CN209913236U

CN209913236U - Laser drive circuit and laser device

Info

Publication number: CN209913236U
Application number: CN201921049607.3U
Authority: CN
Inventors: 孙向明
Original assignee: Hubei Bingzheng Tecent Technology Co Ltd
Current assignee: Hubei Bingzheng Tecent Technology Co Ltd
Priority date: 2019-07-04
Filing date: 2019-07-04
Publication date: 2020-01-07
Anticipated expiration: 2029-07-04

Abstract

The utility model discloses a laser drive circuit and laser equipment, the laser drive circuit includes first N channel MOS pipe, second N channel MOS pipe and current mirror; the drain electrode of the first N-channel MOS tube is connected with a preset laser; the drain electrode of the first N-channel MOS tube is connected with the current mirror; the grid electrode of the first N-channel MOS tube is used for acquiring a preset direct-current voltage signal; the source electrode of the first N-channel MOS tube is connected with the drain electrode of the second N-channel MOS tube, and the source electrode of the second N-channel MOS tube is grounded; and the grid electrode of the second N-channel MOS tube is used for acquiring a preset CML signal. Therefore, the second N-channel MOS tube, namely the input tube, is not a tail current tube, and does not run through tail current, so that the situation that the size is large due to the use of the tail current tube is avoided, and the area of a device is correspondingly reduced, and the technical problem that the area of the device is large is solved.

Description

Laser drive circuit and laser device

Technical Field

The utility model relates to a time of flight range finding technical field, in particular to laser instrument drive circuit and laser equipment.

Background

With the continued development of Time of flight (TOF) technology, Time of flight sensors may be applied to implement the TOF technology.

Specifically, a light pulse may be emitted by a time-of-flight sensor, the light pulse may be reflected after encountering an object, the time-of-flight sensor may receive the reflected light pulse, and the distance information between the object and the emitted light pulse and the reflected light pulse may be determined.

During use of the time-of-flight sensor, the laser emitting the light pulses within the time-of-flight sensor will be driven by means of a drive circuit.

For the driving circuit, the driving circuit includes an input tube and a laser, the input tube is used for inputting an input signal related to the optical pulse, and a tail current tube is often used for providing a current flowing through the input tube, so as to finally drive the laser.

However, the size of the tail current tube often determines the size of the tail current, and the size of the tail current can influence the driving capability of the driving laser, so that the size of the tail current tube is often larger, and the area of the device is increased on the whole.

Therefore, there is a technical problem that the device area is large when the time-of-flight sensor is used.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a laser instrument drive circuit and laser equipment aims at solving the great technical problem of device area that exists when using the time of flight sensor.

In order to achieve the above object, the present invention provides a laser driving circuit, which includes a first N-channel metal-oxide-semiconductor field effect transistor MOS transistor, a second N-channel MOS transistor, and a current mirror;

the drain electrode of the first N-channel MOS tube is connected with the negative electrode of a preset laser, and the positive electrode of the preset laser is connected with a preset power supply;

the drain electrode of the first N-channel MOS tube is connected with the current output end of the current mirror;

the grid electrode of the first N-channel MOS tube is used for acquiring a preset direct-current voltage signal;

the source electrode of the first N-channel MOS tube is connected with the drain electrode of the second N-channel MOS tube, and the source electrode of the second N-channel MOS tube is grounded;

and the grid electrode of the second N-channel MOS tube is used for acquiring a logic CML signal in a preset current mode.

Preferably, the gate of the second N-channel MOS transistor is configured to switch to a conducting state when the preset CML signal is a conducting signal;

the drain electrode of the first N-channel MOS tube is used for outputting modulation current to the cathode of the preset laser when the second N-channel MOS tube is in a conducting state;

the current output end of the current mirror is used for outputting bias current to the cathode of the preset laser;

and the negative electrode of the preset laser is used for obtaining the modulation current and the bias current.

Preferably, the drain of the first N-channel MOS transistor is configured to adjust a current value of the modulation current to a current value corresponding to a preset voltage value when the preset dc voltage signal is the preset voltage value, and output the adjusted modulation current to a negative electrode of the preset laser.

Preferably, the gate of the second N-channel MOS transistor is configured to switch to an off state when the preset CML signal is an off signal;

and the negative electrode of the preset laser is used for obtaining the bias current.

Preferably, the current mirror comprises a third N-channel MOS transistor, a fourth N-channel MOS transistor and a preset current source;

the negative electrode of the preset laser is respectively connected with the drain electrode of the third N-channel MOS tube and the grid electrode of the third N-channel MOS tube, and the source electrode of the third N-channel MOS tube is grounded;

the grid electrode of the third N-channel MOS tube is connected with the grid electrode of the fourth N-channel MOS tube, and the source electrode of the fourth N-channel MOS tube is connected with the source electrode of the third N-channel MOS tube;

and the drain electrode of the fourth N-channel MOS tube is connected with the first end of the preset current source, and the second end of the preset current source is connected with the preset power supply.

Preferably, the laser driving circuit further comprises a differential circuit, and the differential circuit is connected with the gate of the second N-channel MOS transistor;

and the differential circuit is used for outputting the preset CML signal.

Preferably, the parasitic capacitance of the first N-channel MOS transistor is smaller than that of the second N-channel MOS transistor.

Preferably, the width-to-length ratio of the first N-channel MOS transistor is smaller than the width-to-length ratio of the second N-channel MOS transistor, and the width-to-length ratio is a ratio of the width to the length.

Preferably, the lengths of the first N-channel MOS transistor and the second N-channel MOS transistor are the same.

In order to achieve the above object, the present invention further provides a laser device, which includes a preset laser and the laser driving circuit;

the preset laser is connected with the laser driving circuit.

The utility model discloses in will set up first N channel MOS pipe, second N channel MOS pipe and current mirror and come the final drive and predetermine the operation of laser instrument. Specifically, the drain electrode of the first N-channel MOS tube is connected with the negative electrode of a preset laser, and the positive electrode of the preset laser is connected with a preset power supply; the drain electrode of the first N-channel MOS tube is connected with the current output end of the current mirror; the grid electrode of the first N-channel MOS tube is used for acquiring a preset direct-current voltage signal; the source electrode of the first N-channel MOS tube is connected with the drain electrode of the second N-channel MOS tube, and the source electrode of the second N-channel MOS tube is grounded; and the grid electrode of the second N-channel MOS tube is used for acquiring a preset CML signal. Therefore, the second N-channel MOS tube, namely the input tube, is not a tail current tube, and does not run through tail current, so that the situation that the size is large due to the use of the tail current tube is avoided, and the area of a device is correspondingly reduced, and the technical problem that the area of the device is large is solved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic circuit diagram of a laser driving circuit according to an embodiment of the present invention.

The reference numbers illustrate:

reference numerals	Name (R)	Reference numerals	Name (R)
				M1	First N-channel MOS tube	100	Current mirror
M2	Second N-channel MOS tube	M3	Third N-channel MOS tube
				L1	Preset laser	M4	Fourth N-channel MOS tube
VDD	Preset power supply	C1	Preset current source

The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

It should be noted that, if directional indications (such as upper, lower, left, right, front and rear … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description relating to "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

The utility model provides a laser drive circuit, wherein, figure 1 is the utility model discloses the circuit structure schematic diagram of a laser drive circuit embodiment.

Referring to fig. 1 in detail, the laser driving circuit includes a first N-channel Metal-Oxide-Semiconductor field effect transistor (MOS) M1, a second N-channel MOS M2, and a current mirror 100;

the drain electrode of the first N-channel MOS tube M1 is connected with the negative electrode of a preset laser L1, and the positive electrode of the preset laser L1 is connected with a preset power supply VDD;

the drain electrode of the first N-channel MOS transistor M1 is connected to the current output terminal of the current mirror 100;

the grid electrode of the first N-channel MOS transistor M1 is used for acquiring a preset direct-current voltage signal;

the source electrode of the first N-channel MOS tube M1 is connected with the drain electrode of the second N-channel MOS tube M2, and the source electrode of the second N-channel MOS tube M2 is grounded;

and the gate of the second N-channel MOS transistor M2 is configured to obtain a preset current mode logic CML signal.

It is understood that the present embodiment provides a laser driving circuit for the preset laser L1, so that the preset laser L1 can emit light pulses, and the TOF technique is applicable.

It should be understood that, when the laser driving circuit drives the preset laser L1, the first N-channel MOS transistor M1 is a control transistor, and obtains a preset dc voltage signal, which can be provided by a preset voltage source and can be denoted as Vctrl; the second N-channel MOS transistor M2 is an input transistor, and acquires a Current Mode Logic (CML) signal, where the CML signal carries modulation information to set an optical pulse emitted by the preset laser L1, and the CML signal may be denoted as Vin. It can be seen that the second N-channel MOS transistor M2, i.e. the input transistor, in the laser driving circuit is not a tail current transistor.

In a specific implementation, the current flowing through the second N-channel MOS transistor M2 may be referred to as a modulation current Imod, and it is found that Imod in this embodiment is not provided by a tail current. When the second N-channel MOS transistor M2 is turned on, the current flowing through the second N-channel MOS transistor M2 is generated by a circuit branch of "VDD-L1-first M1-second M2", not by the tail current transistor, and the tail current is not used here. Obviously, when no large size tail current tube is introduced to provide Imod, there is, of course, a corresponding reduction in overall area.

In the present embodiment, a first N-channel MOS transistor M1, a second N-channel MOS transistor M2, and a current mirror 100 are provided to finally drive the operation of the preset laser L1. Specifically, the drain of the first N-channel MOS transistor M1 is connected to the negative electrode of the preset laser L1, and the positive electrode of the preset laser L1 is connected to the preset power supply VDD; the drain electrode of the first N-channel MOS tube M1 is connected with the current output end of the current mirror 100; the grid electrode of the first N-channel MOS tube M1 is used for acquiring a preset direct-current voltage signal; the source electrode of the first N-channel MOS tube M1 is connected with the drain electrode of the second N-channel MOS tube M2, and the source electrode of the second N-channel MOS tube M2 is grounded; and the gate of the second N-channel MOS transistor M2 is configured to obtain the preset CML signal Vin. Therefore, the second N-channel MOS transistor M2, i.e., the input transistor, is not a tail current transistor, and does not operate through a tail current, so that the situation that the size is large due to the use of the tail current transistor is avoided, and the area of the device is correspondingly reduced, thereby solving the technical problem of large area of the device.

Further, the gate of the second N-channel MOS transistor M2 is configured to switch to a conducting state when the preset CML signal Vin is a conducting signal;

the drain of the first N-channel MOS transistor M1 is configured to output a modulation current to the cathode of the preset laser L1 when the second N-channel MOS transistor M2 is in a conducting state;

a current output end of the current mirror 100 is configured to output a bias current to a negative electrode of the preset laser L1;

and the negative electrode of the preset laser L1 is used for obtaining the modulation current and the bias current.

It is understood that the conducting signal may be a high level signal, and when the input preset CML signal Vin is a high level signal, the second N-channel MOS transistor M2 is in a conducting state, the branch is a path through which a current passes, and the passing current is the modulation current Imod. The current given by the current mirror 100 is denoted as the bias current IBias 2.

Further, for ease of understanding, the circuit node at the negative electrode of the preset laser L1 may be denoted as a.

It should be appreciated that when the second N-channel MOS transistor M2 is in the on state, the current at the circuit node a is the sum of the modulation current Imod and the bias current IBias 2.

Of course, the current flowing through the preset laser L1 can also be referred to as the driving current Ivcsel, so that here, Ivcsel is Imod + IBias 2. Therefore, it can be considered that the positive pole of the laser L1 is preset for obtaining the modulation current and the bias current.

Further, the drain of the first N-channel MOS transistor M1 is configured to adjust the current value of the modulation current to a current value corresponding to a preset voltage value when the preset dc voltage signal is the preset voltage value, and output the adjusted modulation current to the negative electrode of the preset laser L1.

It can be understood that, when the second N-channel MOS transistor M2 is in the on state and the preset dc voltage signal Vctrl is at the preset voltage value, the modulation current Imod exists, and the larger the preset voltage value is, the larger the current value of the modulation current Imod is. Therefore, the current value of the modulation current Imod may be adjusted by adjusting the preset voltage value.

It should be understood that, since the larger the driving current Ivcsel, the stronger the driving capability of the laser driving circuit, the adjusting of the preset voltage value can further adjust the driving capability. By increasing the current value of the modulation current Imod, the driving current Ivcsel can be increased, and finally the driving capability of the laser driving circuit can be enhanced.

Further, the gate of the second N-channel MOS transistor M2 is configured to switch to an off state when the preset CML signal Vin is an off signal;

and the negative electrode of the preset laser L1 is used for obtaining the bias current.

It is understood that the off signal may be a low level signal, and when the input preset CML signal Vin is a low level signal, the second N-channel MOS transistor M2 is in an off state, the second N-channel MOS transistor M2 is turned off, no current flows through the second N-channel MOS transistor M2, and the modulation current Imod passing through the first N-channel MOS transistor M1 and the second N-channel MOS transistor M2 is equal to 0. As can be seen, the preset CML signal Vin can control whether the second N-channel MOS transistor M2 is turned on or off, so as to control whether the modulation current Imod exists or not.

It should be understood that when the second N-channel MOS transistor M2 is in the off state, the current at the circuit node a is only the bias current IBias 2. Therefore, the drive current Ivcsel is IBias 2.

It can be seen that, when the second N-channel MOS transistor M2 is in the on state, the driving current Ivcsel is Imod + IBias2, which is the maximum value of the driving current; when the second N-channel MOS transistor M2 is in the off state, the driving current Ivcsel is IBias2, which is the minimum value of the driving current. Therefore, the modulation current flowing through the preset laser L1 is the difference between the maximum value of the driving current and the minimum value of the driving current, i.e., the modulation current Imod; the bias current flowing through the preset laser L1 is the minimum value of the drive current, here the bias current IBias 2.

Therefore, the cooperative work of the first N-channel MOS transistor M1 and the second N-channel MOS transistor M2 can change the current value of the driving current Ivcsel, thereby playing a role in regulating and controlling the driving capability. The driving capability is adjusted through the first N-channel MOS transistor M1 and the second N-channel MOS transistor M2, and the adjustment flexibility is also provided.

Further, the current mirror 100 includes a third N-channel MOS transistor M3, a fourth N-channel MOS transistor M4, and a preset current source C1;

the negative electrode of the preset laser L1 is respectively connected to the drain of the third N-channel MOS transistor M3 and the gate of the third N-channel MOS transistor M3, and the source of the third N-channel MOS transistor M3 is grounded;

the gate of the third N-channel MOS transistor M3 is connected to the gate of the fourth N-channel MOS transistor M4, and the source of the fourth N-channel MOS transistor M4 is connected to the source of the third N-channel MOS transistor M3;

the drain of the fourth N-channel MOS transistor M4 is connected to the first end of the preset current source C1, and the second end of the preset current source C1 is connected to the preset power supply VDD.

It can be understood that the current mirror 100 is formed by the third N-channel MOS transistor M3 and the fourth N-channel MOS transistor M4, and the purpose of the current mirror is to copy the current source current IBias1 at the preset current source C1 to the left branch of the current mirror 100 in a preset proportion, that is, to obtain the bias current IBias 2.

In addition, the present embodiment does not limit the specific circuit structure of the predetermined current source C1, and the bias current IBias2 is a constant value.

It should be noted that the bias current IBias2 is obtained from the current mirror 100, and the third N-channel MOS transistor M3 is a tail current transistor, so the bias current IBias2 is a tail current provided by the tail current transistor. However, the input tube side in this embodiment is not implemented by the tail current tube providing the tail current, so the device area at the input tube is still reduced.

Further, the laser driving circuit further comprises a differential circuit, and the differential circuit is connected with the gate of the second N-channel MOS transistor M2;

the differential circuit is used for outputting the preset CML signal Vin.

In a specific implementation, the preset CML signal Vin obtained at the gate of the second N-channel MOS transistor M2 may be output by a previous stage circuit, for example, the previous stage circuit may be a differential circuit, and the differential circuit may output the preset CML signal Vin. The CML signal Vin is preset to have two states, i.e., a high level signal and a low level signal.

Further, the parasitic capacitance of the first N-channel MOS transistor M1 is smaller than that of the second N-channel MOS transistor M2.

It should be understood that, in the circuit structure of the laser driving circuit described in this embodiment, the parasitic capacitance of the first N-channel MOS transistor M1 may be set to be smaller than the parasitic capacitance of the second N-channel MOS transistor M2. Since the parasitic capacitance is a direct factor causing the bandwidth reduction of the current signal, the larger the parasitic capacitance, the lower the bandwidth, and by setting the parasitic capacitance of the first N-channel MOS transistor M1 smaller than the parasitic capacitance of the second N-channel MOS transistor M2, the first N-channel MOS transistor M1 can isolate the influence of the larger parasitic parameter caused by the second N-channel MOS transistor M2 on the bandwidth, thereby avoiding the bandwidth reduction too much.

It will be appreciated that excessive bandwidth reduction is avoided, substantially increasing bandwidth and increasing operating speed.

Further, the width-to-length ratio of the first N-channel MOS transistor M1 is smaller than that of the second N-channel MOS transistor M2, and the width-to-length ratio is a ratio of width to length.

In a specific implementation, the parameters of the MOS transistors include a width-to-length ratio, i.e., a ratio of the width to the length, and the width-to-length ratio of the first N-channel MOS transistor M1 may be set to be smaller than that of the second N-channel MOS transistor M2. By setting the width-to-length ratio of the first N-channel MOS transistor M1 to be smaller than the width-to-length ratio of the second N-channel MOS transistor M2, the size of the first N-channel MOS transistor M1 is smaller than the size of the second N-channel MOS transistor M2, and in view of the fact that the larger the size is, the larger the parasitic capacitance is, the parasitic capacitance of the first N-channel MOS transistor M1 may be caused to be smaller than that of the second N-channel MOS transistor M2. Thus, excessive bandwidth reduction can be avoided.

Further, the first N-channel MOS transistor M1 and the second N-channel MOS transistor M2 have the same length.

In a specific implementation, the width of the first N-channel MOS transistor M1 may be 2240um, and the length may be 0.35 um; the width of the second N-channel MOS transistor M2 may be 3600um, and the length may be 0.35 um. It can be seen that the lengths of the first N-channel MOS transistor M1 and the second N-channel MOS transistor M2 can be set to be the same.

It can be understood that, here, the width-to-length ratio of the first N-channel MOS transistor M1 is 2240um/0.35um, and the width-to-length ratio of the second N-channel MOS transistor M2 is 3600um/0.35 um. The width to length ratio can be recorded as W/L.

Further, the first N-channel MOS transistor M1 has a modulation effect on the modulation current Imod in addition to isolating the influence of the parasitic capacitance of the second N-channel MOS transistor M2 on the electrical node a. In addition, only the first N-channel MOS transistor M1, the third N-channel MOS transistor M3 and the fourth N-channel MOS transistor M4 at the electrical node a introduce parasitic capacitance to cause bandwidth reduction, and the simple structure also causes the parasitic capacitance to be small, reduces the bandwidth reduction and improves the speed.

The utility model also provides a laser equipment, this electronic equipment is including predetermineeing laser instrument L1 and above-mentioned laser instrument drive circuit, and this laser instrument drive circuit's concrete structure refers to above-mentioned embodiment, because this laser equipment has adopted the whole technical scheme of above-mentioned all embodiments, consequently has all beneficial effects that the technical scheme of above-mentioned embodiment brought at least, and the repeated description is no longer given here.

Wherein the preset laser L1 is connected with the laser driving circuit.

The laser device may be a time-of-flight sensor.

The above only be the preferred embodiment of the utility model discloses a not consequently restriction the utility model discloses a patent range, all are in the utility model discloses a conceive, utilize the equivalent structure transform of what the content was done in the description and the attached drawing, or direct/indirect application all is included in other relevant technical field the utility model discloses a patent protection within range.

Claims

1. A laser driving circuit is characterized by comprising a first N-channel metal-oxide-semiconductor field effect transistor (MOS) tube, a second N-channel MOS tube and a current mirror;

2. The laser driving circuit as claimed in claim 1, wherein the gate of the second N-channel MOS transistor is configured to switch to a conducting state when the CML signal is a conducting signal;

3. The laser driving circuit according to claim 2, wherein the drain of the first N-channel MOS transistor is configured to adjust a current value of the modulation current to a current value corresponding to a preset voltage value when the preset dc voltage signal is the preset voltage value, and output the adjusted modulation current to a negative electrode of the preset laser.

4. The laser driving circuit according to claim 1, wherein the gate of the second N-channel MOS transistor is configured to switch to an off state when the CML signal is an off signal;

5. The laser driving circuit according to any one of claims 1 to 4, wherein the current mirror comprises a third N-channel MOS transistor, a fourth N-channel MOS transistor and a preset current source;

6. The laser driving circuit according to any one of claims 1 to 4, further comprising a differential circuit connected to a gate of the second N-channel MOS transistor;

and the differential circuit is used for outputting the preset current mode logic CML signal.

7. The laser driving circuit according to any one of claims 1 to 4, wherein the parasitic capacitance of the first N-channel MOS transistor is smaller than the parasitic capacitance of the second N-channel MOS transistor.

8. The laser driving circuit as claimed in claim 7, wherein the width-to-length ratio of the first N-channel MOS transistor is smaller than the width-to-length ratio of the second N-channel MOS transistor, and the width-to-length ratio is a ratio of width to length.

9. The laser driver circuit of claim 8, wherein the first N-channel MOS transistor and the second N-channel MOS transistor are the same length.

10. A laser device comprising a preset laser and a laser driving circuit according to any one of claims 1 to 9;

the preset laser is connected with the laser driving circuit.