CN114355369A - Active quenching and resetting circuit and detection system - Google Patents
Active quenching and resetting circuit and detection system Download PDFInfo
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- CN114355369A CN114355369A CN202011039851.9A CN202011039851A CN114355369A CN 114355369 A CN114355369 A CN 114355369A CN 202011039851 A CN202011039851 A CN 202011039851A CN 114355369 A CN114355369 A CN 114355369A
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Abstract
The present application provides an active quench and reset circuit, comprising: the single-photon avalanche diode is used for receiving an optical signal and generating avalanche current; the initialization module is used for initializing the single-photon avalanche diode; the reset module is used for resetting the single-photon avalanche diode; the clamping module is used for clamping the single photon avalanche diode; and the threshold detection unit is used for detecting the cathode voltage of the single photon avalanche diode, feeding back the detected signal to the reset module and controlling the reset module to be started. The beneficial effect of this application is: the threshold detection unit is arranged to adjust the reset time of the reset module, so that the SPAD can be rapidly quenched and reset, and when the threshold detection module detects that the voltage is reduced below the threshold, the reset module is controlled to reset, so that the quenching and the resetting can be adaptively adjusted.
Description
Technical Field
The present disclosure relates to the field of active quenching and reset circuits, and more particularly, to an active quenching and reset circuit and a probing system.
Background
Time of flight (TOF) is a method of finding a distance to an object by continuously transmitting light pulses to the object, receiving light returning from the object with a sensor, and detecting the Time of flight (round trip) of the light pulses.
Direct Time of flight (DTOF) is one of TOF, and the DTOF technology directly obtains the target distance by calculating the transmitting and receiving Time of an optical pulse, and has the advantages of simple principle, good signal-to-noise ratio, high sensitivity, high accuracy and the like, and receives more and more attention.
Generally, in some DTOF ranging applications, a photo detector array including a Single Photon detector (e.g., a Single Photon) may be used to perform a sensing Avalanche Diode (SPAD) array of reflected radiation. The one or more photodetectors may define detector pixels of the array. SPAD arrays can be used as solid-state photodetectors in imaging applications where high sensitivity and timing resolution may be required. SPADs are based on semiconductor junctions (e.g., p-n junctions) that can detect incident photons, for example, when biased outside of their breakdown region by or in response to a strobe signal having a desired pulse width. A high reverse bias voltage will generate an electric field of sufficient magnitude that a single charge carrier introduced into the depletion layer of the device can cause a self-sustaining avalanche by impact ionization. The avalanche can be quenched, either actively (e.g., by lowering the transistor bias voltage) or passively (e.g., by using the voltage drop across a series resistance) by a quenching circuit to "reset" the device to further detect photons. This single photon detection mode of operation is commonly referred to as the "geiger mode". Quenching and resetting in a general quenching circuit have no self-adaptive function, and the quenching and resetting for the SPAD array needs to wait for a period of time before resetting, so that the speed of ranging is limited.
Disclosure of Invention
An object of the present application is to provide an active quenching and reset circuit and a detection system, so as to solve the problem of too long recovery time of the existing active quenching and reset circuit.
In order to achieve the above purpose, the technical solutions adopted in the embodiments of the present application are as follows:
in a first aspect, an embodiment of the present application provides an active quenching and reset circuit, including: the single-photon avalanche diode is used for receiving an optical signal and generating avalanche current; the initialization module is used for initializing the single-photon avalanche diode; the reset module is used for resetting the single-photon avalanche diode; the clamping module is used for clamping the single photon avalanche diode; and the threshold detection unit is used for detecting the cathode voltage of the single photon avalanche diode, feeding back the detected signal to the reset module and controlling the reset module to be started.
Optionally, the method further comprises: and the selection module is used for controlling the starting of the single photon avalanche diode.
Optionally, the reset module and the clamp module are respectively connected to different power supplies. The threshold value of the threshold value detection unit is adjustable.
Optionally, the initialization module is connected to the same power supply as the reset module.
In a second aspect, an embodiment of the present application provides a detection system, including: a pixel module and peripheral circuitry, the pixel module consisting of at least one pixel, the peripheral circuitry for reading signals in the pixel module, the pixel comprising: the single-photon avalanche diode is used for receiving an optical signal and generating avalanche current; the initialization module is used for initializing the single-photon avalanche diode; the reset module is used for resetting the single-photon avalanche diode; the clamping module is used for clamping the single photon avalanche diode; and the threshold detection unit is used for detecting the cathode voltage of the single photon avalanche diode, feeding back the detected signal to the reset module and controlling the reset module to be started.
Optionally, the pixel further comprises: and the selection module is used for controlling the starting of the single photon avalanche diode.
Optionally, the reset module and the clamp module are respectively connected to different power supplies.
Optionally, the threshold of the threshold detection unit is adjustable.
Optionally, the initialization module and the reset module are connected to the same power supply.
The beneficial effect of this application is: the threshold detection unit is arranged to adjust the reset time of the reset module, so that the SPAD can be rapidly quenched and reset, and when the threshold detection module detects that the voltage is reduced below the threshold, the reset module is controlled to reset, so that the quenching and the resetting can be adaptively adjusted. And the active quenching and resetting circuit provided by the application can also selectively control the opening of the SPAD, so that in the array, when some pixels do not need to work, the pixels can be controlled to be turned off, and the power consumption of the image sensor is reduced.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 is a structural diagram of an image sensor provided in an embodiment of the present application;
fig. 2 is a structural diagram of an active quenching and reset circuit according to an embodiment of the present disclosure;
FIG. 3 is a block diagram of yet another active quench and reset circuit provided in an embodiment of the present application;
fig. 4 is a circuit diagram of an active quench and reset circuit provided in an embodiment of the present application;
fig. 5 is a flowchart illustrating an operation of an active quench and reset circuit according to an embodiment of the present application;
FIG. 6 is a timing diagram of an active quench and reset circuit according to an embodiment of the present application;
fig. 7 is a circuit diagram of another active quench and reset circuit provided in an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
As shown in fig. 1, in general, the image sensor 100 includes a pixel region, i.e., a pixel portion 101 and peripheral circuits, including a pixel driving portion 102 and a pixel readout portion 103, the pixel portion 101 includes pixel units arranged in an array, the pixel portion 101 is configured to receive a light signal and generate a photo-generated electrical signal, the pixel driving portion 102 is configured to drive the pixel portion 101 to read the photo-generated electrical signal, the photo-generated electrical signal is finally read out to the pixel readout portion 103, and the pixel readout portion 103 processes the received photo-generated electrical signal.
For example, the pixel portion may include an array of SPAD devices, that is, each SPAD constitutes a pixel unit, and the SPADs arranged in the array constitute the pixel portion. The pixel unit is composed of the structure shown in fig. 2.
Next, the structure of the pixel provided in the present application is described in detail with reference to fig. 2. As shown in fig. 2, the active quench and reset circuit provided by the present application includes: an initialization module 201, a reset module 202, a clamping module 203, a threshold detection unit 204, and a single photon avalanche diode 205.
In the circuit, the initialization module 201 initializes the single photon avalanche diode 205 after power-on, that is, the single photon avalanche diode 205 is in a state capable of detecting photons, and the cathode voltage is the breakdown voltage Vbr of the single photon avalanche diode 205 and the overvoltage VEB applied thereon to make the single photon avalanche diode operate in the geiger mode.
The reset module 202 is configured to reset the single photon avalanche diode 205 after avalanche breakdown, so that the single photon avalanche diode 205 can be in a state capable of detecting photons again, where the reset module 202 detects a cathode voltage of the single photon avalanche diode 205 through the threshold detection unit 204, and when the cathode voltage of the single photon avalanche diode 205 reaches an inversion threshold of the threshold detection unit 204, the reset module 202 is triggered to reset, so that active reset of the single photon avalanche diode 205 can be achieved.
The clamping module 203 is configured to clamp the single photon avalanche diode 205 after avalanche breakdown, so that the cathode voltage of the single photon avalanche diode 205 after avalanche breakdown is not reduced to near the zero voltage, that is, after avalanche breakdown occurs, the clamping module 203 can set the cathode voltage of the single photon avalanche diode 205 after avalanche breakdown to a voltage lower than the reset voltage, which can cause the threshold detection unit 204 to turn over, so that when the single photon avalanche diode 205 generates breakdown current due to avalanche breakdown, the cathode voltage is the clamping voltage, and the reset module 202 increases the cathode voltage of the single photon avalanche diode 205 based on the clamping voltage to complete reset, so that the single photon avalanche diode 205 is in the state of a photon to be detected again. The working flow of the circuit will be described in detail below, and will not be described herein.
Therefore, the active quenching and resetting circuit provided by the application can rapidly and adaptively quench and reset the single photon avalanche diode 205, and improves the speed of active quenching.
It should be noted that the power supply voltage of the initialization module 201 and the reset module 202 may be a first voltage, the power supply voltage of the clamping module 203 may be a second voltage, and the first voltage and the second voltage are two different voltage values.
Further, the active quenching and reset circuit provided by the present application may further include a selection module 306, as shown in fig. 3, where the selection module 306 is used to control the on and off of the single photon avalanche diode 305. That is, when the selection module 306 is turned off, the single photon avalanche diode 305 is turned on, the reset module 302 and the control single photon avalanche diode 305 form a current path, and similarly, the clamping module 303 and the control single photon avalanche diode 305 also form a current path, and at this time, the threshold detection unit detects the cathode voltage of the single photon avalanche diode 305 and performs reset control. Accordingly, when the selection module is turned on, the single photon avalanche diode 305 path is turned off, the clamping module 303 and the selection module 306 form a current path, that is, the single photon avalanche diode 305 is bypassed, and the quenching and resetting circuit provided by the present application does not work. The rest of the working principle is similar to that of the above-mentioned fig. 2, and the description is omitted here.
Therefore, the active quenching and resetting circuit structure provided by the application also has a pixel control function, namely whether the pixel is in a state of detecting photons is controlled, and if the pixel is turned off, the pixel is not in the state of detecting photons, so that the power consumption of the pixel circuit is further reduced.
It should be noted that the power supply voltage of the initialization module 301 and the reset module 302 may be a first voltage, the power supply voltage of the clamping module 303 may be a second voltage, and the first voltage and the second voltage are two different voltage values.
In the following, referring to fig. 4, a P-Type Metal Oxide Semiconductor (PMOS) is taken as an initialization module, the PMOS is taken as a reset module, the PMOS is taken as a clamp module, and the reverse schmitt trigger plus inverter is taken as a threshold detection module as an example, and the working flow and the working principle of the pixel circuit provided by the present application are described in detail with reference to fig. 5.
S1, initialize the SPAD to enter the state to be detected.
As shown in fig. 4, when power is turned on, por _ H is low, the initialization module MP1 is turned on, SPAD is initialized, and the state to be detected is entered.
SPAD initialization means that the cathode voltage of the SPAD is set for the first time to a voltage that allows it to operate in geiger mode, which in this application may be the sum of the breakdown voltage Vb of the SPAD and the overvoltage, i.e. VOV.
Note that, in the embodiment of the present application, the anode voltage of the SPAD is connected to the ground voltage.
S2, SPAD detects the photon and avalanche breaks down, and the clamping module clamps the cathode voltage.
When the SPAD detects a photon and avalanche breakdown occurs, the clamping module MPQ is turned on, charging up through the transistor like the cathode node a of the SPAD until the voltage at node a is set to Vb.
It should be noted that the gate voltage of the clamping module MPQ can be controlled by the output of the SPAD circuit. Specifically, when the SPAD circuit detects photons and avalanche breakdown occurs, the output signal controls the clamping module MPQ to be turned on and charge the point A.
And S3, a threshold detection module detects the anode voltage of the SPAD and starts a reset module to reset.
Further, as the voltage at point a decreases, the threshold voltage detection module, i.e., the schmitt trigger shown in fig. 4, flips, the transistor MP2 is turned on by the threshold detection module, and the voltage at point a is raised to VOV by the reset module MP 2.
S4, the SPAD reverts to the state to be detected.
When the cathode voltage of the SPAD is raised to VOV, the SPAD can receive the photons again, i.e. the SPAD is restored to the state to be detected.
It should be noted that the power supply voltage of the initialization module MP1 and the reset module MP2 is VOV, the power supply voltage of the clamping module 303 is Vb, and the two voltages are two different voltage values, for example, VOV may be 22V, and Vb may be 15V.
The timing diagram of the voltage at each node in the circuit is shown in fig. 6, and the principle thereof has been described in detail above, and is not repeated herein.
Optionally, an embodiment of the present application provides another active quenching and resetting circuit, which further includes a selection module, where the selection module is configured to control on and off of the single photon avalanche diode. As shown in fig. 7, the selection block is composed of a transistor MPS and a transistor MNS1, and the transistor MPS in the selection block is connected to the reset block.
When QB is low, the transistors MPS, MPT, and MNT are turned on, the transistors MNS1 and MNS2 are turned off, and the SPAD operates normally and outputs; when QB is high, the transistors MPS, MPT and MNT are turned off, the transistors MNS1 and MNS2 are turned on, and the SPAD bias is zero at this time, so that photon detection cannot be performed, and the output is in a high-impedance state.
Therefore, the active quenching and resetting circuit provided by the application can also selectively control the opening of the SPAD, so that in the array, when some pixels do not need to work, the pixels can be controlled to be closed, and the power consumption of the image sensor is reduced.
An embodiment of the present application further provides a detection system, including: a pixel module and peripheral circuitry, the pixel module consisting of at least one pixel, the peripheral circuitry for reading signals in the pixel module, the pixel comprising: the single-photon avalanche diode is used for receiving an optical signal and generating avalanche current; the initialization module is used for initializing the single-photon avalanche diode; the reset module is used for resetting the single-photon avalanche diode; the clamping module is used for clamping the single photon avalanche diode; and the threshold detection unit is used for detecting the cathode voltage of the single photon avalanche diode, feeding back the detected signal to the reset module and controlling the reset module to be started.
As an embodiment, the pixel further includes: and the selection module is used for controlling the starting of the single photon avalanche diode.
In another embodiment, the reset module and the clamp module are respectively connected to different power supplies.
As another embodiment, the threshold of the threshold detection unit is adjustable.
In another embodiment, the initialization module is connected to the same power source as the reset module.
The implementation principle and technical effect of the above device are similar to those of the circuit structure described above, and are not described herein again.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. An active quench and reset circuit, comprising:
the single-photon avalanche diode is used for receiving an optical signal and generating avalanche current;
the initialization module is used for initializing the single photon avalanche diode;
the reset module is used for resetting the single photon avalanche diode;
the clamping module is used for clamping the single photon avalanche diode;
and the threshold detection unit is used for detecting the cathode voltage of the single photon avalanche diode, feeding back a detected signal to the reset module and controlling the on and off of the reset module.
2. The active quench and reset circuit of claim 1 further comprising:
and the selection module is used for controlling the on and off of the single photon avalanche diode.
3. The active quench and reset circuit of claim 2 wherein the reset block and the clamp block are each connected to a different power supply.
4. The active quench and reset circuit of claim 3 wherein the threshold detection unit has an adjustable threshold.
5. The active quench and reset circuit of claim 4 wherein the initialization module is connected to the same power supply as the reset module.
6. A detection system, comprising:
a pixel module consisting of at least one pixel and peripheral circuitry for reading signals in the pixel module, the pixel comprising:
the single-photon avalanche diode is used for receiving an optical signal and generating avalanche current;
the initialization module is used for initializing the single photon avalanche diode;
the reset module is used for resetting the single photon avalanche diode;
the clamping module is used for clamping the single photon avalanche diode;
and the threshold detection unit is used for detecting the cathode voltage of the single photon avalanche diode, feeding back a detected signal to the reset module and controlling the reset module to be started.
7. The detection system of claim 6, wherein the pixel further comprises:
and the selection module is used for controlling the starting of the single photon avalanche diode.
8. The detection system of claim 7, wherein the reset module and the clamp module are each connected to a different power source.
9. The detection system of claim 8, wherein the threshold of the threshold detection unit is adjustable.
10. A detection system according to claim 9, wherein the initialization module is connected to the same power supply as the reset module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011039851.9A CN114355369A (en) | 2020-09-28 | 2020-09-28 | Active quenching and resetting circuit and detection system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011039851.9A CN114355369A (en) | 2020-09-28 | 2020-09-28 | Active quenching and resetting circuit and detection system |
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| CN114355369A true CN114355369A (en) | 2022-04-15 |
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| CN202011039851.9A Pending CN114355369A (en) | 2020-09-28 | 2020-09-28 | Active quenching and resetting circuit and detection system |
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