Optical transmitter module and laser diode driver therefor

Abstract

A laser diode driver includes 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 through a second voltage output line, absorbing current on the second voltage output line according to a voltage on the second voltage output line, and / or providing current to the second voltage output line, the amplification stage unit is located in a lower layer circuit, a first working current of the amplification stage unit constitutes at least part of a lower layer current, the first driving stage unit is located in an upper layer circuit, a second working current of the first driving stage unit constitutes at least part of an upper layer current, and since the lower layer current is continuous with the upper layer current, the working currents of the amplification stage unit and the first driving stage unit can be at least partially multiplexed, so that the power consumption of the laser diode driver can be reduced. The application also provides an optical transmitting 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 an intermediate voltage (VDDH) and ground potential, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The first operating current (IA1) constitutes at least a portion of the lower current.

[0011] A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a corresponding current driving the laser diode. The first driving stage unit is connected between a first voltage (VDD) and an intermediate voltage (VDDH) provided by a power supply, 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 upper current. The intermediate voltage (VDDH) is less than the first voltage (VDD) and greater than the ground potential, such that the first operating current (IA1) 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 (VDD) output by the power supply to an intermediate voltage (VDDH), and output the intermediate voltage (VDDH) through an intermediate voltage output line. The current-voltage adapter is also configured to absorb current on the intermediate voltage output line and / or supply current to the intermediate voltage output line based on the voltage or current on the intermediate 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 an intermediate voltage (VDDH) and ground potential, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The first operating current (IA1) forms at least a portion of the lower current.

[0016] A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a corresponding current driving the laser diode. The first driving stage unit is connected between a first voltage (VDD) and an intermediate voltage (VDDH) provided by a power supply, thereby forming a current path that provides a second operating current (IA2) to the first driving stage unit. The second operating current (IA2) forms at least a portion of the upper current. The intermediate voltage (VDDH) is less than the first voltage (VDD) and greater than the ground potential. The first operating current (IA1) 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 (VDD) output by the power supply into an intermediate voltage (VDDH), and output the intermediate voltage (VDDH) through an intermediate voltage output line. The current-voltage adapter is also configured to absorb current on the intermediate voltage output line and / or supply current to the intermediate voltage output line based on the voltage or current on the intermediate voltage output line. The current-voltage adapter is also connected to a signal input terminal through the intermediate voltage output line to output the intermediate voltage (VDDH) to the signal input terminal, providing the intermediate voltage (VDDH) to the preceding 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 an intermediate voltage (VDDH) and ground potential, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The first operating current (IA1) constitutes at least a portion of the lower current.

[0021] A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a corresponding current driving the laser diode. The first driving stage unit is connected between a first voltage (VDD) and an intermediate voltage (VDDH) provided by a power supply, 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 upper current. The intermediate voltage (VDDH) is less than the first voltage (VDD) and greater than the ground potential, such that at least a portion of the first operating current (IA1) is 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 an intermediate voltage, and outputting the intermediate voltage through an intermediate voltage output line. The current-voltage adapter is further configured to absorb current on the intermediate voltage output line and / or provide current to the intermediate voltage output line based on the voltage or current on the intermediate voltage output line. The current-voltage adapter is also connected to a signal input terminal through the intermediate voltage output line to output the intermediate voltage to the signal input terminal, providing an intermediate voltage or intermediate 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 light emitting module are provided. A first driving stage unit is connected between a first voltage and an intermediate voltage provided by the power supply, located in the upper circuit. An amplification stage unit is connected between the intermediate voltage and ground potential, located in the lower circuit. The intermediate voltage VDDH is less than the first voltage VDD and greater than ground potential, such that the first operating current of the amplification stage unit constitutes at least a portion of the lower current, and the second operating current of the first driving stage unit constitutes at least a portion of the upper current. The lower current is a continuation of the upper current, thus ensuring that the second operating current (IA2) is at least a continuation of at least a portion of the upper current. In other words, the operating currents of the amplification stage unit and the first driving stage unit can be at least partially multiplexed, thereby significantly reducing the total current supplied by the power supply to the laser diode driver and thus 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 2 This 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 1 The 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 two layers using the intermediate 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 driving stage unit is designed on the upper layer and the amplification stage unit on the lower layer, according to the direction of the current. At least a portion of the operating current supplied by the power supply to the driving stage unit flows through the amplification stage unit, becoming at least a portion of its operating current. This allows the current supplied by the power supply to be reused, reducing the total current required by the power supply while fulfilling 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 3aIn 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 intermediate voltage output line 1.5 and the ground potential, where the high potential is the intermediate voltage VDDH and the low potential is ground. The path from the intermediate voltage VDDH output line, through the amplification stage unit, to the ground potential forms the current path for the first operating current IA1 of the amplification stage unit, as shown in Figure 2.7, where the intermediate voltage VDDH is less than the first voltage VDD provided by the power supply 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 intermediate voltage output line 1.5 as the dividing line. The first operating current IA1 of the amplification stage unit constitutes 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 a first voltage (VDD) provided by the power supply and an intermediate voltage VDDH, thereby forming a current path that provides a second operating current IA2 to the first driver stage unit. As shown in Figure 2.9, the second operating current IA2 of the first driver stage unit constitutes at least a portion of the underlying current. Figures 3d1-3d4Four 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 2a In 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 first voltage VDD.

[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, it converts the lower common-mode level (voltage between VDDH and GND) output by the amplification stage unit to a higher level (between VDD and VDDH). Since the amplification stage unit 2.2 operates between the intermediate voltage VDDH and ground, its output signal level is between VDDH and ground potential. The first driver stage unit 2.4 operates between the first voltage and the intermediate voltage VDDH. If the amplification stage unit directly outputs the amplified electrical signal to the first driver stage unit, it may lead to a mismatch in signal levels between the two units. The first level conversion circuit, connected between the first voltage VDD and ground, can convert the lower input voltage signal level to a higher output voltage signal level. For example, it can convert a signal with a level between 0 and VDDH to a signal between VDDH and VDD, thus satisfying the signal level adaptation requirements between the amplification stage unit and the first driver stage unit. The first level conversion circuit 2.3 is connected between the first voltage VDD and the ground potential, thereby forming a current path that provides the 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.

[0066] Figures 3c1-3c3 The diagram shows three specific circuit structures of the first level conversion circuit 2.3. Figure 3c1This 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 3c2 Common-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 (first voltage VDD) and ground 1.8 to convert the first voltage VDD output by the power supply into an intermediate voltage VDDH, and output the intermediate voltage VDDH through the intermediate voltage output line 1.5.

[0072] It can be seen from the foregoing embodiment that there are three potentials for the operation of the laser diode driver, which are respectively a first voltage VDD, an intermediate voltage VDDH, and a ground potential. The relationship among the three is that the intermediate voltage VDDH is lower than the first voltage VDD and higher than the ground potential. In this document, the current flowing from the first voltage VDD to the intermediate voltage VDDH is referred to as an upper-layer current, and the current flowing from the intermediate voltage VDDH to the ground is referred to as a lower-layer current, so the lower-layer current should be a continuation of the upper-layer current. In this embodiment, the amplifier stage unit is connected between the intermediate voltage VDDH and the ground, and a first operating current IA1 is provided between the first voltage VDD and the intermediate voltage VDDH for the amplifier stage unit, and the first operating current IA1 belongs to the lower-layer current. The first driving stage unit is connected between the first voltage VDD and the intermediate voltage VDDH, and a second operating current IA2 is provided between the first voltage VDD and the intermediate voltage for the first driving stage unit, and the second operating current IA2 belongs to the upper-layer current. Therefore, the first operating current IA1 is at least partially a continuation of at least part of the second operating current IA2, that is, part of the current can be reused between the second operating current IA2 and the first operating current IA1. In operation, the power supply needs to provide operating currents for the input stage unit 2.1, the amplifier 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 Itot that the power supply needs to provide to the laser diode driver is the sum of the set operating currents of the input stage unit 2.1, the amplifier stage unit 2.2, the first level conversion circuit 2.3 and the first driving stage unit 2.4. In this embodiment, since the first operating current IA1 is at least partially a continuation of at least part of the second operating current IA2, that is, current reuse exists between the second operating current IA2 and the first operating current IA1, therefore, the total current Itot that the power supply needs to provide to the laser diode driver is smaller than the sum of the set operating currents of the input stage unit 2.1, the amplifier 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, thereby reducing the total current Itot required by the laser diode driver. A reduction in the total current Itot means that the power consumption of the laser diode driver during operation can be reduced. In a laser diode driver, the amplifier stage unit and the first driving stage unit are the main units thereof, and also the two units with the largest power consumption, and the corresponding first operating current IA1 and second operating current IA2 are also relatively large. Therefore, after reusing the second operating current IA2 for the first operating current IA1, the total current Itot required by the laser diode driver can be greatly reduced, generally by 30% to 45%, so the power consumption of the laser diode driver during operation is also reduced accordingly.With the reduced power consumption of the laser diode driver, it can be applied to low-power scenarios. On the other hand, the saved power can be used to add modules for optimizing signals (such as improving gain, increasing bandwidth, and other high-speed performance), or to improve the performance of the amplification stage unit and the first driving stage unit.

[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 intermediate 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 intermediate voltage VDDH, and ground potential. Since the intermediate voltage VDDH is located in the middle, the external interference signals on the first voltage VDD will cause voltage fluctuations in the intermediate voltage VDDH. At the same time, there is also mutual interference between the circuit between the first voltage VDD and the intermediate voltage VDDH and the circuit between the intermediate voltage VDDH and ground potential, which will also cause voltage fluctuations in the intermediate voltage VDDH. The voltage fluctuations in the intermediate 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 intermediate voltage VDDH flows to the lower-level current between the intermediate 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 intermediate 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 intermediate 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 intermediate 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 intermediate 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 intermediate voltage output line 1.5 and also supply current to it. On one hand, when voltage fluctuations in the intermediate voltage VDDH cause a voltage increase, the push-pull regulator absorbs current on the intermediate voltage output line 1.5, for example, by removing low-to-medium frequency current fluctuations, thus reducing voltage fluctuations on the intermediate 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 intermediate 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 intermediate 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 some embodiments, the current-voltage adapter is also connected to the signal input terminal 16 via the intermediate voltage output line 1.5, outputting the intermediate voltage VDDH to the signal input terminal 1.6 to provide the intermediate 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 first operating current IA1 is a continuation of at least a portion of the second operating current IA2. Please refer to [reference needed]. Figure 2 and Figure 2a The intermediate voltage output line 1.5 is connected to the signal input terminal 1.6 via resistor RT, providing the intermediate 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 IA1 required by the amplification stage unit are lower-level currents, and the second operating current IA2 of the first drive 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 IA2, and the current IA1 is also a part of the current IA2. 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 actually needs to provide to the laser diode driver is less than the sum of the set operating currents of each module. Because the larger currents IA1, IA2, and the pre-stage drive current I0 in the circuit system are multiplexed, 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.

[0077] 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 IA2 and (I0+IA1). For example, when IA2>(I0+IA1), the push-pull regulator can absorb the excess unreusable current on the intermediate voltage output line 1.5, i.e., IA6 flows to the right, IA7≈IA6, and IA5 is very small. When IA2<(I0+IA1), the push-pull regulator can supply the missing reused current on the intermediate voltage output line 1.5, IA6 flows to the left, IA5≈IA6, and IA7 is very small.

[0078] 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 intermediate 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.

[0079] Example 2:

[0080] 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.

[0081] The difference between Embodiment 2 and Embodiment 1 is that the connection method of the input level unit 2.1 is different.

[0082] For example, Figure 4aThe input stage unit is connected between the intermediate voltage VDDH output line and ground, thus forming a current path that provides a third operating current to the input stage unit, making the third operating current part of the lower-level current. In this embodiment, since the second operating current IA2 required by the first driving stage unit is at least a part of the upper-level current, and the first operating current IA1 of the amplification stage unit and the third operating current IA3 of the input stage unit are at least parts of the lower-level current, and the at least part of the lower-level current is a continuation of the at least part of the upper-level current, at least a portion of the first operating current IA1 and the third operating current IA3 can reuse at least a portion of the current from the second operating current IA2. 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.

[0083] Please refer to Figure 4b The laser diode driver 40 shown has an input stage unit 2.1 connected between the power supply and the intermediate voltage VDDH output line, thus forming a current path providing a fourth operating current to the input stage unit, which constitutes part of the upper-level current. The laser diode driver also includes a second level-shifting circuit 2.12 connected between the output of the input stage unit and the input of the amplification stage unit for signal level adaptation between the two units. The laser diode driver further includes a third level-shifting circuit 4.2 connected between the signal input terminal 1.6 and the input stage unit for signal level adaptation between the signal input terminal 1.6 and the input stage unit 2.1. The second and third level-shifting circuits can be connected between the first voltage VDD and ground potential, and their circuit structure can be implemented using the same structure as the first level-shifting circuit in Embodiment 1. In this embodiment, since the first operating current IA1 required by the amplification stage unit is at least a part of the lower layer current, and the fourth operating current of the input stage unit and the second operating current IA2 of the first driving stage unit are at least a part of the upper layer current, at least a part of the first operating current IA1 can be reused from the second operating current IA2 and the fourth operating current, so that the total current required by the input stage unit, the amplification stage unit and the first driving stage unit is 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, so as to reduce the power consumption of the laser diode driver during operation.

[0084] Example 3:

[0085] like Figure 4bAs 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 an intermediate voltage VDDH and outputting it to the intermediate 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.

[0086] In some embodiments, the laser diode driver further includes a linear regulator 4.22 connected between the intermediate voltage output line 1.5 and the amplification stage unit to regulate the intermediate voltage on the intermediate voltage output line 1.5 before supplying it to the amplification stage unit. In this embodiment, adding a linear regulator can further reduce the impact of voltage fluctuations on the intermediate voltage VDDH on the amplification stage unit.

[0087] Example 4:

[0088] 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.

[0089] 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 lower 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 intermediate voltage VDDH and ground, and can input a lower common-mode level. The first driving stage unit is used to input a higher common-mode level. Therefore, the first set of outputs of the first level conversion circuit 2.3 is connected to the first driving stage unit 2.4, which converts the electrical signal of the first set of outputs into a corresponding current. The second set of outputs of the first level conversion circuit is connected to the second driving stage unit 4.6, which converts the electrical signal of 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.

[0090] Since the first driver stage unit is used to input a higher common-mode level and the second driver stage unit is used to input a lower common-mode level, the first level conversion circuit 2.3 can input a lower common-mode level and output a higher common-mode level. Conversely, the first level conversion circuit can also input a higher common-mode level and output a lower common-mode level.

[0091] 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.

[0092] 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.

[0093] Example 5:

[0094] This embodiment provides a specific circuit for a current-voltage adapter.

[0095] 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.

[0096] Output stage 5.2 outputs the intermediate voltage VDDH to intermediate voltage output line 1.5 and provides drive current and / or draws current based on the voltage and / or current of intermediate voltage output line 1.5. Output stage 5.2 also feeds back the intermediate voltage VDDH of intermediate 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 large output currents (such as up to hundreds of milliamps), and output stage 5.2 has the ability to supply and / or draw large currents.

[0097] The second input of error amplifier 5.1 is connected to the reference voltage VREF. Error amplifier 5.1 differentially amplifies the intermediate 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 intermediate voltage VDDH and the reference voltage VREF, ensuring that the intermediate voltage VDDH of the intermediate 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.

[0098] Please refer to Figure 7a , Figure 7a A specific embodiment of the error amplifier 5.1 and the output stage 5.2 is shown.

[0099] 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 intermediate voltage output line. On the other hand, interference may cause fluctuations in the intermediate voltage VDDH output by the intermediate voltage output line, or interference may cause fluctuations in the current on the intermediate voltage output line. In both cases, the intermediate voltage output line may lack current for multiplexing, resulting in a lower intermediate voltage VDDH, or it may generate excess current, resulting in a higher intermediate 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 intermediate voltage output line may experience voltage fluctuations, causing the intermediate voltage VDDH to be greater than or less than a preset voltage value (e.g., VREF). The decrease or increase of VDDH is fed back to the error amplifier 5.1. The error amplifier 5.1 amplifies the change of 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 intermediate voltage VDDH near the reference voltage VREF.

[0100] 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 the intermediate 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 intermediate 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.

[0101] 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 the reference voltage on the intermediate 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.

[0102] When the intermediate voltage VDDH of the intermediate voltage output line fluctuates, or when the current of the intermediate voltage output line increases, causing the intermediate voltage VDDH to rise, the intermediate 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 intermediate voltage VDDH and the reference voltage VREF. This ΔV is reflected in the current mirror load circuit 5.4. The voltage change of the output of 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 intermediate voltage VDDH can be detected and the change can be amplified by several factors to control the operation of the output stage 5.2.

[0103] 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 intermediate voltage VDDH for feedback 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 T4 form the branch of the input intermediate 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.

[0104] 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 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 is connected to the first terminal of the second capacitor C1 and is used to output voltage VE to the output stage 5.2. The second terminal of the second capacitor C1 is connected to ground potential.

[0105] In this embodiment, when the input feedback voltage of the differential amplifier circuit 5.3 changes, i.e., when the intermediate voltage VDDH changes, the driving current of the sixth transistor T3 changes due to the voltage change, which in turn causes a current change in the branch of the differential amplifier circuit 5.3 that receives the intermediate voltage VDDH. Since the branch of the differential amplifier circuit 5.3 that receives the intermediate 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 input reference voltage VREF 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 intermediate 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 intermediate input voltage VDDH in the differential amplifier circuit 5.3 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 intermediate 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.

[0106] In this embodiment, the eighth transistor T5 and the thirteenth transistor T10 are P-type transistors, and 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 can be 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 adopt another transistor type, those skilled in the art can adaptively adjust the structure of the error amplifier 5.1 according to the situation.

[0107] The following describes the principle of current sinking and current sourcing of the output stage 5.2. Please refer to Figure 7b and Figure 7c .

[0108] Figure 7b illustrates the principle of current sinking of the output stage. In this embodiment, when the upper-layer current is greater than the lower-layer current, excess current will be generated on the intermediate voltage output line, causing the intermediate voltage VDDH to rise, or when VDDH fluctuates and rises slightly, in both cases VDDH is fed back to the input terminal of the differential amplifier circuit. At this time, VDDH>VREF, so that the voltage VX output from the VDDH branch of the differential output of the differential amplifier circuit decreases, and the voltage VY output from the VREF branch increases, and the voltage VE output by the error amplifier 5.1 decreases, for example, VE<VDDH. Since the gate voltage of the transistor MN1 decreases, the source voltage of the transistor MN1 also decreases accordingly (the transistor MN1 and the current source form the first source follower 5.7), thereby making the gate voltage of the first transistor MP2 relatively low, so that the gate-source voltage difference of the first transistor MP2 becomes relatively large, and the first transistor MP2 is turned on, so that the excess current on the intermediate voltage output line flows to the ground through the first transistor MP2, thereby sinking current from the intermediate voltage output line. Meanwhile, since the gate voltage of the transistor MP1 decreases, the source voltage of the transistor MP1 also decreases, so that the gate-source voltage difference of the second transistor MN2 becomes relatively small (may be lower than the threshold voltage of the second transistor MN2), therefore the second transistor MN2 is almost turned off, so that the output stage 5.2 is in a current sinking state at this time.

[0109] Figure 7cIt illustrates the principle of current supply by the output stage. When the upper-layer current is greater than the lower-layer current, the current available for multiplexing on the intermediate voltage output line will be insufficient, causing the intermediate voltage VDDH to decrease; or when VDDH fluctuates and decreases slightly, in both cases, VDDH is fed back to the input terminal of the differential amplifier circuit. At this time, VDDH < VREF, so that VX output from the VDDH branch of the double-ended output of the differential amplifier circuit increases, and the voltage VY output from the VREF branch decreases, which causes the voltage VE output by the error amplifier 5.1 to increase, for example, VE > VDDH. Since the gate voltage of transistor MP1 increases, the source voltage of transistor MP1 also increases accordingly (transistor MP1 and the current source form the second source follower 5.8), which makes the gate voltage of the second transistor MN2 relatively high, so that the gate-source voltage difference of the second transistor MN2 becomes relatively large, and the second transistor MN2 is turned on, so that the current generated between the power supply and the intermediate voltage output line flows to the intermediate voltage output line through the second transistor MN2, thereby driving current can be supplied to the intermediate voltage output line. Meanwhile, since the gate voltage of transistor MN1 increases, the source voltage of transistor MN1 also increases, and the gate-source voltage difference of the first transistor MP2 becomes relatively small (may be lower than the threshold voltage of the first transistor MP2), therefore the first transistor MP2 is almost turned off, so that the output stage 5.2 is in a current supply state at this time.

[0110] It can be seen from the above embodiment that the first transistor MP2 and the second transistor MN2 form a push-pull circuit to achieve supplying driving current and sinking current to the intermediate voltage output line. When the output voltage of the error amplifier 5.1 increases, the second transistor MN2 is turned on and the first transistor MP2 is turned off, so that the formed push-pull circuit supplies driving current to the intermediate voltage output line. When the output of the error amplifier 5.1 decreases, the first transistor MP2 is turned on and the second transistor MN2 is turned off, so that the formed push-pull circuit absorbs current from the intermediate voltage output line.

[0111] As can be seen from the above embodiments, based on the push-pull circuit providing drive current and drawing current to the intermediate 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 between 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.

[0112] In some embodiments, there may be excess current on the intermediate 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 intermediate 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 intermediate voltage output line generates fluctuating voltage. In this case, excess current will be generated on the intermediate voltage output line, causing the intermediate voltage VDDH to become higher. The higher intermediate voltage VDDH is fed back to the error amplifier 5.1, causing the output stage 5.2 to absorb the excess current on the intermediate voltage output line, thereby maintaining that the upper current is always equal to its lower current and stabilizing the intermediate voltage VDDH to be close to the reference voltage VREF.

[0113] 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 intermediate voltage output line. The operating principle of output stage 5.2 in this embodiment is as follows: When excess current is generated on the intermediate voltage output line, causing the intermediate voltage VDDH to rise, the voltage VE output by error amplifier 5.1 decreases, for example, below the intermediate 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 intermediate voltage output line to flow to ground through current input transistor T11. At this point, the intermediate 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 intermediate voltage VDDH of the intermediate voltage output line decreases and eventually stabilizes near the reference voltage VREF.

[0114] In some embodiments, the output stage 5.2 may also 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 intermediate voltage output line, thereby forming a source follower with the current input transistor T11, so that the intermediate voltage VDDH of the intermediate voltage output line is reduced and eventually stabilized near the reference voltage VREF.

[0115] In some embodiments, there may be a lack of current for multiplexing on the intermediate voltage output line, i.e., the upper current is less than the lower current. To balance the upper and lower currents, output stage 5.2 is designed to provide drive current based on voltage or current fluctuations on the intermediate 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 intermediate voltage output line experiences voltage fluctuations. In this case, there will be a lack of current for multiplexing on the intermediate voltage output line, causing the intermediate voltage VDDH to drop. The lowered intermediate voltage VDDH is fed back to error amplifier 5.1, causing output stage 5.2 to provide current for multiplexing to the intermediate voltage output line, thereby maintaining the upper current always equal to its lower current and stabilizing the intermediate voltage VDDH near the reference voltage VREF.

[0116] 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 intermediate 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 intermediate voltage output line, causing the intermediate voltage VDDH to decrease, the voltage VE output by the error amplifier 5.1 increases, for example, above the intermediate 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 intermediate voltage output line to flow through the current output transistor T12 to the intermediate voltage output line. At this point, the intermediate 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 intermediate voltage VDDH of the intermediate voltage output line increases and eventually stabilizes near the reference voltage VREF.

[0117] 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 intermediate voltage output line, thereby forming a source follower with the current output transistor T12, so that the intermediate voltage VDDH of the intermediate voltage output line increases and eventually stabilizes near the reference voltage VREF.

[0118] As can be seen from the above embodiments, since the output stage 5.2 can only absorb the current on the intermediate voltage output line through the current input transistor T11 and the third source follower 5.5, or only supply the current to the intermediate 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 intermediate voltage output line, and make the intermediate voltage VDDH of the intermediate voltage output line stable near the reference voltage VREF.

[0119] 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.

[0120] As can be seen from the above embodiments, when upper-layer and lower-layer currents are multiplexed, there may be unreasonable multiplexing situations between the upper-layer and lower-layer currents. The current-voltage adapter, by providing current to or absorbing current from the intermediate voltage output line, can satisfy the reasonable multiplexing between the upper-layer and lower-layer currents, thereby reducing the overall power consumption of the laser diode driver. Furthermore, when upper-layer and lower-layer currents are multiplexed, there may also be mutual interference between the upper and lower-layer circuits. The current-voltage adapter, by absorbing current from the intermediate 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] Example 6:

[0126] 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.

[0127] 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.

[0128] 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 an intermediate voltage VDDH, and outputs the intermediate voltage VDDH through the intermediate voltage output line. The current-voltage adapter is also configured to absorb current on the intermediate voltage output line and / or supply current to the intermediate voltage output line. The current-voltage adapter is also connected to a signal input terminal via the intermediate voltage output line, outputting the intermediate voltage VDDH to the signal input terminal to provide the intermediate voltage VDDH or the intermediate voltage VDDH and drive current to the preceding output circuit.

[0129] A laser diode emits light via the current output from its driver. In some embodiments, the cathode of the laser diode is grounded, and the anode is connected to the current output terminal of the 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 the intermediate voltage output line, and the cathode is connected to the current output terminal of the driver; in this case, the laser diode is a common-anode laser diode.

[0130] As can be seen from the above embodiments, there are three potentials used for the operation of the laser diode driver: the first voltage VDD, the intermediate voltage VDDH, and the ground potential. The current generated between the first voltage VDD and the intermediate voltage VDDH forms the upper-layer current, which flows from the first voltage VDD to the intermediate voltage VDDH.

[0131] 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.

[0132] 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 an intermediate voltage (VDDH) and ground potential, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The first operating current (IA1) constitutes at least a portion of the lower current. A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a corresponding current driving the laser diode. The first driving stage unit is connected between a first voltage (VDD) and an intermediate voltage (VDDH) provided by a power supply, 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 upper current. The intermediate voltage (VDDH) is less than the first voltage (VDD) and greater than the ground potential, such that the first operating current (IA1) is at least a continuation of at least a portion 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 an intermediate voltage (VDDH), and output the intermediate voltage (VDDH) through an intermediate voltage output line. The current-voltage adapter is also configured to absorb current on the intermediate voltage output line and / or supply current to the intermediate voltage output line based on the voltage or current on the intermediate 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 an intermediate voltage (VDDH) and ground potential, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The first operating current (IA1) forms at least a portion of the lower current. A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a corresponding current driving the laser diode. The first driving stage unit is connected between a first voltage (VDD) and an intermediate voltage (VDDH) provided by a power supply, thereby forming a current path that provides a second operating current (IA2) to the first driving stage unit. The second operating current (IA2) forms at least a portion of the upper current. The intermediate voltage (VDDH) is less than the first voltage (VDD) and greater than the ground potential. The first operating current (IA1) is at least a continuation of at least a portion 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 into an intermediate voltage (VDDH), and output the intermediate voltage (VDDH) through an intermediate voltage output line. The current-voltage adapter is also configured to absorb current on the intermediate voltage output line and / or provide current to the intermediate voltage output line based on the voltage or current on the intermediate voltage output line. The current-voltage adapter is also connected to a signal input terminal through the intermediate voltage output line to output the intermediate voltage (VDDH) to the signal input terminal, providing the intermediate 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 an intermediate voltage output line. The pre-stage drive current (I0) constitutes part of the lower-level current, such that at least a portion of the pre-stage drive current (I0) and the first operating current (IA1) is a continuation of at least a portion of the second operating current (IA2).

4. The laser diode driver as described in claim 1 or 2, characterized in that, The current-voltage adapter includes a cascaded error amplifier and an output stage. The output stage is configured to output an intermediate voltage (VDDH) and provide drive current and / or draw current based on voltage or current fluctuations on the intermediate voltage output line. The output terminal of the output stage is connected to the intermediate voltage output line and to the first input terminal of the error amplifier, for feeding back the real-time voltage on the intermediate 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 intermediate 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 selectively provide drive current and draw current based on voltage or current fluctuations on the intermediate 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 intermediate 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 intermediate 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 intermediate 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 intermediate 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 intermediate 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 intermediate 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 intermediate 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 claimed in claim 11, 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 to input the reference voltage (VREF). The control electrode of the sixth transistor is used to input the intermediate 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 an intermediate voltage and outputting it to the intermediate 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, which is connected between the intermediate voltage output line and the amplification stage unit to regulate the intermediate voltage on the intermediate voltage output line and then supply it to the amplification 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 lower 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 intermediate voltage (VDDH) and the ground potential. 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 an intermediate voltage (VDDH) and ground potential, thereby forming a current path that provides a first operating current (IA1) to the amplification stage unit. The first operating current (IA1) constitutes at least a portion of the lower current. A first driving stage unit is configured to input an amplified electrical signal and convert the amplified electrical signal into a corresponding current driving the laser diode. The first driving stage unit is connected between a first voltage (VDD) and an intermediate voltage (VDDH) provided by a power supply, 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 upper current. The intermediate voltage (VDDH) is less than the first voltage (VDD) and greater than the ground potential, such that at least a portion of the first operating current (IA1) is a continuation of at least a portion 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 less 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 intermediate voltage (VDDH) and ground potential. 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 intermediate voltage (VDDH) output line and the ground potential, thereby forming a current path that provides a third operating current to the input stage unit, so that the third operating current constitutes part of the lower current.

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 intermediate voltage output line, thereby forming a current path that provides a fourth operating current to the input stage unit, which constitutes part of the upper-level 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. 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 an intermediate voltage (VDDH), and output the intermediate voltage (VDDH) through an intermediate voltage output line. The current-voltage adapter is also configured to absorb current on the intermediate voltage output line and / or provide current to the intermediate voltage output line based on the voltage or current on the intermediate voltage output line. The current-voltage adapter is also connected to a signal input terminal through the intermediate voltage output line to output the intermediate voltage (VDDH) to the signal input terminal, providing the intermediate voltage (VDDH) to the pre-amplifier output circuit or providing the intermediate voltage (VDDH) and drive current. 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 intermediate voltage output line, and the cathode is connected to the current output terminal of the laser diode driver.

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