure 2 , an embodiment of the present application also provides a bias voltage providing circuit for an avalanche photodiode that can be applied to the above PON gateway. Among them, the bias voltage providing circuit for the avalanche photodiode may include a bias voltage input unit, a bias voltage control input processing unit, and an avalanche photodiode protection unit.

[0068] Specifically, the bias voltage input unit is used to output a diode bias voltage. The first end of the bias voltage control input processing unit is connected to the output end of the bias voltage input unit, and is used to obtain and output the diode bias voltage. The first end of the avalanche photodiode protection unit is connected to the second end of the bias voltage control input processing unit, and the second end of the avalanche photodiode protection unit is connected to the target avalanche photodiode. The avalanche photodiode protection unit is used to apply the diode bias voltage to the target avalanche photodiode so that the target avalanche photodiode performs photoelectric conversion. And, the third end of the avalanche photodiode protection unit is connected to the output end of the bias voltage input unit. When the light intensity of the target avalanche photodiode exceeds a preset light intensity (the preset light intensity can be determined according to actual needs), the photocurrent of the target avalanche photodiode exceeds a preset current. The avalanche photodiode protection unit responds to the photocurrent of the target avalanche photodiode exceeding the preset current (the preset current can also be configured according to actual needs), and reduces the diode bias voltage applied to the target avalanche photodiode, so that the photocurrent of the target avalanche photodiode is reduced to complete the overcurrent protection of the target avalanche photodiode.

[0069] Based on the above, since the avalanche photodiode protection unit can not only apply a diode bias voltage to the target avalanche photodiode, enabling the target avalanche photodiode to perform photoelectric conversion, but also respond to the photocurrent of the target avalanche photodiode exceeding a preset current by reducing the diode bias voltage applied to the target avalanche photodiode, thereby reducing the photocurrent of the target avalanche photodiode to complete the overload protection of the target avalanche photodiode and preventing the target avalanche photodiode from being damaged due to overload. Therefore, the problem in the prior art that the target avalanche photodiode is easily damaged due to overload can be improved.

[0070] In the first aspect, it should be noted that for the bias voltage input unit, the specific composition of the bias voltage input unit is not limited and can be selected accordingly according to actual needs.

[0071] For example, in an alternative embodiment, in order to ensure that the required diode bias voltage can be output through the bias voltage input unit, combined with Figure 3 , the bias voltage input unit may include a second MOS transistor K2, a tenth resistor R10, a second inductive element L2, and a Schottky diode D2.

[0072] Specifically, the second MOS transistor K2 is an N-type MOS transistor. The source electrode of the second MOS transistor K2 is grounded. The gate electrode of the second MOS transistor K2 serves as the control terminal of the bias voltage input unit and is connected to the control unit included in the bias voltage supply circuit of the target avalanche photodiode APD to control whether the drain electrode and the source electrode are conducting based on the pulse width modulation signal output by the control unit. The first end of the tenth resistor R10 is connected to the gate electrode of the second MOS transistor K2, and the second end of the tenth resistor R10 is grounded. The first end of the second inductive element L2 serves as the input terminal of the bias voltage input unit and is connected to an external power supply. The second end of the second inductive element L2 is connected to the drain electrode of the second MOS transistor K2. The anode of the Schottky diode D2 is connected to the second end of the second inductive element L2, and the cathode of the Schottky diode D2 serves as the output terminal of the bias voltage input unit and is connected to the first end of the bias voltage control input processing unit.

[0073] Based on this, under the control of the pulse width modulation signal output by the control unit through the second MOS transistor K2, the control of the diode bias voltage can be achieved. That is to say, the bias voltage input unit actually belongs to a DC-DC device, which is used to boost the voltage provided by the external power supply (the voltage control can be achieved by controlling the alternating conduction and cutoff between the drain electrode and the source electrode of the second MOS transistor K2, such as controlling the duty cycle of the pulse width modulation signal), so as to output the corresponding diode bias voltage.

[0074] It can be understood that, based on the above embodiments, in order to improve the stability of the output diode bias voltage, the bias voltage input unit may further include a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, and a seventh capacitor C7.

[0075] Specifically, the first end of the third capacitor C3 is connected to the first end of the second inductor element L2, and the second end of the third capacitor C3 is grounded. The first end of the fourth capacitor C4 is connected to the first end of the second inductor element L2, and the second end of the fourth capacitor C4 is grounded. The first end of the fifth capacitor C5 is connected to the first end of the second inductor element L2, and the second end of the fifth capacitor C5 is grounded. The first end of the sixth capacitor C6 is connected to the cathode of the Schottky diode D2, and the second end of the sixth capacitor C6 is grounded. The first end of the seventh capacitor C7 is connected to the cathode of the Schottky diode D2, and the second end of the seventh capacitor C7 is grounded.

[0076] In the second aspect, it should be noted that for the bias voltage control input processing unit, the specific composition of the bias voltage control input processing unit is not limited and can be selected accordingly according to the actual situation.

[0077] For example, in an alternative embodiment, in order to be able to output the diode bias voltage to the target avalanche photodiode APD through the bias voltage control input processing unit and also be able to implement RSSI (Received Signal Strength Indicator, which is used to reflect the light intensity of the target avalanche photodiode APD. Exemplarily, this current value is proportional to the intensity of the received optical signal) current monitoring of the target avalanche photodiode APD, the bias voltage control input processing unit may include a second triode Q2, a third triode Q3, a fourth triode Q4, an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, and C8.

[0078] Specifically, the second triode Q2 belongs to a PNP type triode, and the collector of the second triode Q2 serves as the second end of the bias voltage control input processing unit and is connected to the first end of the target avalanche photodiode APD protection unit. The third triode Q3 belongs to a PNP type triode, and the base of the third triode Q3 is connected to the collector of the third triode Q3, and the base of the third triode Q3 is connected to the base of the second triode Q2. The fourth triode Q4 belongs to a PNP type triode, and the base of the fourth triode Q4 is connected to the collector of the second triode Q2, and the emitter of the fourth triode Q4 is connected to the collector of the third triode Q3. The first end of the eleventh resistor R11 serves as the first end of the bias voltage control input processing unit and is connected to the output end of the bias voltage input unit, and the second end of the eleventh resistor R11 is connected to the emitter of the second triode Q2. The first end of the twelfth resistor R12 is connected to the first end of the eleventh resistor R11, and the second end of the twelfth resistor R12 is connected to the emitter of the third triode Q3. The first end of the thirteenth resistor R13 is connected to the collector of the fourth triode Q4, and the second end of the thirteenth resistor R13 is used to output a target RSSI current, and the target RSSI current is used to reflect the light intensity of the target avalanche photodiode APD. The first end of the C8 is connected to the second end of the thirteenth resistor R13, and the second end of the C8 is grounded.

[0079] Regarding the above circuit structure, it should be noted that the second triode Q2, the third triode Q3, and the fourth triode Q4 can form a current source, which can be used to copy and output the photocurrent of the target avalanche photodiode APD. In this way, reliable monitoring of the current can be achieved, thereby avoiding a large difference between the input current and the output current caused by the base current mismatch of the conventional mirror current source, and further avoiding the inaccurate monitoring of the received RSSI current. In addition, through the cooperation of the thirteenth resistor R13 and the C8, a filter network for the target RSSI current can be formed to ensure the reliability of the output target RSSI current.

[0080] In the third aspect, regarding the avalanche photodiode protection unit, it should be noted that the specific composition of the avalanche photodiode protection unit is not limited and can be selected accordingly according to actual needs.

[0081] For example, in an alternative embodiment, in order to enable the avalanche photodiode protection unit to provide reliable overcurrent protection for the target avalanche photodiode APD, the avalanche photodiode protection unit may include a first resistor R1, a first triode Q1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5.

[0082] Specifically, the first end of the first resistor R1 serves as the first end of the avalanche photodiode protection unit and is connected to the second end of the bias voltage control input processing unit, and the second end of the first resistor R1 serves as the second end of the avalanche photodiode protection unit and is connected to the target avalanche photodiode APD. The first triode Q1 is a PNP type triode, and the emitter of the first triode Q1 is connected to the first end of the first resistor R1. The first end of the second resistor R2 is connected to the second end of the first resistor R1, and the second end of the second resistor R2 is connected to the base of the first triode Q1. The first end of the third resistor R3 is connected to the collector of the first triode Q1. The first end of the fourth resistor R4 is connected to the second end of the third resistor R3, and the second end of the fourth resistor R4 is grounded. The first end of the fifth resistor R5 is connected to the second end of the third resistor R3, and the second end of the fifth resistor R5 serves as the third end of the avalanche photodiode protection unit and is connected to the output end of the bias voltage input unit.

[0083] Moreover, when the light intensity of the target avalanche photodiode APD exceeds the preset light intensity, the photocurrent of the target avalanche photodiode APD exceeds the preset current. In response to the photocurrent of the target avalanche photodiode APD exceeding the preset current, the first triode Q1 conducts between its emitter and collector to reduce the diode bias voltage applied to the target avalanche photodiode APD, so that the photocurrent of the target avalanche photodiode APD is reduced to complete the overcurrent protection of the target avalanche photodiode APD. That is to say, after the emitter and collector of the first triode Q1 are conducted, it is equivalent to connecting a resistor in parallel on the feedback path, thereby reducing the output voltage. Since the decrease in the bias voltage leads to a decrease in the multiplication factor, the current flowing through the target avalanche photodiode is reduced, playing a protective role.

[0084] Wherein, the voltage at the connection node of the third resistor R3 and the fourth resistor R4 serves as the feedback voltage, and through the feedback regulation of the avalanche photodiode protection unit, the diode bias voltage output by the bias voltage input unit is V FB *(1 + R5 / R4), V FBis the feedback voltage, R5 is the resistance value of the fifth resistor R5, and R4 is the resistance value of the fourth resistor R4.

[0085] In addition, in an alternative embodiment, since the current on the target avalanche photodiode APD exceeds 2 mA, it will cause damage to the target avalanche photodiode APD. Therefore, the resistance value of the first resistor R1 can be between 400 - 1 kΩ. The resistance value of the third resistor R3 can be configured according to the resistance value of the fifth resistor R5, where the resistance value of the fifth resistor R5 can be 220 kΩ; the resistance value of the fourth resistor R4 can be 3.9 kΩ. The resistance value of the second resistor R2 can be 100 kΩ; since the Vce voltage of the first triode Q1 is always controlled at about 1.2 V and the maximum current of the circuit is in the mA level, where the resistance values of the eleventh resistor R11 and the twelfth resistor R12 can be in the tens of ohms, therefore, the corresponding impedance can be ignored, which is equivalent to the parallel connection of the third resistor R3 and the fifth resistor R5 when a large optical input is present, thereby reducing the diode bias voltage.

[0086] Among them, the experimental data when a large optical signal of 5 dbm is connected are as follows:

[0087]

[0088] In addition, when a large optical signal is connected, the voltage stabilization time of the target avalanche photodiode APD is as Figure 4 shown. In this way, compared with the traditional circuit protection, the stabilization time is improved from the ms level to the us level, greatly enhancing the protection function of the device.

[0089] It can be understood that, based on the above embodiment, in an alternative embodiment, in order to achieve reliable driving of the target avalanche photodiode APD, the avalanche photodiode protection unit may further include a sixth resistor R6, a first inductance element L1, and a first capacitor C1.

[0090] Specifically, the first end of the sixth resistor R6 is connected to the second end of the first resistor R1. The first end of the first inductance element L1 is connected to the second end of the sixth resistor R6, and the second end of the first inductance element L1 serves as the second end of the avalanche photodiode protection unit and is connected to the target avalanche photodiode APD. The first end of the first capacitor C1 is connected to the second end of the first inductance element L1, and the second end of the first capacitor C1 is grounded. In this way, a voltage filtering network can be formed.

[0091] It can be understood that, based on the above embodiments, in an alternative embodiment, the avalanche photodiode protection unit may further include a second capacitor C2.

[0092] Specifically, the first end of the second capacitor C2 is connected to the first end of the fifth resistor R5, and the second end of the second capacitor C2 is connected to the second end of the fifth resistor R5.

[0093] It should be further noted that, in order to ensure the safe operation of the bias voltage supply circuit of the avalanche photodiode, in an alternative embodiment, the bias voltage supply circuit of the avalanche photodiode may further include a control unit and a discharge unit.

[0094] Specifically, the control unit is connected to the target internal connection node of the avalanche photodiode protection unit. The control unit is used to collect the voltage of the target internal connection node, and this voltage is used as the feedback voltage. There is a correlation between this feedback voltage and the diode bias voltage applied to the target avalanche photodiode APD, so that the control unit can determine whether there is an overvoltage situation in the target avalanche photodiode APD based on this feedback voltage. The first end of the discharge unit is connected to the target internal connection node, the second end of the discharge unit is connected to the output end of the bias voltage input unit, and the third end of the discharge unit is grounded.

[0095] Moreover, when the control unit determines that there is an overvoltage situation in the target avalanche photodiode APD, by controlling the voltage of the target internal connection node, the second end and the third end of the discharge unit are made to conduct, thereby discharging the output end of the bias voltage input unit.

[0096] It can be understood that, in the above embodiments, the specific composition of the discharge unit is not limited and can be selected accordingly according to actual needs.

[0097] For example, in an alternative embodiment, in order to achieve rapid release of high voltage, the discharge unit may include a seventh resistor R7, an eighth resistor R8, a first MOS transistor K1, a ninth resistor R9, and a discharge diode D1.

[0098] Specifically, the first end of the seventh resistor R7 serves as the first end of the discharge unit and is connected to the target internal connection node (such as the connection node between the third resistor R3 and the fourth resistor R4 mentioned above). The first end of the eighth resistor R8 is connected to the second end of the seventh resistor R7, and the second end of the eighth resistor R8 is grounded. The first end of the ninth resistor R9 is connected to the drain of the first MOS transistor K1, and the second end of the ninth resistor R9 serves as the second end of the discharge unit and is connected to the output end of the bias input unit. The anode of the discharge diode D1 is connected to the source of the first MOS transistor K1, and the cathode of the discharge diode D1 is grounded.

[0099] Based on this, when the control unit determines that there is an overvoltage situation in the target avalanche photodiode APD, it can raise the voltage of the target internal connection node, making the drain and source of the first MOS transistor K1 conduct, thereby forming a discharge loop through the discharge diode D1.

[0100] In summary, the bias voltage supply circuit and PON gateway for the avalanche photodiode provided in this application include a bias input unit, a bias control input processing unit, and an avalanche photodiode protection unit. When the light intensity of the target avalanche photodiode exceeds the preset light intensity, the photocurrent of the target avalanche photodiode exceeds the preset current. The avalanche photodiode protection unit responds to the photocurrent of the target avalanche photodiode exceeding the preset current and reduces the diode bias voltage applied to the target avalanche photodiode, so that the photocurrent of the target avalanche photodiode is reduced to complete the overload protection of the target avalanche photodiode. Based on the above content, since the avalanche photodiode protection unit can not only apply the diode bias voltage to the target avalanche photodiode, enabling the target avalanche photodiode to perform photoelectric conversion, but also respond to the photocurrent of the target avalanche photodiode exceeding the preset current and reduce the diode bias voltage applied to the target avalanche photodiode, so that the photocurrent of the target avalanche photodiode is reduced to complete the overload protection of the target avalanche photodiode, preventing the target avalanche photodiode from being damaged due to overload. Therefore, it can improve the problem in the prior art that the target avalanche photodiode is easily damaged due to overload.

[0101] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A bias voltage providing circuit for an avalanche photodiode, characterized in that: include: A bias input unit, wherein the bias input unit is used to output a diode bias voltage; A bias control input processing unit, wherein a first terminal of the bias control input processing unit is connected to an output terminal of the bias input unit, and is used to obtain and output the diode bias voltage; an avalanche photodiode protection unit, wherein a first end of the avalanche photodiode protection unit is connected to a second end of the bias control input processing unit, a second end of the avalanche photodiode protection unit is connected to a target avalanche photodiode, and the avalanche photodiode protection unit is used to apply the diode bias voltage to the target avalanche photodiode so that the target avalanche photodiode performs photoelectric conversion; Furthermore, the third end of the avalanche photodiode protection unit is connected to the output end of the bias input unit. When the light intensity of the target avalanche photodiode exceeds the preset light intensity, the photocurrent of the target avalanche photodiode exceeds the preset current. In response to the photocurrent of the target avalanche photodiode exceeding the preset current, the avalanche photodiode protection unit reduces the diode bias voltage applied to the target avalanche photodiode, so that the photocurrent of the target avalanche photodiode is reduced to complete the overload protection of the target avalanche photodiode.

2. The bias voltage providing circuit for an avalanche photodiode according to claim 1, characterized in that: The avalanche photodiode protection unit comprises: a first resistor, wherein a first end of the first resistor serves as a first end of the avalanche photodiode protection unit and is connected to a second end of the bias control input processing unit, and a second end of the first resistor serves as a second end of the avalanche photodiode protection unit and is connected to the target avalanche photodiode; A first transistor, wherein the first transistor is a PNP transistor, and an emitter of the first transistor is connected to a first end of the first resistor; a second resistor, wherein a first end of the second resistor is connected to a second end of the first resistor, and a second end of the second resistor is connected to a base of the first transistor; A third resistor, wherein a first end of the third resistor is connected to the collector of the first transistor; a fourth resistor, wherein a first end of the fourth resistor is connected to a second end of the third resistor, and a second end of the fourth resistor is grounded; a fifth resistor, wherein a first end of the fifth resistor is connected to a second end of the third resistor, and a second end of the fifth resistor is connected to an output end of the bias input unit as a third end of the avalanche photodiode protection unit; Furthermore, when the light intensity of the target avalanche photodiode exceeds the preset light intensity, the photocurrent of the target avalanche photodiode exceeds the preset current, and in response to the photocurrent of the target avalanche photodiode exceeding the preset current, the first transistor reduces the diode bias voltage applied to the target avalanche photodiode by connecting the emitter and the collector of the first transistor, so that the photocurrent of the target avalanche photodiode is reduced, thereby completing the overload protection of the target avalanche photodiode; The voltage of the connection node between the third resistor and the fourth resistor is used as the feedback voltage, and the diode bias voltage output by the bias input unit is V through the feedback adjustment of the avalanche photodiode protection unit. FB *(1+R5 / R4), V FB is the feedback voltage, R5 is the resistance value of the fifth resistor, and R4 is the resistance value of the fourth resistor.

3. The bias voltage providing circuit for an avalanche photodiode according to claim 2, characterized in that: The avalanche photodiode protection unit also includes: a sixth resistor, wherein a first end of the sixth resistor is connected to a second end of the first resistor; A first inductor element, wherein a first end of the first inductor element is connected to a second end of the sixth resistor, and a second end of the first inductor element serves as a second end of the avalanche photodiode protection unit and is connected to the target avalanche photodiode; A first capacitor, wherein a first end of the first capacitor is connected to a second end of the first inductor element, and a second end of the first capacitor is grounded.

4. The bias voltage providing circuit for an avalanche photodiode according to claim 2, characterized in that: The avalanche photodiode protection unit also includes: A second capacitor, wherein a first end of the second capacitor is connected to a first end of the fifth resistor, and a second end of the second capacitor is connected to a second end of the fifth resistor.

5. The bias voltage providing circuit for an avalanche photodiode according to claim 1, characterized in that: The bias voltage providing circuit of the avalanche photodiode also includes: A control unit, wherein the control unit is connected to a target internal connection node of the avalanche photodiode protection unit, and the control unit is used to collect a voltage of the target internal connection node, and the voltage is used as a feedback voltage, and the feedback voltage is correlated with a diode bias voltage applied to the target avalanche photodiode, so that the control unit can determine whether the target avalanche photodiode has an overvoltage condition based on the feedback voltage; a discharge unit, wherein a first end of the discharge unit is connected to the target internal connection node, a second end of the discharge unit is connected to the output end of the bias input unit, and a third end of the discharge unit is grounded; Furthermore, when the control unit determines that the target avalanche photodiode has an overvoltage condition, the control unit controls the voltage of the target internal connection node to connect the second end and the third end of the discharge unit, thereby discharging the output end of the bias input unit.

6. The bias voltage supply circuit for an avalanche photodiode according to claim 5, characterized in that: The discharge unit comprises: a seventh resistor, wherein a first end of the seventh resistor serves as a first end of the discharge unit and is connected to the target internal connection node; an eighth resistor, wherein a first end of the eighth resistor is connected to a second end of the seventh resistor, and a second end of the eighth resistor is grounded; A first MOS transistor, wherein the first MOS transistor is an N-type MOS transistor, and a gate of the first MOS transistor is connected to the second end of the seventh resistor; a ninth resistor, wherein a first end of the ninth resistor is connected to the drain of the first MOS tube, and a second end of the ninth resistor serves as a second end of the discharge unit and is connected to the output end of the bias input unit; A discharge diode, wherein an anode of the discharge diode is connected to the source of the first MOS tube, and a cathode of the discharge diode is grounded.

7. The bias voltage providing circuit for an avalanche photodiode according to any one of claims 1 to 6, characterized in that: The bias input unit comprises: a second MOS transistor, wherein the second MOS transistor is an N-type MOS transistor, the source of the second MOS transistor is grounded, and the gate of the second MOS transistor serves as the control end of the bias input unit and is connected to the control unit included in the bias voltage providing circuit of the avalanche photodiode, so as to control whether the drain and the source are connected based on the pulse width modulation signal output by the control unit; a tenth resistor, wherein a first end of the tenth resistor is connected to the gate of the second MOS transistor, and a second end of the tenth resistor is grounded; A second inductor element, wherein a first end of the second inductor element is connected to an external power source as an input end of the bias input unit, and a second end of the second inductor element is connected to a drain of the second MOS tube; A Schottky diode, wherein the anode of the Schottky diode is connected to the second end of the second inductor element, and the cathode of the Schottky diode serves as the output end of the bias input unit and is connected to the first end of the bias control input processing unit.

8. The bias voltage providing circuit for an avalanche photodiode according to claim 7, characterized in that: The bias input unit further includes: A third capacitor, wherein a first end of the third capacitor is connected to the first end of the second inductor element, and a second end of the third capacitor is grounded; a fourth capacitor, wherein a first end of the fourth capacitor is connected to the first end of the second inductor element, and a second end of the fourth capacitor is grounded; a fifth capacitor, wherein a first end of the fifth capacitor is connected to the first end of the second inductor element, and a second end of the fifth capacitor is grounded; a sixth capacitor, wherein a first end of the sixth capacitor is connected to the cathode of the Schottky diode, and a second end of the sixth capacitor is grounded; A seventh capacitor, wherein a first end of the seventh capacitor is connected to the cathode of the Schottky diode, and a second end of the seventh capacitor is grounded.

9. The bias voltage providing circuit for an avalanche photodiode according to any one of claims 1 to 6, characterized in that: The bias control input processing unit comprises: A second triode, wherein the second triode is a PNP type triode, and the collector of the second triode serves as the second end of the bias control input processing unit and is connected to the first end of the avalanche photodiode protection unit; A third triode, wherein the third triode is a PNP triode, and the base of the third triode is connected to the collector of the third triode, and the base of the third triode is connected to the base of the second triode; A fourth triode, wherein the fourth triode is a PNP triode, and the base of the fourth triode is connected to the collector of the second triode, and the emitter of the fourth triode is connected to the collector of the third triode; an eleventh resistor, wherein a first end of the eleventh resistor serves as a first end of the bias control input processing unit and is connected to an output end of the bias input unit, and a second end of the eleventh resistor is connected to an emitter of the second transistor; a twelfth resistor, wherein a first end of the twelfth resistor is connected to the first end of the eleventh resistor, and a second end of the twelfth resistor is connected to the emitter of the third transistor; a thirteenth resistor, wherein a first end of the thirteenth resistor is connected to the collector of the fourth transistor, and a second end of the thirteenth resistor is used to output a target RSSI current, and the target RSSI current is used to reflect the light intensity of the target avalanche photodiode; An eighth capacitor, wherein a first end of the eighth capacitor is connected to a second end of the thirteenth resistor, and a second end of the eighth capacitor is grounded.

10. A PON gateway, characterized in that: include: Target avalanche photodiode; The bias voltage providing circuit for an avalanche photodiode as described in any one of claims 1 to 9, wherein the bias voltage providing circuit for an avalanche photodiode is used to provide a diode bias voltage to the target avalanche photodiode and perform corresponding overload protection.

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