Driver and optical module

Abstract

The invention discloses a driver and an optical module, the driver comprises a current source, the driver is connected with a modulator, and the modulator adjusts common-mode voltage Vcmn of the output end of the driver according to the magnitude of direct current provided by the current source for the driver; the driver further comprises a modulation bias circuit, and the modulation bias circuit can adjust the size of the direct current provided by the current source according to a comparison result between the common-mode voltage Vcmn of the output end of the driver and a preset voltage, so that the common-mode voltage Vcmn of the output end of the driver can be adjusted to be the same as the preset voltage through the modulator. According to the invention, the problem that the reliability and the performance of optical modules in mass production are inconsistent due to unstable common-mode voltage of the output end of the driver is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of driver application, and in particular relates to a driver and an optical module. Background Art

[0002] With the development of AI technology, large models, big data, and large computing power are increasingly becoming the core constraints of AIGC applications. Large models and data sets are the software foundation for the development of AIGC, while computing power is the most important infrastructure. AI is mainly based on parallel computing, and the core processor is mainly GPU. However, in addition to GPU performance, communication factors will also become a shortcoming that restricts supercomputing, requiring high-speed optical modules to match, such as 400G~1.6T optical modules. As the market demand for optical modules increases, users' performance requirements for optical modules are also getting higher and higher.

[0003] Existing optical modules include drivers and modulators. Changes in manufacturing process or ambient temperature will affect the resistance value R of the load resistor in the modulator, the output voltage Vref of the current mirror in the driver's current source, and the performance of the transistor or field effect transistor, thereby making the common mode voltage Vcmn at the driver output unstable, resulting in the bandwidth and extinction ratio of the optical signal deteriorating. Especially for mass-produced drivers, due to the differences in manufacturing process, it is difficult to ensure the consistency of Vcmn, resulting in performance differences between mass-produced optical modules.

[0004] In the design of some traditional optical modules, the optical module will dynamically control the common mode voltage Vcmn at the output of the driver through the peripheral circuit of the driver. For example, the current of the driver is sampled through the peripheral circuit, and the current is converted into voltage Vcmn, and then Vcmn is fed back to the control unit, and then the closed-loop dynamic control of Vcmn is achieved through software. This design is mainly suitable for optical modules whose common mode voltage Vcmn at the output of the driver is not constant due to changes in ambient temperature, and the peripheral circuit will occupy a lot of space in the optical module, increasing production costs. Summary of the invention

[0005] The object of the present invention is to provide a driver and an optical module to solve the problem of inconsistent reliability and performance of mass-produced optical modules caused by unstable common-mode voltage at the output end of the driver.

[0006] The present invention is achieved through the following technical solutions: A driver, the driver includes a current source, the driver is connected to a modulator, and the modulator adjusts the common mode voltage Vcmn of the driver output terminal according to the magnitude of the DC current provided by the current source to the driver; The driver also includes a modulation bias circuit, which can adjust the magnitude of the DC current provided by the current source according to the comparison result between the common mode voltage Vcmn at the output end of the driver and the preset voltage, so that the common mode voltage Vcmn at the output end of the driver can be adjusted to the same as the preset voltage through the modulator.

[0007] In some embodiments, the modulation bias circuit includes a comparator; One input terminal of the comparator is connected to the output terminal of the driver, and is used to compare the common mode voltage Vcmn of the output terminal of the driver with a preset voltage, and can output a first voltage V0 according to the comparison result, and adjust the magnitude of the direct current provided by the current source through the first voltage V0; In the process of adjusting the common mode voltage Vcmn at the output end of the driver, the comparator can gradually change the output first voltage V0 until the common mode voltage Vcmn at the output end of the driver is the same as the preset voltage Vset.

[0008] In some embodiments, the current source includes a current mirror and a transistor connected in sequence, the input end of the current mirror is connected to the output end of the comparator, and one end of the transistor is grounded.

[0009] In some embodiments, the current source includes a current mirror and a field effect transistor connected in sequence, the input end of the current mirror is connected to the output end of the comparator, and one end of the field effect transistor is grounded.

[0010] In some embodiments, the modulation bias circuit further includes a buffer for isolating a signal between the comparator and the current mirror, wherein an input end of the buffer is connected to an output end of the comparator, and an output end of the buffer is connected to an input end of the current mirror.

[0011] In some embodiments, the buffer is used to adjust the first voltage V0 output by the comparator to within a set range.

[0012] In some embodiments, the modulation bias circuit is integrated within the driver.

[0013] The present invention also relates to an optical module, comprising the above-mentioned driver.

[0014] In some embodiments, further comprising a modulator and a power supply VDD; The modulator includes two identical load resistors and two identical PN junctions, namely a first load resistor R1, a second load resistor R2, a first PN junction D1 and a second PN junction D2. One end of the first load resistor R1 is connected to a power supply VDD, and the other end of the first load resistor R1 is respectively connected to an output end of the driver and a positive electrode of the first PN junction D1, the negative electrode of the first PN junction D1 is respectively connected to a negative electrode of the second PN junction D2 and a bias voltage Vbias, the positive electrode of the second PN junction D2 is respectively connected to another output end of the driver and one end of the second load resistor R2, and the other end of the second load resistor R2 is connected to the power supply VDD.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention uses a modulation bias circuit to adjust the magnitude of the direct current provided by the current source according to the comparison result between the common-mode voltage at the output end of the driver and the preset voltage, so that the common-mode voltage at the output end of the driver can be adjusted to be the same as the preset voltage through the modulator, and automatic adjustment of the common-mode voltage at the output end of the driver is achieved without the need for software and peripheral circuits, ensuring that the common-mode voltage at the output end of the driver is stable, so that the reliability and performance of mass-produced optical modules are consistent; and the modulation bias circuit is simple and integrated in the driver, saving the internal space of the optical module and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 4 is a circuit diagram of a modulation bias circuit of a driver in an embodiment of the present invention.

[0018] Figure 2 is a circuit diagram of a current source in an embodiment of the present invention.

[0019] Figure 3 4 is a circuit diagram of the connection between the driver and the modulator in the optical module in an embodiment of the present invention.

[0020] Figure 4 Schematic diagram of the change of Vcmn when Vcmn is greater than Vset in an embodiment of the present invention.

[0021] Figure 5 Schematic diagram of the change of V0 when Vcmn is greater than Vset in an embodiment of the present invention.

[0022] Figure 6Schematic diagram of the change of V1 when Vcmn is larger than Vset in an embodiment of the present invention.

[0023] Figure 7 Schematic diagram of the change of Vref when Vcmn is larger than Vset in an embodiment of the present invention.

[0024] Figure 8 Schematic diagram of the change of Ic when Vcmn is greater than Vset in an embodiment of the present invention.

[0025] Where t is time, V is voltage, and I is current. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions 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 only part of the embodiments of the present invention, not all of the embodiments.

[0027] Example 1 A driver, the driver includes a current source, the driver is connected to a modulator, and the modulator adjusts the common mode voltage Vcmn of the driver output terminal according to the magnitude of the direct current Ic provided by the current source to the driver; The driver also includes a modulation bias circuit, which can adjust the magnitude of the DC current Ic provided by the current source according to the comparison result between the common mode voltage Vcmn at the output end of the driver and the preset voltage Vset, so that the common mode voltage Vcmn at the output end of the driver can be adjusted to be the same as the preset voltage Vset through the modulator.

[0028] A modulation bias circuit is used to adjust the magnitude of the DC current Ic provided by the current source according to the comparison result between the common-mode voltage Vcmn at the output end of the driver and the preset voltage Vset, so that the common-mode voltage Vcmn at the output end of the driver can be adjusted to be the same as the preset voltage Vset through the modulator, and automatic adjustment of the common-mode voltage Vcmn at the output end of the driver is achieved without the need for software and peripheral circuits, thereby ensuring the stability of the common-mode voltage Vcmn at the output end of the driver, and ensuring consistent reliability and performance of mass-produced optical modules.

[0029] In some embodiments, reference Figure 1 , the modulation bias circuit includes a comparator; One input terminal of the comparator is connected to the output terminal of the driver, and is used to compare the common mode voltage Vcmn of the output terminal of the driver with a preset voltage, and can output a first voltage V0 according to the comparison result, and adjust the magnitude of the direct current provided by the current source through the first voltage V0; In the process of adjusting the common mode voltage Vcmn at the output end of the driver, the comparator can gradually change the output first voltage V0 until the common mode voltage Vcmn at the output end of the driver is the same as the preset voltage Vset.

[0030] In some embodiments, reference Figure 2 The current source includes a current mirror and a transistor Q1 connected in sequence, the input end of the current mirror is connected to the output end of the comparator, the output end of the current mirror is connected to the base of the transistor Q1, the emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to the driver.

[0031] In some embodiments, the current source includes a current mirror and a field effect transistor connected in sequence, the input end of the current mirror is connected to the output end of the comparator, the output end of the current mirror is connected to the gate of the field effect transistor, the source of the field effect transistor is grounded, and the drain of the field effect transistor is connected to the driver.

[0032] In some embodiments, reference Figure 1 The modulation bias circuit also includes a buffer for isolating the signal between the comparator and the current mirror, the input end of the buffer is connected to the output end of the comparator, and the output end of the buffer is connected to the input end of the current mirror.

[0033] In some embodiments, the buffer is used to adjust the first voltage V0 output by the comparator to within a set range, and the buffer outputs a voltage V1.

[0034] Since there is a loop between the bias adjustment circuit and the driver, if the adjustment is improper, the differential output of the driver will have a large fluctuation, which will eventually lead to oscillation; and the adjustment range of the first voltage V0 output by the comparator is large. If the current mirror is directly controlled by the first voltage V0, the voltage Vref output by the current mirror will have a large fluctuation, which will in turn cause the DC current Ic provided by the current source to have a large fluctuation, making the differential output of the driver prone to oscillation. Therefore, a buffer is set between the comparator and the current mirror to isolate the signal between the comparator and the current mirror, and the first voltage V0 output by the comparator is adjusted to within a set range, that is, the voltage V1 output by the buffer is limited to within a set range, to ensure that the DC current Ic provided by the current source is stable and quickly balanced, to avoid oscillation of the differential output of the driver, and finally to achieve stable automatic adjustment of the common mode voltage Vcmn at the output end of the driver.

[0035] In some embodiments, the modulation bias circuit is integrated within the driver.

[0036] The modulation bias circuit is simple and integrated in the driver, which saves the internal space of the optical module and reduces the production cost.

[0037] The process of the above driver automatically adjusting the common mode voltage Vcmn is: The comparator obtains the common mode voltage Vcmn at the output end of the driver, and compares the common mode voltage Vcmn with the preset voltage Vset; When the common mode voltage Vcmn is greater than the preset voltage Vset, Figure 5 Due to the characteristics of the comparator, in the process of adjusting the common mode voltage Vcmn at the output end of the driver, the first voltage V0 output by the comparator gradually decreases until the common mode voltage Vcmn at the output end of the driver is adjusted to be the same as the preset voltage Vset; Figure 6 , the output voltage V1 of the buffer will gradually increase as the first voltage V0 decreases; Figure 7 , accordingly, the output voltage Vref of the current mirror gradually increases with the change of the output voltage V1; Figure 8 , the DC current Ic output by transistor Q1 gradually increases with the change of the output voltage Vref of the current mirror; Figure 4 The modulator adjusts the common mode voltage Vcmn at the output end of the driver to be the same as the preset voltage Vset according to the DC current Ic.

[0038] When the common mode voltage Vcmn is smaller than the preset voltage Vset, due to the characteristics of the comparator, in the process of adjusting the common mode voltage Vcmn at the output end of the driver, the first voltage V0 output by the comparator gradually increases until the common mode voltage Vcmn at the output end of the driver is adjusted to be the same as the preset voltage Vset; Figure 6 , the output voltage V1 of the buffer will gradually decrease as the first voltage V0 increases; Figure 7 , accordingly, the output voltage Vref of the current mirror gradually decreases with the change of the output voltage V1; Figure 8 , the DC current Ic output by transistor Q1 gradually decreases as the output voltage Vref of the current mirror changes; Figure 4 The modulator adjusts the common mode voltage Vcmn at the output end of the driver to be the same as the preset voltage Vset according to the DC current Ic.

[0039] The present invention also relates to an optical module, comprising the above-mentioned driver.

[0040] In some embodiments, reference Figure 3 , also including the modulator and the power supply VDD; The modulator includes two identical load resistors and two identical PN junctions, namely a first load resistor R1, a second load resistor R2, a first PN junction D1 and a second PN junction D2. One end of the first load resistor R1 is connected to a power supply VDD, and the other end of the first load resistor R1 is respectively connected to an output end of the driver and a positive electrode of the first PN junction D1, the negative electrode of the first PN junction D1 is respectively connected to a negative electrode of the second PN junction D2 and a bias voltage Vbias, the positive electrode of the second PN junction D2 is connected to another output end of the driver and one end of the second load resistor R2, and the other end of the second load resistor R2 is connected to the power supply VDD.

[0041] Due to the influence of manufacturing process and ambient temperature, the output voltage Vref of the current mirror, the load resistors R1 and R2 of the modulator, and the performance of the transistor Q1 will change, thereby causing the common mode voltage Vcmn at the output of the driver to change. The bias voltage Vbias between the first PN junction D1 and the second PN junction D2 of the modulator and the common mode voltage Vcmn at the output of the driver will directly affect the modulation effect of the optical signal, such as the bandwidth and extinction ratio, and ultimately lead to the deterioration of the bandwidth and extinction ratio of the optical signal. Figure 3 The calculation formula of the common-mode voltage Vcmn at the output of the driver is: Vcmn=VDD-R*Ic / 2. It can be seen that the common-mode voltage Vcmn of the driver is affected by the DC current Ic provided by the current source. Therefore, a modulation bias circuit is used to adjust the size of the DC current Ic provided by the current source according to the comparison result between the common-mode voltage Vcmn at the output of the driver and the preset voltage Vset. The modulator can adjust the common-mode voltage Vcmn at the output of the driver to be the same as the preset voltage Vset, ensuring that the common-mode voltage Vcmn at the output of the driver is stable, so that the reliability and performance of mass-produced optical modules are consistent.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A driver, characterized in that: The driver comprises a current source, the driver is connected to a modulator, and the modulator adjusts the common mode voltage Vcmn of the output end of the driver according to the magnitude of the direct current provided by the current source to the driver; The driver also includes a modulation bias circuit, which can adjust the magnitude of the DC current provided by the current source according to the comparison result between the common mode voltage Vcmn at the output end of the driver and the preset voltage, so that the common mode voltage Vcmn at the output end of the driver can be adjusted to be the same as the preset voltage through the modulator.

2. The driver according to claim 1, characterized in that: The modulation bias circuit includes a comparator; One input terminal of the comparator is connected to the output terminal of the driver, and is used to compare the common mode voltage Vcmn of the output terminal of the driver with a preset voltage, and can output a first voltage V0 according to the comparison result, and adjust the magnitude of the direct current provided by the current source through the first voltage V0; In the process of adjusting the common mode voltage Vcmn at the output end of the driver, the comparator can gradually change the output first voltage V0 until the common mode voltage Vcmn at the output end of the driver is the same as the preset voltage Vset.

3. The driver according to claim 2, characterized in that: The current source comprises a current mirror and a transistor connected in sequence, the input end of the current mirror is connected to the output end of the comparator, and one end of the transistor is grounded.

4. The driver according to claim 2, characterized in that: The current source comprises a current mirror and a field effect tube connected in sequence, the input end of the current mirror is connected to the output end of the comparator, and one end of the field effect tube is grounded.

5. The driver according to claim 3 or 4, characterized in that: The modulation bias circuit also includes a buffer for isolating the signal between the comparator and the current mirror, wherein the input end of the buffer is connected to the output end of the comparator, and the output end of the buffer is connected to the input end of the current mirror.

6. The driver according to claim 5, characterized in that: The buffer is used to adjust the first voltage V0 output by the comparator to within a set range.

7. The driver according to claim 1, characterized in that: The modulation bias circuit is integrated in the driver.

8. An optical module, characterized in that: The invention comprises the driver according to any one of claims 1 to 7.

9. The optical module according to claim 8, characterized in that: Also includes a modulator and power supply VDD; The modulator includes two identical load resistors and two identical PN junctions, namely a first load resistor R1, a second load resistor R2, a first PN junction D1 and a second PN junction D2. One end of the first load resistor R1 is connected to a power supply VDD, and the other end of the first load resistor R1 is respectively connected to an output end of a driver and a positive electrode of the first PN junction D1, the negative electrode of the first PN junction D1 is respectively connected to a negative electrode of the second PN junction D2 and a bias voltage Vbias, the positive electrode of the second PN junction D2 is respectively connected to another output end of the driver and one end of the second load resistor R2, and the other end of the second load resistor R2 is connected to the power supply VDD.

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