CN113132659B - Pixel unit, array, image sensor and electronic equipment - Google Patents
Pixel unit, array, image sensor and electronic equipment Download PDFInfo
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- CN113132659B CN113132659B CN202110443167.5A CN202110443167A CN113132659B CN 113132659 B CN113132659 B CN 113132659B CN 202110443167 A CN202110443167 A CN 202110443167A CN 113132659 B CN113132659 B CN 113132659B
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/70—SSIS architectures; Circuits associated therewith
- H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/50—Control of the SSIS exposure
- H04N25/57—Control of the dynamic range
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Abstract
The application provides a pixel cell, array, image sensor and electronic equipment, the pixel cell includes: the gain control circuit comprises a photosensitive circuit, a gain adjusting circuit and a first switch circuit connected between the photosensitive circuit and the gain adjusting circuit; the photosensitive circuit is used for sensing an optical signal and converting the optical signal into an electrical signal; the first switch circuit is used for controlling the connection between the photosensitive circuit and the gain adjusting circuit to be switched on or off according to the size of the optical signal so as to change the signal amplification gain of the photosensitive circuit. Therefore, one frame of HDR image can be obtained through single exposure and single signal acquisition of the pixel unit, and the processing efficiency is improved.
Description
Technical Field
The present disclosure relates to image sensor technologies, and particularly, to a pixel unit, an array, an image sensor, and an electronic device.
Background
In recent years, a Complementary Metal-Oxide-Semiconductor (CMOS) Image Sensor (CIS) has been widely used in various fields such as consumption, industry, medical care, and safety, and the demand for the CIS has been increasing due to a complicated application scenario.
In a commonly used 4T CIS, each pixel unit is composed of 4 transistors and a Photodiode (PD), and the photodiode receives an illumination signal, converts the illumination signal into an electrical signal, and amplifies and outputs the electrical signal via the transistors. In order to capture a High-Dynamic Range (HDR) image, each pixel unit in the CIS needs to perform multiple exposures with different durations or multiple exposures with different gains to acquire a multi-frame image, so that the multi-frame image is output as a frame HDR image by a multi-frame synthesis method, but the efficiency of outputting the HDR image is low due to the multi-exposure method.
Disclosure of Invention
The application provides a pixel unit, an array, an image sensor and an electronic device, which improve the efficiency of outputting HDR images.
In a first aspect, the present application provides a pixel cell comprising: the gain control circuit comprises a photosensitive circuit, a gain adjusting circuit and a first switch circuit connected between the photosensitive circuit and the gain adjusting circuit;
the photosensitive circuit is used for sensing optical signals and converting the optical signals into electric signals;
the first switch circuit is used for controlling the connection between the photosensitive circuit and the gain adjusting circuit to be switched on or off according to the size of the optical signal so as to change the signal amplification gain of the photosensitive circuit.
In one possible implementation, the gain adjustment circuit includes: a second switching circuit and a first capacitor;
one end of the first capacitor is connected with the first switch circuit and the second switch circuit respectively, the other end of the first capacitor is grounded, the second switch circuit is further connected with a power supply and an input end of a first control signal respectively, and the first control signal is used for controlling the second switch circuit to be switched on or switched off.
In one possible embodiment, the second switching circuit includes: a first transistor;
the first end of the first transistor is connected with the first switch circuit, the second end of the first transistor is connected with the power supply, and the third end of the first transistor is connected with the input end of the first control signal.
In one possible embodiment, the first switching circuit includes: a first diode;
the anode of the first diode is connected with the gain adjusting circuit, and the cathode of the first diode is connected with the photosensitive circuit.
In one possible embodiment, the light sensing circuit includes: a photodiode, a second transistor, a third transistor, a fourth transistor, and a fifth transistor;
the anode of the photodiode is grounded, and the cathode of the photodiode is connected with the first end of the second transistor;
a second end of the second transistor is connected with a first end of the third transistor and a third end of the fourth transistor respectively, the third end of the second transistor is connected with an input end of a second control signal, and the second control signal is used for controlling the second transistor to be switched on or switched off;
a second end of the third transistor is connected with a power supply, a third end of the third transistor is connected with an input end of a third control signal, and the third control signal is used for controlling the third transistor to be switched on or switched off;
a first end of the fourth transistor is connected with a second end of the fifth transistor, and a second end of the fourth transistor is connected with a power supply;
the first end of the fifth transistor is an output end of the electric signal, the third end of the fifth transistor is connected with an input end of a fourth control signal, and the fourth control signal is used for controlling the fifth transistor to be switched on or switched off.
In a possible embodiment, the method further comprises: a third switch circuit;
the third switch circuit is connected between the first switch circuit and the photosensitive circuit, the third switch circuit is connected with an input end of a fifth control signal, and the third switch circuit is used for controlling connection on-off between the first switch circuit and the photosensitive circuit according to the fifth control signal.
In one possible embodiment, the third switching circuit includes: a sixth transistor;
the first end of the sixth transistor is connected with the photosensitive circuit, the second end of the sixth transistor is connected with the first switch circuit, and the third end of the sixth transistor is connected with the input end of the fifth control signal.
In a second aspect, the present application provides a pixel array comprising a plurality of pixel units as described in the first aspect or a possible embodiment arranged in a plurality of rows and a plurality of columns.
In a third aspect, the present application provides an image sensor comprising a pixel array as described in the second aspect.
In a fourth aspect, the present application provides an electronic device comprising an image sensor as described in the third aspect.
The application provides a pixel unit, an array, an image sensor and electronic equipment, the pixel unit is according to the light intensity of the incident light of accepting, the size automatically regulated signal amplification gain of the light signal of sensing promptly, thereby can realize in image sensor, every pixel unit all can independently be according to the light signal automatic adjustment gain that separately senses, the signal amplification gain of different pixel units can be different, can obtain a frame HDR image through single exposure and single signal acquisition, need not to carry out many times of exposure and multiframe image synthesis processing, efficiency is improved.
Drawings
In order to more clearly illustrate the embodiments of the present application 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 introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
FIG. 1 is a schematic diagram of a CIS pixel layout;
FIG. 2 is a circuit diagram of a pixel unit with a 4T structure;
FIG. 3 is a circuit diagram of a pixel unit with a 5T structure;
fig. 4 is a first schematic structural diagram of a pixel unit according to an embodiment of the present disclosure;
fig. 5 is a first circuit diagram of a pixel unit according to an embodiment of the present disclosure;
fig. 6 is a circuit characteristic graph of a pixel unit according to an embodiment of the present disclosure;
fig. 7 is a second schematic structural diagram of a pixel unit according to an embodiment of the present disclosure;
fig. 8 is a second circuit diagram of a pixel unit according to 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. 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.
First, a pixel layout of the CIS is explained, as shown in fig. 1, which is a schematic diagram of a pixel layout of the CIS including m × n pixel units, m × n pixel units P in the CISijAre all the same pixel unit, and each pixel unit comprises an independent circuit structure.
The pixel unit generally adopts a 4T structure, and is a circuit diagram of the pixel unit with the 4T structure shown in fig. 2, and as shown in fig. 2, one pixel unit is composed of 4 NMOS transistors (a reset transistor RST0, a transmission transistor TX0, a source follower SF0 and a row selector RS0) and one photodiode PD 0. The photodiode PD0 receives incident light, converts the sensed light signal into a sensing electrical signal, and the sensing electrical signal passes through the transmission tube TX0, completes signal amplification via the source follower SF0, and passes through the row selector RS0 to be output as an output signal Vout 0. The output signal Vout0 can reflect the light intensity of the incident light through algorithm integration, so as to obtain the light intensity information of the corresponding position of the pixel.
As can be seen from the circuit diagram of the 4T-structured pixel unit, the signal amplification gain of the source follower SF0 is fixed, and thus the amplification gain of each pixel unit in the image sensor using the 4T-structured pixel unit is the same. If the HDR function needs to be implemented, multiple frames of images with different exposures need to be taken for synthesis, that is, the above-mentioned optical signal conversion process needs to be performed multiple times, multiple exposures and synthesis of multiple frames of images lead to a long processing time, that is, the efficiency of outputting HDR images is low.
In order to improve the efficiency, it can be considered to improve on the basis of a 4T structure pixel unit to realize the variable gain output of each pixel unit, and fig. 3 is a circuit diagram of a pixel unit with a 5T structure. On the basis of the circuit of the 4T structure shown in fig. 2, a gain control transistor DCG and a capacitor C0 are added. Similar to fig. 2, the photodiode PD0 receives incident light and converts an optical signal into an electrical signal, except that in the process of amplifying and outputting the electrical signal of the photodiode PD0, the gain control transistors DCG of all the pixel units are turned off first to collect an output signal once, and at this time, the amplification gain of the pixel units is high, so that a first high-gain image can be obtained; and then, the gain control transistors DCG of all the pixel units are turned on, so that the capacitor C0 participates in signal output, the signal amplification gain of the pixel units is reduced at the moment, a second output signal is acquired, a second low-gain image is acquired, one-time exposure is realized, images with different brightness are output by using two different gains of all the pixel units, and the images are combined into one frame of HDR image.
Compared with the scheme in fig. 2, the scheme in fig. 3 can reduce the number of exposures, and improve the efficiency of the input HDR image to some extent, but it is still in essence to perform multiple signal acquisitions to obtain multiple frames of images, and then synthesize one frame of HDR image by using the multiple frames of images, so the signal acquisition and image synthesis processing time is still long.
Therefore, the embodiment of the application provides a pixel unit capable of outputting an HDR image by single-exposure single-signal acquisition, and a switching circuit and a gain adjusting circuit are added on the basis of a photosensitive circuit including a photodiode, and the switching circuit can be automatically adjusted to be turned on or off according to the intensity of incident light received by the photodiode, so as to connect or disconnect the gain adjusting circuit to the photosensitive circuit, thereby realizing automatic gain adjustment of the pixel unit. The incident light of each pixel unit can be different according to the actual situation, so that the gain adjustment of each pixel unit is independently and automatically completed without uniform control. Moreover, each pixel can automatically adjust the gain according to the incident light, so that an image formed by single exposure and output of each pixel is a frame HDR image, multiple exposure and multi-frame image synthesis processing are not needed, and the efficiency is improved.
Hereinafter, the pixel unit provided in the present application will be described in detail by specific embodiments. It is to be understood that the following detailed description may be combined with other embodiments, and that the same or similar concepts or processes may not be repeated in some embodiments.
Fig. 4 is a first schematic structural diagram of a pixel unit according to an embodiment of the present disclosure. As shown in fig. 4, the pixel unit includes: a light sensing circuit 41, a gain adjustment circuit 42, and a first switching circuit 43 connected between the light sensing circuit and the gain adjustment circuit.
The light sensing circuit 41 is used for sensing an optical signal and converting the optical signal into an electrical signal.
The first switch circuit 43 is used for controlling the connection between the photosensitive circuit 41 and the gain adjusting circuit 42 to be switched on or off according to the magnitude of the optical signal so as to change the signal amplification gain of the photosensitive circuit 41.
In the embodiment of the present application, the light sensing circuit 41 may include a light sensing element, for example, a photodiode PD, and the light sensing circuit 41 senses a light signal through the light sensing element, amplifies a sensing electrical signal obtained by sensing the light signal by the light sensing element, and then outputs an electrical signal, where the electrical signal may reflect light intensity information of the pixel unit. In the embodiment of the present application, a circuit structure of the photosensitive circuit 41 for amplifying the sensing electrical signal is not specifically limited, and the photosensitive circuit 41 may include any signal amplifying circuit with fixed amplification gain in the prior art, for example, the photosensitive circuit 41 may be a 4T structure circuit shown in fig. 2.
The sensing electrical signal of the sensing element in the light sensing circuit 41 changes with the magnitude of the optical signal (i.e. the magnitude of the light intensity of the incident light), the first switch circuit 43 is connected to the light sensing circuit 41, and the first switch circuit 43 can be controlled to be turned on or off when the sensing electrical signal changes, that is, the first switch circuit 43 can control the connection between the light sensing circuit 41 and the gain adjusting circuit 42 to be turned on or off according to the magnitude of the optical signal.
For example, when the light intensity of the incident light is small, the sensing electrical signal of the sensing element in the light sensing circuit 41 is not enough to turn on the first switch circuit 43, the connection between the light sensing circuit 41 and the gain adjustment circuit 42 is disconnected, the gain adjustment circuit 42 does not participate in the signal conversion process of the light sensing circuit 41, and the signal amplification gain of the light sensing circuit 41 is the inherent signal amplification gain of the circuit structure of the light sensing circuit 41.
For example, when the light intensity of the incident light is larger, the sensing electrical signal of the sensing element in the light sensing circuit 41 turns on the first switch circuit 43, the connection between the light sensing circuit 41 and the gain adjusting circuit 42 is turned on, and the gain adjusting circuit 42 participates in the signal conversion process of the light sensing circuit 41, so that the signal amplification gain of the light sensing circuit 41 is reduced.
It can be seen from the above statements that the pixel units in the embodiments of the present application automatically adjust the signal amplification gain according to the light intensity of the received incident light, that is, the magnitude of the sensed light signal, so that in an image sensor with multiple pixel units, each pixel unit can independently and automatically adjust the gain according to the respective sensed light signal, the signal amplification gains of different pixel units can be different, one frame of HDR image can be obtained through single exposure and single signal acquisition, multiple exposures and multiple frames of image synthesis processing are not required, and the efficiency is improved.
On the basis of the embodiment shown in fig. 4, a pixel unit according to an embodiment of the present application will be further described with reference to a more detailed circuit diagram. Fig. 5 is a first circuit diagram of a pixel unit according to an embodiment of the present disclosure.
As shown in fig. 5, the gain adjustment circuit 42 includes: a second switching circuit and a first capacitor C1; one end of the first capacitor C1 is connected to the first switch circuit 43 and the second switch circuit, the other end of the first capacitor C1 is grounded, the second switch circuit is further connected to the power supply and the input end of the first control signal, and the first control signal is used to control the second switch circuit to be turned on or off.
In one possible embodiment, the second switching circuit includes: a first transistor RST 1; a first terminal of the first transistor RST1 is connected to the first switch circuit 43, a second terminal of the first transistor RST1 is connected to a power supply, and a third terminal of the first transistor RST1 is connected to an input terminal of a first control signal.
In one possible embodiment, the first switching circuit 43 includes: a first diode D1; the anode of the first diode D1 is connected to the gain adjustment circuit 42, and the cathode of the first diode D1 is connected to the light sensing circuit 41.
In one possible embodiment, the light sensing circuit 41 adopts a 4T structure, that is, as shown in fig. 5, the light sensing circuit 41 includes: a photodiode PD, a second transistor TX, a third transistor RST, a fourth transistor SF, and a fifth transistor RS.
An anode of the photodiode PD is grounded, and a cathode of the photodiode PD is connected to the first terminal of the second transistor TX.
A second terminal of the second transistor TX is connected to a first terminal of the third transistor RST and a third terminal of the fourth transistor SF, respectively, a third terminal of the second transistor TX is connected to an input terminal of a second control signal, and the second control signal is used to control the second transistor TX to be turned on or off.
The second end of the third transistor RST is connected with the power supply, the third end of the third transistor RST is connected with the input end of a third control signal, and the third control signal is used for controlling the third transistor RST to be turned on or turned off.
A first terminal of the fourth transistor SF is connected to a second terminal of the fifth transistor RS, and a second terminal of the fourth transistor SF is connected to a power supply.
The first end of the fifth transistor RS is an output end of the electrical signal, the third end of the fifth transistor RS is connected with an input end of a fourth control signal, and the fourth control signal is used for controlling the fifth transistor RS to be switched on or switched off.
The operation principle of the pixel unit according to the embodiment of the present application is described with reference to fig. 5. As shown in fig. 5, the pixel unit includes 5 NMOS transistors, wherein the second transistor TX, the third transistor RST, the first transistor RST1, the fifth transistor RS are used as switches, the fourth transistor SF is used as a signal amplifier, the photodiode PD is used for converting optical signals and electrical signals, and the pixel unit further includes a first diode D1 and a first capacitor C1. Wherein a parasitic capacitance C exists at the node FDfdThe photodiode PD has PN junction capacitance Cpd. The first capacitor C1 may be sized according to the application.
When the pixel unit works, in the illumination stage, the second transistor TX is turned off, and the photodiode PD generates electricity under illuminationVoltage variation, the varying voltage being stored in its PN junction capacitance CpdIn (1). Then in the signal read phase the second transistor TX is turned on, CpdIs different from the voltage at node FD by CpdAnd CfdCauses a change in the voltage at the node FD, this changed voltage is amplified by the fourth transistor SF, and finally a change in the output electrical signal av is generated by the fifth transistor RSoutAnd the conversion output from the optical signal to the electric signal is realized. Thus, the change Δ V of the output electric signaloutDirectly reflecting the light intensity information of the pixel cell. Normally, the amplification factor of the fourth transistor SF is fixed, and thus the voltage change amount Δ V at the node FDfdVariation Δ V directly influencing output electric signalout。
Specifically, when the pixel unit is initially reset, the first transistor RST1 is turned on under the control of a first control signal, the third transistor RST is turned on under the control of a third control signal, the first control signal and the third control signal may be the same control signal, and the second transistor TX is turned on under the control of a second control signal, so that the first capacitor C1, the first diode D1 and the photodiode PD are reset by the power supply VDD, and after initial reset, a connection point of the first capacitor C1 and the first diode D1, a cathode of the photodiode PD and the node FD are all at high potentials and equal to each other. After the reset is completed, the first transistor RST1, the third transistor RST and the second transistor TX are all turned off. The photodiode PD receives incident light, which causes the voltage of the photodiode PD to drop, and the stronger the light, the more the voltage of the photodiode PD drops.
And a signal reading node, the second transistor TX is turned on under the control of a second control signal, and the fifth transistor RS is turned on under the control of a fourth control signal. When the light intensity is low, the voltage drop of the photodiode PD is small, the voltage drop of the photodiode PD causes the voltage drop at the node FD to be small, so that the voltage difference between the node FD and the first capacitor C1 is not large, the voltage difference does not reach the forward conducting voltage of the first diode D1 (for example, the forward conducting voltage is about 0.7V, which can be set according to actual needs), the first diode D1 is not conducted, no current flows through the first diode D1, and the circuit characteristic of the light sensing circuit 41 is similar to that of the commonly used 4T structure (fig. 2).
When the light intensity is higher, the voltage of the photodiode PD is decreased more, the voltage decrease of the photodiode PD causes the voltage decrease at the node FD more, so that the voltage difference between the first capacitor C1 and the node FD is greater than the forward conduction voltage of the first diode D1, the first diode D1 is turned on, the first capacitor C1 participates in charging and discharging, and the voltage difference is equivalent to the capacitor C at the node FDfdThe amplification is performed, and the signal amplification gain of the light receiving circuit 41 is reduced. That is, when the light intensity is high, the gain of the pixel unit is reduced to prevent signal saturation distortion, and it is ensured that no overexposure occurs in a high-brightness area, and compared with the conventional pixel unit with a 4T structure, the pixel unit has a higher upper limit of a dynamic range.
It can be seen from the above description of the operating principle of the pixel units under different light intensities that the gain conversion of each pixel is automatic negative feedback adjustment, and no external circuit is needed to be additionally controlled, so that the area of the external circuit can be saved, and because the output Signal is subjected to the feedback adjustment, the electric Signal output by each pixel unit is the gain automatically adjusted according to the light intensity at the pixel, an HDR Image can be directly output, and Image synthesis is performed without performing multiple exposure or multiple Signal acquisition in fig. 2 or fig. 3, so that the design difficulty and complexity of an external supporting circuit are reduced, the computing capability requirement of a peripheral Image Processing unit (ISP) is also reduced, the chip cost can be saved, and the power consumption of HDR photography or video taking is reduced.
For the sake of understanding, the signal amplification gain in the pixel unit will be more intuitively described below. The following variables are first defined:
Vfd0: the initial voltage at node FD before signal read.
Vfdt: the terminal voltage at node FD after signal read is complete.
Vpd0: after the illumination is completed, the initial voltage in the photodiode PD before the signal reading.
Vpdt: after the signal reading is finished, the photodiodeEnd voltage of PD
VC10: before the signal is read, the initial voltage of the first capacitor C1 (usually equal to Vfd0, and can be adjusted according to the requirement).
Cfd0: initial capacitance value at node FD before signal read.
Cfdt: the final capacitance value at node FD after signal read is complete.
Cpd0: the initial capacitance value of the photodiode PD before signal reading.
Cpdt: after the signal reading is completed, the final capacitance value of the photodiode PD.
As can be seen from the circuit characteristics of the circuit diagram shown in fig. 5, when the light intensity received by the pixel unit is weak during signal reading, the voltage of the photodiode PD does not change much, and after the second transistor TX is turned on, the first diode D1 is turned off, and the voltage at the node FD is defined by the following formula (1):
wherein, Cfdt+CpdtIs not much changed, can be regarded as a constant, then VfdtAnd Vpd0Correlation, and correlation slope
Associated with the photodiode PD and node FD capacitance.
If the light intensity received by the pixel unit is stronger, the voltage of the node FD drops more after the second transistor TX is turned on due to a larger voltage change of the photodiode PD, the first diode D1 is turned on, the first capacitor C1 participates in charging and discharging, and then the voltage difference between the first capacitor C1 and the node FD is always kept as the forward conducting voltage of the first diode D1, and the voltage at the node FD is defined by the following formula (2):
wherein, Cfdt+CpdtThe + C1 does not vary much, and A' can be considered as a constant, VfdtIs still in contact with Vpd0Correlation, but slope of correlation
In relation to the photodiode PD and the node FD capacitance and the first capacitance C1, it can be seen that the slope of the correlation becomes smaller, i.e., the signal amplification gain of the pixel unit decreases, compared to when the light intensity is low.
As shown in FIG. 6 as VfdtAnd Vpd0The slope of the curve is the gain value of the pixel unit, the larger the slope is, the larger the signal amplification gain of the pixel unit is, and V ispd0Larger indicates lower light intensity. As can also be seen from fig. 6, the gain of the pixel unit can be automatically adjusted according to the light intensity, when the light intensity is weak, the exposure is insufficient, and the output signal follows a high gain mode; when the light intensity is strong, the exposure is excessive, the output signal follows a low gain mode, and the oversaturated pixels in a common mode can be output as unsaturated or nearly saturated signals after the gain is reduced, so that the HDR effect is achieved.
On the basis of the above embodiments, the embodiment of the present application further provides a pixel unit, as shown in fig. 7, the pixel unit further includes a third switch circuit 44 on the basis of fig. 4; the third switch circuit 44 is connected between the first switch circuit 43 and the photosensitive circuit 41, the third switch circuit 44 is connected with an input end of a fifth control signal, and the third switch circuit 44 is used for controlling the connection between the first switch circuit 43 and the photosensitive circuit 41 according to the fifth control signal.
Alternatively, as shown in fig. 8, the third switch circuit 44 includes: and a sixth transistor G1. A first terminal of the sixth transistor G1 is connected to the node FD in the light sensing circuit 41, a second terminal of the sixth transistor G1 is connected to the first switching circuit 43 (the first diode D1), and a third terminal of the sixth transistor G1 is connected to an input terminal of a fifth control signal.
When the sixth transistor G1 is turned on under the control of the fifth control signal, the gain automatic adjustment function of the pixel unit is turned on; when the sixth transistor G1 is turned off under the control of the fifth control signal, the gain auto-adjustment function of the pixel unit is turned off. Thus, the gain automatic adjustment function of the pixel unit can be turned on or off as needed, so as to realize the output of the HDR image or the normal image as needed.
The embodiment of the present application further provides a pixel array, which includes a plurality of pixel units arranged in a plurality of rows and a plurality of columns, where the pixel unit is the pixel unit according to any embodiment of the present application.
The embodiment of the application also provides an image sensor, which comprises the pixel array.
An embodiment of the application also provides an electronic device, which comprises the image sensor.
Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.
Claims (9)
1. A pixel cell, comprising: the gain control circuit comprises a photosensitive circuit, a gain adjusting circuit and a first switch circuit connected between the photosensitive circuit and the gain adjusting circuit;
the photosensitive circuit is used for sensing optical signals and converting the optical signals into electric signals;
the first switch circuit is used for controlling the connection between the photosensitive circuit and the gain adjusting circuit to be switched on or off according to the size of the optical signal so as to change the signal amplification gain of the photosensitive circuit;
further comprising: a third switch circuit;
the third switch circuit is connected between the first switch circuit and the photosensitive circuit, the third switch circuit is connected with an input end of a fifth control signal, and the third switch circuit is used for controlling connection on-off between the first switch circuit and the photosensitive circuit according to the fifth control signal.
2. The pixel cell of claim 1, wherein the gain adjustment circuit comprises: a second switching circuit and a first capacitor;
one end of the first capacitor is connected with the first switch circuit and the second switch circuit respectively, the other end of the first capacitor is grounded, the second switch circuit is further connected with a power supply and an input end of a first control signal respectively, and the first control signal is used for controlling the second switch circuit to be switched on or switched off.
3. The pixel cell of claim 2, wherein the second switching circuit comprises: a first transistor;
the first end of the first transistor is connected with the first switch circuit, the second end of the first transistor is connected with the power supply, and the third end of the first transistor is connected with the input end of the first control signal.
4. The pixel cell of claim 1, wherein the first switching circuit comprises: a first diode;
the anode of the first diode is connected with the gain adjusting circuit, and the cathode of the first diode is connected with the photosensitive circuit.
5. The pixel cell of any of claims 1-4, wherein the light sensing circuit comprises: a photodiode, a second transistor, a third transistor, a fourth transistor, and a fifth transistor;
the anode of the photodiode is grounded, and the cathode of the photodiode is connected with the first end of the second transistor;
a second end of the second transistor is connected with a first end of the third transistor and a third end of the fourth transistor respectively, the third end of the second transistor is connected with an input end of a second control signal, and the second control signal is used for controlling the second transistor to be switched on or switched off;
a second end of the third transistor is connected with a power supply, a third end of the third transistor is connected with an input end of a third control signal, and the third control signal is used for controlling the third transistor to be switched on or switched off;
a first end of the fourth transistor is connected with a second end of the fifth transistor, and a second end of the fourth transistor is connected with a power supply;
the first end of the fifth transistor is an output end of the electric signal, the third end of the fifth transistor is connected with an input end of a fourth control signal, and the fourth control signal is used for controlling the fifth transistor to be switched on or switched off.
6. The pixel cell according to any one of claims 1 to 4, wherein the third switching circuit comprises: a sixth transistor;
the first end of the sixth transistor is connected with the photosensitive circuit, the second end of the sixth transistor is connected with the first switch circuit, and the third end of the sixth transistor is connected with the input end of the fifth control signal.
7. A pixel array comprising a plurality of pixel cells according to any one of claims 1-6 arranged in a plurality of rows and columns.
8. An image sensor comprising the pixel array of claim 7.
9. An electronic device characterized by comprising the image sensor of claim 8.
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| CN202110443167.5A CN113132659B (en) | 2021-04-23 | 2021-04-23 | Pixel unit, array, image sensor and electronic equipment |
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| CN202110443167.5A CN113132659B (en) | 2021-04-23 | 2021-04-23 | Pixel unit, array, image sensor and electronic equipment |
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| CN113132659A CN113132659A (en) | 2021-07-16 |
| CN113132659B true CN113132659B (en) | 2022-07-12 |
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