Constant-current driving circuit and pump laser

Abstract

The utility model discloses a constant current drive circuit and a pump laser, and relates to the technical field of laser drive circuits, the constant current drive circuit comprises a PWM modulation circuit, a control switch, a laser diode, a first resistor and an operational amplifier feedback circuit; the PWM modulation circuit is used for being connected with a power supply of the pump laser; the PWM modulation circuit, the control switch, the laser diode and the first resistor are sequentially connected and then grounded; the operational amplifier feedback circuit is connected with the first resistor and the PWM modulation circuit, and the operational amplifier feedback circuit is used for amplifying the voltage applied to the first resistor and feeding back the amplified voltage to the PWM modulation circuit to form a negative feedback closed loop, so that the voltage applied to the first resistor is constant. The operational amplifier feedback circuit can be constructed by adopting discrete devices, the reliability of the discrete devices is higher than that of a single chip microcomputer, and the operational amplifier feedback circuit is more suitable for the seabed environment on the premise of ensuring that the pump laser is driven by constant current.

Description

Technical Field

[0001] The invention relates to the technical field of laser driving circuits, and in particular to a constant current driving circuit and a pump laser. Background Art

[0002] At present, as the main international and regional communication transmission equipment, submarine optical cables undertake 90% of international communication business and are the main carrier for the rapid development of the global information optical communication industry. Therefore, the marine communication transmission system is still the preferred mode of cross-regional transmission. In terms of transoceanic communications, operators are still the main source of demand for submarine cable communications. The core equipment for long-distance networking of submarine communication networks is submarine repeaters. Among them, the constant current drive circuit is used to drive the pump laser in the submarine repeater to emit light stably and amplify the optical signal of the communication system transmission line. Therefore, a stable constant current is crucial to the performance of the submarine repeater.

[0003] In the prior art, constant current drive circuits mostly use single-chip microcomputers to achieve constant drive current. However, submarine repeaters are in the deep sea, and once a failure occurs, the maintenance cost is high, the price is high, and the risk is high. The reliability of single-chip microcomputers is limited. Therefore, if submarine repeaters use single-chip microcomputers to generate constant drive current, there are safety risks. Summary of the invention

[0004] The embodiments of the present invention provide a constant current driving circuit and a pump laser to solve the technical problem that the constant current driving circuit in the prior art uses a single chip microcomputer to generate a constant driving current, which poses a safety risk to submarine equipment.

[0005] In a first aspect, a constant current drive circuit is provided, comprising: a PWM modulation circuit, a control switch, a laser diode, a first resistor and an operational amplifier feedback circuit;

[0006] The PWM modulation circuit is used to connect to the power supply of the pump laser;

[0007] The PWM modulation circuit, the control switch, the laser diode, and the first resistor are connected in sequence and then grounded;

[0008] The operational amplifier feedback circuit is connected to the first resistor and the PWM modulation circuit. The operational amplifier feedback circuit is used to amplify the voltage applied to the first resistor and then feed it back to the PWM modulation circuit to form a negative feedback closed loop, so that the voltage applied to the first resistor is constant.

[0009] In some embodiments, the operational amplifier feedback circuit includes an operational amplifier, a second resistor, and a third resistor;

[0010] A first end of the second resistor is connected to the inverting input terminal of the operational amplifier, and a second end of the second resistor is grounded;

[0011] The first end of the third resistor is connected to the inverting input end of the operational amplifier, and the second end of the third resistor is connected to the output end of the operational amplifier and the PWM modulation circuit;

[0012] A non-inverting input terminal of the operational amplifier is connected to a first end of the first resistor.

[0013] In some embodiments, the PWM modulation circuit includes a PWM controller, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor;

[0014] A first end of the fourth resistor is connected to the output end of the operational amplifier, and a second end of the fourth resistor is connected to the feedback pin of the PWM controller;

[0015] A first end of the fifth resistor is connected to a power supply of the pump laser and a power supply pin of the PWM controller, and a second end of the fifth resistor is connected to an output pin of the PWM controller;

[0016] A first end of the sixth resistor is connected to an output pin of the PWM controller, and a second end of the sixth resistor is connected to the control switch.

[0017] In some embodiments, the control switch is a PNP transistor, the emitter of the PNP transistor is connected to the power supply of the pump laser, the base of the PNP transistor is connected to the first end of the sixth resistor, and the collector of the PNP transistor is connected to the anode of the laser diode.

[0018] In some embodiments, the constant current driving circuit further includes: a first inductor and a protection diode;

[0019] The first end of the first inductor is connected to the collector of the PNP transistor, and the second end of the first inductor is connected to the anode of the laser diode;

[0020] An anode of the protection diode is grounded, and a cathode of the protection diode is connected to a first end of the first inductor.

[0021] In some embodiments, the constant current driving circuit further includes:

[0022] A DC-DC converter is provided between a power supply of the pump laser and a power supply pin of the PWM controller.

[0023] In some embodiments, the second resistor is an adjustable resistor.

[0024] In some embodiments, the constant current driving circuit further includes: a first capacitor and a seventh resistor;

[0025] A first end of the seventh resistor is connected to a first end of the first resistor, a second end of the seventh resistor is connected to a first end of the first capacitor, and a second end of the first capacitor is grounded.

[0026] In some embodiments, the first resistor is a precision resistor with an accuracy less than 1%.

[0027] In a second aspect, a pump laser is provided, comprising the aforementioned constant current drive circuit.

[0028] The beneficial effects brought about by the technical solution provided by the present invention include:

[0029] The embodiment of the present invention provides a constant current drive circuit and a pump laser. The constant current drive circuit is provided with an operational amplifier feedback circuit. The operational amplifier feedback circuit can be constructed using discrete devices. The reliability of discrete devices is higher than that of single-chip microcomputers. Under the premise of ensuring constant current driving of the pump laser, the circuit is more suitable for submarine environments and can avoid the risk of fault maintenance as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A principle block diagram of a constant current drive circuit provided by an embodiment of the present invention;

[0032] Figure 2 A circuit diagram of a constant current drive circuit provided by an embodiment of the present invention;

[0033] Figure 3 A circuit diagram of an operational amplifier feedback circuit of a constant current drive circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The embodiment of the present invention provides a constant current driving circuit, which can solve the technical problem that the constant current driving circuit in the prior art uses a single chip microcomputer to generate a constant driving current, which poses a safety risk to submarine equipment.

[0036] See also Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a constant current driving circuit, including: a PWM modulation circuit, a control switch, a laser diode D1, a first resistor R1 and an operational amplifier feedback circuit.

[0037] The PWM modulation circuit is used to be connected to a power source of a pump laser. The PWM modulation circuit, the control switch, the laser diode D1, and the first resistor R1 are connected in sequence and then grounded.

[0038] The operational amplifier feedback circuit is connected to the first resistor R1 and the PWM modulation circuit. The operational amplifier feedback circuit is used to amplify the voltage applied to the first resistor and then feed it back to the PWM modulation circuit to form a negative feedback closed loop, so that the voltage applied to the first resistor is constant.

[0039] The constant current driving circuit in the embodiment of the present invention is provided with an operational amplifier feedback circuit. The operational amplifier feedback circuit can be constructed using discrete devices. The reliability of discrete devices is significantly higher than that of single-chip microcomputers. Under the premise of ensuring constant current driving of the pump laser, it is more suitable for the submarine environment and can avoid the risk of maintenance failure as much as possible.

[0040] As an optional implementation, in one embodiment of the utility model, the operational amplifier feedback circuit includes an operational amplifier Ua, a second resistor R2 and a third resistor R3.

[0041] The first end of the second resistor R2 is connected to the inverting input terminal of the operational amplifier Ua, and the second end of the second resistor R2 is grounded. The first end of the third resistor R3 is connected to the inverting input terminal of the operational amplifier Ua, and the second end of the third resistor R3 is connected to the output terminal of the operational amplifier Ua and the PWM modulation circuit. The non-inverting input terminal of the operational amplifier Ua is connected to the first end of the first resistor R1.

[0042] Furthermore, the PWM modulation circuit includes a PWM controller Ub, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6.

[0043] A first end of the fourth resistor R4 is connected to the output end of the operational amplifier Ua, and a second end of the fourth resistor R4 is connected to a feedback pin of the PWM controller Ub.

[0044] A first end of the fifth resistor R5 is connected to a power supply of the pump laser and a power pin of the PWM controller Ub, and a second end of the fifth resistor R5 is connected to an output pin of the PWM controller Ub.

[0045] A first end of the sixth resistor R6 is connected to an output pin of the PWM controller Ub, and a second end of the sixth resistor R6 is connected to the control switch.

[0046] Furthermore, the control switch is a PNP transistor Q1, the emitter of the PNP transistor Q1 is connected to the power supply of the pump laser, the base of the PNP transistor Q1 is connected to the first end of the sixth resistor R6, and the collector of the PNP transistor Q1 is connected to the anode of the laser diode D1. It should be noted that the control switch can also be a MOS tube, but the constant current of the pump laser used in the submarine repeater is relatively large. If the MOS tube is used to work in the variable resistance area to control the current of the pump laser, after working for a long time, the MOS tube will overheat and cause breakdown, and the drive circuit will fail. Therefore, the MOS tube can be used as an alternative, and the transistor is preferably used as the control switch.

[0047] Specifically, see Figure 2 As shown, the PWM controller Ub outputs a pulse square wave, which enters the base of the PNP transistor Q1. The collector of the PNP transistor Q1 applies voltage to the laser diode D1 and the first resistor R1. The voltage applied to the first resistor R1 is amplified by the operational amplifier Ua and then fed back to the PWM controller Ub, forming a negative feedback closed loop, thereby keeping the voltage applied to the first resistor R1 constant, that is, the entire circuit realizes constant drive current control.

[0048] In addition, the second resistor R2 is an adjustable resistor. Figure 2 and Figure 3 As shown, due to the virtual disconnection and virtual shorting functions of the operational amplifier Ua, the voltage U2 is the same as the voltage U1. The second resistor R2 and the third resistor R3 are connected in series, and the voltage division calculation method is U2=U3*(R2 / (R2+R3)). The voltage U2 can be adjusted by adjusting the resistance value of the second resistor R2. Increasing the resistance value of the second resistor R2 increases the voltage U2. The change in voltage U2 causes the change in voltage U1, and the driving current becomes larger. Reducing the resistance value of the second resistor R2 reduces the voltage U2. The change in voltage U2 causes the change in voltage U1, and the driving current becomes smaller. In this way, the current value of the constant current drive can be controlled. Therefore, the resistance value of the second resistor R2 can be changed to adjust the circuit driving current, with high precision and good stability.

[0049] In addition, under the same driving current condition, the voltage of the first resistor R1 can be reduced according to the amplification factor of the operational amplifier feedback circuit, thereby reducing the heat generated by the first resistor R1 and improving the circuit conversion efficiency.

[0050] As an optional implementation, in a utility model embodiment, the constant current drive circuit further includes: a first inductor L1 and a protection diode D2.

[0051] The first end of the first inductor L1 is connected to the collector of the PNP transistor Q1, and the second end of the first inductor L1 is connected to the anode of the laser diode D1. The anode of the protection diode D2 is grounded, and the cathode of the protection diode D2 is connected to the first end of the first inductor L1. The first inductor L1 and the protection diode D2 are used together to output a DC voltage smoothed by the square wave voltage emitted from the collector of the PNP transistor Q1 to the laser diode D1, so that the laser diode D1 emits laser.

[0052] As an optional implementation, in one embodiment of the utility model, the constant current drive circuit further includes: a DC-DC converter, which is provided between the power supply of the pump laser and the power supply pin of the PWM controller Ub. The DC-DC converter converts electric energy of one voltage value into electric energy of another voltage value, and can convert the power supply of the device into the working voltage required by the PWM controller Ub to meet the use requirements.

[0053] As an optional implementation, in a utility model embodiment, the constant current driving circuit further includes: a first capacitor C1 and a seventh resistor R7.

[0054] The first end of the seventh resistor R7 is connected to the first end of the first resistor R1, the second end of the seventh resistor R7 is connected to the first end of the first capacitor C1, and the second end of the first capacitor C1 is grounded. The first capacitor C1 and the seventh resistor R7 form an RC series circuit, and the RC series circuit can filter the voltage U1 applied to the first resistor R1 obtained by the operational amplifier Ua, improve the accuracy of the obtained voltage U1, and thus ensure the stability of the driving current.

[0055] As an optional implementation, in a utility model embodiment, the first resistor R1 is a precision resistor with an accuracy of less than 1%, which is beneficial for the operational amplifier Ua to accurately obtain the voltage U1 applied to the first resistor R1, thereby ensuring the stability of the current in the constant current drive circuit.

[0056] An embodiment of the present invention further provides a pump laser, comprising the aforementioned constant current driving circuit.

[0057] The pump laser in the embodiment of the present invention has a constant current drive circuit provided with an operational amplifier feedback circuit. The operational amplifier feedback circuit can be constructed using discrete devices. The reliability of discrete devices is significantly higher than that of single-chip microcomputers. Under the premise of ensuring constant current drive of the pump laser, it is more suitable for submarine environments and can avoid the risk of maintenance failures as much as possible.

[0058] In the description of the present invention, it should be noted that the terms "upper", "lower", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0059] It should be noted that, in the present invention, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0060] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features of the present invention.

Claims

1. A constant current driving circuit, characterized in that: include: PWM modulation circuit, control switch, laser diode, first resistor and operational amplifier feedback circuit; The PWM modulation circuit is used to connect to the power supply of the pump laser; The PWM modulation circuit, the control switch, the laser diode, and the first resistor are connected in sequence and then grounded; The operational amplifier feedback circuit is connected to the first resistor and the PWM modulation circuit. The operational amplifier feedback circuit is used to amplify the voltage applied to the first resistor and then feed it back to the PWM modulation circuit to form a negative feedback closed loop, so that the voltage applied to the first resistor is constant.

2. The constant current driving circuit according to claim 1, characterized in that: The operational amplifier feedback circuit includes an operational amplifier, a second resistor and a third resistor; A first end of the second resistor is connected to the inverting input terminal of the operational amplifier, and a second end of the second resistor is grounded; The first end of the third resistor is connected to the inverting input end of the operational amplifier, and the second end of the third resistor is connected to the output end of the operational amplifier and the PWM modulation circuit; A non-inverting input terminal of the operational amplifier is connected to a first end of the first resistor.

3. The constant current driving circuit according to claim 2, characterized in that: The PWM modulation circuit includes a PWM controller, a fourth resistor, a fifth resistor, a sixth resistor and a seventh resistor; A first end of the fourth resistor is connected to the output end of the operational amplifier, and a second end of the fourth resistor is connected to the feedback pin of the PWM controller; A first end of the fifth resistor is connected to a power supply of the pump laser and a power supply pin of the PWM controller, and a second end of the fifth resistor is connected to an output pin of the PWM controller; A first end of the sixth resistor is connected to an output pin of the PWM controller, and a second end of the sixth resistor is connected to the control switch.

4. The constant current driving circuit according to claim 3, characterized in that: The control switch is a PNP transistor, the emitter of the PNP transistor is connected to the power supply of the pump laser, the base of the PNP transistor is connected to the first end of the sixth resistor, and the collector of the PNP transistor is connected to the anode of the laser diode.

5. The constant current driving circuit according to claim 4, characterized in that: Also includes: a first inductor and a protection diode; The first end of the first inductor is connected to the collector of the PNP transistor, and the second end of the first inductor is connected to the anode of the laser diode; An anode of the protection diode is grounded, and a cathode of the protection diode is connected to a first end of the first inductor.

6. The constant current driving circuit according to claim 3, characterized in that: Also includes: A DC-DC converter is provided between a power supply of the pump laser and a power supply pin of the PWM controller.

7. The constant current driving circuit according to claim 2, characterized in that: The second resistor is an adjustable resistor.

8. The constant current driving circuit according to claim 1, characterized in that: Also includes: a first capacitor and a seventh resistor; A first end of the seventh resistor is connected to a first end of the first resistor, a second end of the seventh resistor is connected to a first end of the first capacitor, and a second end of the first capacitor is grounded.

9. The constant current driving circuit according to claim 1, characterized in that: The first resistor is a precision resistor with an accuracy less than 1%.

10. A pump laser, characterized in that: The invention comprises the constant current driving circuit as described in any one of claims 1 to 9.

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