CN110389328B - Pixel unit based on dynamic threshold voltage, photoelectric modulation method and application thereof - Google Patents
Pixel unit based on dynamic threshold voltage, photoelectric modulation method and application thereof Download PDFInfo
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- CN110389328B CN110389328B CN201810337858.5A CN201810337858A CN110389328B CN 110389328 B CN110389328 B CN 110389328B CN 201810337858 A CN201810337858 A CN 201810337858A CN 110389328 B CN110389328 B CN 110389328B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
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Abstract
The invention provides a pixel unit based on dynamic threshold voltage, a photoelectric modulation method and application thereof.A photoelectric conversion module generates photo-generated charge carriers by photoelectric conversion of incident light, wherein the incident light comprises received radiation and background light, and the received radiation comprises laser radiation and the background light; the transmission module is used for respectively storing photo-generated charge carriers generated by laser radiation and background light into two primary nodes through space separation; the threshold controlled transmission module is used for transmitting photo-generated charge carriers generated by laser radiation in the primary node to the secondary node and leaving the photo-generated charge carriers generated by background light in the primary node; the threshold controlled transfer module includes a threshold voltage that is the same as a voltage value of photogenerated charge carriers generated by the background light stored in the primary node. The invention controls the photo-generated charge carriers collected by the primary node through the threshold voltage, removes background light information and improves the background light suppression effect.
Description
Technical Field
The invention belongs to the field of semiconductor devices, and particularly relates to a pixel unit based on dynamic threshold voltage, a photoelectric modulation method and application thereof.
Background
With the development of science and technology, people increasingly and deeply research optics, wherein the laser ranging technology has the advantages of high precision, high measuring speed and the like, and is widely applied to the industry fields of automobiles, artificial intelligence, games, machine vision and the like. The time-of-flight (TOF) ranging method is generally adopted during ranging, the time-of-flight ranging method aims at measuring real-time information and needs to modulate a light source and a high-precision receiver, the principle is that the light source emits modulated light waves, the light irradiates the target and is reflected back, the high-precision receiver receives reflected light, the distance of the target can be calculated by calculating the time of the light emitted to the receiver to receive the reflected light, the light propagation distance is actually twice of the target distance in the process, the light propagation speed is high, so the method has higher requirements on the speed and the sensitivity of the receiver, in addition, the light source and the receiver need to work simultaneously to realize functions, and the TOF ranging method needs to be matched with the light source and the receiver.
In the field of special imaging such as ranging, high dynamic, high frame frequency, and the like, it is generally necessary to perform pixel-level separation on common-mode offsets such as background light, dark current, noise, and the like, and an effective received signal to ensure an optimal image signal-to-noise ratio, but a PPD device, a transmission gate, and a single Tap storage node that are not optimized cannot modulate a received effective optical signal, and a common-mode signal such as background light cannot be separated from a received effective signal, so that high-performance image signal output and application cannot be realized.
Disclosure of Invention
In view of the defects in the prior art, an object of the present invention is to provide a pixel unit, a photoelectric modulation method and an application thereof, which solve the problem in the prior art that the echo signal in the background light is weak so that the background light information cannot be effectively separated during the remote measurement.
In order to solve the technical problems, the invention adopts the following technical scheme:
a photoelectric modulation method based on dynamic threshold voltage comprises the following steps:
generating photo-generated charge carriers by photoelectric conversion of incident light, the incident light including received radiation and background light, the received radiation including laser radiation and background light;
the photo-generated charge carriers generated by the received radiation and the background light are respectively stored into two primary nodes through spatial separation;
transferring photo-generated charge carriers generated by laser radiation in the primary node to the secondary node, and leaving the photo-generated charge carriers generated by background light in the primary node; and a threshold voltage is arranged between the primary node and the secondary node, and the threshold voltage is the same as the voltage value of a photo-generated charge carrier generated by background light stored in the primary node.
Further, the photoelectric conversion occurs in a photoelectric conversion module;
the photo-generated charge carriers are transferred to one of the two primary nodes through the transfer module;
a threshold controlled transmission module is arranged between the primary node and the secondary node;
the transmission module adjusts the on and off of the transmission module through a modulation signal.
Further, the photoelectric conversion module comprises a clamping voltage, the primary node comprises a primary node voltage, and the secondary node comprises a secondary node voltage, wherein the clamping voltage is less than the primary node voltage, and the primary node voltage is less than the secondary node voltage.
Further, the transmission module comprises a primary turn-off voltage and a primary turn-on voltage, the threshold controlled transmission module comprises a secondary turn-off voltage and a threshold voltage, wherein the primary turn-off voltage is the same as the secondary turn-off voltage, and the primary turn-on voltage and the threshold voltage are both greater than the clamping voltage and less than the primary node voltage.
Further, the photo-generated charge carriers stored in the primary node and the secondary node are read by the buffer and converted into voltage values by the buffer, respectively.
Further, the photo-generated charge carriers stored in the primary node are completely extracted through a primary restorer;
the photo-generated charge carriers stored in the secondary nodes are completely extracted through a secondary restorer;
the first-stage restorer is triggered through a first-stage reset signal, and the second-stage restorer is triggered through a second-stage reset signal.
Further, the primary reset signal is triggered by a primary reset voltage, which is greater than the clamping voltage and less than the primary node voltage.
The invention also provides a pixel unit based on the dynamic threshold voltage, which comprises:
a photoelectric conversion module for generating photo-generated charge carriers by photoelectrically converting incident light including received radiation and background light, the received radiation including laser radiation and background light;
the transmission module is used for respectively storing photo-generated charge carriers generated by received radiation and background light into two primary nodes through spatial separation;
the threshold controlled transmission module is used for transmitting photo-generated charge carriers generated by laser radiation in the primary node to the secondary node and leaving the photo-generated charge carriers generated by background light in the primary node; the threshold controlled transfer module includes a threshold voltage that is the same as a voltage value of photogenerated charge carriers generated by background light stored in the primary node.
Further, the transmission module adjusts the on and off of the transmission module through a modulation signal.
Further, the photoelectric conversion module comprises a clamping voltage, the primary node comprises a primary node voltage, and the secondary node comprises a secondary node voltage, wherein the clamping voltage is less than the primary node voltage, and the primary node voltage is less than the secondary node voltage.
Further, the transmission module comprises a primary turn-off voltage and a primary turn-on voltage, the threshold controlled transmission module comprises a secondary turn-off voltage and a threshold voltage, wherein the primary turn-off voltage is the same as the secondary turn-off voltage, and the primary turn-on voltage and the threshold voltage are both greater than the clamping voltage and less than the primary node voltage.
Further, the photo-generated charge carriers stored in the primary node and the secondary node are read by the source follower and are converted into voltage values by the source follower.
Further, the photo-generated charge carriers stored in the primary node are completely extracted through a primary restorer;
the photo-generated charge carriers stored in the secondary nodes are completely extracted through a secondary restorer;
the first-stage restorer is triggered through a first-stage reset signal, and the second-stage restorer is triggered through a second-stage reset signal.
Further, the primary reset signal is triggered by a primary reset voltage, and the primary reset voltage is greater than the clamping voltage and less than the threshold voltage.
Furthermore, the system also comprises N-level nodes, wherein N is a natural number which is more than or equal to 3;
and threshold controlled transmission modules are arranged between the N-level node and the N-1 level node and are used for transmitting photo-generated charge carriers generated by laser radiation to the N-level node and leaving the photo-generated charge carriers generated by background light in the N-1 level node.
The invention also provides an application of photoelectric modulation, and the pixel unit provided by the invention is used for separating common-mode signals from effective signals.
Compared with the prior art, the invention has the following technical effects:
the invention controls the photo-generated charge carriers collected by the primary node through the threshold voltage, removes background light information, and receives laser radiation information in the secondary node as much as possible, thereby improving the background light inhibition effect.
Drawings
FIG. 1 is a schematic view of the overall structure of the apparatus of the present invention.
FIG. 2 is a first example of the operation of the apparatus of the present invention;
FIG. 3 is a second example of the operation of the apparatus of the present invention;
FIG. 4 is a third example of the operation of the apparatus of the present invention;
FIG. 5 is a schematic diagram of modulation signals of a transmission gate and a threshold gate;
FIG. 6 is a schematic diagram of one embodiment of the present invention;
FIG. 7 is a schematic diagram of a pixel cell at a three level node according to one embodiment of the present invention;
FIG. 8 is a schematic diagram of a pixel cell at a three level node according to another embodiment of the present invention.
The present invention will be explained in further detail with reference to the accompanying drawings.
Detailed Description
The following embodiments of the present invention are provided, and it should be noted that the present invention is not limited to the following embodiments, and all equivalent changes based on the technical solutions of the present invention are within the protection scope of the present invention.
The embodiment provides a dynamic threshold voltage-based photoelectric modulation method, which comprises the following steps:
generating photo-generated charge carriers by photoelectric conversion of incident light, the incident light including received radiation and background light, the received radiation including laser radiation and background light;
photo-generated charge carriers generated by received radiation and background light are respectively stored into two primary nodes through spatial separation;
transferring photo-generated charge carriers generated by laser radiation in the primary node to the secondary node, and leaving the photo-generated charge carriers generated by background light in the primary node; a threshold voltage is arranged between the primary node and the secondary node, and the threshold voltage is the same as the voltage value of a photo-generated charge carrier generated by background light stored in the primary node.
The method has the advantages that the quantity of the photo-generated charge carriers in the two primary nodes transferred to the corresponding secondary nodes is controlled, so that the photo-generated charge carriers in the primary nodes with few photo-generated charge carriers are not transferred to the corresponding secondary nodes, the photo-generated charge carriers in the primary nodes are converted by background light, the photo-generated charge carriers in the other primary nodes are converted by the background light and the received laser radiation, the photo-generated charge carriers converted by the background light are basically remained in the primary nodes, and only the photo-generated charge carriers converted by the received laser radiation exist in the secondary nodes, so that the background light and the received laser radiation can be separated. In addition, in the case of long-distance ranging, generally, the radiation received by the pixel unit is very weak, and the background light is stronger than the received radiation, in which case, the difference between the numbers of photo-generated charge carriers in the two primary nodes is very weak, and if the comparison or subtraction is directly performed, the error is larger.
Wherein the photoelectric conversion occurs in the photoelectric conversion module;
the photoelectric conversion module in this embodiment may be any region or device that can convert light into electric charges, and is preferably a clamping photodiode. The primary and secondary nodes are containers, preferably capacitors, that can store charge. The threshold controlled transmission module can be a threshold grid which is a switching device controlled by voltage, such as an MOS tube.
The photo-generated charge carriers are transferred to one of the two primary nodes through the transmission module;
a threshold controlled transmission module is arranged between the first-level node and the second-level node;
the transmission module adjusts the on and off of the transmission module through a modulation signal.
The method has the advantages that the on and off of the transmission module are controlled by the modulation signal, so that when the light incident to the photoelectric conversion module is the received radiation, the transmission module corresponding to the primary node for storing and receiving the radiation is controlled to be on, and the photo-generated charge carriers converted by the received radiation are transferred to the corresponding primary node; when only the background light exists, the other transmission module is controlled to be switched on, so that only the photogenerated charge carriers converted by the background light are stored in the primary node for storing the background light.
The transmission module in this embodiment is a switching device controlled by voltage, preferably a MOS transistor.
As shown in fig. 2, the received radiation is converted into charges on the clamping photodiode, the first transfer gate TX1 and the second transfer gate TX2 are controlled by the modulation signal shown in fig. 5, the first transfer gate TX1 is firstly turned on, at this time, the charges in the clamping photodiode flow into the first primary node FD1 through the first transfer gate TX1, and the first transfer gate TX1 is turned off after a pulse width time;
as shown in fig. 3, according to the control of the modulation signal, the second transfer gate TX2 is turned on, and only the background light received by the photodiode is clamped, so that the charges flow into the second primary node FD2 through the second transfer gate TX2, and the second transfer gate TX2 is turned off after one pulse width;
by arranging the first transmission module and the second transmission module and controlling through the modulation signal, the charges converted by the received radiation in the photoelectric conversion module can be stored in the first primary node, and the charges converted by the background light in the photoelectric conversion module without laser radiation can be stored in the second primary node, so that the spatial separation of the received radiation and the background light for respectively converting the charges is realized.
Because the first transmission module and the second transmission module have the same turn-on time, the charges converted by the received radiation stored in the first primary node contain the charges converted by the background light with the same quantity as that stored in the second primary node, so the invention only needs to use the charges in the first primary node to subtract the charges in the second primary node, thereby realizing the removal of the background light in the received radiation.
The photoelectric conversion module in this embodiment includes a clamping voltage, the primary node includes a primary node voltage, and the secondary node includes a secondary node voltage, where the clamping voltage is less than the primary node voltage, and the primary node voltage is less than the secondary node voltage.
The clamping voltage of the photoelectric conversion module is the clamping voltage of the clamping photodiode, and the primary node voltage and the secondary node voltage are the maximum value of the voltage converted by the charges stored in the capacitor. In this way, it is possible to realize that the photogenerated charge carriers in the photoelectric conversion module can flow into the primary node and the photogenerated charge carriers in the primary node can flow into the secondary node.
In this embodiment, the transmission module includes a primary turn-off voltage and a primary turn-on voltage, and the threshold-controlled transmission module includes a secondary turn-off voltage and a threshold voltage, where the primary turn-off voltage and the secondary turn-off voltage are the same, and the primary turn-on voltage and the threshold voltage are both greater than the clamping voltage and less than the primary node voltage.
As shown in fig. 4, once the second transfer gate TX2 is turned off, the first and second gate TX3 and TX4 are turned on at the same time by setting the on-threshold voltage, so that the charges in the second primary node FD2 do not flow into the second secondary node FD4, and thus the charges in the first primary node FD1 partially flow into the first secondary node FD3, the charges in the first secondary node FD3 substantially do not contain background light, the charges in the second secondary node FD4 only contain very little noise charges, and after one period, the charge difference between the first secondary node FD3 and the second secondary node FD4 is calculated, so that the background light in the received radiation can be accurately separated, and the rest of the noise can be removed.
The laser radiation received by the photoelectric conversion module is often weak during long-distance ranging, so that the charge amount in the two primary nodes is almost the same, the error is large when the charge amount in the two primary nodes is directly subtracted, the charge converted by the background light is left in the primary nodes by setting the threshold voltage of the threshold controlled transmission module, only the charge converted by the laser radiation is transferred to the secondary nodes, and the charge amount in the secondary nodes is taken out for calculation after multiple times of cyclic transfer, so that the charge amount difference between the two secondary nodes is large.
The technical effects are as follows: reducing the error of removing the background light.
Fig. 5 shows on and off control signals of the first and second transmission gates TX1 and TX2, and the first and second gate TX3 and TX 4.
The control signals of the first transmission module and the second transmission module are modulated by the modulation signal emitted by the laser radiation; the rising edges of the control signals of the two threshold-controlled transmission modules are triggered by the falling edges of the control signal of the second transmission module.
The reason for setting the characteristics: since the emission of the laser radiation is modulated by the modulation signal, the control signals of the first transmission module and the second transmission module also need to be modulated by the modulation signal, so that the synchronization with the laser radiation can be performed to separate the background light from the laser radiation.
Fig. 6 shows an embodiment of the present invention, implemented in CMOS.
In this embodiment, the primary node comprises a primary node voltage, and the secondary node comprises a secondary node voltage, wherein the clamping voltage is less than the primary node voltage, and the primary node voltage is less than the secondary node voltage. In fig. 6, the primary nodes are the capacitor FD1 and the capacitor FD2, the secondary nodes are the capacitor FD3 and the capacitor FD4, the voltage of the primary node is VDD1, and the voltage of the secondary node is VDD 2; the clamp voltage is VDD.
In this embodiment, the transmission gate includes a first-level turn-off voltage and a first-level turn-on voltage, and the threshold gate includes a second-level turn-off voltage and a threshold voltage, where the first-level turn-off voltage and the second-level turn-off voltage are the same, and both the first-level turn-on voltage and the threshold voltage are greater than the clamping voltage and less than the first-level node voltage. In this embodiment, the turn-off voltages of the transmission gate and the threshold gate are both 0V, that is, the primary turn-off voltage and the secondary turn-off voltage are 0V; the transmission gates in fig. 6 are MOS transistors TX1 and TX2, the threshold gates are MOS transistors TX3 and TX4, and the turn-on voltages of TX1, TX2, TX3, and TX4 are controlled by an external circuit, so that the primary turn-on voltage and the threshold voltage are both greater than the clamping voltage VDD and less than the primary node voltage VDD 1.
In this embodiment, the threshold voltage is equal to a voltage value converted by the photo-generated charge carriers stored in the primary node having less photo-generated charge carriers stored in the two primary nodes and is greater than the clamp voltage.
The threshold voltage in this embodiment is equal to the voltage of the photogenerated charge carrier conversion for storing the background light conversion, so that the photogenerated charge carrier for the background light conversion is always remained in the primary node, and the photogenerated charge carrier for the laser radiation conversion is transferred to the secondary node each time the threshold gate is turned on.
The present embodiment further includes buffers for reading photo-generated charge carriers stored in the primary node and the secondary node, respectively, and converting them into voltage values, respectively. The buffer in this embodiment may be a source follower, in which the source voltage follows the gate voltage, and the gate is connected to the secondary node or the primary node, so that the source follower may read the voltage converted by the photo-generated charge carriers stored in the primary node or the secondary node.
In FIG. 6, there are 4 source followers M1\ M2\ M3\ M4 respectively to read the voltage values V of two primary nodes FD1\ FD2 and two secondary nodes FD3\ FD4FD1\VFD2\VFD3\VFD4(ii) a Specifically, the source follower is a MOS transistor, the source voltage of which follows the gate voltage, and the gate is connected to the secondary node or the primary node, so that the source follower can read the voltage converted by the photo-generated charge carriers stored in the primary node or the secondary node.
Because the more photo-generated current charge carriers of the background light conversion in the primary node will accumulate, it needs to be cleared. The embodiment also comprises a primary restorer group and a secondary restorer group, wherein the primary restorer group comprises 2 primary restorers, and the 2 primary restorers are respectively used for completely extracting photo-generated charge carriers stored in the primary nodes;
the secondary reset group comprises 2 secondary resets, and the 2 secondary resets are respectively used for carrying out extraction operation on photo-generated charge carriers stored in the secondary nodes.
Wherein, the condition that the first-level restorer resets the first-level node is as follows: the first-stage reset signal is triggered by a first-stage reset voltage, and the first-stage reset voltage is greater than the clamping voltage and less than a first-stage node voltage.
Fig. 1 shows a pixel cell based on a dynamic threshold voltage. The pixel unit comprises a photoelectric conversion module, a light-induced charge carrier generation module and a light-induced charge carrier generation module, wherein the photoelectric conversion module is used for generating photo-generated charge carriers by photoelectric conversion of incident light, the incident light comprises receiving radiation and background light, and the receiving radiation comprises laser radiation and the background light; the transmission module is used for respectively storing photo-generated charge carriers generated by received radiation and background light into two primary nodes through spatial separation; the threshold controlled transmission module is used for transmitting photo-generated charge carriers generated by laser radiation in the primary node to the secondary node and leaving the photo-generated charge carriers generated by background light in the primary node; the threshold controlled transfer module includes a threshold voltage that is the same as a voltage value of photogenerated charge carriers generated by background light stored in the primary node.
In the pixel unit in this embodiment, a node storing a photo-generated charge carrier forms a second-stage separation through the threshold gate, and the on-state voltage of the threshold gate causes the photo-generated charge carrier converted by the background light to be retained in the first-stage node, so that almost no photo-generated charge carrier exists in the second-stage node corresponding to the first-stage node storing the background light, and substantially all the photo-generated charge carrier converted by the laser radiation exists in the second-stage node corresponding to the first-stage node storing the radiation, so that the background light and the laser radiation can be separated.
Further, the transmission module and the threshold controlled transmission module adjust the on and off of the transmission module and the threshold controlled transmission module through modulation signals.
Further, the photoelectric conversion module comprises a clamping voltage, the primary node comprises a primary node voltage, and the secondary node comprises a secondary node voltage, wherein the clamping voltage is less than the primary node voltage, and the primary node voltage is less than the secondary node voltage.
Further, the transmission module comprises a primary turn-off voltage and a primary turn-on voltage, the threshold controlled transmission module comprises a secondary turn-off voltage and a threshold voltage, wherein the primary turn-off voltage is the same as the secondary turn-off voltage, and the primary turn-on voltage and the threshold voltage are both greater than the clamping voltage and less than the primary node voltage.
Further, the photo-generated charge carriers stored in the primary node and the secondary node are read by the buffer and converted into voltage values by the buffer, respectively.
Further, the photo-generated charge carriers stored in the primary node are completely extracted through a primary restorer; the photo-generated charge carriers stored in the secondary node are completely extracted through a secondary restorer; the first-stage restorer is triggered through a first-stage reset signal, and the second-stage restorer is triggered through a second-stage reset signal.
Furthermore, the primary reset signal is triggered by a primary reset voltage, and when the threshold voltage is dynamic, the primary reset voltage is greater than the clamping voltage and less than the threshold voltage; when the threshold voltage is dynamic, the primary reset voltage is greater than the clamp voltage and less than the primary node voltage.
The present embodiment provides a specific structure diagram as shown in fig. 6, wherein the primary nodes are the capacitor FD1 and the capacitor FD2, the secondary nodes are the capacitor FD3 and the capacitor FD4, the voltage of the primary node is VDD1, and the voltage of the secondary node is VDD 2; the clamp voltage is VDD. The transmission gates are MOS transistors TX1 and TX2, the threshold gates are MOS transistors TX3 and TX4, the conduction voltages of TX1, TX2, TX3 and TX4 are controlled by an external circuit, and only the primary conduction voltage and the primary threshold voltage are both larger than a clamping voltage VDD and smaller than a primary node voltage VDD 1. In FIG. 6, there are 4 source followers M1\ M2\ M3\ M4 respectively to read the voltage values V of two primary nodes FD1\ FD2 and two secondary nodes FD3\ FD4FD1\VFD2\VFD3\VFD4(ii) a Specifically, the source follower is a MOS transistor, the source voltage of which follows the gate voltage, and the gate is connected to the secondary node or the primary node, so that the source follower can read the voltage converted by the photo-generated charge carriers stored in the primary node or the secondary node.
The photoelectric conversion module, the transmission module, the primary node, the threshold-controlled transmission module, and the secondary node in this embodiment are integrated on a chip and implemented in a CMOS manner.
The two-stage resetter resets the two-stage node after each cycle.
The pixel unit in this embodiment may further include a multi-level node, and the background light and the laser radiation are separated by the multi-level node, so that only the laser radiation exists in the last-level node.
The system also comprises N-level nodes, wherein N is a natural number more than or equal to 3; fig. 7 and 8 are schematic diagrams of a pixel unit when N is 3. In fig. 7, the node voltages of the primary node and the secondary node are the same, and the node voltage of the tertiary node is greater than the node voltages of the primary node and the secondary node. In fig. 8, the node voltage of the secondary node is greater than the node voltage of the primary node, and the node voltage of the tertiary node is greater than the node voltage of the secondary node.
Threshold controlled transmission modules are arranged between the N-level node and the N-1 level node and used for transmitting photo-generated charge carriers generated by laser radiation to the N-level node and keeping the photo-generated charge carriers generated by background light in the N-1 level node.
The invention also provides an application of photoelectric modulation, and the pixel unit provided by the invention is used for separating common-mode signals from effective signals.
Claims (15)
1. A photoelectric modulation method based on dynamic threshold voltage is characterized by comprising the following steps:
generating photo-generated charge carriers by photoelectric conversion of incident light, the incident light including received radiation and background light, the received radiation including laser radiation and background light;
the photo-generated charge carriers generated by the received radiation and the background light are respectively stored into two primary nodes through spatial separation;
transferring photo-generated charge carriers generated by laser radiation in the primary node to the secondary node, and leaving the photo-generated charge carriers generated by background light in the primary node; and a threshold voltage is arranged between the primary node and the secondary node, and the threshold voltage is the same as the voltage value of a photo-generated charge carrier generated by background light stored in the primary node.
2. The electro-optical modulation method according to claim 1, characterized in that the electro-optical conversion occurs in a photoelectric conversion module;
the photo-generated charge carriers are transferred to one of the two primary nodes through the transfer module;
a threshold controlled transmission module is arranged between the primary node and the secondary node;
the transmission module adjusts the on and off of the transmission module through a modulation signal.
3. The method of claim 2, wherein the photoelectric conversion module comprises a clamp voltage, the primary node comprises a primary node voltage, and the secondary node comprises a secondary node voltage, wherein the clamp voltage is less than the primary node voltage, and the primary node voltage is less than the secondary node voltage.
4. The electro-optic modulation method of claim 3 wherein the transmission module comprises a primary turn-off voltage and a primary turn-on voltage, and the threshold controlled transmission module comprises a secondary turn-off voltage and a threshold voltage, wherein the primary turn-off voltage and the secondary turn-off voltage are the same, and the primary turn-on voltage and the threshold voltage are both greater than the clamping voltage and less than the primary node voltage.
5. The method of claim 1, wherein the photogenerated charge carriers stored in the primary node and the secondary node are read by a buffer and converted into voltage values by the buffer, respectively.
6. The electro-optical modulation method of claim 3 wherein the photogenerated charge carriers stored in the primary node are drained by a primary reset;
the photo-generated charge carriers stored in the secondary nodes are completely extracted through a secondary restorer;
the first-stage restorer is triggered through a first-stage reset signal, and the second-stage restorer is triggered through a second-stage reset signal.
7. The electro-optic modulation method of claim 6 wherein the primary reset signal is triggered by a primary reset voltage that is greater than a clamp voltage and less than a primary node voltage.
8. A dynamic threshold voltage based pixel cell, comprising:
a photoelectric conversion module for generating photo-generated charge carriers by photoelectrically converting incident light including received radiation and background light, the received radiation including laser radiation and background light;
the transmission module is used for respectively storing photo-generated charge carriers generated by received radiation and background light into two primary nodes through spatial separation;
the threshold controlled transmission module is used for transmitting photo-generated charge carriers generated by laser radiation in the primary node to the secondary node and leaving the photo-generated charge carriers generated by background light in the primary node; the threshold controlled transfer module includes a threshold voltage that is the same as a voltage value of photogenerated charge carriers generated by background light stored in the primary node.
9. The pixel cell of claim 8, wherein the transmission module adjusts its on and off by modulating a signal.
10. The pixel cell of claim 9, wherein the photoelectric conversion module comprises a clamp voltage, wherein the primary node comprises a primary node voltage, and wherein the secondary node comprises a secondary node voltage, and wherein the clamp voltage is less than the primary node voltage and the primary node voltage is less than the secondary node voltage.
11. The pixel cell of claim 10, wherein the transfer block comprises a primary off voltage and a primary on voltage, and wherein the threshold controlled transfer block comprises a secondary off voltage and a threshold voltage, wherein the primary off voltage and the secondary off voltage are the same, and wherein the primary on voltage and the threshold voltage are both greater than the clamp voltage and less than the primary node voltage.
12. The pixel cell of claim 8, wherein the photogenerated charge carriers stored in the primary node and the secondary node are read by a source follower and converted to voltage values by the source follower, respectively.
13. The pixel cell of claim 10, wherein photogenerated charge carriers stored in the primary node are drained by a primary reset;
the photo-generated charge carriers stored in the secondary nodes are completely extracted through a secondary restorer;
the first-stage restorer is triggered through a first-stage reset signal, and the second-stage restorer is triggered through a second-stage reset signal.
14. The pixel cell of claim 13, wherein the primary reset signal is triggered by a primary reset voltage, the primary reset voltage being greater than the clamp voltage and less than a threshold voltage.
15. Use of electro-optical modulation, characterized in that the separation of common-mode signals from useful signals is performed by a pixel cell according to any of claims 8 to 14.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810337858.5A CN110389328B (en) | 2018-04-16 | 2018-04-16 | Pixel unit based on dynamic threshold voltage, photoelectric modulation method and application thereof |
| PCT/CN2018/106127 WO2019200831A1 (en) | 2018-04-16 | 2018-09-18 | Signal separation method, pixel unit, and pixel array |
| US16/980,867 US11190721B2 (en) | 2018-04-16 | 2018-09-18 | Signal separation method, pixel unit, and pixel array |
Applications Claiming Priority (1)
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