A brain-like color recognition unit based on a vertical triple-junction detector

Abstract

The present invention discloses a brain-like color recognition unit based on a vertical three-junction detector, which relates to the field of brain-like visual recognition technology. The brain-like color recognition unit provided by the present invention utilizes a vertical three-junction detector to detect and identify the wavelength of visible light, and outputs a photocurrent related to the wavelength. The photocurrent is converted into a voltage signal proportional to red, green, and blue by a conversion unit. The "winner takes all" neuron circuit simulates the color recognition mode of the human brain, performs brain-like signal processing of the voltage signal in the manner of "the stronger the stronger, the weaker the weaker", amplifies the difference between different color information, and converts it into a digital signal that is easy to process and calculate, thereby realizing brain-like recognition of visible light color. The brain-like color recognition unit is based on a standard CMOS process, takes the human retina and brain as a research reference, combines neuron circuits with silicon-based detectors, and will promote the development of integrated and miniaturized brain-like visual recognition chips.

Description

Technical Field

[0001] The present invention relates to the field of brain-like visual recognition, and in particular to a brain-like color recognition unit based on a vertical three-junction detector. Background Art

[0002] The 21st century is a century of intelligence, informatization, computing, and networking. The ultimate goal of artificial intelligence is to emulate, simulate, and learn from the neural structure and information processing of the human brain to achieve or surpass human intelligence. Brain-inspired vision is the application of artificial intelligence technology to machine vision, drawing inspiration from the biological brain. In biological vision, color is one of the most powerful and important visual signals. With the recent development of technologies such as smart transportation, connected vehicles, and visible light communication, color detection and recognition has become a research hotspot.

[0003] The human visual system's ability to discern color information in visible light relies on the structure and function of the retina. Traditionally, discrete color filters have been applied to the surface of photodetectors, making them responsive only to incident light of specific wavelengths. However, this approach is expensive, bulky, and incompatible with standard CMOS processes. Another color recognition method uses organic dye polymers on the surface of image sensors, but this approach is complex, costly, and susceptible to performance degradation after high temperatures or prolonged exposure. Based on the varying penetration depths of light of different wavelengths in silicon, vertically stacked triple-junction detectors with varying junction depths can be designed to detect red, green, and blue wavelengths, thereby distinguishing between different colors and achieving a function similar to that of the human retina. Vertical triple-junction detectors can capture full color information in a single pixel, and their fabrication process is simple and compatible with standard CMOS processes, enabling monolithic integration of color detectors and information processing circuits. The color digital silicon photomultiplier pixel unit proposed in patent CN107830939A requires through-silicon via (TSV) technology for 3D stacking, which is challenging and costly. Furthermore, the avalanche diode requires a high operating voltage, which can easily cause electronic circuit breakdown. The detector used in this patent is simple to manufacture, low-cost, and suitable for large-scale integrated production. However, given the fixed process, the depths of the various wells cannot be changed, resulting in the spectral response curve of the vertical triple-junction detector being unable to be flexibly adjusted according to demand. Furthermore, due to the similar wavelengths of green and red light, there is severe spectral overlap near long wavelengths, resulting in reduced resolution of the vertical triple-junction detector.

[0004] Vertical triple-junction detectors can detect visible light wavelengths and output color information, but they cannot identify color information. Currently, color recognition is primarily achieved through hardware or software methods. For example, patent CN210802699U utilizes hardware circuits, including a main control circuit, a color collection module, a display circuit, and a transmission circuit, to achieve color detection and identification. However, these hardware-based color recognition units often require circuits for signal amplification, filtering, and A / D conversion. These complex circuit structures can cause signal delays during processing, impacting the real-time performance of color recognition. Most color recognition algorithms have numerous constraints and poor robustness, making efficient and accurate recognition difficult to achieve in industrial environments. The "winner-takes-all" circuit is a competitive neural network circuit. The subthreshold transistors in the circuit possess the basis functions required to simulate biological processes. By simulating the color information processing mechanism of the brain's nervous system, it can identify and filter the color information output by the vertical triple-junction detector. The circuit requires a small number of transistors, resulting in a compact circuit structure, low chip area, and low power consumption. The color recognition unit proposed in this patent can perform brain-like processing on the color information output by the vertical three-junction detector, "the stronger the stronger, the weaker the weaker", expand the difference between different color information, improve the resolution and recognition accuracy of the vertical three-junction detector, and obtain real-time color information of the three primary colors of red, green and blue. The information recognition processing process is simple and efficient, which reduces the requirements for post-processing calculations and greatly improves the efficiency of color recognition.

[0005] Currently, the market lacks monolithic, miniaturized, low-cost, convenient, and efficient visible light color recognition chips. In industries such as industry, artificial intelligence, and the military, there is a huge market demand for color recognition units that enhance computer vision capabilities by simulating the physical mechanisms of color recognition in the human brain. Achieving brain-like color recognition for visible light will significantly promote the development and widespread adoption of brain-inspired vision technologies. Summary of the Invention

[0006] In order to overcome the above-mentioned defects in the prior art, the present invention provides a brain-like color recognition unit based on a vertical three-junction detector to achieve real-time and effective recognition of the three primary colors of visible light (red, green and blue) and digitize the color information.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a brain-like color recognition unit based on a vertical three-junction detector, comprising a visible light detection part and a brain-like recognition part, wherein the output current of the vertical three-junction detector is connected to a conversion unit, which converts the output current of the vertical multi-junction detector into a voltage signal proportional to the red, green and blue light. The output port of the conversion unit is connected to a voltage-type "winner-takes-all" neuron circuit, which only responds to the unit with the strongest input signal and suppresses the responses of other units. The voltage-type "winner-takes-all" circuit processes the color information output by the vertical three-junction detector to solve the problem of low wavelength recognition accuracy of the detector due to spectral overlap, and converts the color information into a digital signal in real time.

[0008] The vertical triple-junction detector is based on a standard CMOS process and includes NIMP, PIMP, Nwell, Pwell, Deep Nwell, and Psub layers. The NIMP, Pwell, Deep Nwell, and Psub layers are stacked vertically from top to bottom. The NIMP and Pwell layers form a shallow junction diode, the Pwell and Deep Nwell layers form an intermediate diode, and the Deep Nwell and Psub layers form a deep junction diode. The three diodes are located at different depths to achieve visible light detection and output a current signal related to the wavelength of visible light.

[0009] The conversion unit amplifies the three output currents of the vertical triple junction detector in equal proportion and converts them into voltage form, then performs correlation conversion on the voltage signal and outputs a voltage signal proportional to red, green and blue.

[0010] In the voltage-type "winner-takes-all" neuron circuit, the gates of the first NMOS transistor M3, the second NMOS transistor M7, and the third NMOS transistor M11 serve as voltage input terminals, the sources of the first NMOS transistor M3, the second NMOS transistor M7, and the third NMOS transistor M11 are connected together and connected to the drain of the seventh NMOS transistor M13, the drain of the first NMOS transistor M3 is connected to the drain of the first PMOS transistor M1, the drain of the second NMOS transistor M7 is connected to the drain of the second PMOS transistor M2, the drain of the third NMOS transistor M11 is connected to the drain of the third PMOS transistor M5, the gates of the fourth NMOS transistor M4, the fifth NMOS transistor M8, and the sixth NMOS transistor M12 are connected together and connected to the input voltage VA, the first PMOS transistor M1 and the second PMOS transistor M2, the third PMOS transistor M5 and the fourth PMOS transistor M6, the fifth PMOS transistor M9, and the sixth PMOS transistor M10 respectively form current mirrors, the gates of the first PMOS transistor M1 and the second PMOS transistor M2 are connected and connected to the The drain of the first NMOS transistor M3 is connected to the drain of the first PMOS transistor M1, the gates of the third PMOS transistor M5 and the fourth PMOS transistor M6 are connected, and are connected to the drain of the second NMOS transistor M7 and the drain of the third PMOS transistor M5, the gates of the fifth PMOS transistor M9 and the sixth PMOS transistor M10 are connected, and are connected to the drain of the third NMOS transistor M11 and the drain of the fifth PMOS transistor M9, the drains of the second PMOS transistor M2, the fourth PMOS transistor M6, and the sixth PMOS transistor M10 are respectively connected to the drains of the fourth NMOS transistor M4, the fifth NMOS transistor M8, and the sixth NMOS transistor M12 and serve as output terminals, the sources of the first PMOS transistor M1, the second PMOS transistor M2, the third PMOS transistor M5, the fourth PMOS transistor M6, the fifth PMOS transistor M9, and the sixth PMOS transistor M10 are connected to the power supply VDD, and the sources of the fourth NMOS transistor M4, the fifth NMOS transistor M8, the sixth NMOS transistor M12, and the seventh NMOS transistor M13 are connected to GND.

[0011] The beneficial effects of the present invention are as follows:

[0012] 1) The brain-inspired color recognition unit simulates the color recognition mode of the human brain, can effectively detect and identify the wavelength of visible light, and convert color information into a digital signal that is easy to calculate and process. It can be directly connected to a microprocessor or other circuit, reducing the difficulty of subsequent calculations. At the same time, the manufacturing process is compatible with standard CMOS technology, which can realize the monolithic integration of the color recognition unit;

[0013] 2) Vertical triple-junction detectors can be fabricated using standard CMOS processes, which are simple. By vertically stacking PN junctions of varying depths, full color information can be obtained within a single pixel. Compared to adding discrete filters, this saves chip area and avoids light loss, such as refraction loss, caused by discrete filters, resulting in higher quantum efficiency.

[0014] 3) The "winner takes all" neuron circuit requires a small number of transistors, has a simple circuit structure, and a compact layout. It can imitate the human brain's mechanism for processing color information, identify and process the color information output by the vertical three-junction detector on a "stronger gets stronger, weaker gets weaker" basis, and provide real-time response to input voltage changes. This can solve the problem of low wavelength recognition accuracy caused by spectral response overlap in the vertical three-junction detector, thereby improving the color recognition accuracy of the vertical three-junction detector.

[0015] In summary, the present invention, based on the human retina and brain as research references, can achieve visible light color recognition. The entire unit is compatible with standard CMOS processes and can be integrated on a single chip, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A functional block diagram of a brain-like color recognition unit provided by an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of the structure of a vertical triple-junction color detector provided by an embodiment of the present invention;

[0019] Figure 3 A circuit diagram of a vertical triple-junction detector signal conversion unit provided by an embodiment of the present invention;

[0020] Figure 4 A circuit diagram of a "winner-takes-all" neuron circuit provided by an embodiment of the present invention;

[0021] Figure 5 The simulation results of the "winner takes all" neuron circuit provided by the embodiment of the present invention;

[0022] Figure 6 Schematic diagram of the brain-inspired color recognition unit provided by an embodiment of the present invention recognizing green light. DETAILED DESCRIPTION

[0023] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] Figure 1 The functional block diagram of a brain-inspired color recognition unit provided by an embodiment of the present invention is shown. The unit comprises a vertical three-junction detector, a conversion unit, and a "winner-takes-all" circuit. The vertical three-junction detector absorbs visible light and outputs a photocurrent. The conversion unit converts the photocurrent into a voltage signal proportional to the visible light color. This voltage signal is then connected to the input of the "winner-takes-all" neuron circuit, which identifies and processes the three input signals. The unit with the highest input voltage outputs a high level, while the remaining units output low levels. This digitizes the visible light color information and enables visible light recognition.

[0025] Figure 2 The cross-sectional structure of a vertical triple-junction detector based on a standard CMOS process, provided by an embodiment of the present invention, is shown. By vertically stacking an N+ injection layer (NIMP), a P-well (Pwell), a deep N-well (Deep Nwell), and a substrate (Psub), three PN junctions at different depths are formed. Due to the varying penetration depths of visible light in silicon, blue light is mostly absorbed by the shallow PN junction, green light is mostly absorbed by the middle PN junction, and red light is mostly absorbed by the deep PN junction, generating a photocurrent related to the wavelength of visible light.

[0026] Figure 3 A conversion unit consisting of a transimpedance amplifier and a conversion circuit provided by an embodiment of the present invention is shown. In a vertical triple-junction detector, the three vertically stacked PN junctions share a common anode or cathode, resulting in overlapping output currents. Through the conversion unit, the output electrode of the vertical triple-junction detector is connected to the transimpedance amplifier, which converts the photocurrent into a voltage. After the voltage is converted by the conversion circuit, the overlapping currents of the vertical triple-junction detector can be converted to output a voltage signal proportional to the color of visible light.

[0027] Figure 4A circuit diagram of a "winner-takes-all" neuron circuit provided by an embodiment of the present invention is shown. In the voltage-type "winner-takes-all" neuron circuit, the gates of the first NMOS transistor M3, the second NMOS transistor M7, and the third NMOS transistor M11 serve as voltage input terminals. The sources of the first NMOS transistor M3, the second NMOS transistor M7, and the third NMOS transistor M11 are connected together and connected to the drain of the seventh NMOS transistor M13. The drain of the first NMOS transistor M3 is connected to the drain of the first PMOS transistor M1, and the drain of the second NMOS transistor M7 is connected to the drain of the second PMOS transistor M13. The drain of the third NMOS transistor M11 is connected to the drain of the third PMOS transistor M5, the gates of the fourth NMOS transistor M4, the fifth NMOS transistor M8 and the sixth NMOS transistor M12 are connected together and connected to the input voltage VA, the first PMOS transistor M1 and the second PMOS transistor M2, the third PMOS transistor M5 and the fourth PMOS transistor M6, the fifth PMOS transistor M9 and the sixth PMOS transistor M10 respectively form a current mirror, the gates of the first PMOS transistor M1 and the second PMOS transistor M2 are connected and connected to the first NMOS transistor The drain of the S transistor M3 is connected to the drain of the first PMOS transistor M1, the gates of the third PMOS transistor M5 and the fourth PMOS transistor M6 are connected and connected to the drain of the second NMOS transistor M7 and the drain of the third PMOS transistor M5, the gates of the fifth PMOS transistor M9 and the sixth PMOS transistor M10 are connected and connected to the drain of the third NMOS transistor M11 and the drain of the fifth PMOS transistor M9, the drains of the second PMOS transistor M2, the fourth PMOS transistor M6 and the sixth PMOS transistor M10 are connected to the fourth NMOS transistor M4, the fifth NMOS transistor M5 and the drain of the fifth PMOS transistor M11, respectively. The drains of the OS transistor M8 and the sixth NMOS transistor M12 are connected and serve as output terminals. The sources of the first PMOS transistor M1, the second PMOS transistor M2, the third PMOS transistor M5, the fourth PMOS transistor M6, the fifth PMOS transistor M9, and the sixth PMOS transistor M10 are connected to the power supply VDD. The sources of the fourth NMOS transistor M4, the fifth NMOS transistor M8, the sixth NMOS transistor M12, and the seventh NMOS transistor M13 are connected to GND. The circuit implements a "stronger gets stronger, weaker gets weaker" signal processing for the input signal through a global feedback suppression mechanism. In the brain-inspired color recognition unit, a "winner takes all" neuron circuit is used to identify and filter the output signals of the vertical three-junction detector, amplifying the differences between the color information of different PN junctions and selecting the detector's strongest output signal, thus achieving brain-inspired color recognition of visible light.

[0028] Figure 5The simulation results of a "winner-takes-all" neuron circuit provided by an embodiment of the present invention are shown. During the simulation, the voltage of Vin1 is 1V, the voltage of Vin2 is 2V, and the voltage of Vin3 varies from 0V to 3.3V. When Vin3 is less than 2V, the voltage of Vin2 is maximum, OUT2 outputs 3.3V, and OUT1 and OUT3 output 0V. When the voltage of Vin3 is greater than 2V, the voltage of Vin3 is maximum, and the gate voltage of the transistor corresponding to Vin3 increases, causing the source voltage of the transistor to increase, that is, the voltage of the common node VC increases. The increase in the VC node voltage reduces the current of the transistors corresponding to Vin1 and Vin2 until the transistors are turned off, and all the current flows into the unit corresponding to Vin3. OUT3 outputs 3.3V, and the remaining units output 0V. From the circuit simulation results, it can be seen that within the minimum resolution, the "winner-takes-all" neuron circuit can achieve the function of "the strong get stronger, the weak get weaker", amplify the difference between input signals, and identify the largest input signal.

[0029] Figure 6 A schematic diagram shows a brain-inspired color recognition unit based on a standard CMOS multi-wavelength detector, provided by an embodiment of the present invention, identifying green light. Assuming green light illuminates a vertical three-junction detector, according to the vertical three-junction detector's spectral response curve, the photocurrent generated by the middle PN junction is maximum at this time. After passing through the conversion unit, the output voltage of the conversion unit branch corresponding to green light is maximum. The "winner-takes-all" neuron circuit has the maximum input voltage for the green light circuit branch. Simultaneously, a global feedback inhibition mechanism suppresses the current in the branches corresponding to blue and red light, causing them to output a low level. The branch corresponding to green light outputs a high voltage, while the branches corresponding to blue and red light output a low voltage. The brain-inspired color recognition unit's judgment results can be observed by connecting its output to an oscilloscope.

[0030] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention are intended to be covered by the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. A brain-like color recognition unit based on a vertical triple-junction detector, characterized in that: Including visible light detection part and brain-like recognition part; The visible light detection part includes a vertical three-junction detector and a conversion unit. The vertical three-junction detector detects visible light and identifies its wavelength. The output current of the vertical three-junction detector is connected to the conversion unit. The conversion unit converts the output current of the vertical three-junction detector into a voltage signal proportional to red, green and blue light. The brain-like recognition part includes a voltage-type "winner-takes-all" neuron circuit. The input end of the voltage-type "winner-takes-all" neuron circuit is connected to the output port of the conversion unit. The circuit only responds to the unit with the strongest input signal and suppresses the responses of other units. The voltage-type "winner-takes-all" circuit processes the color information output by the vertical three-junction detector and converts the color information into a digital signal in real time.

2. The brain-like color recognition unit according to claim 1, characterized in that: The vertical triple-junction detector is based on a standard CMOS process and includes NIMP, PIMP, Nwell, Pwell, Deep Nwell, and Psub layers. The NIMP, Pwell, DeepNwell, and Psub layers are stacked vertically from top to bottom. The NIMP and Pwell layers form a shallow junction diode, the Pwell and DeepNwell layers form an intermediate diode, and the Deep Nwell and Psub layers form a deep junction diode. The three diodes are located at different depths and have different sensitivities to red, green, and blue, enabling visible light detection and outputting a current signal related to the visible light wavelength.

3. The brain-like color recognition unit according to claim 1, characterized in that: The conversion unit amplifies the three output currents of the vertical triple-junction detector in equal proportion and converts them into voltage form, then performs relevant conversion on the voltage signal based on Kirchhoff's law and outputs a voltage signal proportional to red, green and blue.

4. The brain-like color recognition unit according to claim 1, characterized in that: In the voltage-type "winner-takes-all" neuron circuit, the gates of the first NMOS transistor M3, the second NMOS transistor M7, and the third NMOS transistor M11 serve as voltage input terminals, the sources of the first NMOS transistor M3, the second NMOS transistor M7, and the third NMOS transistor M11 are connected together and connected to the drain of the seventh NMOS transistor M13, the drain of the first NMOS transistor M3 is connected to the drain of the first PMOS transistor M1, the drain of the second NMOS transistor M7 is connected to the drain of the second PMOS transistor M2, the drain of the third NMOS transistor M11 is connected to the drain of the third PMOS transistor M5, the gates of the fourth NMOS transistor M4, the fifth NMOS transistor M8, and the sixth NMOS transistor M12 are connected together and connected to the input voltage VA, the first PMOS transistor M1 and the second PMOS transistor M2, the third PMOS transistor M5 and the fourth PMOS transistor M6, the fifth PMOS transistor M9, and the sixth PMOS transistor M10 respectively form current mirrors, the gates of the first PMOS transistor M1 and the second PMOS transistor M2 are connected and connected to the drain of the third PMOS transistor M5. A drain of the first NMOS transistor M3 is connected to the drain of the first PMOS transistor M1, gates of the third PMOS transistor M5 and the fourth PMOS transistor M6 are connected, and are connected to the drain of the second NMOS transistor M7 and the drain of the third PMOS transistor M5, gates of the fifth PMOS transistor M9 and the sixth PMOS transistor M10 are connected, and are connected to the drain of the third NMOS transistor M11 and the drain of the fifth PMOS transistor M9, drains of the second PMOS transistor M2, the fourth PMOS transistor M6, and the sixth PMOS transistor M10 are respectively connected to the drains of the fourth NMOS transistor M4, the fifth NMOS transistor M8, and the sixth NMOS transistor M12 and serve as output terminals, sources of the first PMOS transistor M1, the second PMOS transistor M2, the third PMOS transistor M5, the fourth PMOS transistor M6, the fifth PMOS transistor M9, and the sixth PMOS transistor M10 are connected to the power supply VDD, and sources of the fourth NMOS transistor M4, the fifth NMOS transistor M8, the sixth NMOS transistor M12, and the seventh NMOS transistor M13 are connected to GND.

5. The brain-like color recognition unit according to claim 4, characterized in that: Substrates of the first PMOS transistor M1, the second PMOS transistor M2, the third PMOS transistor M5, the fourth PMOS transistor M6, the fifth PMOS transistor M9 and the sixth PMOS transistor M10 are connected to the power supply VDD, and substrates of the fourth NMOS transistor M4, the fifth NMOS transistor M8, the sixth NMOS transistor M12 and the seventh NMOS transistor M13 are connected to GND.

6. The brain-like color recognition unit according to claim 4, characterized in that: The voltage-type "winner takes all" neuron circuit realizes the signal processing of the input signal of "the strong gets stronger and the weak gets weaker" through the global feedback inhibition mechanism, thereby identifying and screening the output signals of the vertical three-junction detector, expanding the difference between the color information of different PN junctions, selecting the strongest output signal of the detector, and realizing brain-like color recognition of visible light.

7. The brain-inspired color recognition unit according to claim 1, characterized in that: The voltage-type "winner-takes-all" neuron circuit is combined with a silicon-based detector based on standard CMOS technology to effectively detect visible light wavelengths and simultaneously digitize color information, thereby realizing brain-like recognition of color information.

8. The brain-inspired color recognition unit according to claim 1, characterized in that: By utilizing MOS transistors in a subthreshold state in the voltage-type "winner-takes-all" neuron circuit, which have the basis functions required to simulate biological processes, the brain's nervous system's processing mechanism of color information is simulated to process color information in a "stronger, stronger, weaker" manner. The brain-like color recognition unit uses the human retina and brain as research references, is compatible with standard CMOS processes, and performs real-time visible light detection and brain-like recognition of visible light color information.

Images