Optical transmitter module and laser diode driver therefor

Abstract

A laser diode driver comprises a signal input terminal for inputting an electrical signal, an amplification stage unit for amplifying the electrical signal, a first driving stage unit for converting the amplified signal into a corresponding current, and a current-voltage adapter for outputting a second voltage via a second voltage output line, for absorbing current on the second voltage output line and / or for providing current to the second voltage output line in dependence on a voltage or current on the second voltage output line, the amplification stage unit being located in an upper layer of circuitry, a first operating current of the amplification stage unit forming at least part of an upper layer current, the first driving stage unit being located in a lower layer of circuitry, such that a second operating current is at least partly a continuation of the at least part of the upper layer current, such that operating currents of the amplification stage unit and the first driving stage unit can be at least partly multiplexed, so that power consumption of the laser diode driver can be reduced. The application also provides an optical transmission module.

Description

Technical Field

[0001] This invention relates to the field of optical communication, and more specifically to an optical emitting module and its laser diode driver. Background Technology

[0002] In communication systems, using optical fiber to transmit high-speed signals offers advantages over cable transmission, including lower loss, higher performance, and lower cost. A common application in optical communication is active optical fiber, which supports interfaces for protocols such as USB, HDMI, and DisplayPort. Active optical fiber consists of a laser diode driver, a laser diode, an optocoupler, optical fiber, a photodiode, a transimpedance amplifier, and other modules. The laser diode driver (LDD) is the first stage in the active optical fiber's signal path. Its input is typically the interface output driver circuit of a multimedia playback device (hereinafter referred to as the pre-stage output circuit). The laser diode driver's function is to convert electrical signals to optical signals; it modulates the output current to change the output optical power of the laser diode.

[0003] In practical applications, laser diode drivers consume a significant amount of current and generate considerable heat in the overall communication system. For example, a commonly used laser diode driver circuit might look like this: Figure 1 As shown, the power supply voltage VDD needs to provide the operating currents I1, I2, and I3 for the input stage, amplification stage, and driver stage, respectively. The total current Itot provided by the power supply voltage VDD is the sum of I1, I2, and I3, and Itot represents the total power consumption.

[0004] In the applications described above, some interfaces require the active optical cable's LDD to provide voltage and current to the pre-amplifier output circuit. For example, if the LDD's power supply voltage VDD is 5V, it needs to provide a lower 3.3V voltage (hereinafter referred to as VDDH) and a preset current to the pre-amplifier output circuit. Figure 1 As shown, by adding a linear regulator (LDO) or a DC-DC converter (DCDC converter) inside the LDD, VDDH (e.g., 3.3V) is generated from VDD (e.g., 5V); VDDH provides current I0 to the output circuit of the preceding stage through the interface matching resistor. This further increases the current consumption of the LDD. Figure 1 As shown, the total current Itot is:

[0005] Itot=(I0+I1+I2+I3)*X*N≈(I0+I2+I3)*X*N…………(1)

[0006] Where X is the current conversion coefficient and N is the number of paths. It is evident that the larger Itot is, the greater the total power consumption and the more heat generated. Reducing the power consumption of laser diode drivers is a long-standing problem in this field, and power consumption limitations also affect the high-speed performance of laser diode driver circuits. Summary of the Invention

[0007] The main technical problem addressed by this invention is how to reduce the power consumption of laser diode drivers.

[0008] According to a first aspect, one embodiment provides a laser diode driver, comprising:

[0009] The signal input terminal is configured to connect to the pre-amplifier output circuit and receive at least an electrical signal output by the pre-amplifier output circuit.

[0010] An input signal processing circuit is configured to process an electrical signal input to a signal input terminal. The input signal processing circuit includes an amplification stage unit configured to amplify the electrical signal and output an amplified electrical signal. The amplification stage unit is connected between a first voltage and a second voltage provided by a power supply, thereby forming a current path that provides a first operating current to the amplification stage unit. The second voltage is less than the first voltage and greater than ground potential. The first operating current forms at least a portion of the upper current.

[0011] The first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a current that drives the corresponding laser diode. The first driving stage unit is connected between a second voltage and ground potential, thereby forming a current path that provides a second operating current to the first driving stage unit, such that the second operating current is at least a continuation of at least a portion of the upper current.

[0012] A current-voltage adapter is configured to connect between a power supply and ground, convert a first voltage output by the power supply into a second voltage, and output the second voltage through a second voltage output line. The current-voltage adapter is also configured to absorb current on the second voltage output line and / or supply current to the second voltage output line based on the voltage or current on the second voltage output line.

[0013] According to a second aspect, one embodiment provides a laser diode driver, comprising:

[0014] The signal input terminal is configured to connect to the pre-amplifier output circuit and receive at least an electrical signal output by the pre-amplifier output circuit.

[0015] An input signal processing circuit is configured to process an electrical signal input to a signal input terminal. The input signal processing circuit includes an amplification stage unit configured to amplify the electrical signal and output an amplified electrical signal. The amplification stage unit is connected between a first voltage and a second voltage provided by a power supply, thereby forming a current path that provides a first operating current to the amplification stage unit. The second voltage is less than the first voltage and greater than ground potential. The first operating current forms at least a portion of the upper current.

[0016] The first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a current that drives the corresponding laser diode. The first driving stage unit is connected between a second voltage and ground potential, thereby forming a current path that provides a second operating current to the first driving stage unit, such that the second operating current is at least a continuation of at least a portion of the upper current.

[0017] A current-voltage adapter is configured to connect between a power supply and ground, convert a first voltage output by the power supply into a second voltage, and output the second voltage through a second voltage output line. The current-voltage adapter is also configured to absorb current on the second voltage output line and / or supply current to the second voltage output line based on the voltage or current on the second voltage output line. The current-voltage adapter is also connected to a signal input terminal through the second voltage output line to output the second voltage to the signal input terminal, providing a second voltage to the pre-amplifier output circuit.

[0018] According to a third aspect, one embodiment provides a laser diode driver, comprising:

[0019] The signal input terminal is configured to connect to the pre-amplifier output circuit and receive at least an electrical signal output by the pre-amplifier output circuit.

[0020] An input signal processing circuit is configured to process an electrical signal input to a signal input terminal. The input signal processing circuit includes an amplification stage unit configured to amplify the electrical signal and output an amplified electrical signal. The amplification stage unit is connected between a first voltage and a second voltage provided by a power supply, thereby forming a current path that provides a first operating current to the amplification stage unit. The second voltage is less than the first voltage and greater than ground potential. The first operating current forms at least a portion of the upper current.

[0021] The first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a current that drives the corresponding laser diode. The first driving stage unit is connected between a second voltage and ground potential, thereby forming a current path that provides a second operating current to the first driving stage unit, such that the second operating current is at least a continuation of at least a portion of the upper current.

[0022] A first level conversion circuit is connected between the output terminal of the amplification stage unit and the input terminal of the first driving stage unit, and is used for signal level adaptation between the amplification stage unit and the first driving stage unit.

[0023] According to a fourth aspect, one embodiment provides an optical emitting module, comprising:

[0024] At least one laser diode driver as described in the third aspect;

[0025] A current-voltage adapter is configured to be connected between a power supply and ground, converting a first voltage output by the power supply into a second voltage, and outputting the second voltage through a second voltage output line. The current-voltage adapter is also configured to absorb current on the second voltage output line and / or provide current to the second voltage output line based on the voltage or current on the second voltage output line. The current-voltage adapter is also connected to a signal input terminal through the second voltage output line to output the second voltage to the signal input terminal, providing the second voltage or the second voltage and drive current to the front-end output circuit.

[0026] A laser diode that corresponds one-to-one with a laser diode driver, the laser diode emitting light by being driven by the current output from the laser diode driver.

[0027] According to the above embodiment, a laser diode driver and a light emitting module are provided. The amplification stage unit is connected between the first voltage and the second voltage provided by the power supply and is located in the upper circuit. The first operating current of the amplification stage unit constitutes at least part of the upper current. The first driving stage unit is connected between the second voltage and the ground potential and is located in the lower circuit. The second operating current of the first driving stage unit constitutes at least part of the lower current. Since the lower current is a continuation of the upper current, the operating currents of the amplification stage unit and the first driving stage unit can be at least partially multiplexed. Therefore, the total current required by the laser diode driver is greatly reduced, thereby reducing the power consumption of the laser diode driver. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the laser diode driver mentioned in the background section;

[0029] Figure 2This is a schematic diagram of the structure of a laser diode driver according to one embodiment;

[0030] Figure 2a This is a schematic diagram of the structure of a laser diode driver according to another embodiment;

[0031] Figure 2b This is a schematic diagram of the structure of a laser diode driver according to another embodiment;

[0032] Figure 3a This is a schematic diagram of the structure of an input stage unit according to one embodiment;

[0033] Figure 3b This is a schematic diagram of the structure of an amplification stage unit in one embodiment;

[0034] Figure 3c1 This is a schematic diagram of the structure of a first level conversion circuit according to one embodiment;

[0035] Figure 3c2 This is a schematic diagram of the structure of the first level conversion circuit in another embodiment;

[0036] Figure 3c3 This is a schematic diagram of the structure of a first level conversion circuit according to another embodiment;

[0037] Figure 3d1 This is a schematic diagram of the structure of a first driving stage unit according to one embodiment;

[0038] Figure 3d2 This is a schematic diagram of the structure of the first driving stage unit in another embodiment;

[0039] Figure 3d3 This is a schematic diagram of the structure of the first driving stage unit in yet another embodiment;

[0040] Figure 3d4 This is a schematic diagram of the structure of the first driving stage unit in another embodiment;

[0041] Figure 4a This is a schematic diagram of the structure of a laser diode driver according to one embodiment;

[0042] Figure 4b This is a schematic diagram of the structure of a laser diode driver according to another embodiment;

[0043] Figure 5a This is a schematic diagram of the structure of a laser diode driver according to one embodiment;

[0044] Figure 5b This is a schematic diagram of the structure of a laser diode driver according to another embodiment;

[0045] Figure 6 This is a schematic diagram of the structure of a current-voltage adapter according to one embodiment;

[0046] Figure 7a A detailed circuit diagram of a current-voltage adapter according to one embodiment;

[0047] Figure 7b and Figure 7c These are schematic diagrams illustrating the principles of current absorption and current supply, respectively.

[0048] Figure 8a This is a schematic diagram of the output stage in one embodiment;

[0049] Figure 8b This is a schematic diagram of the output stage in another embodiment. Detailed Implementation

[0050] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0051] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0052] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0053] In researching ways to reduce the power consumption of laser diode drivers, the inventors noticed that during operation of the laser diode driver circuit, the input stage, amplification stage, and driving stage are each supplied with their own operating current by a power supply. Figure 1The laser diode driver 10 shown has independent, or parallel, operating currents I1, I2, and I3. The total current Itot supplied by the power supply is the sum of the operating currents of each functional module, resulting in a relatively large total current Itot and consequently, high power consumption. The inventors envision that if the operating currents I1, I2, and I3 of the input stage, amplification stage, and driver stage could be reused, it would help reduce the total current supplied by the power supply. During operation, the laser diode driver circuit primarily experiences high operating currents, particularly I2 required by the amplification stage and I3 required by the driver stage. Therefore, reusing the operating currents of the amplification and driver stages would significantly reduce the total current supplied by the power supply.

[0054] The concept of this invention is to divide the functional modules of the laser diode driver into upper and lower layers using the second voltage VDDH provided by the laser diode driver. The amplification stage unit and the driving stage unit are located on different layers, forming a series connection between them. This allows at least a portion of the current to be reused between the amplification stage unit and the driving stage unit. In this embodiment, the amplification stage unit is designed on the upper layer and the driving stage unit on the lower layer according to the current direction. At least a portion of the operating current supplied by the power supply to the amplification stage unit flows through the driving stage unit, becoming at least a portion of the operating current of the driving stage unit. This allows the current supplied by the power supply to be reused, reducing the total current required by the power supply while completing the basic functions of the amplification stage unit and the driving stage unit, thus reducing the power consumption of the laser diode driver.

[0055] The inventive concept of the present invention will be described below through specific embodiments.

[0056] Example 1:

[0057] This embodiment provides a laser diode driver. The laser diode driver generates a driving current for the laser diode based on the electrical signal output from the pre-amplifier circuit. The laser diode generates a corresponding optical signal based on the magnitude of the driving current, and the optical signal is transmitted to a remote location via optical fiber. Please refer to [reference needed]. Figure 2 The laser diode driver 20 includes a signal input terminal 1.6, an input signal processing circuit, a first level conversion circuit 2.3, a first driving stage unit 2.4, and a current and voltage adapter 2.5, which are described in detail below.

[0058] Signal input terminal 1.6 is configured to connect to the pre-amplifier output circuit 1.1 and to input at least the electrical signal output by the pre-amplifier output circuit. For example, signal input terminal 1.6 is configured to provide an interface that matches the pre-amplifier output circuit. In some embodiments, the pre-amplifier output circuit may be an interface output driver circuit of a multimedia playback device, such as the output driver circuit of a transmission protocol interface like USB, HDMI, or DP, and signal input terminal 1.6 can transmit the electrical signal output by the pre-amplifier output circuit 1.1 to the next stage circuit. In some embodiments, signal input terminal 1.6 can be used to input differential signals output by the pre-amplifier output circuit, for example, by inputting differential signals through two input terminals, VIN+ and VIN-, and outputting the differential signals to the input signal processing circuit. In some embodiments, signal input terminal 1.6 can also be used to input single-ended signals output by the pre-amplifier output circuit.

[0059] The input signal processing circuit is used to process the electrical signal input at signal input terminal 1.6. In some embodiments, the input signal processing circuit includes an input stage unit 2.1 and an amplification stage unit 2.2. The input terminal of the input stage unit is connected to the signal input terminal 1.6, and the output terminal is connected to the input terminal of the amplification stage unit 2.2. The input stage unit 2.1 is used to input electrical signals from signal input terminal 1.6 and output them to the amplification stage unit 2.2. In some embodiments, the input stage unit 2.1 can also preprocess the input electrical signal, such as noise reduction and / or preliminary amplification. In some embodiments, the input stage unit 2.1 is connected between the power supply 1.3 and ground 1.8, such as... Figure 2 As shown, input stage unit 2.1 is connected between the first voltage VDD provided by the power supply and ground potential. The path from the power supply, through input stage unit 2.1, to the ground potential forms the operating current path for input stage unit 2.1. Figure 2.6 indicates the operating current IA3 of input stage unit 2.1. A specific circuit for input stage unit 2.1 is shown below. Figure 3a As shown, 3.1 is the fixed bias voltage VC, and 3.2 are the differential output voltages V1+ and V1- of the input stage. V1+ and V1- are also the input voltages of the amplification stage. Figure 3a In the input stage unit circuit example shown, input stage unit 2.1 is designed between VDD and ground and can be constructed using common MOSFETs, current sources, resistors, and inductors. This input stage example uses a common current-mode amplifier circuit and employs a common-source, common-gate structure. The voltage divider between the upper and lower MOSFETs ensures circuit reliability even when VDD is high (since the MOSFET VDS voltage is not too large). The common-mode output level of this input stage unit circuit is suitable for the input level of the amplification stage unit.

[0060] Amplification stage unit 2.2 is used to amplify or further amplify the electrical signal preprocessed by the input stage unit and output the amplified electrical signal. In some embodiments, the amplification stage unit is connected between the power supply and the second voltage output line 1.5. The high potential is the first voltage VDD provided by the power supply, and the low potential is the second voltage VDDH. The current path from the power supply, the amplification stage unit to the second voltage output line forms the first operating current IA1 of the amplification stage unit, as shown in Figure 2.7, where the second voltage VDDH is less than the first voltage VDD and greater than the ground potential. In this paper, the current is divided into upper current and lower current according to the direction of the current, with the second voltage output line 1.5 as the dividing line. The first operating current IA1 of the amplification stage unit forms at least a part of the upper current.

[0061] Amplification stage unit 2.2 can be a single-stage amplification or a multi-stage amplification. A specific amplifier circuit is as follows: Figure 3b As shown, 3.3 represents the differential output voltages V2+ and V2- of the amplification stage, which are also the input voltages of the level conversion stage. Figure 3b The amplifier circuit shown consists of three cascaded current-mode amplifier circuits, which can provide a large gain, but also consume a lot of current.

[0062] Those skilled in the art will understand that the input signal processing circuit may also omit the input stage unit 2.1.

[0063] The first driver stage unit 2.4 is used to input the amplified electrical signal and convert it into a corresponding current driving the laser diode. In some embodiments, the first driver stage unit 2.4 is connected between the second voltage VDDH and ground potential, thereby forming a current path that provides a second operating current IA2 to the first driver stage unit, as indicated by 2.9 in the figure. The second operating current IA2 forms part of the lower-level current. Figures 3d1-3d4 Four specific circuits of the first driving stage unit are shown. Among them, 3.6 is a redundant load circuit, which is used to maintain the similarity of the output load on both sides of the circuit. Here, it is used to simulate the impedance characteristics of the laser diode and can be composed of devices such as resistors, capacitors, inductors, diodes, and MOSFETs.

[0064] Figure 2 In the illustrated embodiment, the output terminal 1.12 of the first driving stage unit 2.4 is connected to the anode of the laser diode 1.13, and the cathode of the laser diode 1.13 is grounded. In the figure, 1.19 refers to the driving current ILD provided by the first driving stage unit 2.4 flowing through the laser diode. Figure 2aIn the embodiment shown, the output terminal of the first driving stage unit 2.4 is connected to the cathode of the laser diode 1.13, and the anode of the laser diode 1.13 is connected to the second voltage output line.

[0065] The first level conversion circuit 2.3 is connected between the output of the amplification stage unit 2.2 and the input of the first driver stage unit 2.4. The first level conversion circuit 2.3 is used for signal level adaptation between the amplification stage unit 2.2 and the first driver stage unit 2.4, specifically converting the higher common-mode level (voltage between VDDH and VDD) output by the amplification stage unit to a lower level (between GND and VDDH). The first level conversion circuit 2.3 is connected between the first voltage VDD and ground potential, thus forming a current path that provides operating current for the first level conversion circuit. In the figure, 2.8 refers to the operating current IA4 of the first level conversion circuit 2.3. Since the amplification stage unit 2.2 operates between the first voltage VDD and the second voltage VDDH, its output signal level is between VDD and VDDH. The first driving stage unit 2.4 operates between the second voltage VDDH and ground potential. If the amplification stage unit directly outputs the amplified electrical signal to the first driving stage unit, it may cause a mismatch in signal levels between the amplification stage unit and the first driving stage unit. The first level conversion circuit can convert the signal level with a higher input voltage to a lower input voltage signal level for output. For example, it can convert a signal with a level between VDDH and VDD to a signal between 0 and VDDH, thereby satisfying the signal level compatibility between the amplification stage unit and the first driving stage unit.

[0066] Figures 3c1-3c3 The diagram shows three specific circuit structures of the first level conversion circuit 2.3. Figure 3c1 This common-mode level conversion is achieved using a source follower. Specifically, it includes a transistor connected between the power supply VDD and ground, and a current source. The current source is connected between ground potential and the source of the transistor. The drain of the transistor is connected to the first voltage VDD, and the gate of the transistor is connected to the output of the amplifier stage. The input of the first driver stage is connected to the source of the transistor. When the amplifier stage 2.2 outputs a differential signal, the source follower also forms a differential input, differential output source follower, such as... Figure 3c1 As shown, V2+ and V2- are the differential output voltages of the amplification stage, and also the differential input signals of the first level conversion circuit 2.3. 3.4 are the differential output signals V3+ and V3- of the first level conversion circuit 2.3, and also the differential input signals of the first driver stage unit 2.4.

[0067] Figure 3c2Common-mode level conversion is achieved through AC coupling, specifically using a RC network consisting of capacitors and resistors. The first terminal of the capacitor is connected to the output of the amplifier stage, and the second terminal is connected to the input of the first driver stage, used for DC blocking and AC passing. The resistor is connected between a bias voltage and the second terminal of the capacitor to provide the bias voltage. This AC coupling method of level conversion requires virtually no operating current, and therefore has almost no power consumption.

[0068] Figure 3c3 The common-mode level conversion is achieved by a current-mode amplifier (cascode structure) including a PMOS transistor input.

[0069] Figures 3c1-3c3 The three circuits shown are for input differential signals. Each circuit consists of two parts with the same structure. Those skilled in the art will understand that when the input signal is a single-ended signal, only one part of the three circuits is needed to achieve the level conversion function.

[0070] Those skilled in the art will understand that the first level conversion circuit can also implement level conversion using other existing methods. Those skilled in the art will also understand that in some embodiments, there may be no first level conversion circuit between the amplification stage unit and the first driver stage unit.

[0071] The current-voltage adapter 2.5 is connected between the power supply 1.3 (the first voltage VDD) and the ground 1.8, and is used to convert the first voltage VDD output by the power supply into the second voltage VDDH, and output the second voltage VDDH through the second voltage output line 1.5, so as to form the first voltage VDD, the second voltage VDDH and the ground potential for the operation of the laser diode driver. It can be seen from the above embodiments that there are three potentials for the operation of the laser diode driver, which are the first voltage VDD, the second voltage VDDH and the ground potential. In this article, the current flowing from the first voltage VDD to the second voltage VDDH is called the upper-layer current, and the current flowing from the second voltage VDDH to the ground is called the lower-layer current. Therefore, the lower-layer current should be the continuation of the upper-layer current. When the amplification stage unit is connected between the first voltage VDD and the second voltage VDDH, the first voltage VDD and the second voltage VDDH provide the first working current IA1 for it. Therefore, the first working current IA1 belongs to the upper-layer current. When the first driving stage unit is connected between the second voltage VDDH and the ground potential, the second voltage VDDH and the ground potential provide the second working current IA2 for it. The second working current IA2 belongs to the lower-layer current. Therefore, at least part of the second working current IA2 is the continuation of at least part of the upper-layer current, that is, part of the current can be reused between the second working current IA2 and the first working current IA1. During operation, the power supply needs to provide working current for the input stage unit 2.1, the amplification stage unit 2.2, the first level conversion circuit 2.3 and the first driving stage unit 2.4. In the prior art, the total current that the power supply needs to provide to the laser diode driver is the sum of the set working currents of the input stage unit 2.1, the amplification stage unit 2.2, the first level conversion circuit 2.3 and the first driving stage unit 2.4. In this embodiment, since the second working current IA2 of the first driving stage unit 2.4 is at least part of the continuation of the first working current IA1 of the amplification stage unit 2.2, that is, there is current reuse between the second working current IA2 and the first working current IA1. Therefore, the total current that the power supply needs to provide to the laser diode driver is less than the sum of the set working currents of the input stage unit 2.1, the amplification stage unit 2.2, the first level conversion circuit 2.3 and the first driving stage unit 2.4, that is, Itot < IA1 + IA2 + IA3 + IA4, so that the total current Itot required by the laser diode driver is reduced. The reduction of the total current Itot means that the power consumption during the operation of the laser diode driver can be reduced. In the laser diode driver, since the amplification stage unit and the first driving stage unit are its main units and also the two units with the largest power consumption, the corresponding first working current IA1 and second working current IA2 are relatively large.Therefore, by multiplexing the second operating current IA2 to the first operating current IA1, the total current Itot required by the laser diode driver can be significantly reduced, typically by 30%-45%, thus reducing the power consumption of the laser diode driver during operation. This reduced power consumption allows for applications in low-power scenarios, and the saved power can be used to add modules for optimizing signals (e.g., to improve gain, increase bandwidth, and other high-speed performance), or to improve the performance of the amplification stage and the first driver stage.

[0072] In some embodiments, the current-voltage adapter is also connected to the signal input terminal 1.6 via the second voltage output line 1.5, outputting the second voltage VDDH to the signal input terminal 1.6 to provide the second voltage VDDH to the pre-amplifier output circuit 1.1. Furthermore, a pre-amplifier drive current I0 can also be provided to the pre-amplifier output circuit 1.1 as needed, such that at least a portion of the pre-amplifier drive current I0 and the second operating current IA2 is a continuation of at least a portion of the first operating current IA1. Please refer to [reference needed]. Figure 2 and Figure 2a The second voltage output line 1.5 is connected to the signal input terminal 1.6 via resistor RT, providing the second voltage VDDH and the pre-stage drive current I0 to the pre-stage output circuit. In this embodiment, since the pre-stage drive current I0 of the pre-stage output circuit and the second operating current IA2 required by the first drive stage unit are lower-level currents, and the first operating current IA1 of the amplification stage unit is an upper-level current, that is, the current I0 supplied to the pre-stage output drive circuit is also a part of the current IA1, and the current IA2 is also a part of the current IA1. Since the pre-stage drive current I0, the second operating current IA2, and the first operating current IA1 can share some current, the total current that the power supply voltage actually needs to provide to the laser diode driver is less than the sum of the set operating currents of each module. Since the larger currents IA1, IA2, and the pre-stage drive current I0 in the circuit system are shared, the total current Itot required by the laser diode driver is reduced, and the power consumption of the laser diode driver during operation is also reduced.

[0073] In some applications, on the one hand, there may be external interference signals (voltage fluctuations) of tens to hundreds of millivolts on the first voltage VDD provided by the power supply, and there may also be mutual interference between the upper and lower layers of circuits inside the chip, resulting in voltage fluctuations on the second voltage VDDH. Both of these situations will affect the actual operating current of each functional unit in the upper and lower layers. Specifically, the laser diode driver in the above embodiment operates at the first voltage VDD, the second voltage VDDH, and ground potential. Since the second voltage VDDH is located in the middle, the external interference signals on the first voltage VDD will cause voltage fluctuations in the second voltage VDDH. At the same time, there is also mutual interference between the circuit between the first voltage VDD and the second voltage VDDH and the circuit between the second voltage VDDH and ground potential, which will also cause voltage fluctuations in the second voltage VDDH. The voltage fluctuations in the second voltage VDDH will affect the signal path inside the laser diode driver, thereby affecting its driving performance. On the other hand, the laser diode driver may operate in different modes. In different operating modes, the amplification stage unit and the driving stage unit have their own preset operating currents. The sum of the preset operating currents of the upper-level functional units (including the amplification stage unit) is not necessarily equal to the sum of the preset operating currents of the lower-level functional units. Since the upper-level current between the first voltage VDD and the second voltage VDDH flows to the lower-level current between the second voltage VDDH and ground potential, when the upper-level current is significantly greater than the lower-level current, excess unreusable current will be generated on the output line of the second voltage VDDH. Conversely, when the upper-level current is significantly less than the lower-level current, there will be a lack of reusable current on the output line of the second voltage VDDH. Both situations will affect the performance of the laser diode driver and even its function. For example, the VDDH supplied to the front-stage output circuit may be unstable, too high, or too low.

[0074] In order to ensure that the upper and lower functional units can operate according to the preset operating current, in this embodiment, the current and voltage adapter 2.5 can be a push-pull regulator. The push-pull regulator is configured to provide a stable second voltage VDDH on the one hand, and form a push-pull circuit on the other hand. It selectively provides drive current and draw current according to the voltage or current fluctuation on the second voltage output line, so that the upper and lower functional units can operate according to the preset operating current.

[0075] In this embodiment, the push-pull regulator can absorb current on the second voltage output line 1.5 and also supply current to it. On one hand, when voltage fluctuations in the second voltage VDDH cause a voltage increase, the push-pull regulator absorbs current on the second voltage output line 1.5, for example, removing low-to-medium frequency current fluctuations, thus reducing voltage fluctuations on the second voltage VDDH. On the other hand, when the upper-layer current is greater than the lower-layer current, the push-pull regulator absorbs excess, unreusable current on the second voltage output line 1.5; conversely, when the upper-layer current is less than the lower-layer current, the push-pull regulator provides the missing reusable current on the second voltage output line 1.5. Therefore, the push-pull regulator not only satisfies the reasonable reuse between the upper and lower-layer currents, thereby reducing the overall power consumption of the laser diode driver, but also reduces interference from the first voltage VDD and mutual interference between the upper and lower layers, thereby improving the overall performance of the laser diode driver.

[0076] In addition, a stable VDDH voltage is generated by the push-pull regulator, which can simultaneously extract or supply current that cannot be reused between IA1 and (I0+IA2). For example, when IA1>(I0+IA2), the excess unreusable current on the second voltage output line 1.5 can be absorbed by the push-pull regulator, i.e., IA6 flows to the right, IA7≈IA6, and IA5 is very small. When IA1<(I0+IA2), the missing reused current on the second voltage output line 1.5 can be supplied by the push-pull regulator, IA6 flows to the left, IA5≈IA6, and IA7 is very small.

[0077] In some embodiments, when no current needs to be supplied to the pre-amplifier output circuit, i.e., the pre-amplifier drive current I0 = 0, a DC blocking capacitor can be added between the signal input terminal and the pre-amplifier output circuit to isolate the DC voltage and current, thus eliminating the need to supply power to the pre-amplifier output circuit. Figure 2b As shown. When current needs to be supplied to the preamp output circuit, a terminating resistor RT, typically 50 ohms, is added between the second voltage output line 1.5 and the signal input terminal. The terminating resistor RT serves both as impedance matching for the transmission line connecting the preamp output circuit and the laser diode driver, and as a means to transmit the preamp drive current I0 to supply current to the preamp output circuit.

[0078] Example 2:

[0079] In Embodiment 1, the input stage unit 2.1 is connected between the power supply and ground, that is, between the first voltage VDD and the ground potential. Therefore, the current flowing through the input stage unit is neither a higher-level current nor a lower-level current, so the total current Itot required by the laser diode driver needs to be added to the operating current required by the input stage unit. However, the operating current required by the input stage unit is usually less than the first operating current IA1 and the second operating current IA2, so it will not significantly affect the total current Itot required by the laser diode driver.

[0080] The difference between Embodiment 2 and Embodiment 1 is that the connection method of the input level unit 2.1 is different.

[0081] For example, Figure 4a The input stage unit is connected between the second voltage VDDH output line and ground, thereby forming a current path that provides a third operating current to the input stage unit, such that the third operating current is at least a continuation of at least a portion of the upper-level current. The laser diode driver also includes a second level conversion circuit 2.12, which is connected between the output of the input stage unit and the input of the amplification stage unit for signal level adaptation between the input stage unit and the amplification stage unit. In this embodiment, since the amplification stage unit operates between the first voltage VDD and the second voltage VDDH, while the input stage unit operates between the second voltage VDDH and ground potential, a second level conversion circuit 2.12 can be added to satisfy the signal level adaptation between the amplification stage unit and the input stage unit. The second level conversion circuit 2.12 can be implemented using the same structure as the first level conversion circuit in Embodiment 1. In this embodiment, since the third operating current IA3 of the input stage unit and the second operating current IA2 required by the first driving stage unit are respectively at least a portion of the upper layer current, and the first operating current IA1 of the amplification stage unit is at least a portion of the upper layer current, some currents can be reused among the third operating current IA3, the second operating current IA2 and the first operating current IA1. This makes the total current actually required by the power supply to the input stage unit, the amplification stage unit and the first driving stage unit less than the sum of the first operating current IA1, the second operating current IA2 and the third operating current IA3, thereby reducing the total current Itot required by the laser diode driver and reducing the power consumption of the laser diode driver during operation.

[0082] Please refer to Figure 4bThe laser diode driver 40 shown has its input stage unit 2.1 connected between the power supply and the second voltage VDDH output line, thus forming a current path to provide a fourth operating current to the input stage unit, which forms part of the upper current. The laser diode driver also includes a third level conversion circuit 4.2 connected between the signal input terminal 1.6 and the input stage unit 2.1, used for signal level adaptation between the signal input terminal 1.6 and the input stage unit 2.1. In this embodiment, since the input stage unit 2.1 operates between the first voltage VDD and the second voltage VDDH, the third level conversion circuit 4.2 can be added to satisfy the signal level adaptation between the signal input terminal and the input stage unit. The third level conversion circuit can be implemented using the same structure as the first level conversion circuit in Embodiment 1. In this embodiment, since the fourth operating current of the input stage unit and the first operating current IA1 required by the amplification stage unit are at least part of the upper layer current, and the second operating current IA2 of the first driving stage unit is a continuation of at least part of the upper layer current, a portion of the current can be reused between the fourth operating current, the first operating current IA1, and the second operating current IA2. This makes the total current required by the input stage unit, the amplification stage unit, and the first driving stage unit less than the sum of the first operating current IA1, the second operating current IA2, and the fourth operating current, thereby reducing the total current Itot required by the laser diode driver and reducing the power consumption of the laser diode driver during operation.

[0083] Example 3:

[0084] like Figure 4b As shown, in some embodiments, the laser diode driver further includes a DC-DC converter 4.20. The input of the DC-DC converter 4.20 is connected to a power supply, converting the first voltage provided by the power supply into a second voltage VDDH, and outputting it to the second voltage output line 1.5. In this embodiment, when the lower-level current is very large, for example, when the current required by the front-end output circuit is very large, the upper-level current (e.g., the first operating current IA1 of the amplification stage unit) cannot be fully reused. The DC-DC converter can reduce the current consumed from the first voltage VDD.

[0085] In some embodiments, the laser diode driver further includes a linear regulator 4.22 connected between the second voltage output line 1.5 and the first driver stage unit to regulate the second voltage on the second voltage output line 1.5 before supplying it to the first driver stage unit. In this embodiment, adding a linear regulator can further reduce the impact of voltage fluctuations on the second voltage VDDH on the first driver stage unit.

[0086] Example 4:

[0087] This embodiment provides a laser diode driver, which differs from Embodiment 1 in that the first level conversion circuit is different, and will be described in detail below.

[0088] In this embodiment, as Figure 5a and Figure 5b As shown, the first level conversion circuit 2.3 is connected between the first voltage VDD and ground potential. The first level conversion circuit 2.3 has two sets of level outputs, where the common-mode level of the second set of outputs is greater than the common-mode level of the first set of outputs. The laser diode driver also includes a second driving stage unit 4.6, which is connected between the first voltage VDD and the second voltage VDDH and can input a higher common-mode level. The first driving stage unit is used to input a lower common-mode level. Therefore, the first set of outputs from the first level conversion circuit 2.3 is connected to the first driving stage unit 2.4, which converts the electrical signal from the first set of outputs into a corresponding current. The second set of outputs from the first level conversion circuit is connected to the second driving stage unit 4.6, which converts the electrical signal from the second set of outputs into a corresponding current. The current output from the first driving stage unit 2.4 and the current output from the second driving stage unit 4.6 are used together to drive the laser diode.

[0089] Since the first driver stage unit is used to input a lower common-mode level and the second driver stage unit is used to input a higher common-mode level, the common-mode level input to the first level conversion circuit 2.3 can be considered the lower common-mode level, while the common-mode level output by the first level conversion circuit 2.3 can be considered the higher common-mode level. Conversely, depending on the connection position of the first driver stage unit, the common-mode level input to the first level conversion circuit can also be considered the higher common-mode level, while the common-mode level output by the first level conversion circuit can be considered the lower common-mode level.

[0090] The output terminals of both the first driver stage unit 2.4 and the second driver stage unit 4.6 are connected to the anode of the laser diode, and the cathode of the laser diode is grounded. Figure 5a As shown. Figure 5b As shown, the output terminals of the first driving stage unit 2.4 can also be connected to the cathode of the laser diode, and the output terminal of the second driving stage unit 4.6 can be connected to the anode of the laser diode.

[0091] Adding a second driver stage unit can improve the high-speed performance of the current driving the laser diode, thereby optimizing the signal eye diagram. In some embodiments, the second driver stage unit can be implemented using techniques commonly used by those skilled in the art, such as feedforward equalization (FFE), asymmetric equalization, etc., to improve the high-speed performance of the current driving the laser diode, which will not be elaborated here.

[0092] Example 5:

[0093] This embodiment provides a specific circuit for a current-voltage adapter.

[0094] In one embodiment, the circuit of the current-voltage adapter is as follows: Figure 6 As shown, it includes a cascaded error amplifier 5.1 and an output stage 5.2.

[0095] Output stage 5.2 outputs the second voltage VDDH to the second voltage output line 1.5, and provides drive current and / or draws current based on the voltage and / or current of the second voltage output line 1.5. Output stage 5.2 also feeds back the second voltage VDDH of the second voltage output line 1.5 to the first input terminal of error amplifier 5.1. The function of output stage 5.2 is to provide drive capability for outputting large currents (such as up to hundreds of milliamps), and output stage 5.2 has the ability to supply and / or draw large currents.

[0096] The second input of error amplifier 5.1 is connected to the reference voltage VREF. Error amplifier 5.1 differentially amplifies the second voltage VDDH and the reference voltage VREF and outputs them to output stage 5.2. This controls output stage 5.2 to selectively provide drive current and / or draw current based on the difference between the second voltage VDDH and the reference voltage VREF, ensuring that the second voltage VDDH on the second voltage output line 1.5 eventually stabilizes near the reference voltage VREF. The function of error amplifier 5.1 is to provide a large gain for the negative feedback loop to stabilize the voltage VDDH through output stage 5.2, making VDDH≈VREF.

[0097] Please refer to Figure 7a , Figure 7a A specific embodiment of the error amplifier 5.1 and the output stage 5.2 is shown.

[0098] Figure 7aIn the illustrated embodiment, on the one hand, the upper-layer current and the lower-layer current may not be completely equal, meaning there may be redundant current or insufficient current on the second voltage output line. On the other hand, interference may cause fluctuations in the second voltage VDDH output by the second voltage output line, or interference may cause fluctuations in the current on the second voltage output line. In both cases, the second voltage output line may lack current for multiplexing, resulting in a lower second voltage VDDH, or it may generate excess current, resulting in a higher second voltage VDDH. For example, due to different driving modes, the upper-layer current of a laser diode driver may be greater than or equal to its lower-layer current, or it may be less than or equal to its lower-layer current, or the second voltage output line may experience voltage fluctuations, causing the second voltage VDDH to be greater than or less than a preset voltage value (e.g., VREF). The second voltage VDDH, which decreases or increases, is fed back to the error amplifier 5.1. The error amplifier 5.1 amplifies the change in VDDH by several times and controls the output stage 5.2 to provide the missing multiplexed current to the intermediate voltage output line when VDDH decreases (e.g., less than VREF) and to absorb the excess current from the intermediate voltage output line when VDDH increases (e.g., greater than VREF), thereby maintaining the upper current always equal to the lower current and stabilizing the second voltage VDDH near the reference voltage VREF.

[0099] Please refer to Figure 7aOutput stage 5.2 employs a push-pull circuit; the current-voltage adapter can also be called a push-pull regulator. Output stage 5.2 includes a push-pull circuit and a signal transmission circuit connected between the power supply and ground. The push-pull circuit includes a first transistor MP2 and a second transistor MN2 connected in series between the power supply and ground. The sources of the first transistor MP2 and the second transistor MN2 are connected together and connected to a second voltage output line. The input terminal of the signal transmission circuit is connected to the output terminal of the error amplifier, and the output terminal of the signal transmission circuit is connected to the gates of the first transistor and the second transistor, respectively. The output voltage of the signal transmission circuit is positively correlated with its input voltage to transmit the output signal of the error amplifier to the first transistor and the second transistor. The first transistor and the second transistor are controlled based on the output signal of the error amplifier, causing one to turn on or off while the other turns off or on. In one embodiment, the signal transmission circuit includes a first source follower 5.7 and a second source follower 5.8 connected between the power supply and ground. The gates of the first source follower 5.7 and the second source follower 5.8 are connected to the output of the error amplifier 5.1. The sources of the first source follower 5.7 and the second source follower 5.8 are connected to the gates of the first transistor MP2 and the second transistor MN2, respectively. The drains of the first source follower 5.7 and the second source follower 5.8 are connected to the second voltage output line. In a specific embodiment, the first source follower 5.7 includes a transistor MN1 and a current source connected between the source of transistor MN1 and ground. The second source follower 5.8 includes a transistor MP1 and a current source connected between the source of transistor MP1 and the power supply. In other embodiments, the signal transmission circuit can also be implemented using other circuit structures.

[0100] Error amplifier 5.1 includes a differential amplifier circuit 5.3 (a dual-input dual-output amplifier) ​​and a current mirror load circuit 5.4. The two input terminals of the differential amplifier circuit 5.3 are respectively connected to the real-time feedback voltage and reference voltage on the second voltage output line. Its output terminal is connected to the input terminal of the current mirror load circuit 5.4. The output terminal of the current mirror load circuit 5.4 serves as the output of error amplifier 5.1 and is connected to output stage 5.2. The current mirror load circuit 5.4 generates a current change in the differential amplifier circuit 5.3 when the input feedback voltage changes, thus making the output voltage change a multiple of the feedback voltage change. The differential amplifier circuit has an input transconductance Gm, and the current mirror load circuit has an output impedance Rout. The transconductance Gm of the differential amplifier circuit converts the input voltage difference into current, and the output impedance Rout of the current mirror load circuit converts the aforementioned current into output voltage. Therefore, the error amplifier amplifies the change in feedback voltage by a factor of N, where the amplification factor N is equal to Gm multiplied by Rout.

[0101] When the second voltage VDDH of the second voltage output line fluctuates, or when the current of the second voltage output line increases, causing the second voltage VDDH to rise, the second voltage VDDH is fed back to the input of the differential amplifier circuit 5.3. At this time, there is a deviation ΔV between the second voltage VDDH and the reference voltage VREF. This ΔV is reflected in the current mirror load circuit 5.4. The voltage change output by the current mirror load circuit 5.4 will be N times ΔV. Usually, N is greater than 1, so that even a slight fluctuation in the second voltage VDDH can be detected, and the change is amplified by several times to control the operation of the output stage 5.2.

[0102] In some embodiments, the differential amplifier circuit 5.3 employs a differential pair circuit with dual-input and dual-output, including a fourth transistor T1, a fifth transistor T2, a sixth transistor T3, a seventh transistor T4, and a third current source IS1. The fourth transistor T1, fifth transistor T2, sixth transistor T3, and seventh transistor T4 are connected sequentially. The third current source IS1 is connected between ground potential and the connection node between the fifth transistor T2 and the sixth transistor T3. The gate of the fifth transistor T2 is used to input the reference voltage VREF, the gate of the sixth transistor T3 is used to input the second voltage VDDH fed back from the output stage 5.2, and the gates of both the fourth transistor T1 and the seventh transistor T4 are used to input the bias voltage VBN1. In this circuit, the fourth transistor T1 and the fifth transistor T2 form the branch of the input reference voltage VREF of the differential amplifier circuit 5.3, and the first terminal (drain) of the fourth transistor T1 is used to connect to the current mirror load circuit 5.4. The sixth transistor T3 and the seventh transistor form the branch of the input second voltage VDDH of the differential amplifier circuit 5.3, and the first terminal (drain) of the seventh transistor T4 is used to connect to the current mirror load circuit 5.4.

[0103] The current mirror load circuit 5.4 includes an eighth transistor T5, a ninth transistor T6, a tenth transistor T7, an eleventh transistor T8, a twelfth transistor T9, a thirteenth transistor T10, a fourth current source IS2, a fifth current source IS3, and a second capacitor C1. The fourth current source IS2, the eighth transistor, the ninth transistor T6, and the tenth transistor T7 are connected between the first voltage VDD and ground potential, while the first terminal (source) of the eighth transistor T5 is also connected to the first terminal (drain) of the fourth transistor T1. The fifth current source IS3, the eleventh transistor T8, the twelfth transistor T9, and the thirteenth transistor T10 are also connected between the first voltage VDD and ground potential, while the first terminal (source) of the thirteenth transistor T10 is also connected to the first terminal (drain) of the seventh transistor T4. The control terminals (gates) of the eighth transistor T5 and the thirteenth transistor T10 are both connected to the bias voltage VBP1, and the control terminals (gates) of the ninth transistor T6 and the twelfth transistor T9 are both connected to the bias voltage VBN2. The control terminals (gates) of the tenth transistor T7 and the eleventh transistor T8 are connected to the connection node between the eighth transistor T5 and the ninth transistor T6, respectively. The connection node between the twelfth transistor T9 and the thirteenth transistor T10 outputs voltage VE to the output stage 5.2.

[0104] In this embodiment, when the differential amplifier circuit 5.3 experiences a change in the input feedback voltage, i.e., a change in the second voltage VDDH, the driving current of the sixth transistor T3 changes due to the voltage change. This causes a current change in the branch of the differential amplifier circuit 5.3 that receives the second voltage VDDH. Since the branch of the differential amplifier circuit 5.3 that receives the second voltage VDDH and the branch that receives the input reference voltage VREF share the third current source IS1, the branch of the differential amplifier circuit 5.3 that receives the second voltage VDDH also experiences a current change. Furthermore, because the branch of the differential amplifier circuit 5.3 that receives the input reference voltage VREF shares the fourth current source IS2 with the eighth transistor T5, the ninth transistor T6, and the tenth transistor T7, and the branch of the differential amplifier circuit 5.3 that receives the second input voltage VDDH shares the fifth current source IS3 with the eleventh transistor T8, the twelfth transistor T9, and the thirteenth transistor T10, a change in the current of the branch of the differential amplifier circuit 5.3 that receives the second input voltage VDDH will also cause a change in the current of the current mirror load circuit 5.4, resulting in a change in the output voltage VE. After the gain of the differential amplifier circuit 5.3 and the current mirror load circuit 5.4, the change in the output voltage VE is N times the change in the second voltage VDDH. If the output impedance of the current mirror load circuit 5.4 is Rout, and the input transconductance of the differential amplifier circuit 5.3 is Gm, then the gain N of the error amplifier is equal to Gm multiplied by Rout.

[0105] In this embodiment, the eighth transistor T5 and the thirteenth transistor T10 are P-type transistors, while the fourth transistor T1, the fifth transistor T2, the sixth transistor T3, the seventh transistor T4, the ninth transistor T6, the tenth transistor T7, the eleventh transistor T8, and the twelfth transistor T9 are N-type transistors. It is understood that when the fourth transistor T1, the fifth transistor T2, the sixth transistor T3, the seventh transistor T4, the eighth transistor T5, the ninth transistor T6, the tenth transistor T7, the eleventh transistor T8, the twelfth transistor T9, and the thirteenth transistor T10 use a different transistor type, those skilled in the art can make adaptive adjustments to the structure of the error amplifier 5.1 as appropriate.

[0106] The following section explains the principles of current extraction and current supply in output stage 5.2. Please refer to [link / reference]. Figure 7b and Figure 7c .

[0107] Figure 7b The principle of current draw from the output stage is illustrated. In this embodiment, when the upper current is greater than the lower current, excess current is generated on the second voltage output line, causing the second voltage VDDH to rise. Alternatively, when VDDH fluctuates and rises slightly, VDDH is fed back to the input of the differential amplifier circuit. In this case, VDDH > VREF, causing the voltage VX output by the VDDH branch of the differential amplifier circuit to decrease, the voltage VY output by the VREF branch to increase, and the voltage VE output by the error amplifier 5.1 to decrease, for example, to be lower than the second voltage VDDH. As the gate voltage of transistor MN1 decreases, the source voltage of transistor MN1 also decreases (transistor MN1 and the current source constitute the first source follower 5.7), resulting in a lower gate voltage of the first transistor MP2. Therefore, the gate-source voltage difference of the first transistor MP2 becomes larger, and the first transistor MP2 turns on, allowing excess current on the second voltage output line to flow to ground through the first transistor MP2, thus drawing current from the second voltage output line. At the same time, as the gate voltage of transistor MP1 decreases, the source voltage of transistor MP1 also decreases, so the gate-source voltage difference of the second transistor MN2 becomes smaller (possibly lower than the threshold voltage of the second transistor MN2). Therefore, the second transistor MN2 is almost turned off, making the output stage 5.2 in a current-absorbing state at this time.

[0108] Figure 7cThe principle of the output stage providing current is shown. When the upper-layer current is greater than the lower-layer current, the current for multiplexing is lacking on the second voltage output line, and the second voltage VDDH becomes low. Or when VDDH fluctuates and slightly decreases, in both cases, VDDH is fed back to the input terminal of the differential amplifier circuit. At this time, VDDH < VREF, which causes the VX output by the VDDH branch of the differential amplifier circuit's differential output to increase, and the VY voltage output by the VREF branch to decrease, making the voltage VE output by the error amplifier 5.1 increase, for example, higher than the second voltage VDDH. Since the gate voltage of the transistor MP1 increases, the source voltage of the transistor MP1 also becomes higher (the transistor MP1 and the current source form the second source follower 5.8), making the gate voltage of the second transistor MN2 relatively high. Therefore, the gate-source voltage difference of the second transistor MN2 becomes larger, and the second transistor MN2 conducts, causing the current generated between the power supply and the second voltage output line to flow through the second transistor MN2 to the second voltage output line, thereby providing a driving current to the second voltage output line. At the same time, since the gate voltage of the transistor MN1 increases, the source voltage of the transistor MN1 also becomes higher, and the gate-source voltage difference of the first transistor MP2 becomes smaller (possibly lower than the threshold voltage of the first transistor MP2). Therefore, the first transistor MP2 is almost turned off, making the output stage 5.2 in the current supply state at this time.

[0109] As can be seen from the above embodiments, the first transistor MP2 and the second transistor MN2 form a push-pull circuit to realize providing a driving current and drawing current to the second voltage output line. When the output voltage of the error amplifier 5.1 increases, the second transistor MN2 conducts and the first transistor MP2 turns off, so that the formed push-pull circuit provides a driving current to the second voltage output line. When the output of the error amplifier 5.1 decreases, the first transistor MP2 conducts and the second transistor MN2 turns off, so that the formed push-pull circuit draws current from the second voltage output line.

[0110] As can be seen from the above embodiments, based on the push-pull circuit providing drive current and drawing current to the second voltage output line, a signal transmission circuit is formed by the first source follower 5.7 and the second source follower 5.8. The output voltage of the signal transmission circuit is positively correlated with its input voltage. Furthermore, due to the formed signal transmission circuit, when the push-pull circuit outputs in a push-pull manner, the first transistor MP2 may not be completely turned off when the second transistor MN2 is on, and vice versa. Moreover, due to the presence of the current source, the static current and corresponding power consumption of the signal transmission circuit are relatively stable, making the operating current and corresponding power consumption of the push-pull circuit related to the signal transmission circuit. For example, when the operating current of the signal transmission circuit is I, the operating current of the push-pull circuit is nI, and this n value is directly proportional to the transconductance between the first transistor MP2 and the second transistor MN2 and the transistors MP1 and MN1. Therefore, when designing the output stage 5.2, the power consumption of the signal transmission circuit and the push-pull circuit can be kept within a preset range. Compared with the uncertain power consumption of the push-pull circuit when it works alone, the output stage 5.2 in this embodiment can be designed for power consumption as needed, thereby meeting more power consumption requirements, such as low power consumption scenarios.

[0111] In some embodiments, there may be excess current on the second voltage output line, i.e., the upper current is greater than the lower current. In order to balance the upper and lower currents, the output stage 5.2 is designed to draw current based on the voltage or current fluctuations on the second voltage output line. For example, the upper current of the laser diode driver is always greater than or equal to its lower current, or the second voltage output line generates fluctuating voltage. In this case, excess current will be generated on the second voltage output line, causing the second voltage VDDH to go higher. The higher second voltage VDDH is fed back to the error amplifier 5.1, causing the output stage 5.2 to absorb the excess current on the second voltage output line, thereby maintaining that the upper current is always equal to its lower current and stabilizing the second voltage VDDH to be close to the reference voltage VREF.

[0112] Please refer to Figure 8a , Figure 8aA specific embodiment of the current-sucking operation of output stage 5.2 is shown. Output stage 5.2 includes a current input transistor T11 and a third source follower 5.5 connected between the power supply and ground. The gate of the third source follower 5.5 is connected to the output of error amplifier 5.1, and its source is connected to the gate of current input transistor T11. Current input transistor T11 is a P-type transistor with its drain grounded and its source connected to the second voltage output line. The operating principle of output stage 5.2 in this embodiment is as follows: When excess current is generated on the second voltage output line, causing the second voltage VDDH to go high, the voltage VE output by error amplifier 5.1 decreases, for example, below the second voltage VDDH. Then, due to the voltage following effect of the third source follower 5.5, the gate voltage of current input transistor T11 also decreases, thereby turning on current input transistor T11, allowing excess current on the second voltage output line to flow to ground through current input transistor T11. At this time, the second voltage output line and the current input transistor T11 can be regarded as forming a source follower. As a result, due to the decrease in the gate voltage of the current input transistor T11, the second voltage VDDH of the second voltage output line decreases and eventually stabilizes near the reference voltage VREF.

[0113] In some embodiments, the output stage 5.2 may further include a current source connected between the source of the current input transistor T11 and the first voltage VDD. In this case, the current source replaces the second voltage output line, thereby forming a source follower with the current input transistor T11, so that the second voltage VDDH of the second voltage output line decreases and eventually stabilizes near the reference voltage VREF.

[0114] In some embodiments, there may be a lack of current for multiplexing on the second voltage output line, i.e., the upper current is less than the lower current. To balance the upper and lower currents, the output stage 5.2 is designed to provide drive current based on voltage or current fluctuations on the second voltage output line. For example, the upper current of a laser diode driver is always less than or equal to its lower current, or the second voltage output line experiences voltage fluctuations. In this case, there will be a lack of current for multiplexing on the second voltage output line, causing the second voltage VDDH to go low. The lowered second voltage VDDH is fed back to the error amplifier 5.1, causing the output stage 5.2 to provide current for multiplexing to the second voltage output line, thereby maintaining the upper current always equal to its lower current and stabilizing the second voltage VDDH near the reference voltage VREF.

[0115] Please refer to Figure 8b , Figure 8bA specific embodiment of output stage 5.2 providing current is shown. Output stage 5.2 includes a current output transistor T12 and a fourth source follower 5.6 connected between the power supply and ground. The gate of the fourth source follower 5.6 is connected to the output of the error amplifier 5.1, and its source is connected to the gate of the current output transistor T12. The current output transistor T12 is an N-type transistor with its drain connected to the power supply and its source connected to the second voltage output line. The operating principle of output stage 5.2 in this embodiment is as follows: When there is a lack of current for multiplexing on the second voltage output line, causing the second voltage VDDH to go low, the voltage VE output by the error amplifier 5.1 increases, for example, above the second voltage VDDH. Then, due to the voltage following effect of the fourth source follower 5.6, the gate voltage of the current output transistor T12 also increases, thereby turning on the current output transistor T12, allowing the current generated between the power supply and the second voltage output line to flow through the current output transistor T12 to the second voltage output line. At this time, the second voltage output line and the current output transistor T12 can be regarded as forming a source follower. As a result, due to the increase in the gate voltage of the current output transistor T12, the second voltage VDDH of the second voltage output line increases and eventually stabilizes near the reference voltage VREF.

[0116] In some embodiments, the output stage 5.2 may also include a current source connected between the source of the current output transistor T12 and ground. In this case, the current source replaces the second voltage output line, thereby forming a source follower with the current output transistor T12, so that the second voltage VDDH of the second voltage output line increases and eventually stabilizes near the reference voltage VREF.

[0117] As can be seen from the above embodiments, since the output stage 5.2 can only absorb the current on the second voltage output line through the current input transistor T11 and the third source follower 5.5, or only supply the current to the second voltage output line through the current output transistor T12 and the fourth source follower 5.6, the current voltage adapter can provide drive current or absorb current according to the voltage or current fluctuations on the second voltage output line, and make the second voltage VDDH of the second voltage output line stable near the reference voltage VREF.

[0118] In the above embodiment, the first transistor MP2 is a P-type transistor, the second transistor MN2 is an N-type transistor, the corresponding first source follower 5.7 is an N-type source follower, and the second source follower 5.8 is a P-type source follower. Transistors MP1 and MP2 are P-type transistors, while transistors MN1 and MN2 are N-type transistors. It is understood that when transistors MP1, MN1, MP2, and MN2 are P-type or N-type transistors, those skilled in the art can make adaptive adjustments to the structure of the output stage 5.2 as appropriate.

[0119] As can be seen from the above embodiments, when the upper-layer current and lower-layer current are multiplexed, there may be unreasonable multiplexing situations between the upper-layer current and lower-layer current. The current-voltage adapter, by providing current to or absorbing current from the second voltage output line, can satisfy the reasonable multiplexing between the upper-layer current and lower-layer current, thereby reducing the overall power consumption of the laser diode driver. Furthermore, when the upper-layer current and lower-layer current are multiplexed, there may also be mutual interference between the upper and lower layer circuits. The current-voltage adapter, by absorbing current from the second voltage output line, can also reduce interference from the first voltage VDD and mutual interference between the upper and lower layer circuits, thereby improving the overall performance of the laser diode driver.

[0120] Please refer to Figure 7a As shown, the current-voltage adapter includes a cascaded error amplifier and an output stage. The output node of the output stage is connected back to the input of the error amplifier. This is an internally active feedback circuit module, forming a circuit loop. The loop typically has a relatively large DC low-frequency gain. Through appropriate feedback polarity (negative feedback) at both ends, the two ends mutually suppress each other, thus stabilizing the operation. However, if the circuit characteristics are poorly designed, the voltage and current will be continuously amplified along the loop, causing mutual interference between the two ends and resulting in oscillations.

[0121] To prevent loop oscillations due to improper circuit design, in the improved embodiment, the current-voltage adapter further includes a debouncing circuit. The debouncing circuit is connected to both the error amplifier and the output stage, and is used to adjust the high-frequency gain of the feedback loop formed by the error amplifier and the output stage to less than 1. In a specific embodiment, the debouncing circuit includes a second capacitor, one end of which is connected to the connection node between the error amplifier and the output stage, and the other end is grounded.

[0122] As the frequency increases, the unavoidable internal parasitic capacitance of the device and the external load capacitance of the module will cause the feedback polarity to gradually change (also known as phase change), evolving from negative feedback to positive feedback. The loop gain generally decreases gradually due to the presence of these capacitors. In this embodiment, the second capacitor C1 can adjust the decrease in loop gain and the phase change as the frequency increases, so that before it becomes true positive feedback, the loop gain is reduced to below 1 (i.e., it becomes attenuated). In this way, the voltage and current will not be continuously amplified along the loop, thereby avoiding oscillation.

[0123] In other embodiments, the anti-shake circuit may also be a network including capacitors, wherein the capacitors connect the high-frequency signal of the loop to ground when the loop is at a high frequency.

[0124] Example 6:

[0125] This embodiment provides a light emitting module, which includes at least one laser diode driver, a current-voltage adapter, and laser diodes corresponding to the laser diode drivers. The following is a detailed description of the module.

[0126] The laser diode driver can be the laser diode driver described in the above embodiments. The laser diode driver is used to generate a drive current for the laser diode based on the electrical signal output from the pre-amplifier output circuit.

[0127] The current-voltage adapter can be the same as the one described in the above embodiments. The current-voltage adapter converts the first voltage VDD output by the power supply to a second voltage VDDH, and outputs the second voltage VDDH through a second voltage output line. The current-voltage adapter is also configured to absorb current on the second voltage output line and / or supply current to the second voltage output line. The current-voltage adapter is also connected to a signal input terminal via the second voltage output line, outputting the second voltage VDDH to the signal input terminal to provide the second voltage VDDH or the second voltage VDDH and drive current to the preceding output circuit.

[0128] A laser diode emits light via the current output from a laser diode driver. In some embodiments, the cathode of the laser diode is grounded, and the anode is connected to the current output terminal of the laser diode driver; in this case, the laser diode is a common-cathode laser diode. In some embodiments, the anode of the laser diode is connected to a second voltage output line, and the cathode is connected to the current output terminal of the laser diode driver; in this case, the laser diode is a common-anode laser diode.

[0129] As described in the above embodiments, there are three potentials used for the operation of the laser diode driver: a first voltage VDD, a second voltage VDDH, and ground. The current generated between the first voltage VDD and the second voltage VDDH forms the upper-layer current, which flows from the first voltage VDD to the second voltage VDDH. When the amplification stage unit is connected between the first voltage VDD and the second voltage VDDH, a first operating current IA1 is provided between them, thus forming at least a portion of the upper-layer current. The current generated between the second voltage VDDH and ground forms the lower-layer current, thus becoming at least a portion of the lower-layer current when the upper-layer current flows from the first voltage VDD to the second voltage VDDH, and the lower-layer current flows from the second voltage VDDH to ground. When the first driving stage unit is connected between the second voltage VDDH and ground, a second operating current IA2 is provided between them, thus the second operating current IA2 is at least a continuation of at least a portion of the upper-layer current.

[0130] Depending on the needs of the actual application, the amplification stage unit, the first level conversion circuit, and the first driving stage unit in the above embodiments can be fabricated into a single chip. Alternatively, several groups consisting of the amplification stage unit, the first level conversion circuit, and the first driving stage unit can be fabricated together with the current and voltage adapter into a single chip. Or, several groups consisting of the amplification stage unit, the first level conversion circuit, and the first driving stage unit can be fabricated together with the current and voltage adapter and the laser diode into a single chip.

[0131] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A laser diode driver, characterized in that... include: The signal input terminal is configured to connect to the pre-amplifier output circuit and receive at least an electrical signal output by the pre-amplifier output circuit. An input signal processing circuit is configured to process an electrical signal input to a signal input terminal. The input signal processing circuit includes an amplification stage unit configured to amplify the electrical signal and output an amplified electrical signal. The amplification stage unit is connected between a first voltage (VDD) and a second voltage (VDDH) provided by a power supply, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The second voltage (VDDH) is less than the first voltage (VDD) and greater than ground potential. The first operating current (IA1) constitutes at least a portion of the upper current. A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a current that drives the corresponding laser diode. The first driving stage unit is connected between a second voltage (VDDH) and ground potential, thereby forming a current path that provides a second operating current (IA2) to the first driving stage unit. The second operating current (IA2) constitutes at least a portion of the lower current and is at least a continuation of the upper current. A current-voltage adapter is configured to connect between a power supply and ground, convert a first voltage (VDD) output by the power supply to a second voltage (VDDH), and output the second voltage (VDDH) through a second voltage output line. The current-voltage adapter is also configured to absorb current on the second voltage output line and / or supply current to the second voltage output line based on the voltage or current on the second voltage output line.

2. A laser diode driver, characterized in that... include: The signal input terminal is configured to connect to the pre-amplifier output circuit and receive at least an electrical signal output by the pre-amplifier output circuit. An input signal processing circuit is configured to process an electrical signal input to a signal input terminal. The input signal processing circuit includes an amplification stage unit configured to amplify the electrical signal and output an amplified electrical signal. The amplification stage unit is connected between a first voltage (VDD) and a second voltage (VDDH) provided by a power supply, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The second voltage (VDDH) is less than the first voltage (VDD) and greater than ground potential. The first operating current (IA1) constitutes at least a portion of the upper current. A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a current that drives the corresponding laser diode. The first driving stage unit is connected between a second voltage (VDDH) and ground potential, thereby forming a current path that provides a second operating current (IA2) to the first driving stage unit. The second operating current (IA2) constitutes at least a portion of the lower layer current, and the second operating current (IA2) is at least a continuation of at least a portion of the upper layer current. A current-voltage adapter is configured to connect between a power supply and ground, convert a first voltage (VDD) output by the power supply to a second voltage (VDDH), and output the second voltage (VDDH) through a second voltage output line. The current-voltage adapter is also configured to absorb current on the second voltage output line and / or supply current to the second voltage output line based on the voltage or current on the second voltage output line. The current-voltage adapter is also connected to a signal input terminal through the second voltage output line to output the second voltage (VDDH) to the signal input terminal, providing the second voltage (VDDH) to the pre-amplifier output circuit.

3. The laser diode driver as described in claim 2, characterized in that, The current-voltage adapter also provides a pre-stage drive current (I0) to the pre-stage output circuit via a second voltage output line, such that at least a portion of the pre-stage drive current (I0) and the second operating current (IA2) is a continuation of at least a portion of the first operating current (IA1).

4. The laser diode driver as described in any one of claims 1-3, characterized in that, The current-voltage adapter includes a cascaded error amplifier and an output stage. The output stage is configured to output a second voltage (VDDH) and provide drive current and / or draw current based on voltage or current fluctuations on the second voltage output line. The output terminal of the output stage is connected to the second voltage output line and to the first input terminal of the error amplifier to feed back the real-time voltage on the second voltage output line to the first input terminal of the error amplifier. The second input terminal of the error amplifier is connected to a reference voltage (VREF). The error amplifier is configured to differentially amplify the second voltage (VDDH) and the reference voltage (VREF) and then output them to the output stage.

5. The laser diode driver as described in claim 4, characterized in that, The output stage is configured to provide drive current and draw current based on voltage or current fluctuations on the second voltage output line. The output stage includes a push-pull circuit connected between the power supply and ground. The push-pull circuit includes a first transistor and a second transistor connected in series between the power supply and ground. The first transistor and the second transistor are configured to turn one on or off while the other is off or on, based on the control of the error amplifier output signal. The series node of the first transistor and the second transistor is connected to the second voltage output line.

6. The laser diode driver as described in claim 5, characterized in that, The output stage also includes a signal transmission circuit connected between the power supply and ground. The input terminal of the signal transmission circuit is connected to the output terminal of the error amplifier, and the output terminal of the signal transmission circuit is connected to the gates of the first transistor and the second transistor, respectively. The output voltage of the signal transmission circuit is positively correlated with its input voltage.

7. The laser diode driver as described in claim 6, characterized in that, The signal transmission circuit includes a first source follower and a second source follower connected between the power supply and ground. The gates of the first source follower and the second source follower are connected to the output terminal of the error amplifier. The sources of the first source follower and the second source follower are respectively connected to the gates of the first transistor and the second transistor. The drains of the first source follower and the second source follower are connected to the second voltage output line.

8. The laser diode driver as described in claim 7, characterized in that, The first transistor is a P-type transistor, the second transistor is an N-type transistor, the first source follower is an N-type source follower, and the second source follower is a P-type source follower.

9. The laser diode driver as described in claim 4, characterized in that, The output stage is configured to draw current based on the voltage or current on the second voltage output line. The output stage includes a current input transistor and a third source follower connected between the power supply and ground. The gate of the third source follower is connected to the output of the error amplifier, and its source is connected to the gate of the current input transistor, which is a P-type transistor with its drain grounded and its source connected to the second voltage output line.

10. The laser diode driver as described in claim 4, characterized in that, The output stage is configured to provide drive current based on the voltage or current on the second voltage output line. The output stage includes a current output transistor and a fourth source follower connected between the power supply and ground. The gate of the fourth source follower is connected to the output of the error amplifier, and its source is connected to the gate of the current output transistor. The current output transistor is an N-type transistor with its drain connected to the power supply and its source connected to the second voltage output line.

11. The laser diode driver as claimed in claim 4, characterized in that, The error amplifier includes a differential amplifier circuit and a current mirror load circuit. The two input terminals of the differential amplifier circuit are respectively input to the real-time feedback voltage and the reference voltage on the second voltage output line. Its output terminal is connected to the input terminal of the current mirror load circuit. The output terminal of the current mirror load circuit serves as the output of the error amplifier and is connected to the output stage. The current mirror load circuit is used to generate a current change when the differential amplifier circuit changes due to the change in the input feedback voltage, so that the change in the output voltage is a multiple of the change in the feedback voltage.

12. The laser diode driver as described in claim 5, characterized in that, The differential amplifier circuit includes a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, and a third current source. The current mirror load circuit includes an eighth transistor, a ninth transistor, a tenth transistor, an eleventh transistor, a twelfth transistor, a thirteenth transistor, a fourth current source, and a fifth current source. The fourth and fifth transistors are connected between the third and fourth current sources. The sixth and seventh transistors are connected between the third and fifth current sources. The control electrode of the fifth transistor is used for the input reference voltage (VREF). The control electrode of the sixth transistor is used for the input of the second voltage (VDDH) for the output stage feedback. The eighth, ninth, and tenth transistors are connected between the fourth current source and ground potential. The eleventh, twelfth, and thirteenth transistors are connected between the fifth current source and ground potential. The control electrodes of the tenth and eleventh transistors are respectively connected to the node between the eighth and ninth transistors. The node between the twelfth and thirteenth transistors is used for the differential amplification output of the error amplifier. The control electrodes of the fourth, seventh, eighth, ninth, twelfth, and thirteenth transistors are respectively connected to an appropriate bias voltage.

13. The laser diode driver as described in any one of claims 4-12, characterized in that, The current-voltage adapter also includes a de-jitter circuit, which is connected to the error amplifier and the output stage respectively, and is used to adjust the high-frequency gain of the feedback loop formed by the error amplifier and the output stage to less than 1.

14. The laser diode driver as described in claim 13, characterized in that, The anti-shake circuit includes a second capacitor, one end of which is connected to the connection node between the error amplifier and the output stage, and the other end is grounded.

15. The laser diode driver as described in any one of claims 1-3, characterized in that, It also includes a DC-DC converter, whose input terminal is connected to a power supply, converting the first voltage provided by the power supply into a second voltage and outputting it to the second voltage output line.

16. The laser diode driver as described in any one of claims 1-3, characterized in that, It also includes a linear regulator connected between the second voltage output line and the first drive stage unit to regulate the second voltage on the second voltage output line and then supply it to the first drive stage unit.

17. The laser diode driver as described in any one of claims 1-3, characterized in that, It also includes a first level conversion circuit, which is connected between the output terminal of the amplification stage unit and the input terminal of the first driving stage unit, for signal level adaptation between the amplification stage unit and the first driving stage unit.

18. The laser diode driver as claimed in claim 17, characterized in that, The first level conversion circuit is connected between the first voltage (VDD) and the ground potential.

19. The laser diode driver as claimed in claim 18, characterized in that, The first level conversion circuit has two sets of output terminals, wherein the common-mode level of the second set of output terminals is greater than the common-mode level of the first set of output terminals. The laser diode driver further includes a second driving stage unit connected between the first voltage (VDD) and the second voltage (VDDH). The first set of output terminals is connected to the first driving stage unit, and the first driving stage unit converts the electrical signal output from the first set of output terminals into a corresponding current. The second set of output terminals is connected to the second driving stage unit, and the second driving stage unit converts the electrical signal output from the second set of output terminals into a corresponding current. The current output by the first driving stage unit and the current output by the second driving stage unit are used together to drive the laser diode.

20. The laser diode driver as claimed in claim 17, characterized in that, The first level conversion circuit uses a source follower to achieve common-mode level conversion, or uses AC coupling to achieve common-mode level conversion, or uses a common-source common-gate structure to achieve common-mode level conversion.

21. A laser diode driver, characterized in that... include: The signal input terminal is configured to connect to the pre-amplifier output circuit and receive at least an electrical signal output by the pre-amplifier output circuit. An input signal processing circuit is configured to process an electrical signal input to a signal input terminal. The input signal processing circuit includes an amplification stage unit configured to amplify the electrical signal and output an amplified electrical signal. The amplification stage unit is connected between a first voltage (VDD) and a second voltage (VDDH) provided by a power supply, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The second voltage (VDDH) is less than the first voltage (VDD) and greater than ground potential. The first operating current (IA1) constitutes at least a portion of the upper current. A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a current that drives the corresponding laser diode. The first driving stage unit is connected between a second voltage (VDDH) and ground potential, thereby forming a current path that provides a second operating current (IA2) to the first driving stage unit. The second operating current (IA2) constitutes at least a portion of the lower current and is at least a continuation of the upper current. A first level conversion circuit is connected between the output terminal of the amplification stage unit and the input terminal of the first driving stage unit, and is used for signal level adaptation between the amplification stage unit and the first driving stage unit.

22. The laser diode driver as claimed in claim 21, characterized in that, The first level conversion circuit is connected between the first voltage (VDD) and ground potential. The first level conversion circuit has two sets of level outputs, wherein the common-mode level of the second set of outputs is greater than the common-mode level of the first set of outputs. The laser diode driver also includes a second driving stage unit connected between the first voltage (VDD) and the second voltage (VDDH). The first set of level outputs is connected to the first driving stage unit, and the second set of level outputs is connected to the second driving stage unit. The first driving stage unit and the second driving stage unit respectively convert the two sets of level signals output by the first level conversion circuit into corresponding currents. The current output by the first driving stage unit and the current output by the second driving stage unit are used together to drive the laser diode.

23. The laser diode driver as described in claim 21, characterized in that, The first level conversion circuit uses a source follower to achieve common-mode level conversion, or uses AC coupling to achieve common-mode level conversion, or uses a common-source common-gate structure to achieve common-mode level conversion.

24. The laser diode driver as described in claim 1, 2, or 21, characterized in that, The input signal processing circuit further includes an input stage unit, the input terminal of which is connected to a signal input terminal, and the output terminal of which is connected to the input terminal of an amplification stage unit.

25. The laser diode driver as described in claim 24, characterized in that, The input stage unit is connected between the power supply and ground.

26. The laser diode driver as claimed in claim 24, characterized in that, The input stage unit is connected between the second voltage (VDDH) output line and ground potential, thereby forming a current path that provides a third operating current to the input stage unit, such that the third operating current is at least a continuation of at least a portion of the upper current; the laser diode driver also includes a second level conversion circuit, which is connected between the output terminal of the input stage unit and the input terminal of the amplification stage unit for signal level adaptation between the input stage unit and the amplification stage unit.

27. The laser diode driver as claimed in claim 24, characterized in that, The input stage unit is connected between the power supply and the second voltage output line, thereby forming a current path that provides a fourth operating current to the input stage unit. The fourth operating current forms part of the upper current. The laser diode driver also includes a third level conversion circuit connected between the signal input terminal and the input stage unit for signal level adaptation between the signal input terminal and the input stage unit.

28. An optical emitting module, characterized in that... include: At least one laser diode driver as described in any one of claims 21-27; A current-voltage adapter is configured to connect between a power supply and ground, convert a first voltage (VDD) output by the power supply to a second voltage (VDDH), and output the second voltage (VDDH) through a second voltage output line. The current-voltage adapter is also configured to absorb current on the second voltage output line and / or provide current to the second voltage output line based on the voltage or current on the second voltage output line. The current-voltage adapter is also connected to a signal input terminal through the second voltage output line to output the second voltage (VDDH) to the signal input terminal, providing the second voltage (VDDH) or the second voltage (VDDH) and drive current to the pre-amplifier output circuit. A laser diode that corresponds one-to-one with a laser diode driver, the laser diode emitting light by being driven by the current output from the laser diode driver.

29. The optical emitting module as described in claim 28, characterized in that, The cathode of the laser diode is grounded, and the anode is connected to the current output terminal of the laser diode driver; or the anode of the laser diode is connected to the second voltage output line, and the cathode is connected to the current output terminal of the laser diode driver.

Images