Pixel structure integrated with negative voltage switch and image sensor thereof
Patent Information
- Application Number
- CN202610862519.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-15
- Publication Date
- 2026-10-16
AI Technical Summary
在能量收集方面传统的时分复用型架构无法持续能量收集导致应用受限；异步像素虽然可提升能量收集效率,但现有结构仍以PWM像素为基础，填充因子仅有30%左右，明显低于有源像素，并且由于输出事件流的格式无法兼容传统的串行外设接口（SerialPeripheralInterface,SPI）导致成本增加
[0014]本申请的有益效果是：本申请的一种集成负电压开关的像素结构及其图像传感器，包括像素电路和负电压开关电路，像素电路用于接收光信号，并获取光电二极管电压，进而根据光信号，输出成像信号；负电压开关电路用于当光电二极管电压小于反相单元的翻转阈值电压时，控制像素电路切换至能量收集模式。本申请通过负电压开关电路实现当光电二极管电压低于翻转阈值电压时，自动将像素电路切换至能量收集模式，而非传统的复位模式，显著拓宽了传感器的能量收集窗口，实现了能量的循环利用，从而有效降低了整体功耗能够拓宽能量收集窗口，且兼容传统SPI接口。
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Figure CN122934098A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of sensor chip design technology, and in particular to a pixel structure with an integrated negative voltage switch and its image sensor. Background Technology
[0002] Self-powered image sensors are intelligent systems that do not require an external power supply and rely on ambient light to achieve autonomous imaging. Their core lies in the deep integration and synergistic optimization of low-power pixel design and efficient energy harvesting technology. In terms of energy harvesting, traditional time-division multiplexing architectures cannot continuously harvest energy, limiting their applications. While asynchronous pixels can improve energy harvesting efficiency, existing structures are still based on PWM pixels, with a fill factor of only about 30%, significantly lower than active pixels. Furthermore, the incompatibility of the output event stream format with traditional Serial Peripheral Interface (SPI) increases costs. Summary of the Invention
[0003] To address the aforementioned technical problems, the purpose of this application is to provide a pixel structure and its image sensor that integrates a negative voltage switch, which can broaden the energy harvesting window and is compatible with the traditional SPI interface.
[0004] To achieve the above objectives, one aspect of this application proposes a pixel structure integrating a negative voltage switch, comprising: The pixel circuit is used to receive light signals, obtain the voltage of the photodiode, and then output an imaging signal based on the light signals. A negative voltage switching circuit, connected to the pixel circuit, is used to control the pixel circuit to switch to energy harvesting mode when the voltage of the photodiode is less than the flip threshold voltage of the inverting unit.
[0005] In some embodiments, the pixel circuit includes: A reset circuit, connected to the floating diffusion node, is used to reset the pixel circuit. A photodiode, connected to the negative voltage switching circuit, is used to receive the optical signal and convert the optical signal into electrical charge; A first switching circuit, connected to the photodiode and the floating diffusion node, is used to transfer the charge to the floating diffusion node; An amplifier circuit, connected to the reset circuit and the floating diffusion node, is used to buffer and amplify the voltage signal of the floating diffusion node to obtain an amplified signal; The second switching circuit is connected to the amplifier circuit and is used to control the output timing of the amplified signal to obtain the imaging signal. A load circuit, connected to the photodiode and the second switching circuit, is used to provide a static operating point for the amplifier circuit.
[0006] In some embodiments, the negative voltage switching circuit includes: The inverting unit is connected to the pixel circuit and the energy harvesting output terminal, and is used to obtain a level signal based on the relationship between the photodiode voltage and the flip threshold voltage; A third switching circuit and a fourth switching circuit, wherein the third switching circuit is connected to the pixel circuit and the inverting unit, and the fourth switching circuit is connected to the third switching circuit, the inverting unit and the energy harvesting output terminal, and are used to control the pixel circuit to switch to energy harvesting mode or imaging mode according to the level signal.
[0007] In some embodiments, the reset circuit includes a first transistor, the first switching circuit includes a second transistor, a first terminal of the first transistor is used to receive a reset control signal, a first terminal of the second transistor is used to receive a first transmission control signal, a second terminal of the first transistor is connected to a first voltage source voltage and a second terminal of the amplifier circuit, a third terminal of the first transistor and a second terminal of the second transistor are both connected to the floating diffusion node, and a third terminal of the second transistor is connected to the negative terminal of the photodiode and the negative voltage switching circuit.
[0008] In some embodiments, the amplification circuit includes a third transistor, the second switching circuit includes a fourth transistor, a first terminal of the fourth transistor is used to receive a row selection signal, a first terminal of the third transistor is connected to the floating diffusion node, a second terminal of the third transistor is connected to the first voltage source voltage and the second terminal of the reset circuit, a third terminal of the third transistor is connected to the second terminal of the fourth transistor, and a third terminal of the fourth transistor is connected to the second terminal of the load circuit.
[0009] In some embodiments, the load circuit includes a fifth transistor, a first terminal of which is connected to a second voltage source, a second terminal of which is connected to a third terminal of the second switching circuit, and a third terminal of which is connected to the positive terminal of the photodiode.
[0010] In some embodiments, the third switching circuit includes a sixth transistor, the first terminal of which is used to receive a second transmission control signal, the second terminal of which is connected to the second terminal of the fourth switching circuit, and the third terminal of which is connected to the inverting unit and the pixel circuit.
[0011] In some embodiments, the fourth switching circuit includes a seventh transistor, the first terminal of which is connected to the inverting unit, the second terminal of which is connected to the second terminal of the third switching circuit, and the third terminal of which is connected to the inverting unit and the energy harvesting output terminal.
[0012] In some embodiments, the inverting unit includes an eighth transistor and a ninth transistor. The first terminal of the eighth transistor and the first terminal of the ninth transistor are both connected to the third terminal of the pixel circuit and the third switching circuit. The second terminal of the eighth transistor is connected to the voltage of the first voltage source. The third terminal of the eighth transistor and the second terminal of the ninth transistor are both connected to the first terminal of the fourth switching circuit. The third terminal of the ninth transistor is connected to the third terminal of the fourth switching circuit and the energy harvesting output terminal.
[0013] To achieve the above objectives, another aspect of the embodiments of this application proposes an image sensor including a pixel structure with an integrated negative voltage switch as described above.
[0014] The beneficial effects of this application are as follows: This application discloses a pixel structure and image sensor with an integrated negative voltage switch, including a pixel circuit and a negative voltage switch circuit. The pixel circuit is used to receive light signals and acquire the photodiode voltage, and then output an imaging signal based on the light signals. The negative voltage switch circuit is used to control the pixel circuit to switch to energy harvesting mode when the photodiode voltage is lower than the flip threshold voltage of the inverting unit. This application achieves automatic switching of the pixel circuit to energy harvesting mode when the photodiode voltage is lower than the flip threshold voltage, instead of the traditional reset mode, by using a negative voltage switch circuit. This significantly widens the energy harvesting window of the sensor, realizes energy recycling, and effectively reduces overall power consumption. It can widen the energy harvesting window and is compatible with the traditional SPI interface. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments of this application are described below. It should be understood that the drawings described below are only for the purpose of clearly illustrating some embodiments of the technical solutions in this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0016] Figure 1 This is a structural block diagram of a pixel structure for an integrated negative voltage switch provided in one embodiment of this application; Figure 2 This is a circuit schematic diagram of a pixel structure with an integrated negative voltage switch provided in one embodiment of this application; Figure 3A timing diagram of the node voltage Vc provided in one embodiment of this application; Figure 4 The simulation result diagram is provided for one embodiment of this application. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.
[0018] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”
[0019] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.
[0020] Self-powered image sensors are intelligent systems that do not require an external power supply and rely on ambient light to achieve autonomous imaging. Their core lies in the deep integration and synergistic optimization of low-power pixel design and efficient energy harvesting technology. In terms of energy harvesting, traditional time-division multiplexing architectures cannot continuously harvest energy, limiting their applications. While asynchronous pixels can improve energy harvesting efficiency, existing structures are still based on PWM pixels, with a fill factor of only about 30%, significantly lower than active pixels. Furthermore, the incompatibility of the output event stream format with traditional Serial Peripheral Interface (SPI) increases costs.
[0021] In view of this, this application proposes a pixel structure with an integrated negative voltage switch, including a pixel circuit and a negative voltage switch circuit. The pixel circuit receives light signals and acquires the photodiode voltage, and then outputs an imaging signal based on the light signals. The negative voltage switch circuit controls the pixel circuit to switch to energy harvesting mode when the photodiode voltage is lower than the flip threshold voltage of the inverting unit. This application achieves automatic switching of the pixel circuit to energy harvesting mode when the photodiode voltage is lower than the flip threshold voltage, instead of the traditional reset mode, by using a negative voltage switch circuit. This significantly widens the energy harvesting window of the sensor, realizes energy recycling, and effectively reduces overall power consumption. It also widens the energy harvesting window and is compatible with the traditional SPI interface.
[0022] Reference Figure 1 , Figure 1 This is a structural block diagram of a pixel structure with an integrated negative voltage switch provided in one embodiment of this application. This application proposes a pixel structure with an integrated negative voltage switch, comprising: The pixel circuit is used to receive light signals, obtain the voltage of the photodiode, and then output an imaging signal based on the light signals. The negative voltage switching circuit, connected to the pixel circuit, is used to control the pixel circuit to switch to energy harvesting mode when the photodiode voltage is less than the flip threshold voltage of the inverting unit.
[0023] It should be noted that the pixel structure in this embodiment is an asynchronous energy harvesting pixel structure, compatible with the traditional SPI interface, and introduces a negative voltage switching circuit based on the traditional 4T active pixel circuit. This circuit can monitor the voltage of the photodiode in real time and automatically switch the pixel circuit to energy harvesting mode when it falls below the flip-flop threshold voltage of the inverting unit, instead of the traditional reset mode. Through the above adaptive switching mechanism, the energy harvesting window of the sensor is significantly widened, realizing energy recycling and thus effectively reducing the overall power consumption.
[0024] As a further optional implementation, the pixel circuit includes: The reset circuit, connected to the floating diffusion node, is used to reset the pixel circuit. A photodiode, connected to a negative voltage switching circuit, is used to receive optical signals and convert them into electrical charges. The first switching circuit, connected to the photodiode and the floating diffusion node, is used to transfer charge to the floating diffusion node; An amplifier circuit, connected to a reset circuit and a floating diffusion node, is used to buffer and amplify the voltage signal from the floating diffusion node to obtain an amplified signal. The second switching circuit is connected to the amplifier circuit and is used to control the output timing of the amplified signal to obtain the imaging signal. The load circuit, connected to the photodiode and the second switching circuit, is used to provide a static operating point for the amplifier circuit.
[0025] As a further optional implementation, the negative voltage switching circuit includes: The inverting unit, connected to the pixel circuit and the energy harvesting output, is used to obtain the level signal based on the relationship between the photodiode voltage and the flip threshold voltage; The third and fourth switching circuits are connected to the pixel circuit and the inverting unit, respectively. The third switching circuit is connected to the third switching circuit, the inverting unit, and the energy harvesting output terminal. They are used to control the pixel circuit to switch to energy harvesting mode or imaging mode according to the level signal.
[0026] Specifically, the transistors in the inverting unit, the third switching circuit, and the fourth switching circuit constitute a negative voltage switch, when the photodiode voltage V... PD When the voltage is below the negative voltage switch's flip-flop threshold, the output signal of the inverting unit is high. At this time, the negative voltage switch is turned on, connecting the negative terminal of the photodiode to the energy harvesting output terminal, and the pixel circuit enters energy harvesting mode. When the photodiode voltage V... PD When the voltage is higher than the flip threshold voltage, the level signal output by the inverting unit is low. At this time, the negative voltage switch is turned off, and the pixel circuit enters the imaging mode.
[0027] Reference Figure 2 , Figure 2 The circuit diagram of the pixel structure with integrated negative voltage switch provided in one embodiment of this application is shown. Further, as an optional implementation, the reset circuit includes a first transistor, the first switching circuit includes a second transistor, the first terminal of the first transistor is used to receive a reset control signal, the first terminal of the second transistor is used to receive a first transmission control signal, the second terminal of the first transistor is connected to the voltage of the first voltage source and the second terminal of the amplifier circuit, the third terminal of the first transistor and the second terminal of the second transistor are both connected to the floating diffusion node, and the third terminal of the second transistor is connected to the negative terminal of the photodiode and the negative voltage switching circuit.
[0028] Specifically, the first transistor M1 is a reset transistor used to set the potential of the floating diffusion node (FD) back to the reference value, ensuring that the next signal readout is not affected by residual charge from the previous cycle and preparing for subsequent signal sampling. The second transistor M2 is a transfer transistor used to transfer the charge (optical signal) accumulated in the photodiode PD to the floating diffusion node FD. This second transistor M2 allows the pixel to achieve complete charge transfer and supports correlated double sampling (CDS) to significantly reduce noise.
[0029] Reference Figure 2As an optional implementation, the amplifier circuit includes a third transistor, the second switching circuit includes a fourth transistor, the first terminal of the fourth transistor is used to receive a row selection signal, the first terminal of the third transistor is connected to a floating diffusion node, the second terminal of the third transistor is connected to the second terminal of the first voltage source voltage and the reset circuit, the third terminal of the third transistor is connected to the second terminal of the fourth transistor, and the third terminal of the fourth transistor is connected to the second terminal of the load circuit.
[0030] Specifically, the third transistor M3 is a source-follower amplifier transistor used to buffer and amplify the voltage signal on the floating diffusion node FD to drive subsequent analog-to-digital conversion or row / column readout circuits, thereby obtaining an amplified signal and improving the stability and driving capability of the pixel output signal. The fourth transistor M4 is a row selection transistor used to control whether a pixel is selected by the current row / column to be read. When a row of pixels is read, the fourth transistor M4 is turned on; otherwise, it remains off, realizing row-level addressing.
[0031] Reference Figure 2 As an optional implementation, the load circuit includes a fifth transistor, the first terminal of which is connected to the voltage of the second voltage source, the second terminal of which is connected to the third terminal of the second switching circuit, and the third terminal of which is connected to the positive terminal of the photodiode.
[0032] Specifically, the fifth transistor M5 is a load transistor, which is used to provide current or voltage load to the pixel circuit, so that the imaging signal can stably drive the readout circuit at the back end, thereby effectively reading out the voltage signal of each pixel.
[0033] Reference Figure 2 As an optional implementation, the third switching circuit includes a sixth transistor, the first terminal of which is used to receive a second transmission control signal, the second terminal of which is connected to the second terminal of the fourth switching circuit, and the third terminal of which is connected to the inverting unit and the pixel circuit.
[0034] Reference Figure 2 As an optional implementation, the fourth switching circuit includes a seventh transistor, the first terminal of which is connected to the inverting unit, the second terminal of which is connected to the second terminal of the third switching circuit, and the third terminal of which is connected to the inverting unit and the energy harvesting output terminal.
[0035] Specifically, the sixth transistor M6 and the seventh transistor M7 are connected in series and are both clock-controlled switches. They are turned on when the output signal of the inverting unit is high and turned off when the output signal of the inverting unit is low.
[0036] Reference Figure 2As an optional implementation, the inverting unit includes an eighth transistor and a ninth transistor. The first terminal of the eighth transistor and the first terminal of the ninth transistor are both connected to the third terminal of the pixel circuit and the third switching circuit. The second terminal of the eighth transistor is connected to the voltage of the first voltage source. The third terminal of the eighth transistor and the second terminal of the ninth transistor are both connected to the first terminal of the fourth switching circuit. The third terminal of the ninth transistor is connected to the third terminal of the fourth switching circuit and the energy harvesting output terminal.
[0037] Specifically, the eighth transistor M8 and the ninth transistor M9 form an inverter. When the photodiode voltage is greater than the flip threshold voltage, it outputs a low level, and when the photodiode voltage is less than the flip threshold voltage, it outputs a high level.
[0038] In some optional embodiments, the first transistor M1 to the seventh transistor M7 and the ninth transistor M9 can be n18 transistors using standard CMOS technology, wherein the gate length L of the first transistor M1 to the fourth transistor M4 and the sixth transistor M6 to the seventh transistor M7 is 180nm and the gate width W is 220nm; the gate length L of the fifth transistor M5 is 10µ and the gate width W is 220nm; and the eighth transistor M8 is a 3.3V p33 transistor with a gate length L of 3µ and a gate width W of 300nm.
[0039] The structure of the pixel structure of the integrated negative voltage switch in the embodiments of this application has been described above. Its working principle will be further explained below.
[0040] During the initial activation phase (reset control signal PRST = high level, first transmission control signal PTG = high level, second transmission control signal...), =low level), the photodiode PD is reset to V REF Voltage. The subsequent exposure process causes the photodiode voltage V to... PD Monotonically decaying. When the second PTG / When the level flips, the photodiode voltage V PD The sampled data is used for readout. When the photodiode voltage V... PD When the switching threshold voltage of the ninth transistor M9 is exceeded, the inverter composed of the eighth transistor M8 and the ninth transistor M9 flips, driving the node voltage Vc at node C to rise to the first voltage source voltage VDD. At this time, aPTG is high, the sixth transistor M6 and the seventh transistor M7 are activated, initiating the energy harvesting process, which continues until the next frame reset signal arrives. The timing changes of the node voltage Vc are as follows: Figure 3 As shown.
[0041] The structure and working principle of a pixel structure with an integrated negative voltage switch according to an embodiment of this application have been described above. It can be understood that, compared with existing pixel structures, the pixel structure of this application introduces a negative voltage switch circuit on the basis of a traditional 4T active pixel circuit. This circuit can monitor the voltage of the photodiode in real time and automatically switch the pixel circuit to energy harvesting mode when it falls below the flip-flop threshold voltage of the inverting unit, instead of the traditional reset mode. Through this adaptive switching mechanism, the energy harvesting window of the sensor is significantly widened, energy recycling is achieved, and overall power consumption is effectively reduced.
[0042] To further verify the effectiveness of the negative voltage switching circuit proposed in the embodiments of this application, the effects of the embodiments of this application will be further explained below in conjunction with simulation experiments.
[0043] The frequency is set to: Energy harvesting output V EH The voltage was -350mV, the power supply voltage was 1V, the frequency was 5MHz, the exposure time was 16.4µs, the frame period was 984µs, the photocurrent was set to 200pA, and the simulation time was 2ms. The simulation results are as follows: Figure 4 As shown. Figure 4 In the text, "v / idc; tan(V)" represents the photodiode voltage V. PD ,from Figure 4 As can be seen from this, when the photodiode voltage V PD When the voltage drops to the switching threshold voltage (39.767947mV), the sixth transistor M6 and the seventh transistor M7 turn on, and the photodiode voltage V... PD Because of the energy harvesting output terminal V EH When connected together, the voltage value instantly jumps to -350mV, demonstrating the effectiveness of the negative voltage switching circuit in this embodiment.
[0044] This application also provides an image sensor, which includes the pixel structure with integrated negative voltage switch described above.
[0045] It is understood that the content of the above pixel structure embodiments is applicable to this image sensor embodiment. The specific functions implemented by this image sensor embodiment are the same as those of the above pixel structure embodiments, and the beneficial effects achieved are also the same as those achieved by the above pixel structure embodiments.
[0046] In the foregoing description of this specification, the references to terms such as "one embodiment," "another embodiment," or "some embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0047] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.
[0048] The above is a detailed description of the preferred embodiments of this application, but this application is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.
Claims
1. A pixel structure integrating a negative voltage switch, characterized in that, include: The pixel circuit is used to receive light signals, obtain the voltage of the photodiode, and then output an imaging signal based on the light signals. A negative voltage switching circuit, connected to the pixel circuit, is used to control the pixel circuit to switch to energy harvesting mode when the voltage of the photodiode is less than the flip threshold voltage of the inverting unit.
2. The pixel structure with integrated negative voltage switch according to claim 1, characterized in that, The pixel circuit includes: A reset circuit, connected to the floating diffusion node, is used to reset the pixel circuit. A photodiode, connected to the negative voltage switching circuit, is used to receive the optical signal and convert the optical signal into electrical charge; A first switching circuit, connected to the photodiode and the floating diffusion node, is used to transfer the charge to the floating diffusion node; An amplifier circuit, connected to the reset circuit and the floating diffusion node, is used to buffer and amplify the voltage signal of the floating diffusion node to obtain an amplified signal; The second switching circuit is connected to the amplifier circuit and is used to control the output timing of the amplified signal to obtain the imaging signal. A load circuit, connected to the photodiode and the second switching circuit, is used to provide a static operating point for the amplifier circuit.
3. The pixel structure with integrated negative voltage switch according to claim 1, characterized in that, The negative voltage switching circuit includes: The inverting unit is connected to the pixel circuit and the energy harvesting output terminal, and is used to obtain a level signal based on the relationship between the photodiode voltage and the flip threshold voltage; A third switching circuit and a fourth switching circuit, wherein the third switching circuit is connected to the pixel circuit and the inverting unit, and the fourth switching circuit is connected to the third switching circuit, the inverting unit and the energy harvesting output terminal, and are used to control the pixel circuit to switch to energy harvesting mode or imaging mode according to the level signal.
4. The pixel structure with integrated negative voltage switch according to claim 2, characterized in that, The reset circuit includes a first transistor, and the first switching circuit includes a second transistor. The first terminal of the first transistor is used to receive a reset control signal, and the first terminal of the second transistor is used to receive a first transmission control signal. The second terminal of the first transistor is connected to the voltage of the first voltage source and the second terminal of the amplifier circuit. The third terminals of the first transistor and the second terminal of the second transistor are both connected to the floating diffusion node. The third terminal of the second transistor is connected to the negative terminal of the photodiode and the negative voltage switching circuit.
5. The pixel structure with integrated negative voltage switch according to claim 2, characterized in that, The amplifier circuit includes a third transistor, the second switching circuit includes a fourth transistor, the first terminal of the fourth transistor is used to receive a row selection signal, the first terminal of the third transistor is connected to the floating diffusion node, the second terminal of the third transistor is connected to the first voltage source voltage and the second terminal of the reset circuit, the third terminal of the third transistor is connected to the second terminal of the fourth transistor, and the third terminal of the fourth transistor is connected to the second terminal of the load circuit.
6. The pixel structure with integrated negative voltage switch according to claim 2, characterized in that, The load circuit includes a fifth transistor, the first terminal of which is connected to the voltage of the second voltage source, the second terminal of which is connected to the third terminal of the second switching circuit, and the third terminal of which is connected to the positive terminal of the photodiode.
7. The pixel structure with integrated negative voltage switch according to claim 3, characterized in that, The third switching circuit includes a sixth transistor. The first terminal of the sixth transistor is used to receive a second transmission control signal. The second terminal of the sixth transistor is connected to the second terminal of the fourth switching circuit. The third terminal of the sixth transistor is connected to the inverting unit and the pixel circuit.
8. The pixel structure with integrated negative voltage switch according to claim 3, characterized in that, The fourth switching circuit includes a seventh transistor, the first terminal of which is connected to the inverting unit, the second terminal of which is connected to the second terminal of the third switching circuit, and the third terminal of which is connected to the inverting unit and the energy harvesting output terminal.
9. The pixel structure with integrated negative voltage switch according to claim 3, characterized in that, The inverting unit includes an eighth transistor and a ninth transistor. The first terminal of the eighth transistor and the first terminal of the ninth transistor are both connected to the third terminal of the pixel circuit and the third switching circuit. The second terminal of the eighth transistor is connected to the voltage of the first voltage source. The third terminal of the eighth transistor and the second terminal of the ninth transistor are both connected to the first terminal of the fourth switching circuit. The third terminal of the ninth transistor is connected to the third terminal of the fourth switching circuit and the energy harvesting output terminal.
10. An image sensor, characterized in that, The pixel structure includes the integrated negative voltage switch as described in any one of claims 1 to 9.