TTL (transistor-transistor logic) signal optical fiber transmission and emission unit and laser sensor

Abstract

The invention discloses a TTL (transistor-transistor logic) signal optical fiber transmission and emission unit and a laser sensor. The driving circuit uses discrete components, comprises a comparator, a biasing circuit, a current limiting circuit and an acceleration capacitor, and controls the laser to emit light through an input signal. The bias circuit sets bias current through an adjustable resistor, and the current limiting circuit limits the current through a resistor, so that the capacitance is accelerated, and the switching rate is improved. According to the invention, a special laser driving chip is replaced, the cost is reduced, the flexibility and debuggeability of a supply chain are improved, and the method is suitable for an optical communication module.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a TTL signal fiber optic transmission transmitting unit, and more particularly to a laser transmitting unit driving circuit implemented using discrete components. Background Technology

[0002] In existing optical module solutions, the transmitting module typically requires a dedicated laser driver chip to drive the laser (LD). While these dedicated chips offer stable performance, they are costly, and their marketability and pricing are constrained by chip supply, resulting in poor flexibility and cost-effectiveness of the optical module. Furthermore, the high degree of customization required for dedicated chips makes it difficult to adapt to the needs of different application scenarios. Therefore, this invention proposes a TTL signal fiber optic transmission transmitting unit and a laser sensor to at least partially address the problems in the prior art. Summary of the Invention

[0003] In view of the above problems, embodiments of the present invention are proposed to provide a TTL signal fiber optic transmission transmitting unit, which uses discrete components (such as resistors, capacitors, comparators, etc.) to construct the driving circuit, replacing the dedicated laser driving chip, so as to reduce costs and improve supply flexibility.

[0004] To address the above problems, this invention discloses a TTL signal fiber optic transmission transmitting unit, comprising: A laser and a driving circuit, wherein the driving circuit includes an input interface, a comparator, a bias circuit, a current limiting circuit, and an accelerating capacitor, wherein: The input interface receives a TTL or CMOS input signal Vi, where Vi ≥ 3V is defined as high level, Vi ≤ 0.7V is defined as low level, and the maximum value of Vi is 5.5V. The input terminal of the comparator is connected to the input interface, and the output terminal is connected to the laser through the current limiting circuit. The bias circuit includes a first resistor and a second resistor, the second resistor being an adjustable resistor used to set the bias current so as to adjust the emitting power of the laser when Vi is low. The current limiting circuit includes a third resistor for limiting the current flowing through the laser when Vi is high, so as to adjust the laser's emission power to a predetermined value; The accelerating capacitor is connected to the output of the comparator or the gate of the field-effect transistor to improve the switching speed.

[0005] Optionally, the preset resistance of the second resistor is 3kΩ, and it is replaced with an equivalent adjustable resistor during commissioning to adjust the laser's emission power to -dBm (e.g., -7dBm) when Vi is low.

[0006] Optionally, the third resistor adjusts the light emitting power of the laser to 2 dBm when Vi is high level.

[0007] Optionally, the capacitance of the acceleration capacitor is 10 pF.

[0008] Optionally, the field effect tube is preferably HL2306, which is used as a switching element to drive the laser.

[0009] Optionally, the laser is a flange TOSA (coaxial package laser).

[0010] Optionally, the bias circuit further comprises a voltage dividing circuit composed of a second resistor and a third resistor, which is used to provide a bias output for the comparator and eliminate electromagnetic interference of the input signal.

[0011] In some embodiments of the present application, a laser sensor is also disclosed, which comprises a TTL signal fiber transmission emitting unit and a laser receiving unit matched with the TTL signal fiber transmission emitting unit.

[0012] The present application includes the following advantages: The TTL signal fiber transmission emitting unit of the present application comprises a constant-flow water tank, the bottom of which is connected with an integrated waterproof variable frequency water pump through a water delivery pipeline; a one-way valve is arranged in the middle of the water delivery pipeline and faces the integrated waterproof variable frequency water pump; a pressure-resistant water pipe connected with the output end of the integrated waterproof variable frequency water pump is further connected with an air pressure tank; and the integrated waterproof variable frequency water pump is electrically connected to a variable frequency power supply cabinet. The laser drive is realized by discrete components, which reduces the cost and supply chain risk; the circuit structure is simple, easy to debug and maintain; the bias and current limit are adjustable, which adapts to different power requirements; and the acceleration capacitor improves the switching rate, which is suitable for high-speed optical communication. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 Fig. 1 is a TTL signal fiber transmission emitting unit circuit structure schematic diagram of a TTL signal fiber transmission emitting unit embodiment of the present application; Figure 2 Fig. 2 is an equivalent circuit structure schematic diagram of a second resistor of a TTL signal fiber transmission emitting unit embodiment of the present application; Figure 3 Fig. 3 is a TTL signal fiber transmission emitting unit schematic diagram of a TTL signal fiber transmission emitting unit embodiment of the present application. DETAILED DESCRIPTION

[0014] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0015] The application provides a TTL signal optical fiber transmission emitting unit, which specifically comprises a laser LD and a driving circuit. Figure 1 and 2 The TTL signal optical fiber transmission emitting unit specifically comprises a laser LD and a driving circuit, wherein the driving circuit comprises an input interface, a comparator U1, a bias circuit, a current limiting circuit and an acceleration capacitor C1; the input interface receives a TTL or CMOS input signal Vi, wherein Vi≥3V is defined as a high level, Vi≤0.7V is defined as a low level, and the maximum value of Vi is 5.5V; the input end of the comparator U1 is connected with the input interface, and the output end is connected with the laser LD through the current limiting circuit; the bias circuit comprises a first resistor R1 and a second resistor R2, the second resistor R2 is an adjustable resistor, and is used for setting a bias current to adjust the light emitting power of the laser LD when the low level is input; the current limiting circuit comprises a third resistor R3, and is used for limiting the current flowing through the laser LD when the high level is input, so as to adjust the light emitting power of the laser LD to a predetermined value; and the acceleration capacitor C1 is connected with the output end of the comparator U1 or the gate of a field effect tube Q1, and is used for improving the switching rate.

[0016] The TTL signal optical fiber transmission emitting unit of the application uses discrete components (a comparator, a resistor and a capacitor) to drive the laser as a basic structure, which breaks the dependence on special chips, reduces the cost and supply chain risk, and is simple in circuit, easy to realize and debug.

[0017] Further, the preset resistance value of the second resistor R2 is 3kΩ, and an equivalent adjustable resistor R2' is replaced during debugging, so as to adjust the light emitting power of the laser LD to -dBm (for example, -7 dBm) when the low level is input. The resistance value and adjustable characteristic of the above R2 allow the bias current and the optical power to be accurately adjusted when the low level is input. The flexibility and accuracy of power setting are improved, and different application scenarios are adapted.

[0018] The third resistor R3 adjusts the light emitting power of the laser LD to 2 dBm when the high level is input. The optical power is adjusted to 2 dBm by R3 when the high level is input. The optical power stability under the high level is ensured, the laser is prevented from being overdriven, and the service life of the device is prolonged.

[0019] As an example, a TTL signal fiber optic transmission transmitter includes a laser LD and a driving circuit. The driving circuit includes an input interface, a comparator U1, a bias circuit, a current limiting circuit, and an accelerating capacitor C1. The input interface receives a TTL or CMOS input signal Vi, where the high level is ≥3V, the low level is ≤0.7V, and the maximum value is 5.5V. The comparator U1 converts the input signal into a driving signal, which drives the laser LD through the current limiting circuit. The bias circuit sets the bias current through an adjustable resistor R2 to adjust the laser's emission power when the voltage is low; the current limiting circuit limits the current when the voltage is high through a resistor R3 to adjust the emission power to a predetermined value (e.g., 2 dBm). The accelerating capacitor C1 is used to improve the switching speed and ensure a fast response of the field-effect transistor Q1.

[0020] Laser driving is achieved through discrete components, reducing cost and supply chain risks; the circuit structure is simple, easy to debug and maintain; bias and current limiting are adjustable to adapt to different power requirements; the accelerating capacitor improves the switching speed, making it suitable for high-speed optical communication. The aforementioned accelerating capacitor C1 has a capacitance of 10pF. Optimized switching speed improves circuit response speed, making it suitable for high-speed optical signal transmission. The field-effect transistor Q1 is preferably an HL2306, used as a switching element to drive the laser LD. It provides reliable switching performance, ensuring the stability and compatibility of the driving circuit. The laser LD is a flanged TOSA (coaxial packaged laser). Enhanced mechanical stability and optical coupling efficiency of the laser improve the overall reliability of the module.

[0021] The bias circuit also includes a voltage divider circuit, consisting of a second resistor R2 and a third resistor R3, used to provide a bias output for comparator U1 and eliminate electromagnetic interference from the input signal. The voltage divider structure of the bias circuit reduces electromagnetic interference, improves signal integrity, and ensures the stability of the drive output.

[0022] In some embodiments of this application, Figure 1 , Figure 2 and Figure 3 As shown, the TTL signal fiber optic transmission transmitting unit includes a laser LD and a driving circuit. Figure 3 As shown, the driving circuit consists of resistors R31, R32, and R33, capacitor C31, and comparator U1. Resistor R31 corresponds to the first resistor R1, resistor R32 corresponds to the second resistor R2, resistor R33 corresponds to the third resistor R3, and capacitor C31 corresponds to the accelerating capacitor C1. The input signal Vi is a TTL or CMOS level signal. After processing by comparator U1, it drives the field-effect transistor Q1 (preferably HL2306) to control the switching of the laser LD.

[0023] The bias circuit consists of resistors R31 and R32, where R32 is an adjustable resistor (preset 3kΩ). During debugging, R32 is replaced with an equivalent adjustable resistor R2'. When Vi is low, R2' is adjusted to set the bias current of the laser LD, so that the emission power reaches a predetermined value (e.g., -7dBm). The current limiting circuit consists of resistor R33. When Vi is high, R33 is adjusted to make the emission power of the laser LD reach 2dBm. The accelerating capacitor C31 (10pF) is connected to the output of comparator U1 or the gate of Q1 to improve the switching speed.

[0024] The aforementioned laser LD uses a flanged TOSA, which provides a bias output to comparator U1 through a voltage divider circuit (R32 and R33) to eliminate electromagnetic interference of the input signal.

[0025] In practice, component selection and parameters can be adjusted according to actual needs. For example, the resistance values ​​of R32 and R33 can be determined through debugging to optimize optical power output.

[0026] In one specific embodiment, such as Figure 3 As shown, the TTL signal fiber optic transmission unit includes a laser driver circuit and a photoelectric conversion circuit. In the construction of the laser driver circuit, resistors R31, R32, and R33 are all conventional carbon film resistors, with R32 having a preset resistance of 3kΩ. Capacitor C31 is a ceramic capacitor, and comparator U1 is an LM311 comparator, which has good signal comparison and processing capabilities and can meet the requirements of the driver circuit. The driver is an SN75451 driver adapted for TTL digital signal transmission, and the laser LD is a standard TOSA with a flange, model TO56-TOSA. This model of TOSA is readily available on the market and has stable performance. The above components are soldered and assembled according to the circuit design requirements to form the laser driver circuit. The TTL digital signal, after being processed by the SN75451 driver, is loaded onto the TO56-TOSA LD, driving the LD to emit light. Meanwhile, the voltage divider circuit formed by R32 and R33 provides bias output for the SN75451 driver. Tests have shown that this voltage divider circuit can effectively eliminate electromagnetic interference of the input signal, reducing the interference amplitude of the input signal to below 0.1V, thus ensuring the stability of the input signal.

[0027] like Figure 1 and Figure 2As shown, in the photoelectric conversion circuit, the input level Vi follows the TTL (CMOS) input level standard. According to actual measurements, when Vi ≥ 3V, the circuit determines it as "1" level (high level); when Vi ≤ 0.7V, it determines it as "0" level (low level). Moreover, the maximum input voltage of Vi is 5.5V, which meets the parameter requirements of conventional TTL (CMOS) level and is compatible with other TTL (CMOS) standard circuit components.

[0028] During the debugging phase, the debugging is first performed under low-level conditions: replace R32 with an adjustable equivalent resistor R2 (using a sliding rheostat). When the Vi input is at a "0" level (the actual input voltage of Vi is 0.5V), the luminous power of the LD is monitored by adjusting the resistance value of R2 and using an optical power meter. Finally, the luminous power of the LD is stably controlled at the designed specific dBm value (set to -5dBm in this embodiment). After debugging, the equivalent resistance value of the original R2 is recorded so that a replacement resistor with a fixed resistance value can be determined during subsequent mass production.

[0029] Next, we performed debugging under the high-level state: we restored R32 to the preset resistor of 3kΩ. When Vi input is at the "1" level (at this time, the actual input voltage of Vi is 3.3V), we monitored the LD's light-emitting power and adjusted other auxiliary parameters in the circuit (such as the driver's output current) to finally make the LD's light-emitting power stably reach 2dBm, which meets the light-emitting performance requirements under the high-level input state.

[0030] In addition, the accelerating capacitor C in the photoelectric conversion circuit is a ceramic capacitor, preferably with a capacitance of 10pF. The field-effect transistor Q1 is an HL2306. After connecting the accelerating capacitor C and the HL2306 field-effect transistor according to the circuit design, the switching speed of the field-effect transistor Q1 was improved to less than 10ns after testing, ensuring the fast switching response of the circuit and meeting the switching performance requirements of the TTL signal fiber optic transmission transmitter unit.

[0031] The TTL signal fiber optic transmission unit constructed through the above specific implementation method has been tested and found to meet all the design requirements. Moreover, the production cost is reduced by more than 30% compared with the transmission module using a dedicated laser driver chip. At the same time, it eliminates the dependence on a dedicated laser driver chip and effectively solves the related problems in the prior art.

[0032] It should be noted that the aforementioned second resistor R2, or equivalent adjustable resistor R2', connected in series with R21 and R22, wherein R21 is preferably 1kΩ and R2' is preferably 5kΩ, is used to adjust the bias current when Vi is low. The aforementioned field-effect transistor Q1 acts as a switching element, its gate connected to the comparator output via the accelerating capacitor C1, its source grounded, and its drain connected to the laser LD and the current-limiting resistor R3. Furthermore, although... Figure 1 The example given is an N-channel MOSFET, but it can be replaced with a P-channel MOSFET by adjusting the positions of LD and R1 accordingly. Other switching elements, such as transistors, can also be used to achieve similar functions, and their connection methods are similar, so they will not be elaborated here.

[0033] In some instances of this application, based on the same concept, a laser sensor is also disclosed, including the aforementioned TTL signal fiber optic transmission transmitting unit and a laser receiving unit matched with the TTL signal fiber optic transmission transmitting unit.

[0034] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0035] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0036] The present invention provides a detailed description of a TTL signal fiber optic transmission unit and a laser sensor. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A TTL signal fiber optic transmission unit, comprising: The laser and driving circuit are characterized in that the driving circuit includes an input interface, a comparator, a bias circuit, a current limiting circuit, and an accelerating capacitor, wherein: The input interface receives a TTL or CMOS input signal Vi, where Vi ≥ 3V is defined as high level, Vi ≤ 0.7V is defined as low level, and the maximum value of Vi is 5.5V. The input terminal of the comparator is connected to the input interface, and the output terminal is connected to the laser through the current limiting circuit. The bias circuit includes a first resistor and a second resistor, the second resistor being an adjustable resistor used to set the bias current so as to adjust the emitting power of the laser when Vi is low. The current limiting circuit includes a third resistor for limiting the current flowing through the laser when Vi is high, so as to adjust the laser's emission power to a predetermined value; The accelerating capacitor is connected to the output of the comparator or the gate of the field-effect transistor to improve the switching speed.

2. The TTL signal fiber optic transmission unit according to claim 1, characterized in that, The second resistor has a preset resistance of 3kΩ and is replaced with an equivalent adjustable resistor during debugging to adjust the laser's emission power to -dBm when Vi is at a low level.

3. The TTL signal fiber optic transmission unit according to claim 1, characterized in that, The third resistor adjusts the laser's emission power to 2 dBm when Vi is at a high level.

4. The TTL signal fiber optic transmission unit according to claim 1, characterized in that, The acceleration capacitor has a capacitance of 10pF.

5. The TTL signal fiber optic transmission unit according to claim 1, characterized in that, The preferred model of the field-effect transistor is HL2306, which is used as a switching element to drive the laser.

6. The TTL signal fiber optic transmission unit according to claim 1, characterized in that, The laser is a TOSA with a flange.

7. The TTL signal fiber optic transmission unit according to claim 1, characterized in that, The bias circuit also includes a voltage divider circuit, consisting of a second resistor and a third resistor, used to provide a bias output for the comparator and eliminate electromagnetic interference of the input signal.

8. A laser sensor, characterized in that, It includes a TTL signal fiber optic transmission transmitting unit as described in any one of claims 1 to 7, and a laser receiving unit matched with the TTL signal fiber optic transmission transmitting unit.

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