High-performance 3TAPS circuit based on single-gate thin film transistor

Abstract

The invention discloses a high-performance 3TAPS circuit based on single-gate thin film transistors, which relates to the technical field of thin film transistors and comprises three single-gate thin film transistors, namely a first single-gate thin film transistor, a second single-gate thin film transistor and a third single-gate thin film transistor which are connected to form a 3T amplifying circuit. The output voltage of the single-gate thin film transistor I controls and broadens the dynamic response range of the 3T amplification circuit through an input signal of a signal end; the single-grid thin film transistor II is used as an amplifier to improve the sensitivity of the 3T amplification circuit under a weak light condition and expand the dynamic response range; the single-gate thin film transistor III is used as a switching device to control the reading of the 3T amplifying circuit; a single-gate thin film transistor is adopted to replace a double-gate thin film transistor, so that the original complexity of application is reduced, the preparation process is simplified, the manufacturing cost is reduced, the device stability is improved, the circuit sensitivity, the signal-to-noise ratio and the dynamic range are improved, and the X-ray detector is suitable for large-area array preparation and low-dose X-ray detection application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film transistors, and particularly relates to a high-performance 3TAPS circuit based on a single-gate thin film transistor. BACKGROUND

[0002] In the current field of X-ray flat panel detector circuit design, the mainstream architecture adopts a passive pixel (PPS) circuit. Although the PPS circuit has a simple structure and low cost, it performs poorly in key indicators such as sensitivity, signal-to-noise ratio, and response speed, especially in weak light or low-dose X-ray conditions, and is significantly limited in detection performance, making it difficult to meet the needs of high-precision medical diagnosis, industrial non-destructive testing, and other application scenarios. In contrast, the active pixel (APS) circuit has a higher gain, a wider dynamic range, and a better signal-to-noise ratio due to the integration of an active amplifier device in each pixel unit, and has gradually become the design direction of high-end detectors. However, the X-ray utilization rate of existing APS circuits is generally low, and most of the time is in an empty state, resulting in limited signal acquisition efficiency and overall system performance.

[0003] To address this problem, existing technologies propose a high-sensitivity APS circuit design based on a dual-gated thin-film transistor (DG-TFT). The DG-TFT structure introduces upper and lower gate control films on a substrate, which can improve pixel gain and reduce leakage current while achieving a wider dynamic range and better signal control capability. With this feature, the DG-TFT structure is expected to replace the traditional PPS architecture in high-performance X-ray detectors to meet the application needs of low dose and high sensitivity. However, due to the complexity of the double-gate structure, the multiple film layers, and the high precision requirements for preparation, the DG-TFT still has significant bottlenecks in terms of large-area uniformity, device stability, and cost control. The immaturity of this technology limits its promotion and popularization in the fields of medical, industrial, and scientific research.

[0004] At the same time, the single-gated thin-film transistor (SG-TFT) has been widely used in display panels, sensor arrays, and other fields due to its simple film layer design, mature preparation process, good device stability, and suitability for large-area preparation. Compared to the DG-TFT, the SG-TFT has obvious advantages in reducing production costs, simplifying process flow, and improving yield. Therefore, if the SG-TFT can be effectively utilized in the APS circuit to construct high-performance pixel units, not only can the circuit performance of high gain and low noise be balanced, but also the production feasibility and system integration can be significantly improved.

[0005] At present, in view of the urgent demand of X-ray flat panel detector for low dose, high sensitivity, high signal-to-noise ratio, the industry urgently needs an innovative circuit architecture that balances performance, cost and process maturity; 3TAPS circuit as an improved APS architecture can realize multiple functions such as signal readout, reset and storage by integrating three thin film transistors in each pixel, thereby improving pixel response speed and dynamic range; if single gate TFT is combined with 3TAPS architecture, it is expected to further reduce process difficulty and production cost while maintaining high performance indicators.

[0006] In summary, the prior art at least has the following technical problems: first, the mainstream PPS circuit has insufficient sensitivity and signal-to-noise ratio, which is difficult to meet the low dose X-ray detection requirement; second, the X-ray utilization rate of the existing APS circuit is low, resulting in limited signal acquisition efficiency; third, the high-performance APS circuit based on DG-TFT has complex manufacturing process, high cost and insufficient device stability, which restricts large-area promotion and mass production; fourth, there is a lack of a new APS circuit design scheme with high performance, low cost and process maturity.

[0007] In summary, the prior art at least has the following technical problems: The PPS circuit used in the existing X-ray flat panel detector circuit has the technical problems of insufficient sensitivity and signal-to-noise ratio, the APS circuit has the technical problem of low X-ray utilization rate, and the high-performance APS circuit based on DG-TFT structure has the technical problems of complex manufacturing process and insufficient device stability. SUMMARY

[0008] The purpose of the present application is to provide a high-performance 3TAPS circuit based on single-gate thin film transistor, to solve the technical problems of insufficient sensitivity and signal-to-noise ratio of the PPS circuit used in the existing X-ray flat panel detector circuit, low X-ray utilization rate of the APS circuit, and complex manufacturing process and insufficient device stability of the high-performance APS circuit based on DG-TFT structure.

[0009] The technical effects of the preferred technical solutions in the many technical solutions provided by the present application are described in detail below.

[0010] In order to solve the above technical problems, the present application provides the following technical solutions: This invention provides a high-performance 3TAPS circuit based on a single-gate thin-film transistor (TFT), comprising three TFTs: TFT-1, TFT-2, and TFT-3. The drain and gate of TFT-1 and the gate of TFT-2 are connected to a signal terminal. The source of TFT-1 is grounded, and an external bias voltage is applied to the drain of TFT-2. The source of TFT-2 is connected to the drain of TFT-3. The gate of TFT-3 serves as a readout terminal, and its source serves as a data terminal, forming a 3T amplifier circuit. The output voltage of TFT-1 is controlled by the input signal at the signal terminal to broaden the dynamic response range of the 3T amplifier circuit. TFT-2 acts as an amplifier to improve the sensitivity of the 3T amplifier circuit under low-light conditions and expands the dynamic response range of the 3T amplifier circuit by lowering the detection limit of the input components at the signal terminal. TFT-3 functions only as a switching device to control the readout of the 3T amplifier circuit.

[0011] In one embodiment, by adjusting the physical size and input current of the single-gate thin-film transistor, the single-gate thin-film transistor is made to operate in the subthreshold region, thereby widening the dynamic response range of the pixel circuit and realizing the logarithmic conversion of the photocurrent input to the signal terminal to the output voltage of the single-gate thin-film transistor.

[0012] In one embodiment, the logarithmic transformation relationship between the input photocurrent and the output voltage of the single-gate thin-film transistor is as follows: V ds1 =V TH1 + ln( ) in, V ds1 This represents the output voltage of the single-gate thin-film transistor. V TH1 This represents the threshold voltage of the single-gate thin-film transistor. I signal This indicates the photocurrent signal input at the signal terminal. This represents the input current of the single-gate thin-film transistor. This represents the subthreshold slope factor of the single-gate thin-film transistor. This represents thermal voltage.

[0013] In one embodiment, by adjusting the physical dimensions and input current of the single-gate thin-film transistor II, the single-gate thin-film transistor II is made to operate in the subthreshold region, exhibiting exponential amplification performance.

[0014] In one embodiment, the relationship between the output current of the second single-gate thin-film transistor and the output voltage of the first single-gate thin-film transistor is as follows: I out =I DS2 · exp[ ] in, I out This represents the output current of the second single-gate thin-film transistor. I DS2 This represents the input current of the second single-gate thin-film transistor. V ds1 This represents the output voltage of the single-gate thin-film transistor. V TH2 This represents the threshold voltage of the second single-gate thin-film transistor. This represents the subthreshold slope factor of the second single-gate thin-film transistor. q It represents the amount of electron charge.

[0015] In one embodiment, a photodiode is further included, which is connected to the 3T amplifier circuit to form a 3T1D active pixel circuit. The anode of the photodiode is connected to the signal terminal to form the sensing part of the 3T1D active pixel circuit. Bias voltages VDD1 and VDD2 are applied to the cathode of the photodiode and the drain of the second single-gate thin-film transistor, respectively. By controlling the first and second single-gate thin-film transistors to operate in the subthreshold region, the output voltage of the first single-gate thin-film transistor is logarithmically related to the incident light intensity of the photodiode, thereby widening the dynamic response range of the 3T1D active pixel circuit. The second single-gate thin-film transistor acts as an in-pixel amplifier to improve the sensitivity of the 3T1D active pixel circuit under low-light conditions, i.e., by lowering the detection lower limit of the photodiode, the dynamic response range of the 3T1D active pixel circuit is expanded. The third single-gate thin-film transistor acts as a switching transistor to control the readout of the 3T1D active pixel circuit.

[0016] In one embodiment, the 3T1D active pixel circuit operates in random readout mode.

[0017] In one embodiment, the random readout mode is as follows: when the single-gate thin-film transistor three is turned on, the single-gate thin-film transistor one is also turned on. Under illumination, the photocurrent generated by the unit light power of the photodiode flows through the output voltage generated by the single-gate thin-film transistor one and acts on the single-gate thin-film transistor two. When the single-gate thin-film transistor two is also working in the subthreshold region, pixel readout is completed directly and quickly, generating a continuous signal output that is linearly related to the instantaneous light intensity. Therefore, the 3T1D active pixel circuit can be randomly read in both space and time, that is, any pixel unit can be accessed and read at any time.

[0018] In one embodiment, it further includes multiple passive pixel units; the multiple passive pixel units are connected in parallel to the signal terminal of the 3T amplifier circuit to form a 3T passive pixel amplifier circuit; the passive pixel unit to be read in the 3T passive pixel amplifier circuit is selected by the row selection function to achieve pixel amplification, and the 3T amplifier circuit is used as an external amplifier circuit so that each of the multiple passive pixel units only needs to retain one switching thin film transistor, which is used to improve the pixel fill rate of the 3T passive pixel amplifier circuit, while also possessing the high sensitivity and wide dynamic range performance of the 3T amplifier circuit.

[0019] In one embodiment, multiple columns of the 3T passive pixel amplifier circuits form a passive pixel matrix to improve detection resolution.

[0020] The high-performance 3TAPS circuit of this invention addresses the technical problems of insufficient sensitivity, low signal-to-noise ratio, low X-ray utilization, and complex and unstable dual-gate thin-film transistor processes in existing X-ray flat panel detector circuits. It achieves the following beneficial effects through a single-gate thin-film transistor: (1) Reduce process complexity and manufacturing cost; This technical solution uses a single-gate thin film transistor (SG-TFT) to replace the existing double-gate thin film transistor (DG-TFT); Since the film structure of the single-gate thin film transistor is simpler and the preparation process is mature, it can significantly reduce the process difficulty and production cost while ensuring the high performance of the 3T amplifier circuit, and improve the feasibility of large-area preparation, device consistency and reliability.

[0021] (2) Improve sensitivity and weak light response capability; by setting a single-gate thin film transistor II as an amplifier in the 3T amplifier circuit, it plays the role of amplifying the signal, thereby enhancing the gain of the input signal, reducing the lower limit of the signal detection, improving the response capability and signal-to-noise ratio under weak light conditions, and meeting the needs of low-dose X-ray detection.

[0022] (3) Expanding the dynamic response range; This technical solution utilizes the output voltage of a single-gate thin-film transistor to control the input signal at the signal terminal, which can significantly expand the dynamic response range of the 3T amplifier circuit, improve the problem of low X-ray utilization and narrow output range of the traditional APS circuit, and improve the overall detection performance.

[0023] (4) Enhance the stability of readout and switching control; the single-gate thin-film transistor 3 acts as an independent switching device, responsible for controlling the readout process, separating amplification and readout, reducing parasitic effects, improving the stability of the output signal and readout speed, and ensuring the reliability of the 3T amplifier circuit under high pixel density and large area array.

[0024] (5) Improve system integration and versatility; This technical solution realizes amplification, control and readout functions through three single-gate thin film transistors. The circuit structure is compact and easy to integrate with the signal processing module of the existing flat panel detector. It is applicable to various X-ray imaging fields such as medical imaging, industrial flaw detection and scientific research.

[0025] In summary, this technical solution not only surpasses the performance of traditional PPS circuits and existing APS circuits, but also has a simple film structure and low manufacturing complexity, thus outperforming the DG-TFT architecture in terms of cost and process maturity. It provides a 3TAPS circuit solution for X-ray flat panel detectors that is highly sensitive, has a high signal-to-noise ratio, a wide dynamic range, and is easy to apply. Attached Figure Description

[0026] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the 3T amplifier circuit structure of the present invention; Figure 2 This is a schematic diagram of the 3T1D active pixel circuit structure of the present invention; Figure 3 This is a timing diagram of random readout of the 3T1D active pixel circuit of the present invention during operation; Figure 4 This is a schematic diagram of the 3T passive pixel amplifier circuit structure of the present invention; Figure 5 This is a schematic diagram of the circuit structure of the passive pixel matrix of the present invention.

[0028] The accompanying figure is labeled as follows: 1. 3T amplifier circuit; TFT1, Single-gate thin-film transistor one; TFT2, Single-gate thin-film transistor two; TFT3, Single-gate thin-film transistor three; ST, Signal terminal; VDD, External bias voltage; RE, Read-end; DE, Data Endpoint. 2. 3T1D active pixel circuit; 21. Photodiode; 3. 3T passive pixel amplifier circuit; 31. Passive pixel unit; 4. Passive pixel matrix. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0030] A specific implementation provides a high-performance 3TAPS circuit based on a single-gate thin-film transistor, comprising three single-gate thin-film transistors: single-gate thin-film transistor 1, single-gate thin-film transistor 2, and single-gate thin-film transistor 3. The drain and gate of single-gate thin-film transistor 1 and the gate of single-gate thin-film transistor 2 are connected to the signal terminal. The source of single-gate thin-film transistor 1 is grounded. An external bias voltage is applied to the drain of single-gate thin-film transistor 2. The source of single-gate thin-film transistor 2 is connected to the drain of single-gate thin-film transistor 3. The gate of single-gate thin-film transistor 3 serves as the read terminal, and its source serves as the data terminal, forming a 3T amplifier circuit. The output voltage of single-gate thin-film transistor 1 is controlled by the input signal at the signal terminal to broaden the dynamic response range of the 3T amplifier circuit. Single-gate thin-film transistor 2... As an amplifier, it improves the sensitivity of the 3T amplifier circuit under low light conditions and expands the dynamic response range; the single-gate thin-film transistor (SMT) acts as a switching device to control the readout of the 3T amplifier circuit; by using a SMT to replace the dual-gate SMT, the complexity of the components in the application is reduced, the fabrication process is simplified, the manufacturing cost is reduced, and the device stability is improved. At the same time, the circuit sensitivity, signal-to-noise ratio, and dynamic range are improved, making it suitable for large-area array fabrication and low-dose X-ray detection applications. It effectively solves the technical problems of insufficient sensitivity and signal-to-noise ratio of the PPS circuit used in existing X-ray flat panel detector circuits, low X-ray utilization of the APS circuit, and the complex fabrication process and insufficient device stability of the high-performance APS circuit based on the DG-TFT structure.

[0031] The first implementation of a high-performance 3TAPS circuit, for example Figure 1As shown, the circuit includes three single-gate thin-film transistors (TFTs): TFT1, TFT2, and TFT3. The drain and gate of TFT1 and the gate of TFT2 are connected to the signal terminal ST. The source of TFT1 is grounded. A bias voltage VDD is applied to the drain of TFT2. The source of TFT2 is connected to the drain of TFT3. The gate of TFT3 serves as the readout terminal RE, and its source as the data terminal DE, forming a 3T amplifier circuit 1. The output voltage of TFT1 is controlled by the input signal at the signal terminal ST, which is used to widen the dynamic response range of the 3T amplifier circuit 1. TFT2 acts as an amplifier to improve the sensitivity of the 3T amplifier circuit 1 under low-light conditions and expands the dynamic response range of the 3T amplifier circuit 1 by lowering the detection limit of the input components at the signal terminal ST. TFT3 acts only as a switching device to control the readout of the 3T amplifier circuit 1.

[0032] Specifically, the high-performance 3TAPS circuit addresses the technical problems of existing X-ray flat panel detector circuits, such as insufficient sensitivity, low signal-to-noise ratio, low X-ray utilization, and complex and unstable dual-gate thin-film transistor processes. It achieves several technical advantages through a single-gate thin-film transistor: reduced process complexity and manufacturing cost. This technical solution uses a single-gate thin-film transistor (SG-TFT) to replace the existing dual-gate thin-film transistor (DG-TFT). Because the single-gate thin-film transistor has a simpler film structure and a mature fabrication process, it can significantly reduce process difficulty and production costs while ensuring the high performance of the 3T amplifier circuit 1, and improve the feasibility of large-area fabrication, device consistency, and reliability.

[0033] To improve sensitivity and low-light response, a single-gate thin-film transistor (TFT2) is set in the 3T amplifier circuit 1 as an amplifier to amplify the signal, enhance the gain of the input signal, reduce the ST detection limit at the signal terminal, improve the response capability and signal-to-noise ratio under low-light conditions, and meet the requirements of low-dose X-ray detection.

[0034] To broaden the dynamic response range, this technical solution utilizes the output voltage of a single-gate thin-film transistor (TFT1) in conjunction with the input signal control of the signal terminal ST. This significantly broadens the dynamic response range of the 3T amplifier circuit 1, improves the problems of low X-ray utilization and narrow output range in traditional APS circuits, and enhances overall detection performance.

[0035] To enhance the stability of readout and switching control, the single-gate thin-film transistor TFT3 acts as an independent switching device, responsible for controlling the readout process. This separates amplification and readout, reduces parasitic effects, improves the stability of the output signal and the readout speed, and ensures the reliability of the 3T amplifier circuit 1 under high pixel density and large area array conditions.

[0036] To improve system integration and versatility, this technical solution uses three single-gate thin-film transistors to achieve amplification, control, and readout functions. The circuit structure is compact and easy to integrate with the signal processing module of existing flat panel detectors. It is suitable for various X-ray imaging fields such as medical imaging, industrial flaw detection, and scientific research testing.

[0037] In summary, this technical solution not only surpasses the performance of traditional PPS circuits and existing APS circuits, but also has a simple film structure and low manufacturing complexity, thus outperforming the DG-TFT architecture in terms of cost and process maturity. It provides a 3TAPS circuit solution for X-ray flat panel detectors that is highly sensitive, has a high signal-to-noise ratio, a wide dynamic range, and is easy to apply.

[0038] As one alternative implementation method: Regarding the control principle and function of the aforementioned single-gate thin-film transistor (TFT1), this implementation is as follows: Figure 1 As shown, by adjusting the physical dimensions and input current of the single-gate thin-film transistor (TFT1), the TFT1 is made to operate in the subthreshold region, which is used to broaden the dynamic response range of the pixel circuit and realize the logarithmic conversion of the photocurrent input at the signal terminal ST to the output voltage of the TFT1.

[0039] Specifically, the logarithmic transformation relationship between the input photocurrent and output voltage of the single-gate thin-film transistor (TFT1) is as follows: V ds1 =V TH1 + ln( ) in, Vds1 This indicates the output voltage of the single-gate thin-film transistor TFT1. V TH1 This represents the threshold voltage of the single-gate thin-film transistor TFT1. I signal This indicates the photocurrent signal input at the signal terminal ST. This represents the input current of the single-gate thin-film transistor TFT1. This represents the subthreshold slope factor of a single-gate thin-film transistor (TFT-1). This represents thermal voltage.

[0040] Specifically, the thermal voltage expression is: V T = KT / q ( K Boltzmann's constant, q The amount of electron charge. T It's temperature.

[0041] In application, a single-gate thin-film transistor (TFT1) can be placed at the front end of a 3T amplifier circuit 1 as an input signal conditioning and voltage-to-current conversion module. By adjusting its physical parameters such as channel length, gate dielectric thickness, and bias voltage, the photocurrent input under low-light conditions can be more easily converted into a stable output voltage signal, thereby achieving precise control and digitization of the input photocurrent at the signal terminal ST.

[0042] This structure can effectively improve the signal-to-noise ratio, reduce readout noise, and increase the dynamic response range of X-ray flat panel detectors under low-dose operating conditions, solving the problem of insufficient gain of traditional APS circuits at low doses.

[0043] In addition, the channel width-to-length ratio is adjusted according to the pixel area of ​​different detectors, and various high-k dielectric materials are used to optimize the gate dielectric to further reduce leakage current and enhance the response capability of the input terminal to weak signals.

[0044] Regarding the control principle and function of the aforementioned single-gate thin-film transistor TFT2, this implementation is as follows: Figure 1 As shown, by adjusting the physical dimensions and input current of the single-gate thin-film transistor TFT2, the single-gate thin-film transistor TFT2 can operate in the subthreshold region, exhibiting exponential amplification performance.

[0045] Specifically, the relationship between the output current of single-gate thin-film transistor TFT2 and the output voltage of single-gate thin-film transistor TFT1 is as follows: I out =I DS2 · exp[ ] in, I out This indicates the output current of the single-gate thin-film transistor TFT2. I DS2 This represents the input current of the single-gate thin-film transistor TFT2. V ds1 This indicates the output voltage of the single-gate thin-film transistor TFT1. V TH2This represents the threshold voltage of the single-gate thin-film transistor TFT2. This represents the subthreshold slope factor of the single-gate thin-film transistor TFT2. q It represents the amount of electron charge.

[0046] In application, the single-gate thin-film transistor TFT2 can be arranged in the intermediate stage of the 3T amplifier circuit 1 as an active amplifier device. By applying an external bias voltage VDD and coupling it with the signal terminal ST, the output signal of the single-gate thin-film transistor TFT1 can be amplified a second time and the current output characteristics can be adjusted.

[0047] In practice, gain optimization can be achieved by adjusting its threshold voltage, mobility, and channel design parameters to ensure a stable output current over a wide dynamic range.

[0048] This structure significantly improves detection sensitivity and signal-to-noise ratio under weak light and low-dose conditions, expands the dynamic response range, and effectively solves the problems of complex manufacturing processes and difficulty in maintaining stable gain in existing DG-TFT circuits.

[0049] In addition, a multi-level programmable bias module is introduced to realize automatic gain adjustment in different working modes; a local calibration unit is added to the pixel array to compensate for threshold drift caused by process differences.

[0050] Regarding the control principle and function of the aforementioned single-gate thin-film transistor three-TFT3, this implementation is as follows: Figure 1 As shown, the single-gate thin-film transistor TFT3 acts as a switching transistor to control the readout function of the 3T amplifier circuit 1, thereby enabling independent control of the arbitrary or continuous readout of the 3T amplifier circuit 1 required by the user.

[0051] In application, the single-gate thin-film transistor TFT3 is arranged as an independent switching transistor at the readout terminal of the 3T amplifier circuit 1 to achieve precise on / off switching between the data terminal DE and the readout control signal.

[0052] Specifically, by applying a periodic or on-demand controlled drive signal to its gate, the single-gate thin-film transistor TFT3 is quickly turned on during readout, achieving fast readout and isolation under high pixel density conditions while maintaining low leakage current; it is reliably turned off during non-readout to avoid interference or leakage of the preceding signal.

[0053] This structure not only ensures the integrity and stability of the output data of the 3T amplifier circuit 1, but also flexibly realizes independent readout control of any pixel or consecutive pixels, solving problems such as slow readout speed, crosstalk interference and unstable output in existing APS circuits, thereby improving the signal-to-noise ratio and dynamic response capability of the whole machine.

[0054] In addition, pulse width modulation (PWM) or level-grading control is introduced at the driver end to reduce power consumption and latency, and partitioned or multiplexed readout structures are used in large-area arrays to further improve readout speed and expand resolution.

[0055] By leveraging the synergistic operation of the three single-gate thin-film transistors in the 3T amplifier circuit 1, this invention significantly simplifies the process structure and reduces costs while maintaining high sensitivity and high gain. It also achieves wide dynamic response and high signal-to-noise ratio readout, meeting the application requirements of low-dose, high-resolution X-ray imaging. Furthermore, by combining extended structures such as adjustable channel parameters, multi-level bias voltage adjustment, local calibration, and time-division multiplexing, the system stability and scalability can be further improved, forming a mass-producible, high-performance X-ray flat panel detector front-end circuit solution.

[0056] A second implementation of a high-performance 3TAPS circuit, for example Figure 2 As shown, the difference between this embodiment and the first embodiment is that it also includes a photodiode 21, which is connected to the 3T amplifier circuit 1 to form a 3T1D active pixel circuit 2; the anode of the photodiode 21 is connected to the signal terminal ST to form the sensing part of the 3T1D active pixel circuit 2; the cathode of the photodiode 21 and the drain of the single-gate thin film transistor TFT2 are respectively given bias voltages VDD1 and VDD2.

[0057] By controlling the single-gate thin-film transistor TFT1 and the single-gate thin-film transistor TFT2 to operate in the subthreshold region, the output voltage of the single-gate thin-film transistor TFT1 is logarithmically related to the incident light intensity of the photodiode 21, which is used to broaden the dynamic response range of the 3T1D active pixel circuit 2; the single-gate thin-film transistor TFT2 is used as an in-pixel amplifier to improve the sensitivity of the 3T1D active pixel circuit 2 under weak light conditions of the photodiode 21, that is, by lowering the detection lower limit of the photodiode 21, the dynamic response range of the 3T1D active pixel circuit 2 is expanded. Among them, the single-gate thin-film transistor TFT3 acts as a switching transistor to control the readout of the 3T1D active pixel circuit 2.

[0058] This implementation example Figure 3As shown in the random readout timing diagram, the 3T1D active pixel circuit 2 operates in random readout mode. In random readout mode, when the single-gate thin-film transistor TFT3 is turned on, the single-gate thin-film transistor TFT1 is also turned on. Under illumination, the photocurrent generated by the unit light power of the photodiode 21 flows through the single-gate thin-film transistor TFT1, and the output voltage generated by the single-gate thin-film transistor TFT2 acts on the single-gate thin-film transistor TFT2. When the single-gate thin-film transistor TFT2 is also working in the subthreshold region, the pixel readout is completed directly and quickly, generating a continuous signal output that is linearly related to the instantaneous light intensity. Therefore, the 3T1D active pixel circuit 2 can perform random readout in both space and time, that is, any pixel unit can be accessed and read at any time.

[0059] In the random read timing diagram, LIGHT indicates that a light signal is shining on photodiode 21.

[0060] In application, photodiode 21 can be integrated with 3T amplifier circuit 1 to construct 3T1D active pixel circuit 2. By adjusting the bias voltage VDD1 of photodiode 21 and the bias voltage VDD2 of single-gate thin film transistor TFT2, single-gate thin film transistor TFT1 and single-gate thin film transistor TFT2 can be made to work stably in the subthreshold region. The output voltage of single-gate thin film transistor TFT1 is logarithmically related to the incident light intensity.

[0061] In practical operation, the readout port can be controlled by activating the single-gate thin-film transistor TFT3 in random readout mode, and simultaneously activating the single-gate thin-film transistor TFT1. This allows the photocurrent generated by photodiode 21 to rapidly act on the amplifying device single-gate thin-film transistor TFT2, achieving continuous signal output and readout of any pixel under low-light conditions. This structure significantly widens the dynamic response range while maintaining high sensitivity and high signal-to-noise ratio, solving the problems of high detection limit, narrow response range, and limited random access in traditional APS circuits under low-light conditions.

[0062] In addition, multi-level programmable bias circuits can be introduced to automatically adjust the threshold and gain according to the illumination conditions; microlens arrays or anti-reflection layers can be added to the photodiode 21 region to further improve photoelectric conversion efficiency; and the signal-to-noise ratio of low-dose signals can be enhanced by supporting multi-frame overlay and time-resolved modes.

[0063] A third implementation of a high-performance 3TAPS circuit, for example Figure 4As shown, the difference between this embodiment and the first embodiment is that it also includes multiple passive pixel units 31; the multiple passive pixel units 31 are connected in parallel to the signal terminal ST of the 3T amplifier circuit 1 to form the 3T passive pixel amplifier circuit 3; the passive pixel unit 31 to be read out in the 3T passive pixel amplifier circuit 3 is selected by the row selection function to realize pixel amplification. The 3T amplifier circuit 1 is used as an external amplifier circuit, so that each passive pixel unit 31 in the multiple passive pixel units 31 only needs to retain one switching thin film transistor to improve the pixel fill rate of the 3T passive pixel amplifier circuit 3, while also having the high sensitivity and wide dynamic range performance of the 3T amplifier circuit 1.

[0064] In application, multiple passive pixel units 31 can be connected in parallel to the signal terminal ST of the 3T amplifier circuit 1. The target passive pixel unit 31 can be selected using the row selection function and the signal can be amplified by the 3T amplifier circuit 1.

[0065] In practice, the address selection of each row of passive pixel unit 31 is achieved through an external control circuit, so that the selected passive pixel unit 31 outputs a signal through its reserved switching thin film transistor, and the corresponding 3T amplifier circuit 1 amplifies and outputs the signal in two stages.

[0066] This structure significantly improves pixel fill rate while maintaining high sensitivity and wide dynamic range. It solves the problems of weak signal, susceptibility to noise interference and insufficient amplification capability of traditional passive pixel circuits, and is superior to fully active pixel structures in terms of cost and process maturity.

[0067] In addition, a dynamic baseline calibration circuit can be added to the signal line of the signal terminal ST of the 3T amplifier circuit 1 connected in parallel with multiple passive pixel units 31 to compensate for process deviations; the 3T amplifier circuit 1 can be arranged in the driving area of ​​the column through modular design to reduce wiring length and parasitic capacitance; and a reconfigurable amplification gain module can be introduced to adapt to different detection scenarios.

[0068] Specifically, this implementation is as follows: Figure 5 As shown, multiple 3T passive pixel amplifier circuits 3 form a passive pixel matrix 4 to improve detection resolution.

[0069] In application, multiple columns of 3T passive pixel amplifier circuits 3 can be combined to form a passive pixel matrix 4, and multi-dimensional scanning and simultaneous reading of multiple channels can be achieved through external column selection and row selection driving.

[0070] In practice, each column or row of passive pixel units 31 can be activated sequentially according to the scanning order, so that their signals are uniformly sent to the corresponding 3T amplifier circuit 1 for amplification and output, thereby improving the overall resolution and reading speed without increasing the number of transistors in each pixel unit.

[0071] This structure significantly improves detection resolution and array scalability while ensuring a high pixel fill rate, solving the problem that traditional passive matrices cannot achieve both high resolution and high signal-to-noise ratio.

[0072] In addition, multi-channel parallel readout technology can be used during reading to reduce the scanning time of the entire array; row and column drive control chips can be integrated on the periphery of the matrix to reduce wiring complexity; and an on-chip ADC module can be introduced to realize digital output of the signal front end to reduce external interference.

[0073] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described.

Claims

1. A high-performance 3TAPS circuit based on single-gate thin-film transistor, characterized in that, it comprises three single-gate thin-film transistors, namely single-gate thin-film transistor one, single-gate thin-film transistor two and single-gate thin-film transistor three; the drain and gate of the single-gate thin-film transistor one and the gate of the single-gate thin-film transistor two are connected to a signal end, the source of the single-gate thin-film transistor one is grounded, the drain of the single-gate thin-film transistor two is externally biased, the source of the single-gate thin-film transistor two is connected to the drain of the single-gate thin-film transistor three, the gate of the single-gate thin-film transistor three serves as a read end, and the source serves as a data end, forming a 3T amplification circuit; the output voltage of the single-gate thin-film transistor one is controlled by the input signal of the signal end, for widening the dynamic response range of the 3T amplification circuit; the single-gate thin-film transistor two serves as an amplifier, for improving the sensitivity of the 3T amplification circuit under weak light conditions and expanding the dynamic response range of the 3T amplification circuit by lowering the detection lower limit of the input components of the signal end; the single-gate thin-film transistor three only serves as a switching device, for controlling the readout of the 3T amplification circuit.

2. The single-gate thin-film transistor based high performance 3T APS circuit according to claim 1, wherein, By adjusting the physical size and input current of the single-gate thin-film transistor one, the single-gate thin-film transistor one works in the sub-threshold region, for widening the dynamic response range of the pixel circuit and realizing the logarithmic conversion of the photocurrent input by the signal end to the output voltage of the single-gate thin-film transistor one.

3. The single-gate thin-film transistor based high performance 3T APS circuit according to claim 2, wherein, The logarithmic conversion relationship between the photocurrent input by the single-gate thin-film transistor one and the output voltage is: V ds1 =V TH1 + ln( ) wherein, V ds1 Vout represents an output voltage of the single-gate thin-film transistor one, V TH1 Vth represents a threshold voltage of the single-gate thin-film transistor one, I signal Iphoto represents a photo current signal inputted from the signal terminal, Iin represents an input current of the single-gate thin-film transistor one, SS represents a sub-threshold slope factor of the single-gate thin-film transistor one, VT represents a thermal voltage.

4. The single-gate thin-film transistor based high performance 3TAPS circuit of claim 1, wherein, By adjusting the physical size and input current of the single-gate thin-film transistor two, the single-gate thin-film transistor two works in the sub-threshold region, exhibiting exponential amplification performance.

5. The single-gate thin-film transistor based high performance 3T APS circuit according to claim 4, wherein, The relationship between the output current of the single-gate thin-film transistor two and the output voltage of the single-gate thin-film transistor one is: I out =I DS2 · exp[ ] wherein, I out represents an output current of the single-gate thin-film transistor two, I DS2 represents an input current of the single-gate thin-film transistor two, V ds1 represents an output voltage of the single-gate thin-film transistor one, V TH2 represents a threshold voltage of the single-gate thin-film transistor two, represents a sub-threshold slope factor of the single-gate thin-film transistor two, q represents an electronic charge amount.

6. The single-gate thin-film transistor based high performance 3T APS circuit of claim 1, wherein, It further comprises a photodiode, which is connected to the 3T amplification circuit to form a 3T1D active pixel circuit; the anode of the photodiode is connected to the signal end, for forming the sensing part of the 3T1D active pixel circuit; the cathode of the photodiode and the drain of the single-gate thin-film transistor two are externally biased with bias voltages VDD1 and VDD2, respectively; By controlling the single-gate thin-film transistor one and the single-gate thin-film transistor two to work in the sub-threshold region, the output voltage of the single-gate thin-film transistor one has a logarithmic relationship with the incident light intensity of the photodiode, for widening the dynamic response range of the 3T1D active pixel circuit; and the single-gate thin-film transistor two serves as an in-pixel amplifier, for improving the sensitivity of the 3T1D active pixel circuit under weak light conditions of the photodiode, i.e. expanding the dynamic response range of the 3T1D active pixel circuit by lowering the detection lower limit of the photodiode; the single-gate thin-film transistor three serves as a switching transistor, for controlling the readout of the 3T1D active pixel circuit.

7. The single-gate thin-film transistor based high performance 3T APS circuit according to claim 6, wherein, The working mode of the 3T1D active pixel circuit is random read mode.

8. The single-gate thin-film transistor based high performance 3T APS circuit according to claim 7, wherein, The random reading mode: when the single-gate thin film transistor three is turned on, the single-gate thin film transistor one is also turned on, and under the light condition, the photoelectric current generated by the unit light power of the photodiode flows through the output voltage generated by the single-gate thin film transistor one, and the output voltage acts on the single-gate thin film transistor two, so that the pixel reading is directly and quickly completed when the single-gate thin film transistor two also works in the sub-threshold region, and a continuous signal output in a linear relationship with the instantaneous light intensity is generated, so that the 3T1D active pixel circuit is randomly readable in space and time, that is, any pixel unit can be accessed and read at any time.

9. The single-gate thin-film transistor based high performance 3T APS circuit of claim 1, wherein, A plurality of passive pixel units are also included; A plurality of the passive pixel units are connected in parallel to the signal end of the 3T amplification circuit to form a 3T passive pixel amplification circuit; The pixel amplification is realized by selecting the passive pixel unit to be read out in the 3T passive pixel amplification circuit through the row selection function, and the 3T amplification circuit is used as an external amplification circuit, so that each passive pixel unit of the plurality of passive pixel units only needs to reserve one switch thin film transistor, thereby improving the pixel fill rate of the 3T passive pixel amplification circuit, and the 3T amplification circuit has high sensitivity and wide dynamic range.

10. The single-gate thin-film transistor based high performance 3T APS circuit according to claim 9, wherein, A plurality of columns of the 3T passive pixel amplification circuit form a passive pixel matrix to improve the detection resolution.

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