Optical module

Abstract

The utility model discloses an optical module, comprising an emission driving unit which comprises a level comparator and a thermistor compensation network, the level comparator receives an electric input signal and a reference electric signal, and the thermistor compensation network receives an output signal of the level comparator and comprises a first branch circuit and a second branch circuit which are connected in series, the first branch comprises a positive temperature coefficient thermistor and a fixed resistor which are connected in series and in parallel, and the second branch comprises a negative temperature coefficient thermistor and a fixed resistor which are connected in series and in parallel; the laser is driven by the emission driving unit to output an optical signal; a receiving optical component that receives an optical input signal; and the receiving driving unit receives the signal output by the receiving optical component and outputs an electric signal. The optical module can realize light source temperature characteristic compensation in a wide temperature area.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical communication, and in particular relates to an optical module. Background Art

[0002] Optical communication modules (optical modules for short) are being used in more and more fields, and more and more special equipment and systems use optical fiber for signal transmission. Currently, not only high-speed data transmission (such as switches and high-speed digital boards) uses optical fiber for transmission, but also low-speed control signals (such as control quantity signals and bus signals of aircraft systems) use optical fiber for transmission.

[0003] In high-reliability fields, such as aircraft engine control signals, optical fiber transmission is also required. This field is characterized by high temperature, requiring the module to have high reliability and transmit low-speed control signals (for example, DC~50MHz, DC means the frequency is infinitely low, up to direct current), and in the high-reliability field as mentioned above, it also has a wide operating temperature range (for example, -55℃~125℃).

[0004] Traditional optical modules are designed for high-speed data transmission and cannot meet the needs of low-frequency industrial control signal applications. In addition, the optoelectronic component type devices available on the market for industrial control applications do not meet the application conditions for a wide temperature range.

[0005] In addition, its circuit is simple, the transmitting end is only a light source, and the receiving end is only a phototransistor. This type of module needs to be matched with a single peripheral driver to complete the photoelectric transmission function. It does not have the ability to adapt to the requirements of a wide temperature range, and the light source is affected by temperature, and its luminous characteristics change greatly. Utility Model Content

[0006] In response to the problems pointed out in the background technology, the purpose of this application is to provide an optical module, introduce a thermistor compensation network, realize the compensation of the temperature characteristics of the light source under a wide temperature range, realize the reliable use of the optical module in a wide temperature range scenario, and after the temperature characteristics of the light source are compensated, improve the accuracy of signal transmission.

[0007] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0008] An optical module, comprising:

[0009] The transmitting drive unit comprises:

[0010] a level comparator receiving an electrical input signal and a reference electrical signal;

[0011] a thermistor compensation network, which receives the output signal of the level comparator, the thermistor compensation network comprising a first branch and a second branch connected in series, the first branch comprising a positive temperature coefficient thermistor and a fixed resistor in series and parallel, the second branch comprising a negative temperature coefficient thermistor and a fixed resistor in series and parallel;

[0012] A laser, which is driven by the emission driving unit to output an optical signal;

[0013] a receiving optical component that receives an optical input signal;

[0014] The receiving driving unit receives the signal output by the light receiving component and outputs an electrical signal.

[0015] In some embodiments of the present application, the transmitting driving unit further includes:

[0016] The first power supply voltage stabilizing unit is used to provide a regulated voltage to the comparator.

[0017] In some embodiments of the present application, the receiving drive unit includes:

[0018] an operational amplifier circuit, which receives the signal output by the light receiving component;

[0019] The level conversion circuit receives the signal output by the operational amplifier circuit and outputs the electrical signal.

[0020] In some embodiments of the present application, the receiving drive unit further includes:

[0021] The second power supply voltage stabilizing unit is used to provide regulated voltage to the operational amplifier circuit and the level conversion circuit respectively.

[0022] In some embodiments of the present application, the operational amplifier circuit is a transimpedance amplifier circuit, which is used to receive the current signal output by the light receiving component and convert it into an amplified voltage signal.

[0023] In some embodiments of the present application, the receiving drive unit further includes:

[0024] The common mode elimination amplifier circuit is used to receive the voltage signal output by the transimpedance amplifier circuit and form voltage negative feedback for the amplifier in the transimpedance amplifier circuit.

[0025] In some embodiments of the present application, the second power supply stabilizing unit provides a dual power supply voltage for the operational amplifier circuit.

[0026] In some embodiments of the present application, the light receiving component is a photodetector or an avalanche photodiode.

[0027] Compared with the prior art, the optical module involved in this application has the following beneficial effects:

[0028] (1) The transmitting drive unit in the optical module is set as a discrete level comparator and thermistor compensation network, which eliminates complex integrated circuits such as the control chip and laser driver chip, simplifies the drive circuit, and can meet the needs of low-speed control signal transmission;

[0029] (2) A thermistor compensation network is used to compensate for the total circuit resistance in a wide temperature range (-55°C ~ 125°C), stabilize the laser's luminous power in a wide temperature range, avoid changes in the laser's luminous power due to the influence of temperature, achieve compensation for the laser's temperature characteristics, and improve the transmission reliability and accuracy of the laser's optical signal.

[0030] After reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, a brief introduction will be given below to the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0032] Figure 1 It is a circuit schematic diagram of an embodiment of a conventional standard optical module;

[0033] Figure 2 is a trend curve of laser threshold current changing with temperature in one embodiment of a conventional standard optical module;

[0034] Figure 3 This is a circuit schematic diagram of an embodiment of the optical module proposed by the utility model;

[0035] Figure 4 It is a schematic diagram of a transmitting driving unit in one embodiment of the optical module proposed by the utility model;

[0036] Figure 5 It is a circuit diagram of a thermistor compensation network in one embodiment of the optical module proposed by the utility model;

[0037] Figure 6 It is a curve showing the change of the resistance of the positive temperature coefficient thermistor of the thermistor compensation network as a function of temperature in one embodiment of the optical module proposed by the utility model;

[0038] Figure 7It is a curve showing the change of the resistance of the negative temperature coefficient thermistor of the thermistor compensation network as a function of temperature in one embodiment of the optical module proposed by the utility model;

[0039] Figure 8 It is a curve showing the change of the resistance of the thermistor compensation network as the temperature changes in one embodiment of the optical module proposed by the utility model;

[0040] Fig. 9 It is a schematic diagram of a receiving driving unit in one embodiment of the optical module proposed by the utility model;

[0041] Fig.10 It is a circuit diagram of a receiving driving unit in one embodiment of the optical module proposed by the utility model;

[0042] Reference numerals:

[0043] 100, transmitting driving unit; 110, level comparator; 120, thermistor compensation network; 121 / 122 / 123, branch circuit; 130, first power supply voltage stabilizing unit;

[0044] 200. Laser;

[0045] 300, light receiving component;

[0046] 400, receiving drive unit; 410, operational amplifier circuit; 420, level conversion circuit; 430, second power supply voltage stabilizing unit; 440, common mode elimination amplifier circuit. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0050] In the description of this application, it should be noted that, 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 indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0052] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the utility model. In addition, the utility model may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the utility model provides various specific examples of processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0053] See also Figure 1 The conventional standard optical module circuit includes a transmitting driver chip, a receiving driver chip and a control chip. The power supply Vcc supplies power to the transmitting driver chip, the receiving driver chip, the control chip, and the transmitting optical components (such as lasers) and the receiving optical components (such as PD (Photo Diode)) in the optical module to ensure the normal photoelectric conversion function of the optical module.

[0054] The transmitting driving chip is used to drive the transmitting light component, and the receiving driving chip is used to drive the receiving light component, and the transmitting driving chip and the receiving driving chip are respectively connected to the control chip.

[0055] During transmission, the electrical signal is input to the transmission driver chip and after being processed by the transmission driver chip, it drives the transmission light component to transmit and output the light signal.

[0056] During reception, the optical receiving component receives the optical signal and generates a response current corresponding to the optical signal. The response current is input to the receiving driver chip, and after being processed by the receiving driver chip, an electrical signal is output to complete the photoelectric conversion process.

[0057] The light emitting component may be an EML (External Modulation Laser) laser, a DML (Direct Modulation Laser), a light emitting diode, an MPD (Monitor PhotoDetector), or the like.

[0058] The light receiving component may also be an APD (Avalanche Photo Diode) or the like.

[0059] The luminous efficiency of a laser is determined by its threshold current, which is greatly affected by temperature changes, especially over a wide temperature range (-55°C to 125°C). Figure 2 , which is a nonlinear change. If current compensation is not performed, the laser light power will fluctuate too much. Too much or too little light power will affect the light receiving end's reception of the light signal, and even damage the light receiving end's light receiving components.

[0060] To prevent the light source from being affected by temperature and significantly changing its luminous properties over a wide temperature range, see Figures 3 to 10 The present application relates to an optical module, which is used to adjust the resistance of the optical transmission circuit at different temperatures by setting a thermistor compensation network 120 in a wide temperature range, compensate for the change of the laser threshold current at different temperatures, thereby stabilizing the laser emission optical power value and improving the reliability and accuracy of signal transmission.

[0061] See also Figure 3 and Figure 4 The emission driving unit 100 formed by discrete components of the level comparator 110 and the thermistor compensation network 120 replaces the original emission driving chip and the control chip, simplifies the driving circuit structure, improves the reliability of the emission driving unit 100 under high and low temperature extremes, and at the same time compensates for the control problem of the laser light emitting power through the thermistor compensation network 120, so as to realize the reliable use of the optical module under a wide temperature range.

[0062] The level comparator 110 receives an input electrical signal Vin and a reference electrical signal Vref, and compares and outputs an electrical signal to the thermistor compensation network 120 .

[0063] The thermistor compensation network 120 includes a first branch and a second branch connected in series, wherein the first branch includes a positive temperature coefficient thermistor and a fixed resistor in series and parallel, and the second branch includes a negative temperature coefficient thermistor and a fixed resistor in series and parallel.

[0064] Specifically, see Figure 5 The thermistor compensation network 120 includes a branch 121, a branch 122 and a branch 123, wherein the branch 121, the branch 122 and the branch 123 are connected in series.

[0065] The branch 121 may include a positive temperature coefficient thermistor (PTC thermistor) R4 and a fixed resistor R1 connected in parallel, the branch 122 may include a negative temperature coefficient thermistor (NTC thermistor) R5 and a fixed resistor R2 connected in parallel, and the branch 123 includes a fixed resistor R3.

[0066] See also Figure 6 , which shows the change curve of the PTC thermistor when its resistance changes with temperature.

[0067] It can be seen that the relationship of the change curve is approximately: R + =K(T-T0)+R0, where R + is the resistance of the PTC thermistor at temperature T, K is the proportional coefficient, T is the current temperature, T0 is the resistance of the PTC thermistor at 25°C, and R0 is the fixed bias value.

[0068] See also Figure 7 , which shows the change curve of the NTC thermistor when its resistance changes with temperature.

[0069] It can be seen that the relationship of the change curve is: R - =R*e B（1 / T1-1 / T2） , where R - is the resistance of the NTC thermistor at temperature T1, R is the nominal resistance of the NTC thermistor at room temperature T2, and B is the characteristic parameter of the NTC thermistor.

[0070] For the thermistor compensation network 120, since the resistance value of the PTC thermistor decreases at low temperatures, the thermistor compensation network 120 can be connected in parallel with the fixed resistor R1 to reduce the total resistance value at low temperatures. At high temperatures, since its resistance value is very large, there is almost no effect.

[0071] Since the resistance of the NTC thermistor decreases at high temperatures, the thermistor compensation network 120 can be connected in parallel with the fixed resistor R2 to reduce the total resistance at high temperatures. At low temperatures, the resistance of the thermistor compensation network 120 is very large and has almost no effect.

[0072] Therefore, at low temperatures, the resistance of the thermistor compensation network 120 is mainly determined by the NTC thermistor, while at high temperatures, the resistance of the thermistor compensation network 120 is mainly determined by the PTC thermistor.

[0073] Therefore, by selecting thermistors with positive and negative temperature coefficients of appropriate parameters, the resistance change of thermistor compensation network 120 can be matched with the change of laser threshold current. Figure 8 shown.

[0074] Thermistor selection can be pre-tested before use.

[0075] For example, a fixed voltage Vz is applied to the a1 terminal of the thermistor compensation network 120, the a2 terminal is connected to the ground, and a thermistor with a medium resistance is selected as a reference thermistor and connected to the positions R4 and R5 in the thermistor compensation network 120 respectively.

[0076] During the testing of the thermistor, a roughly selected fixed resistor and the thermistor within the thermistor compensation network 120 can be tested first.

[0077] The thermistor compensation network 120 is placed in a temperature box, and the voltage values ​​of nodes b1, b2 and b3 are recorded at various temperature points. The resistance-temperature characteristics of the reference thermistor, i.e., the resistance-temperature characteristics data of the reference thermistor value, are calculated using the measured node voltage values ​​according to Kirchhoff's law.

[0078] It should be noted that the resistance values ​​of the fixed resistor R1 and the fixed resistor R2 are set to be relatively large, while the resistance value of the fixed resistor R3 is set to be relatively small.

[0079] In order to reduce the change of the input power supply, the first power supply voltage regulator unit 130 is used to provide a regulated voltage for the level comparator 110, reduce the impact of the input power change, reduce the drift of the transmitted light power of the optical module under the wide temperature range of -55℃~125℃, improve the stability and reliability of the transmitted light signal, and at the same time protect the optical detector and other devices at the receiving end.

[0080] To improve the reliability of receiving signals at the receiving end in a wide temperature range, see Fig. 9The receiving driving unit 400 includes an operational amplifier circuit 410 and a level conversion circuit 420. The operational amplifier circuit 410 is used to receive the weak current output by the light receiving component 300 after receiving the optical signal, and output an amplified voltage signal.

[0081] The level conversion circuit 420 is used to receive the voltage signal and the reference signal output by the operational amplifier circuit 410 and output an electrical signal for a load.

[0082] In some embodiments of the present application, the operational amplifier circuit 410 is a transimpedance amplifier circuit.

[0083] A second power supply voltage regulator unit 430 is used to provide regulated voltages for the operational amplifier circuit 410 and the level conversion circuit 420, respectively. The operational amplifier circuit 410 is powered by a dual power supply ±VCC, which effectively suppresses the influence of active noise on the performance of the operational amplifier circuit 410, improves the power supply stability of the operational amplifier circuit 410, and enhances the ability of the receiving end to resist noise at high and low temperature extreme temperatures, thereby improving the light receiving sensitivity.

[0084] The light receiving component 300 may be Fig.10 The photodiode D2 shown in the figure has the function of realizing photoelectric conversion, converting the received light signal into a weak current signal.

[0085] The operational amplifier circuit 410 converts the weak current signal of the previous stage into a voltage signal and amplifies it to a certain extent. After the current signal is converted into a voltage signal, it is convenient for the subsequent stage circuit to process it.

[0086] In some embodiments of the present application, the transimpedance amplifier circuit includes an amplifier U2, which applies a negative reverse bias voltage to the input photodiode D2 (for example, through resistors R10, R11, R12 and capacitor C10). The negative bias voltage across the photodiode D2 reduces the parasitic capacitance of the photodiode D2. This lower capacitance increases the speed of the transimpedance amplifier circuit.

[0087] Specifically, the negative phase input terminal of the amplifier U2 is connected to the photodiode D2 and also connected to one end of the first voltage negative feedback loop. The other end of the first voltage negative feedback loop is connected to the output terminal of the amplifier U2. The positive phase input terminal of the amplifier U2 is connected to the fixed level Vref.

[0088] Among them, the first voltage negative feedback loop includes resistor R10, resistor R11, resistor R12 and capacitor C10. After the resistor R12 and the capacitor C10 are connected in parallel, one end is connected to the negative phase input terminal of the amplifier U2, and the other end is respectively connected to one end of the resistor R10 and one end of the resistor R11. The other end of the resistor R10 is connected to the fixed level Vref, and the other end of the resistor R11 is connected to the output terminal of the amplifier U2.

[0089] In order to remove the common mode component in the voltage signal output by the transimpedance amplifier circuit, in some embodiments of the present application, see Fig.10 , and also includes a common-mode elimination amplifier circuit 440, wherein the common-mode elimination amplifier circuit 440 includes an amplifier U5.

[0090] As described above, voltage negative feedback is formed on the amplifier U2 in the transimpedance amplifier circuit through the second voltage negative feedback loop.

[0091] The voltage signal output by the amplifier U2 is input to the negative phase input terminal of the amplifier U5, and the other input terminal of the amplifier U5 is connected to the positive phase input terminal of the amplifier U2 through a second voltage negative feedback loop.

[0092] Among them, see Fig.10 The second voltage negative feedback loop includes a resistor R18 and a resistor R19, one end of the resistor R19 is connected to the positive phase input resistor of the amplifier U5 and the other end is grounded, one end of the resistor R18 is connected to the negative phase input terminal of the amplifier U2 and the other end is connected to the connection position between the resistor R19 and the positive phase input terminal of the amplifier U5.

[0093] The second voltage negative feedback loop enables the common-mode elimination amplifier circuit 440 to form negative feedback with the preceding transimpedance amplifier circuit, and performs common-mode component elimination processing on the voltage signal output by the transimpedance amplifier circuit.

[0094] After processing, the signal is amplified by the amplifier U5 and output to the level conversion circuit 420 .

[0095] See also Fig.10 , the level conversion circuit 420 can be selected as the comparator U3.

[0096] The level conversion circuit 420 compares the signal output by the common mode elimination amplifier circuit 440 with a reference level, and the output electrical signal is connected to a user's rear-end load.

[0097] The optical module of the present application is designed to be applicable to wide temperature range scenarios by designing its transmitting driving unit 100 and receiving driving unit 400. Both the transmitting driving unit 100 and the receiving driving unit 400 are constructed with discrete components, eliminating complex circuits such as a micro-control unit and a driving chip, simplifying the driving circuit, and being able to meet the needs of low-speed control signal transmission.

[0098] Of course, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An optical module, characterized in that: include: The transmitting drive unit comprises: a level comparator receiving an electrical input signal and a reference electrical signal; a thermistor compensation network, which receives the output signal of the level comparator, the thermistor compensation network comprising a first branch and a second branch connected in series, the first branch comprising a positive temperature coefficient thermistor and a fixed resistor in series and parallel, the second branch comprising a negative temperature coefficient thermistor and a fixed resistor in series and parallel; A laser, which is driven by the emission driving unit to output an optical signal; a receiving optical component that receives an optical input signal; The receiving driving unit receives the signal output by the light receiving component and outputs an electrical signal.

2. The optical module according to claim 1, characterized in that: The transmitting driving unit also includes: The first power supply voltage stabilizing unit is used to provide a regulated voltage to the comparator.

3. The optical module according to claim 1, characterized in that: The receiving driving unit comprises: an operational amplifier circuit, which receives the signal output by the light receiving component; The level conversion circuit receives the signal output by the operational amplifier circuit and outputs the electrical signal.

4. The optical module according to claim 3, characterized in that: The receiving driving unit also includes: The second power supply voltage stabilizing unit is used to provide regulated voltage to the operational amplifier circuit and the level conversion circuit respectively.

5. The optical module according to claim 4, characterized in that: The operational amplifier circuit is a transimpedance amplifier circuit, which is used to receive the current signal output by the light receiving component and convert it into an amplified voltage signal.

6. The optical module according to claim 5, characterized in that: The receiving driving unit also includes: The common mode elimination amplifier circuit is used to receive the voltage signal output by the transimpedance amplifier circuit and form voltage negative feedback for the amplifier in the transimpedance amplifier circuit.

7. The optical module according to claim 4, characterized in that: The second power supply stabilizing unit provides a dual power supply voltage for the operational amplifier circuit.

8. The optical module according to claim 1, characterized in that: The light receiving component is a photodetector or an avalanche photodiode.

Images