CN115019711A - Amplifying circuit, display screen and terminal equipment - Google Patents

Amplifying circuit, display screen and terminal equipment Download PDF

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Publication number
CN115019711A
CN115019711A CN202111296566.XA CN202111296566A CN115019711A CN 115019711 A CN115019711 A CN 115019711A CN 202111296566 A CN202111296566 A CN 202111296566A CN 115019711 A CN115019711 A CN 115019711A
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China
Prior art keywords
transistor
voltage
unit
photosensitive
pole
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Pending
Application number
CN202111296566.XA
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Chinese (zh)
Inventor
安亚斌
张帅
贺海明
赵明远
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Honor Device Co Ltd
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Honor Device Co Ltd
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Application filed by Honor Device Co Ltd filed Critical Honor Device Co Ltd
Priority to CN202111296566.XA priority Critical patent/CN115019711A/en
Publication of CN115019711A publication Critical patent/CN115019711A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/04—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only
    • H03F3/08—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light
    • H03F3/082—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements with semiconductor devices only controlled by light with FET's
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

The embodiment of the application provides an amplifying circuit, a display screen and terminal equipment, and is applied to the technical field of terminals. The amplifying circuit comprises a difference module, a bias module, a first amplifying unit and a second amplifying unit, wherein the difference module dynamically adjusts first voltage of a control end of the first amplifying unit according to photosensitive voltage of photosensitive signals input by an output end of the photosensitive circuit and difference between the photosensitive voltage and reference voltage input by a reference voltage end, and dynamically adjusts second voltage of the control end of the second amplifying unit through the bias module, so that the first amplifying unit outputs the amplified photosensitive signals to a signal output end under the action of the first voltage and the second amplifying unit under the action of the second voltage. Therefore, the photosensitive signals are amplified through the amplifying circuit, the signal intensity of the photosensitive signals transmitted to the driving chip is improved, and the accuracy of detection results obtained by detection of the driving chip is improved.

Description

Amplifying circuit, display screen and terminal equipment
Technical Field
The application relates to the technical field of terminals, in particular to an amplifying circuit, a display screen and terminal equipment.
Background
With the rapid development of terminal equipment, various photoelectric sensors are integrated on the terminal equipment to realize corresponding functions, for example, a proximity light sensor, an ambient light sensor, a fingerprint sensor and other photoelectric sensors are arranged on the terminal equipment.
However, the signal intensity of the photo-reception signal output by the current photo-sensor is small, which causes the signal intensity of the photo-reception signal received by the driving chip to be also small, and thus causes the accuracy of the detection result recognized by the driving chip according to the photo-reception signal to be low.
Disclosure of Invention
The embodiment of the application provides an amplifying circuit, a display screen and a terminal device to improve the signal intensity of a photosensitive signal input to a driving chip, and therefore the accuracy of a detection result identified by the driving chip is improved.
In a first aspect, an embodiment of the present application provides an amplifying circuit, including: the device comprises a difference module, a bias module and an amplification module, wherein the amplification module comprises a first amplification unit and a second amplification unit; the differential module is respectively connected with a reference voltage end, the output end of the photosensitive circuit, the low-level signal end, the bias module and the control end of the first amplification unit, and the bias module is respectively connected with the high-level signal end, the low-level signal end and the control end of the second amplification unit; the first amplification unit is respectively connected with the low level signal end and the signal output end, and the second amplification unit is respectively connected with the high level signal end and the signal output end; the differential module is used for adjusting a first voltage of a control end of the first amplification unit according to a difference value between a photosensitive voltage of a photosensitive signal input by an output end of the photosensitive circuit and a reference voltage input by a reference voltage end, and adjusting a second voltage of a control end of the second amplification unit through the bias module; the amplifying module is used for outputting the amplified photosensitive signal to the signal output end under the action of the first voltage and the second voltage.
Therefore, the photosensitive signal input by the output end of the photosensitive circuit is amplified through the amplifying circuit, the signal intensity of the photosensitive signal transmitted to the driving chip is improved, the accuracy of the detection result obtained by the detection of the driving chip is improved, the terminal equipment can drive the result obtained by the detection of the chip, and the corresponding device is accurately controlled to execute the function of the terminal equipment. And the photosensitive signal amplifying function can be realized under the two conditions that the photosensitive voltage is greater than the reference voltage and is less than the reference voltage.
In an alternative implementation, the differential module includes a differential unit and a first load unit; the differential unit is respectively connected with the reference voltage end, the output end of the photosensitive circuit, the first load unit and the bias module and is used for adjusting a third voltage of the control end of the first load unit according to a difference value between the photosensitive voltage and the reference voltage; the first load unit is respectively connected with the low-level signal end and the control end of the first amplifying unit and used for adjusting the first voltage of the control end of the first amplifying unit under the action of the third voltage. In this way, through the differential unit and the first load unit, the first voltage of the control terminal of the first amplifying unit can be controlled, so that the working state of the seventh transistor in the first amplifying unit is maintained in the variable resistance region, and the seventh transistor in the first amplifying unit can be used as an amplifier to amplify the photosensitive signal.
In an alternative implementation, the differential cell includes a first transistor and a second transistor; the grid electrode of the first transistor is connected with the reference voltage end, the first pole of the first transistor is connected with the bias module, and the second pole of the first transistor is connected with the first load unit; the grid electrode of the second transistor is connected with the output end of the photosensitive circuit, the first pole of the second transistor is connected with the first pole of the first transistor, and the second pole of the second transistor is connected with the control ends of the first load unit and the first amplifying unit. Therefore, the differential unit is formed by the first transistor and the second transistor, so that the structure of the differential unit is simpler.
In an alternative implementation, the first load unit includes a third transistor and a fourth transistor; the grid electrode of the third transistor is connected with the differential unit, the first pole of the third transistor is connected with the low-level signal end, and the second pole of the third transistor is connected with the differential unit; the grid electrode of the fourth transistor is connected with the differential unit, the first pole of the fourth transistor is connected with the low-level signal end, and the second pole of the fourth transistor is connected with the control end of the first amplification unit. In this way, the first load unit is formed by the third transistor and the fourth transistor, so that the structure of the first load unit is simpler.
In an alternative implementation, the bias module includes a mirror unit and a second load unit; the mirror image unit is respectively connected with the differential module, the high-level signal end, the second load unit and the control end of the second amplifying unit; the second load unit is respectively connected with the low-level signal end and the control end of the second amplifying unit. In this way, the second voltage of the control terminal of the second amplifying unit is controlled by the biasing module, so that the operating state of the eighth transistor in the second amplifying unit is maintained in the variable resistance region, and the eighth transistor in the second amplifying unit can be used as an amplifier to amplify the photosensitive signal.
In an alternative implementation, the mirror unit includes a fifth transistor and a sixth transistor; the grid electrode of the fifth transistor is connected with the control ends of the second load unit and the second amplifying unit, the first pole of the fifth transistor is connected with the high-level signal end, and the second pole of the fifth transistor is connected with the grid electrode of the fifth transistor; the grid electrode of the sixth transistor is connected with the grid electrode of the fifth transistor, the first pole of the sixth transistor is connected with the high-level signal end, and the second pole of the sixth transistor is connected with the differential module. In this way, the fifth transistor and the sixth transistor form a mirror image unit, so that the structure of the mirror image unit is simpler.
In an optional implementation manner, the second load unit includes a load resistor, a first end of the load resistor is connected to the mirror image unit and the control end of the second amplifying unit, and a second end of the load resistor is connected to the low-level signal end. In this way, the load resistor is used as the second load unit, so that the structure of the second load unit is simpler.
In an alternative implementation, the first amplifying unit includes a seventh transistor; the grid electrode of the seventh transistor is connected with the differential module, the first pole of the seventh transistor is connected with the low-level signal end, and the second pole of the seventh transistor is connected with the signal output end. In this way, the seventh transistor is used as the first amplifying unit, and the amplifying function is realized based on the fact that the seventh transistor works in the variable resistance region, so that the structure of the first amplifying unit is simpler.
In an alternative implementation, the second amplifying unit includes an eighth transistor; the grid electrode of the eighth transistor is connected with the bias module, the first pole of the eighth transistor is connected with the high-level signal end, and the second pole of the eighth transistor is connected with the signal output end. In this way, the eighth transistor serves as the second amplifying unit, and the amplifying function is realized based on the fact that the eighth transistor operates in the variable resistance region, so that the structure of the second amplifying unit is simple.
In an optional implementation manner, the amplifying module further includes a voltage stabilizing unit; the voltage stabilizing unit is respectively connected with the signal output end and the control end of the first amplifying unit and is used for stabilizing the amplified photosensitive signal output by the signal output end. In this way, the stability of the amplified photosensitive signal output by the amplifying circuit to the driving chip can be improved by arranging the voltage stabilizing unit in the amplifying circuit.
In an alternative implementation, the voltage stabilizing unit includes a voltage stabilizing capacitor; the first end of the voltage-stabilizing capacitor is connected with the signal output end, and the second end of the voltage-stabilizing capacitor is connected with the control end of the first amplification unit. Therefore, the voltage stabilizing capacitor is used as the voltage stabilizing unit, so that the structure of the voltage stabilizing unit is simpler.
In a second aspect, an embodiment of the present application provides a display screen, which includes a substrate, a photosensitive circuit, and the above-mentioned amplifying circuit, where the photosensitive circuit and the amplifying circuit are both disposed on the substrate.
In a third aspect, an embodiment of the present application provides a terminal device, which includes a driving chip and the display screen, where the driving chip is connected to a signal output end of an amplifying circuit included in the display screen.
The effects of the possible implementations of the second aspect and the third aspect are similar to those of the possible designs of the first aspect and the first aspect, and are not described herein again.
Drawings
Fig. 1 is a schematic structural diagram of a terminal device according to an embodiment of the present application;
fig. 2 is a schematic structural diagram of a display screen according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of an amplifying circuit according to an embodiment of the present disclosure;
fig. 4 is a specific circuit diagram of an amplifying circuit according to an embodiment of the present disclosure;
FIG. 5 is a diagram illustrating an output characteristic of a transistor according to an embodiment of the present application;
fig. 6 is a schematic diagram illustrating simulation of an input photo sensing signal and an output photo sensing signal in an amplifying circuit according to an embodiment of the present disclosure.
Detailed Description
In order to facilitate clear description of technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish identical items or similar items with substantially the same functions and actions. For example, the first chip and the second chip are only used for distinguishing different chips, and the order of the chips is not limited. Those skilled in the art will appreciate that the terms "first," "second," etc. do not denote any order or quantity, nor do the terms "first," "second," etc. denote any order or importance.
It should be noted that in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described herein as "exemplary" or "e.g.," is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.
In the embodiments of the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple.
At present, various photoelectric sensors are integrated on a terminal device to realize corresponding functions. For example, a proximity optical sensor is arranged on the terminal device, and a photosensitive signal generated by the proximity optical sensor is output to a driving chip to detect whether a shielding object approaches the terminal device, so that the terminal device can detect that a user holds the terminal device by using the proximity optical sensor and is close to an ear for conversation, so that a screen is automatically extinguished to achieve the purpose of saving power, the proximity optical sensor can also be used in a leather sheath mode, a pocket mode is automatically unlocked and locked, and the like; and/or, set up the ambient light sensor on terminal equipment, the sensitization signal output that generates the ambient light sensor to drive chip to detect ambient light brightness, terminal equipment can be according to the ambient light brightness self-adaptation regulation display screen luminance of perception, and automatically regulated white balance when ambient light sensor also can be used to shoot, ambient light sensor can also with be close the light sensor cooperation, whether detection terminal equipment is in the pocket, in order to prevent mistake and touch.
In the related art, the photosensor includes a photosensitive circuit, the photosensitive circuit includes a photosensitive unit and a signal reading circuit connected to the photosensitive unit, and an output end of the signal reading circuit is directly connected to the driving chip through a wire. The light sensing unit may include a plurality of light sensing elements connected in parallel, which may be phototransistors.
When incident light irradiates the photosensitive unit, the photosensitive unit converts a light signal of the received incident light into a corresponding photosensitive signal, the photosensitive signal is read out through the signal reading circuit, the photosensitive signal read by the signal reading circuit is transmitted to the driving chip through the wiring, and the driving chip detects according to the received photosensitive signal.
Because the signal intensity of the photosensitive signal generated by the photosensitive unit is often relatively small, and the existence of the wiring resistor can also reduce the signal intensity of the photosensitive signal, the signal intensity of the photosensitive signal transmitted to the driving chip is relatively weak, and even the condition that no signal is transmitted to the driving chip occurs. When the signal intensity of the photosensitive signal is smaller, the driving chip is more difficult to recognize the photosensitive signal, which may result in a lower accuracy of the detection result of the driving chip.
Taking a photoelectric sensor as an ambient light sensor as an example, a photosensitive signal generated by the ambient light sensor is output to a driving chip, the driving chip detects ambient light brightness according to the received photosensitive signal, and then the terminal device can adaptively adjust the brightness of the display screen according to the sensed ambient light brightness. When the ambient light brightness is lower, the brightness of the display screen is adjusted to be lower so as to improve the stimulation of high brightness to human eyes and reduce the power consumption of the terminal equipment; when the ambient light brightness is higher, the brightness of the display screen is adjusted to be higher, and the phenomenon that a user cannot clearly see the display content in the display screen is improved.
However, when the accuracy of the ambient light brightness detected by the driving chip according to the photosensitive signal output by the ambient light sensor is low, the actual brightness of the ambient light may be high, but the ambient light brightness detected by the driving chip is low, and after the terminal device reduces the brightness of the display screen, the display content in the display screen is not visible to the user, which affects the normal use of the user; or, there may be a case where the actual brightness of the ambient light is low, but the ambient light brightness detected by the driving chip is high, so that when the terminal device adjusts the brightness of the display screen to be high, the brightness of the display screen causes irritation to eyes of a user, and power consumption of the terminal device is also increased.
Based on this, an embodiment of the present application provides an amplifying circuit, where the amplifying circuit includes a differential module, a bias module, a first amplifying unit, and a second amplifying unit, where the differential module dynamically adjusts a first voltage at a control terminal of the first amplifying unit according to a difference between a photosensitive voltage of a photosensitive signal input by an output terminal of a photosensitive circuit (i.e., an output terminal of a signal reading circuit) and a reference voltage input by a reference voltage terminal, and dynamically adjusts a second voltage at a control terminal of the second amplifying unit through the bias module, so that the first amplifying unit outputs an amplified photosensitive signal to a signal output terminal under the action of the first voltage and the second amplifying unit under the action of the second voltage. Therefore, the photosensitive signals are amplified through the amplifying circuit, the signal intensity of the photosensitive signals transmitted to the driving chip is improved, the accuracy of detection results obtained by detection of the driving chip is improved, the results obtained by detection of the driving chip can be driven by the terminal equipment, and corresponding devices are accurately controlled to execute functions of the terminal equipment.
For example, when the photoelectric sensor is an ambient light sensor, the photosensitive circuit in the ambient light sensor sends the generated photosensitive signal to the amplifying circuit, the photosensitive signal is amplified by the amplifying circuit, and the amplified photosensitive signal is input to the driving chip, so that the signal intensity of the photosensitive signal received by the driving chip is improved, and the accuracy of the ambient light brightness detected by the driving chip is improved. Therefore, when the low ambient light brightness is detected, the brightness of the display screen is accurately adjusted to be low, and when the high ambient light brightness is detected, the brightness of the display screen is accurately adjusted to be high.
The amplifying circuit provided by the embodiment of the application can be applied to terminal equipment, the terminal equipment can be a device which is provided with a photoelectric sensor for a mobile phone, a tablet computer, a notebook computer, wearable equipment and the like and needs to amplify photosensitive signals output by a photosensitive circuit in the photoelectric sensor, and the specific technology and the specific equipment form adopted by the terminal equipment are not limited by the embodiment of the application.
As shown in fig. 1, the terminal device 100 includes a display screen 10 and a housing 20, the display screen 10 is mounted on the housing 20 and covers the accommodating cavity, which is used for displaying images or videos, and a photosensor may be integrated in the display screen 10, the photosensor includes a photosensitive circuit and an amplifying circuit, the photosensitive circuit includes a photosensitive unit and a signal reading circuit connected to the photosensitive unit, an output end of the signal reading circuit is connected to the amplifying circuit, and a signal output end of the amplifying circuit is connected to the driving chip through a wire.
In an actual product, the display screen 10 includes a substrate, and the light sensing unit and the signal reading circuit in the light sensing circuit, and the amplifying circuit are disposed on the substrate.
As shown in fig. 2, the display screen 10 is divided into a display area 11 and a non-display area 12 surrounding the display area, a plurality of pixel units are arranged in the display area 11, the light sensing units 31 in the light sensing circuits can also be arranged in the display area 11, so as to reduce the occupied area of the light sensing units 31 in the non-display area 12, thereby improving the screen occupation ratio of the terminal device, the number of the light sensing units 31 included in the photosensor is multiple, and the plurality of light sensing units are uniformly distributed in the display area 11. Of course, in some embodiments, the photosensitive unit 31 in the photosensitive circuit may also be disposed in the non-display region 12, and a hole is cut in the non-display region 12, so that the incident light can be irradiated onto the photosensitive unit 31.
The signal reading circuit 32 in the light sensing circuit can be disposed in the display area 11 of the display screen 10, and can also be disposed in the non-display area 12 of the display screen 10. The amplifying circuit 40 in this embodiment may be disposed in the non-display area 12 of the display screen 10, and the driving chip 50 connected to the amplifying circuit 40 may be disposed in the non-display area 12 of the display screen 10, specifically, the driving chip 50 may be directly bonded in the non-display area 12, or the driving chip 50 may be bonded in the non-display area 12 of the display screen 10 by using a Flexible Printed Circuit (FPC), which is not limited in this embodiment.
Note that, as shown in fig. 2, the signal reading circuit 32 and the amplifying circuit 40 may be both disposed at the upper frame of the non-display area 12, and the driving chip 50 may be disposed at the lower frame of the non-display area 12; of course, the positions of the signal reading circuit 32, the amplifying circuit 40 and the driving chip 50 on the display screen 10 are not limited to the positional relationship shown in fig. 2, and the positions thereof may be changed according to actual product requirements, which is not limited in the embodiment of the present application.
Fig. 3 is a schematic structural diagram of an amplifying circuit according to an embodiment of the present disclosure. Referring to fig. 3, the amplifying circuit 40 includes: a difference block 41, a bias block 42 and an amplification block 43, the amplification block 43 comprising a first amplification unit 431 and a second amplification unit 432.
The difference module 41 is respectively connected to the reference voltage terminal V1, the output terminal V2 of the light sensing circuit (i.e., the output terminal of the signal reading short circuit 32 in the light sensing circuit), the low level signal terminal Vgl, the bias module 42, and the control terminal of the first amplifying unit 431; the bias module 42 is respectively connected to the high-level signal end Vgh, the low-level signal end Vgl and the control end of the second amplifying unit 432; the first amplifying unit 431 is connected to the low-level signal terminal Vgl and the signal output terminal Out, respectively, and the second amplifying unit 432 is connected to the high-level signal terminal Vgh and the signal output terminal Out, respectively.
The difference module 41 dynamically adjusts the first voltage at the control terminal of the first amplifying unit 431 according to a difference between the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit and the reference voltage input from the reference voltage terminal V1, and outputs a fourth voltage to the bias module 42; the bias module 42 dynamically adjusts the second voltage of the control terminal of the second amplifying unit 432 under the action of the fourth voltage. The first amplifying unit 431 of the amplifying module 43 outputs the amplified photo-sensing signal to the signal output terminal Out in cooperation with the second amplifying unit 432 of the amplifying module 43 under the action of the first voltage.
In the embodiment of the present application, the reference voltage terminal V1 may be a common voltage terminal Vcom or a ground terminal GND, and the input reference voltage may be 0V, and of course, in some scenarios, the reference voltage input by the reference voltage terminal V1 may also be other voltage values, such as 0.8V. Taking the reference voltage input from the reference voltage terminal V1 as 0V as an example, the relationship between the amplified photo-sensing signal output from the signal output terminal Out and the photo-sensing signal input from the output terminal V2 of the photo-sensing circuit in the embodiment of the present application will be described.
In one case, when the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit is greater than the reference voltage input from the reference voltage terminal V1, the difference module 41 may pull up the fourth voltage output to the bias module 42 and pull down the first voltage at the control terminal of the first amplifying unit 431, and when the fourth voltage output from the difference module 41 to the bias module 42 is pulled up, the bias module 42 may pull down the second voltage at the control terminal of the second amplifying unit 432.
For example, if the type of the transistor in the first amplifying unit 431 is set as an N-type transistor, and the type of the transistor in the second amplifying unit 432 is set as a P-type transistor. Therefore, when the first voltage at the control terminal of the first amplifying unit 431 is pulled down, the divided voltage of the first amplifying unit 431 may be increased, and when the second voltage at the control terminal of the second amplifying unit 432 is pulled down, the divided voltage of the second amplifying unit 432 may be decreased, so that the divided voltage of the first amplifying unit 431 is greater than the divided voltage of the second amplifying unit 432; the voltage value of the amplified photo sensing signal output by the signal output terminal Out is the voltage of the node between the first amplifying unit 431 and the second amplifying unit 432.
Also, the sum of the divided voltages of the first and second amplifying units 431 and 432 is equal to the difference between the high level voltage inputted from the high level signal terminal Vgh and the low level voltage inputted from the low level signal terminal Vgl, and the difference between the high level voltage inputted from the high level signal terminal Vgh and the low level voltage inputted from the low level signal terminal Vgl is a fixed value. Therefore, when the divided voltage of the first amplifying unit 431 is greater than the divided voltage of the second amplifying unit 432, the absolute value of the difference between the voltage value of the amplified photo-sensing signal output by the signal output terminal Out and the high-level voltage input by the high-level signal terminal Vgh can be made smaller than the absolute value of the difference between the voltage value of the amplified photo-sensing signal output by the signal output terminal Out and the low-level voltage input by the low-level signal terminal Vgl.
For example, if the high-level voltage input from the high-level signal terminal Vgh is 7V, the low-level voltage input from the low-level signal terminal Vgl is-7V, and the photosensitive voltage of the photosensitive signal input from the output terminal V2 of the photosensitive circuit is 0.2mV, the voltage value of the amplified photosensitive signal that can be output from the amplifying circuit 40 through the signal output terminal Out is 5V.
Also, when the difference between the light sensing voltage and the reference voltage is larger, the larger the first voltage at the control terminal of the first amplifying unit 431 is pulled down, and the larger the fourth voltage output to the biasing module 42 is pulled up, the larger the biasing module 42 pulls down the second voltage at the control terminal of the second amplifying unit 432. Accordingly, the voltage value of the amplified photosensitive signal output by the signal output terminal Out is closer to the high-level voltage input by the high-level signal terminal Vgh.
In summary, it can be known that, when the photosensitive voltage of the photosensitive signal input by the output terminal V2 of the photosensitive circuit is greater than the reference voltage input by the reference voltage terminal V1, the voltage value of the amplified photosensitive signal output by the signal output terminal Out is a positive value, and the voltage value of the amplified photosensitive signal output by the signal output terminal Out is greater than the photosensitive voltage of the photosensitive signal input by the output terminal V2 of the photosensitive circuit, thereby realizing amplification of the voltage of the photosensitive signal input by the output terminal V2 of the photosensitive circuit. And, when the difference between the light sensing voltage and the reference voltage is larger, the voltage value of the amplified light sensing signal output by the signal output terminal Out is larger.
When the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit is greater than the reference voltage input from the reference voltage terminal V1, the current value of the amplified light sensing signal output from the signal output terminal Out is actually the current value output when the transistor in the second amplifying unit 432 operates in the variable resistance region. Because the transistor in the second amplifying unit 432 operates in the variable resistance region, the transistor in the second amplifying unit 432 is equivalent to an amplifier, so that the current value of the amplified photosensitive signal output by the signal output terminal Out is greater than the current value of the photosensitive signal input by the output terminal V2 of the photosensitive circuit, and the current of the photosensitive signal input by the output terminal V2 of the photosensitive circuit is amplified.
In another case, when the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit is smaller than the reference voltage input from the reference voltage terminal V1, the difference module 41 may pull down the fourth voltage output to the bias module 42 and pull up the first voltage at the control terminal of the first amplifying unit 431, and when the fourth voltage output from the difference module 41 to the bias module 42 is pulled down, the bias module 42 may pull up the second voltage at the control terminal of the second amplifying unit 432.
For example, if the type of the transistor in the first amplifying unit 431 is set as an N-type transistor, and the type of the transistor in the second amplifying unit 432 is set as a P-type transistor. Therefore, when the first voltage at the control terminal of the first amplification unit 431 is pulled up, the divided voltage of the first amplification unit 431 may be decreased, and when the second voltage at the control terminal of the second amplification unit 432 is pulled up, the divided voltage of the second amplification unit 432 may be increased, so that the divided voltage of the first amplification unit 431 is smaller than the divided voltage of the second amplification unit 432; the voltage value of the amplified photo-sensing signal output by the signal output terminal Out is the voltage of the node between the first amplifying unit 431 and the second amplifying unit 432.
Further, the sum of the divided voltages of the first amplification unit 431 and the second amplification unit 432 is equal to the difference between the high-level voltage input from the high-level signal terminal Vgh and the low-level voltage input from the low-level signal terminal Vgl, and therefore, when the divided voltage of the first amplification unit 431 is smaller than the divided voltage of the second amplification unit 432, the absolute value of the difference between the voltage value of the amplified photo-reception signal output from the signal output terminal Out and the high-level voltage input from the high-level signal terminal Vgh is larger than the absolute value of the difference between the voltage value of the amplified photo-reception signal output from the signal output terminal Out and the low-level voltage input from the low-level signal terminal Vgl.
For example, if the high level voltage input by the high level signal end Vgh is 7V, the low level voltage input by the low level signal end Vgl is-7V, and if the photosensitive voltage of the photosensitive signal input by the output end V2 of the photosensitive circuit is-0.2 mV, the voltage value of the amplified photosensitive signal that can be output by the amplifying circuit through the signal output end Out is-5V.
Also, when the difference between the reference voltage and the light sensing voltage is larger, the larger the first voltage at the control terminal of the first amplifying unit 431 is pulled up, and the larger the fourth voltage output to the biasing module 42 is pulled down, the larger the biasing module 42 pulls up the second voltage at the control terminal of the second amplifying unit 432 is. Accordingly, the voltage value of the amplified photo sensing signal output by the signal output terminal Out is closer to the low level voltage input by the low level signal terminal Vgl.
In summary, it can be known that, when the photosensitive voltage of the photosensitive signal input from the output terminal V2 of the photosensitive circuit is less than the reference voltage input from the reference voltage terminal V1, the voltage value of the amplified photosensitive signal output by the signal output terminal Out is a negative value, and the absolute value of the voltage value of the amplified photosensitive signal output by the signal output terminal Out is greater than the absolute value of the photosensitive voltage of the photosensitive signal input from the output terminal V2 of the photosensitive circuit, so as to amplify the voltage of the photosensitive signal input from the output terminal V2 of the photosensitive circuit. And, when the difference between the reference voltage and the photo sensing voltage is larger, the absolute value of the voltage value of the amplified photo sensing signal output by the signal output terminal Out is larger.
When the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit is smaller than the reference voltage input from the reference voltage terminal V1, the current value of the amplified light sensing signal output from the signal output terminal Out is actually the current value output when the transistor in the first amplifying unit 431 operates in the variable resistance region. Because the transistor in the first amplifying unit 431 operates in the variable resistance region, the transistor in the first amplifying unit 431 is equivalent to an amplifier, so that the current value of the amplified photosensitive signal output by the signal output end Out is greater than the current value of the photosensitive signal input by the output end V2 of the photosensitive circuit, thereby amplifying the current of the photosensitive signal input by the output end V2 of the photosensitive circuit.
The relationship between the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit and the reference voltage input from the reference voltage terminal V1 is mainly determined by the light sensing circuit connected to the amplifier circuit 40. In some embodiments, the light sensing voltage of the light sensing signal output by the output terminal V2 of the light sensing circuit is positive voltage, so that the light sensing voltage of the light sensing signal input by the output terminal V2 of the light sensing circuit is greater than the reference voltage input by the reference voltage terminal V1; in other embodiments, the light sensing voltage of the light sensing signal output by the output terminal V2 of the light sensing circuit may be a negative voltage, so that the light sensing voltage of the light sensing signal input by the output terminal V2 of the light sensing circuit is smaller than the reference voltage input by the reference voltage terminal V1.
It will be appreciated that the driving process of the light sensing circuit may include the following stages, which are respectively: a photosensitive integration stage and a signal reading stage, in the photosensitive integration stage, the photosensitive unit converts the received incident light into a photosensitive signal, and in the signal reading stage, the converted photosensitive signal is output from the output end V2 of the photosensitive circuit. Therefore, when the light sensing unit in the light sensing circuit does not receive the illumination signal, or the signal reading circuit in the light sensing circuit is not in the signal reading stage, the output terminal V2 of the light sensing circuit does not input the light sensing signal, and at this time, the voltage value of the output terminal V2 of the light sensing circuit is equal to the reference voltage input by the reference voltage terminal V1, for example, the voltage value of the output terminal V2 of the light sensing circuit and the reference voltage input by the reference voltage terminal V1 are both 0V, and at this time, the voltage value of the light sensing signal output by the amplifying circuit 40 is also 0.
In the embodiment of the present application, as shown in fig. 4, the differential module 41 includes a differential unit 411 and a first load unit 412, and the bias module 42 includes a mirror unit 421 and a second load unit 422. The differential unit 411 is respectively connected with the reference voltage terminal V1, the output terminal V2 of the light sensing circuit, the first load unit 412, the control terminal of the first amplifying unit 431 and the mirror image unit 421 in the bias module 42; the first load unit 412 is connected to the differential unit 411, the low-level signal terminal Vgl, and the control terminal of the first amplification unit 431, respectively. The mirror image unit 421 is respectively connected to the differential unit 411, the high-level signal terminal Vgh, the second load unit 422, and the control terminal of the second amplifying unit 432 in the differential module 41; the second load unit 422 is connected to the mirror unit 421, the low-level signal terminal Vgl, and the control terminal of the second amplifying unit 432, respectively.
Wherein the differential unit 411 includes a first transistor M1 and a second transistor M2, and the first load unit 412 includes a third transistor M3 and a fourth transistor M4; the mirroring unit 421 includes a fifth transistor M5 and a sixth transistor M6, and the second load unit 422 includes a load resistor R; the first amplification unit 431 includes a seventh transistor M7, and the second amplification unit 432 includes an eighth transistor M8.
The gate of the first transistor M1 is connected to the reference voltage terminal V1, and the first pole of the first transistor M1 is connected toThe second pole of the sixth transistor M6 included in the mirror cell 421 in the bias module 42 is connected, and the second pole of the first transistor M1 is connected to the gate and the second pole of the third transistor M3 included in the first load cell 412. A node connected between the first electrode of the first transistor M1 and the second electrode of the sixth transistor M6 is a first node N 1 The gate of the third transistor M3, the second pole of the third transistor M3 and the second pole of the first transistor M1 are connected to the second node N 2 And (4) connecting.
The gate of the second transistor M2 is connected to the output terminal V2 of the light sensing circuit, and the first pole of the second transistor M2 is connected to the first pole of the first transistor M1, i.e. the first pole of the second transistor M2 is also connected to the second pole of the sixth transistor M6 included in the mirror image unit 421; a second pole of the second transistor M2 is connected with a second pole of the fourth transistor M4 included in the first load unit 412, and a second pole of the second transistor M2 is also connected with a gate of the seventh transistor M7 included in the first amplifying unit 431. The gate of the seventh transistor M7 is the control terminal of the first amplifying unit 431, and the first pole of the second transistor M2 and the second pole of the sixth transistor M6 are connected to the first node N 1 Connected, the second pole of the second transistor M2 and the gate of the seventh transistor M7 are connected to the third node N 3 Is connected to thereby effect connection of the second pole of the second transistor M2 with the gate of the seventh transistor M7.
The gate of the third transistor M3 is connected to the second pole of the first transistor M1 included in the differential unit 411, the first pole of the third transistor M3 is connected to the low-level signal terminal Vgl, and the second pole of the third transistor M3 is also connected to the second pole of the first transistor M1 included in the differential unit 411, that is, the second pole of the third transistor M3 is connected to the gate of the third transistor M3.
The gate of the fourth transistor M4 is connected to the second pole of the first transistor M1 included in the differential unit 411, that is, the gate of the fourth transistor M4 is connected to both the gate of the third transistor M3 and the second pole of the third transistor M3, the first pole of the fourth transistor M4 is connected to the low-level signal terminal Vgl, and the second pole of the fourth transistor M4 is connected to the gate of the seventh transistor M7 included in the first amplification unit 431. Due to the fourth crystalThe gate of the transistor M4 and the second node N 2 The gate of the third transistor M3, the second pole of the third transistor M3 and the second pole of the first transistor M1 are connected to the second node N 2 Connected, therefore, the gate of the fourth transistor M4 is enabled to be connected to the second pole of the first transistor M1, the gate of the third transistor M3, and the second pole of the third transistor M3, respectively. And, the second pole of the fourth transistor M4 and the third node N 3 Is connected, and a third node N 3 Is connected to the gate of the seventh transistor M7 to thereby enable connection of the second pole of the fourth transistor M4 to the gate of the seventh transistor M7.
A gate of the fifth transistor M5 is connected to a first terminal of the load resistor R included in the second load unit 422, a gate of the fifth transistor M5 is further connected to a gate of an eighth transistor M8 included in the second amplifying unit 432, and a gate of the eighth transistor M8 is a control terminal of the second amplifying unit 432; a first pole of the fifth transistor M5 is connected to the high-level signal terminal Vgh, and a second pole of the fifth transistor M5 is connected to the gate of the fifth transistor M5, that is, the second pole of the fifth transistor M5 is also connected to the first end of the load resistor R and the gate of the eighth transistor M8 included in the second amplifying unit 432, respectively. Since the gate of the fifth transistor M5 and the second pole of the fifth transistor M5 are connected to the sixth node N 6 A first terminal of the load resistor R and a gate of the eighth transistor M8 are connected to the sixth node N 6 Are connected to thereby realize that the gate of the fifth transistor M5, the second pole of the fifth transistor M5, the first terminal of the load resistor R, and the gate of the eighth transistor M8 are all connected to each other.
The gate of the sixth transistor M6 is connected to the gate of the fifth transistor M5, that is, the gate of the sixth transistor M6 is also connected to the first end of the load resistor R and the gate of the eighth transistor M8 included in the second amplifying unit 432, respectively; a first pole of the sixth transistor M6 is connected to the high-level signal terminal Vgh, a second pole of the sixth transistor M6 is connected to the first pole of the first transistor M1 included in the differential cell 411 in the differential block 41, and a second pole of the sixth transistor M6 is also connected to the first pole of the second transistor M2 included in the differential cell 411. Due to the gate of the sixth transistor M6Pole is also connected to the sixth node N 6 Is connected to the gate of the fifth transistor M5 6 Is connected to thereby effect connection of the gate of the sixth transistor M6 with the gate of the fifth transistor M5.
A first end of the load resistor R is connected to the gate and the second pole of the fifth transistor M5 included in the mirror image unit 421, a first end of the load resistor R is connected to the gate of the sixth transistor M6 included in the mirror image unit 421, and a first end of the load resistor R is further connected to the gate of the eighth transistor M8 included in the second amplifying unit 432; a second terminal of the load resistor R is connected to the low-level signal terminal Vgl.
The gate of the seventh transistor M7 is connected to the second pole of the second transistor M2 included in the differential cell 411 in the differential block 41, and the gate of the seventh transistor M7 is also connected to the second pole of the fourth transistor M4 included in the first load cell 412 in the differential block 41; a first pole of the seventh transistor M7 is connected to the low-level signal terminal Vgl, and a second pole of the seventh transistor M7 is connected to the signal output terminal Out.
The gate of the eighth transistor M8 is connected to the gate and the second pole of the fifth transistor M5 included in the mirror image cell 421 in the bias module 42, the gate of the eighth transistor M8 is also connected to the gate of the sixth transistor M6 included in the mirror image cell 421, and the gate of the eighth transistor M8 is also connected to the first end of the load resistor R included in the second load cell 422 in the bias module 42; a first pole of the eighth transistor M8 is connected to the high-level signal terminal Vgh, and a second pole of the eighth transistor M8 is connected to the signal output terminal Out.
In the operation of the amplifying circuit 40 in the embodiment of the present application, the difference unit 411 may dynamically adjust the third voltage of the gate of the third transistor M3 included in the first load unit 412 and the third voltage of the gate of the fourth transistor M4 included in the first load unit 412 (i.e., the second node N4) according to a difference between the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit and the reference voltage input from the reference voltage terminal V1 2 The third voltage), the gate of the third transistor M3 and the gate of the fourth transistor M4 are the control terminals of the first load unit 412. Therefore, the first load unit 412 may operate at the third voltageIn use, the first voltage at the control terminal of the first amplifying unit 431 is dynamically adjusted.
The bias module 42 is mainly used for controlling the second voltage of the control terminal of the second amplifying unit 432 (i.e. the gate of the eighth transistor M8), so that the operating state of the eighth transistor M8 in the second amplifying unit 432 is maintained in the variable resistance region, and thus the eighth transistor M8 in the second amplifying unit 432 can be used as an amplifier to amplify the photosensitive signal.
The first transistor M1 and the second transistor M2 are both P-type transistors, and the active layer is made of low-temperature polysilicon; the third transistor M3 and the fourth transistor M4 are both N-type transistors, and the active layer is made of low temperature polysilicon or N-type metal oxide semiconductor (e.g., indium gallium zinc oxide, IGZO). The fifth transistor M5 and the sixth transistor M6 are both P-type transistors, and the active layer is made of low-temperature polysilicon; the seventh transistor M7 is an N-type transistor, and the active layer is made of low temperature polysilicon or N-type metal oxide semiconductor (e.g., IGZO); the eighth transistor M8 is a P-type transistor, and the active layer is made of low temperature polysilicon.
The operation of the amplifying circuit 40 will be explained with reference to the specific circuit diagram of the amplifying circuit 40 shown in fig. 4.
As shown in fig. 5, the N-type transistor (i.e., NMOS) generally operates in any one of the off region, the variable resistance region, and the constant current region, and the P-type transistor (i.e., PMOS) generally operates in any one of the off region, the variable resistance region, and the constant current region. In the embodiment of the present application, the amplifying circuit 40 mainly utilizes the characteristic that each transistor included therein operates in the variable resistance region to amplify the photosensitive signal. When the transistor works in the variable resistance region, the transistor can be regarded as a linear resistor controlled by a gate-source voltage Vgs, and the gate-source voltage Vgs of the transistor has a certain linear relation with a current Id flowing through a drain of the transistor.
In the embodiment of the present application, when the amplifying circuit 40 operates, the first transistor M1, the second transistor M2, the third transistor M3, the fourth transistor M4, the fifth transistor M5, the sixth transistor M6, the seventh transistor M7, and the eighth transistor M8 all operate in the variable resistance region.
In one case, when the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit is greater than the reference voltage input from the reference voltage terminal V1, i.e., the light sensing voltage is positively biased with respect to the reference voltage, the resistance of the linear resistor formed by the second transistor M2 increases as the light sensing voltage increases. Since the first transistor M1, the second transistor M2, the third transistor M3 and the fourth transistor M4 all operate in the variable resistor region, the first transistor M1, the second transistor M2, the third transistor M3 and the fourth transistor M4 can be regarded as being formed by connecting two resistors in parallel, wherein one resistor is obtained by connecting a linear resistor formed by the first transistor M1 and a linear resistor formed by the third transistor M3 in series, the other resistor is obtained by connecting a linear resistor formed by the second transistor M2 and a linear resistor formed by the fourth transistor M4 in series, and when the resistance value of a linear resistor formed by the second transistor M2 is increased, the total resistance value of parallel resistors formed by the first transistor M1, the second transistor M2, the third transistor M3 and the fourth transistor M4 is also increased; the parallel resistor is connected in series with the linear resistor of the sixth transistor M6, and the parallel resistor and the linear resistor of the sixth transistor M6 share the same voltage division between the high level voltage input from the high level signal terminal Vgh and the low level voltage input from the low level signal terminal Vgl, so that when the total resistance of the parallel resistors increases, the voltage division of the parallel resistors increases, and the first node N is enabled 1 And a fourth node N 4 The pressure difference therebetween increases.
Due to the fourth node N 4 Is equal to the low level voltage input from the low level signal terminal Vgl, the low level voltage remains unchanged, therefore, when the first node N is connected to the first node N 1 And a fourth node N 4 When the pressure difference between the first node N and the second node N is increased, the first node N can be enabled 1 The voltage of (c) increases. Since the first transistor M1 operates in the variable resistance region, the reference voltage inputted from the reference voltage terminal V1 connected to the gate thereof remains unchanged, so that the resistance of the linear resistor formed by the first transistor M1 also remains unchanged, therefore, when the first node N is connected to the first node N 1 When the voltage of (2) is increased, the second node N can be enabled 2 Also increases.
Due to the second node N 2 Are connected to both the gate of the third transistor M3 and the gate of the fourth transistor M4, and thus, the second node N 2 Is equal to the gate voltage of the third transistor M3 and the gate voltage of the fourth transistor M4. Further, since the third transistor M3 and the fourth transistor M4 are both N-type transistors, when the gate voltage of the third transistor M3 and the gate voltage of the fourth transistor M4 are both increased, the resistance value of the linear resistor formed by the third transistor M3 and the resistance value of the linear resistor formed by the fourth transistor M4 are both decreased, and the third node N is connected to the third node N 3 Is pulled down to Vth 4 -ΔV，Vth 4 Refers to a threshold voltage of the fourth transistor M4, Δ V refers to a difference between a light sensing voltage of a light sensing signal input from the output terminal V2 of the light sensing circuit and a reference voltage input from the reference voltage terminal V1, and the second node N 2 Is automatically turned off to Vth 3 ，Vth 3 Refer to the threshold voltage of the third transistor M3.
Third node N 3 Is directly connected to the gate of the seventh transistor M7, and thus, the third node N 3 Is equal to the gate voltage of the seventh transistor M7, the gate voltage of the seventh transistor M7 is pulled low. When the gate voltage of the seventh transistor M7 is pulled low, the resistance of the linear resistor formed by the seventh transistor M7 increases, so that the divided voltage of the seventh transistor M7 increases, and the divided voltage of the seventh transistor M7 refers to the seventh node N 7 And a fourth node N 4 The pressure difference therebetween.
In addition, the voltage division of the sixth transistor M6 is the fifth node N 5 And a first node N 1 Pressure difference therebetween, fifth node N 5 Is a high level voltage inputted from the high level signal terminal Vgh, the high level voltage is kept unchanged, therefore, when the first node N is connected to the first node N 1 When the voltage of (i.e. the fourth voltage outputted by the differential module 41 to the bias module 42) increases, the divided voltage of the sixth transistor M6 decreases, so that the gate voltage of the sixth transistor M6 is pulled low, i.e. the sixth node N 6 Is pulled low.
Due to the sixth node N 6 And a firstThe gates of the eight transistors M8 are directly connected, and thus, the sixth node N 6 Is equal to the gate voltage of the eighth transistor M8, the gate voltage of the eighth transistor M8 is pulled low. When the gate voltage of the eighth transistor M8 is pulled low, the resistance of the linear resistor formed by the eighth transistor M8 is decreased, so that the divided voltage of the eighth transistor M8 is decreased, and the divided voltage of the eighth transistor M8 is referred to as the fifth node N 5 And a seventh node N 7 The pressure difference therebetween.
In summary, when the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit is greater than the reference voltage input from the reference voltage terminal V1, the divided voltage of the seventh transistor M7 is greater than the divided voltage of the eighth transistor M8, so that the absolute value of the difference between the voltage value of the amplified light sensing signal output from the signal output terminal Out and the high-level voltage input from the high-level signal terminal Vgh is less than the absolute value of the difference between the voltage value of the amplified light sensing signal output from the signal output terminal Out and the low-level voltage input from the low-level signal terminal Vgl. The current value of the amplified photo-reception signal output by the signal output terminal Out is the current value output by the second pole of the eighth transistor M8.
In another case, when the light sensing voltage of the light sensing signal input from the output terminal V2 of the light sensing circuit is smaller than the reference voltage input from the reference voltage terminal V1, i.e. the light sensing voltage is negatively biased with respect to the reference voltage, the resistance of the linear resistor formed by the second transistor M2 decreases with the decrease of the light sensing voltage, so that the total resistance of the parallel resistors formed by the first transistor M1, the second transistor M2, the third transistor M3 and the fourth transistor M4 also decreases. The parallel resistor is connected in series with the linear resistor formed by the sixth transistor M6, and the parallel resistor and the linear resistor formed by the sixth transistor M6 share the same voltage division between the high level voltage input from the high level signal terminal Vgh and the low level voltage input from the low level signal terminal Vgl, so that when the total resistance of the parallel resistors is reduced, the voltage division of the parallel resistors is reduced, and the first node N is enabled to be connected in series with the linear resistor formed by the sixth transistor M6 1 And a fourth node N 4 The pressure difference therebetween decreases.
Due to the fourth node N 4 Is equal to the low level voltage input by the low level signal terminal VglIs unchanged, therefore, when the first node N 1 And a fourth node N 4 When the pressure difference therebetween is reduced, the first node N can be enabled 1 The voltage of (c) decreases. Since the first transistor M1 operates in the variable resistance region, the reference voltage inputted from the reference voltage terminal V1 connected to the gate thereof remains unchanged, so that the resistance of the linear resistor formed by the first transistor M1 also remains unchanged, therefore, when the first node N is connected to the first node N 1 When the voltage of (2) is reduced, the second node N can be enabled 2 The voltage of (c) is also reduced.
Due to the second node N 2 Is equal to the gate voltage of the third transistor M3 and the gate voltage of the fourth transistor M4, so that the gate voltage of the third transistor M3 and the gate voltage of the fourth transistor M4 are both reduced. Also, since the third transistor M3 and the fourth transistor M4 are both N-type transistors, when the gate voltage of the third transistor M3 and the gate voltage of the fourth transistor M4 are both decreased, the resistance value of the linear resistor formed by the third transistor M3 and the resistance value of the linear resistor formed by the fourth transistor M4 are both increased, and the third node N is caused to be an N-type transistor 3 Is pulled up to Vth 4 And the second node N 2 Is automatically turned off to Vth 3 -ΔV。
Third node N 3 Is directly connected to the gate of the seventh transistor M7, and thus, the third node N 3 Is equal to the gate voltage of the seventh transistor M7, the gate voltage of the seventh transistor M7 is also pulled high. When the gate voltage of the seventh transistor M7 is pulled high, the resistance of the linear resistor formed by the seventh transistor M7 may be reduced, so that the divided voltage of the seventh transistor M7 may be reduced.
In addition, the voltage division of the sixth transistor M6 is the fifth node N 5 And a first node N 1 When the first node N is 1 When the voltage of (i.e. the fourth voltage outputted by the difference module 41 to the bias module 42) is decreased, the divided voltage of the sixth transistor M6 is increased, so that the gate voltage of the sixth transistor M6 is pulled high, i.e. the sixth node N 6 Is pulled high.
Due to the sixth node N 6 Is directly connected to the gate of the eighth transistor M8, and therefore, the sixth sectionPoint N 6 Is equal to the gate voltage of the eighth transistor M8, the gate voltage of the eighth transistor M8 is pulled high. When the gate voltage of the eighth transistor M8 is pulled high, the resistance of the linear resistor formed by the eighth transistor M8 may be increased, so that the divided voltage of the eighth transistor M8 may be increased.
In summary, when the photosensitive voltage of the photosensitive signal input from the output terminal V2 of the photosensitive circuit is less than the reference voltage input from the reference voltage terminal V1, the divided voltage of the seventh transistor M7 is less than the divided voltage of the eighth transistor M8, so that the absolute value of the difference between the voltage value of the amplified photosensitive signal output from the signal output terminal Out and the high-level voltage input from the high-level signal terminal Vgh is greater than the absolute value of the difference between the voltage value of the amplified photosensitive signal output from the signal output terminal Out and the low-level voltage input from the low-level signal terminal Vgl. The current value of the amplified photo-reception signal output by the signal output terminal Out is the current value output by the second pole of the seventh transistor M7.
It should be noted that the first transistor M1 and the second transistor M2 may be referred to as differential transistors for receiving differential signals, i.e., receiving the light sensing signal input from the output terminal V2 of the light sensing circuit and receiving a signal corresponding to the reference voltage input from the reference voltage terminal V1, respectively, while the third transistor M3 and the fourth transistor M4 are corresponding load transistors thereof, and the differential module 41 may be referred to as a balanced bridge circuit. The fifth transistor M5 and the sixth transistor M6 form a mirror current source circuit, and the current value output from the second pole of the mirror current source circuit is coupled to the current value output from the second pole of the eighth transistor M8; and the seventh transistor M7 and the eighth transistor M8 may be referred to as common source amplifiers.
In some embodiments, as shown in fig. 4, the amplifying module 43 further includes a voltage stabilizing unit 433; the voltage stabilizing unit 433 is respectively connected to the signal output terminal Out and a control terminal of the first amplifying unit 431 (i.e., a gate of the seventh transistor M7), and is configured to stabilize the amplified photo-sensing signal output by the signal output terminal Out, so as to improve stability of the amplified photo-sensing signal output by the amplifying circuit 40 to the driving chip 50.
The voltage stabilizing unit 433 includes a voltage stabilizing capacitor C, a first end of the voltage stabilizing capacitor C is connected to the signal output terminal Out, and a second end of the voltage stabilizing capacitor C is connected to the control terminal of the first amplifying unit 431 (i.e., the gate of the seventh transistor M7). The voltage stabilizing capacitor is also called miller capacitor.
Fig. 6 is a schematic simulation diagram of an input photo sensing signal and an output photo sensing signal in an amplifying circuit according to an embodiment of the present disclosure. In fig. 6, the abscissa represents the light sensing voltage Vin of the light sensing signal input from the output terminal V2 of the light sensing circuit in mV, the ordinate represents the light sensing voltage Vout of the amplified light sensing signal output from the signal output terminal Out of the amplifying circuit in V, and the 3 curves in the figure respectively represent the relationship between the light sensing voltage Vout of the amplified light sensing signal output from the signal output terminal Out and the light sensing voltage Vin of the light sensing signal input from the output terminal V2 of the light sensing circuit when the resistance values of the load resistors R are different.
Simulation tests show that the absolute value of the photosensitive voltage Vout of the amplified photosensitive signal output by the signal output end Out is larger than the absolute value of the photosensitive voltage Vin of the photosensitive signal input by the output end V2 of the photosensitive circuit, so that the voltage value of the photosensitive signal can be amplified, and the millivolt (mV) photosensitive voltage Vin can be amplified to a volt (V) photosensitive voltage Vout.
In addition, through tests, the amplifying circuit in the embodiment of the present application may further amplify the photosensitive signal at the nano ampere level to the milliampere (mA) level, that is, the current value of the photosensitive signal input by the output terminal V2 of the photosensitive circuit may be at the nano ampere level, and the current value of the amplified photosensitive signal output by the signal output terminal Out of the amplifying circuit 40 is at the milliampere level.
In an actual manufacturing process, if the amplifying circuit 40 shown in fig. 4 is formed on a substrate, each transistor included in the amplifying circuit 40 may be manufactured by sequentially forming an active layer, a gate insulating layer, a gate layer, an interlayer dielectric layer, a source/drain electrode layer, and the like on the substrate.
The active layer comprises an active layer pattern of each transistor in the amplifying circuit, the grid layer comprises a grid electrode of each transistor in the amplifying circuit, the source drain electrode layer comprises a source electrode and a drain electrode of each transistor in the amplifying circuit, and the source electrode and the drain electrode of each transistor are connected with the corresponding active pattern through via holes penetrating through the interlayer dielectric layer and the grid insulating layer.
Of course, the structure of each transistor in the amplifier circuit 40 is not limited to the top gate transistor described above, and may be a bottom gate transistor.
In addition, the active layer patterns of the respective transistors in the amplifier circuit 40 may be provided in the same layer or in different layers; the gates of the transistors in the amplifying circuit 40 may be disposed in the same layer or in different layers; the source and drain of each transistor in the amplifying circuit 40 may be disposed in the same layer or in different layers, which is not limited in this embodiment.
It should be noted that, in the embodiments of the present application, the source and the drain of each transistor are interchangeable under certain conditions, and therefore, the source and the drain of each transistor are not distinguished from the description of the connection relationship. In the embodiment of the present application, in order to distinguish the source and the drain of the transistor, one of the poles is referred to as a first pole, and the other pole is referred to as a second pole, and further, the transistor may be divided into an N-type transistor and a P-type transistor according to the characteristics of the transistor, where the first pole is the source of the transistor and the second pole is the drain of the transistor.
The above embodiments, structural diagrams or simulation diagrams are only schematic illustrations of the technical solutions of the present application, and the dimensional ratios thereof do not limit the scope of the technical solutions, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the above embodiments should be included in the scope of the technical solutions.

Claims (13)

1. An amplification circuit, comprising: the device comprises a difference module, a bias module and an amplification module, wherein the amplification module comprises a first amplification unit and a second amplification unit;
the differential module is respectively connected with a reference voltage end, the output end of the photosensitive circuit, a low level signal end, the bias module and the control end of the first amplification unit, and the bias module is respectively connected with a high level signal end, the low level signal end and the control end of the second amplification unit; the first amplifying unit is respectively connected with the low level signal end and the signal output end, and the second amplifying unit is respectively connected with the high level signal end and the signal output end;
the differential module is used for adjusting a first voltage of a control end of the first amplification unit according to a difference value between a photosensitive voltage of a photosensitive signal input by an output end of the photosensitive circuit and a reference voltage input by the reference voltage end, and adjusting a second voltage of a control end of the second amplification unit through the bias module;
and the amplifying module is used for outputting the amplified photosensitive signal to the signal output end under the action of the first voltage and the second voltage.
2. The amplification circuit according to claim 1, wherein the differential block includes a differential unit and a first load unit;
the differential unit is respectively connected with the reference voltage end, the output end of the photosensitive circuit, the first load unit and the bias module, and is used for adjusting a third voltage of the control end of the first load unit according to a difference value between the photosensitive voltage and the reference voltage;
the first load unit is respectively connected with the low-level signal end and the control end of the first amplification unit, and is used for adjusting the first voltage of the control end of the first amplification unit under the action of the third voltage.
3. The amplifying circuit according to claim 2, wherein the differential unit includes a first transistor and a second transistor;
the grid electrode of the first transistor is connected with the reference voltage end, the first pole of the first transistor is connected with the bias module, and the second pole of the first transistor is connected with the first load unit;
the grid electrode of the second transistor is connected with the output end of the photosensitive circuit, the first pole of the second transistor is connected with the first pole of the first transistor, and the second pole of the second transistor is connected with the control ends of the first load unit and the first amplifying unit.
4. The amplifying circuit according to claim 2, wherein the first load unit includes a third transistor and a fourth transistor;
a gate of the third transistor is connected to the differential unit, a first pole of the third transistor is connected to the low-level signal terminal, and a second pole of the third transistor is connected to the differential unit;
the grid electrode of the fourth transistor is connected with the differential unit, the first pole of the fourth transistor is connected with the low-level signal end, and the second pole of the fourth transistor is connected with the control end of the first amplification unit.
5. The amplification circuit of claim 1, wherein the bias module comprises a mirror unit and a second load unit;
the mirror image unit is respectively connected with the differential module, the high-level signal end, the second load unit and the control end of the second amplifying unit;
and the second load unit is respectively connected with the low-level signal end and the control end of the second amplifying unit.
6. The amplifier circuit according to claim 5, wherein the mirroring unit includes a fifth transistor and a sixth transistor;
a gate of the fifth transistor is connected to the control terminals of the second load unit and the second amplifying unit, a first pole of the fifth transistor is connected to the high-level signal terminal, and a second pole of the fifth transistor is connected to the gate of the fifth transistor;
the grid electrode of the sixth transistor is connected with the grid electrode of the fifth transistor, the first pole of the sixth transistor is connected with the high-level signal end, and the second pole of the sixth transistor is connected with the differential module.
7. The amplifying circuit according to claim 5, wherein the second load unit includes a load resistor, a first end of the load resistor is connected to the mirror unit and the control end of the second amplifying unit, and a second end of the load resistor is connected to the low-level signal end.
8. The amplification circuit according to claim 1, wherein the first amplification unit includes a seventh transistor; the grid electrode of the seventh transistor is connected with the differential module, the first pole of the seventh transistor is connected with the low-level signal end, and the second pole of the seventh transistor is connected with the signal output end.
9. The amplifying circuit according to claim 1, wherein the second amplifying unit includes an eighth transistor; the gate of the eighth transistor is connected to the bias module, the first pole of the eighth transistor is connected to the high-level signal terminal, and the second pole of the eighth transistor is connected to the signal output terminal.
10. The amplification circuit according to any one of claims 1 to 9, wherein the amplification module further comprises a voltage stabilization unit;
and the voltage stabilizing unit is respectively connected with the signal output end and the control end of the first amplifying unit and is used for stabilizing the amplified photosensitive signal output by the signal output end.
11. The amplification circuit according to claim 10, wherein the voltage stabilization unit includes a voltage stabilization capacitor; and the first end of the voltage-stabilizing capacitor is connected with the signal output end, and the second end of the voltage-stabilizing capacitor is connected with the control end of the first amplifying unit.
12. A display screen comprising a substrate, a light sensing circuit, and the amplifying circuit of any one of claims 1 to 11, the light sensing circuit and the amplifying circuit being disposed on the substrate.
13. A terminal device, comprising a driver chip and a display screen according to claim 12, wherein the driver chip is connected to a signal output terminal of an amplifying circuit included in the display screen.
CN202111296566.XA 2021-11-03 2021-11-03 Amplifying circuit, display screen and terminal equipment Pending CN115019711A (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6480178B1 (en) * 1997-08-05 2002-11-12 Kabushiki Kaisha Toshiba Amplifier circuit and liquid-crystal display unit using the same
CN201122422Y (en) * 2007-12-05 2008-09-24 群康科技(深圳)有限公司 LCD device
CN202372617U (en) * 2011-12-21 2012-08-08 深圳国微技术有限公司 Light detection circuit and safety chip with same
CN104200784A (en) * 2014-07-24 2014-12-10 京东方科技集团股份有限公司 Pixel driving circuit and method, array substrate and transflective display device
CN108141180A (en) * 2015-07-30 2018-06-08 电路种子有限责任公司 Low noise transimpedance amplifier based on complementary current field effect transistor devices

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6480178B1 (en) * 1997-08-05 2002-11-12 Kabushiki Kaisha Toshiba Amplifier circuit and liquid-crystal display unit using the same
CN201122422Y (en) * 2007-12-05 2008-09-24 群康科技(深圳)有限公司 LCD device
CN202372617U (en) * 2011-12-21 2012-08-08 深圳国微技术有限公司 Light detection circuit and safety chip with same
CN104200784A (en) * 2014-07-24 2014-12-10 京东方科技集团股份有限公司 Pixel driving circuit and method, array substrate and transflective display device
CN108141180A (en) * 2015-07-30 2018-06-08 电路种子有限责任公司 Low noise transimpedance amplifier based on complementary current field effect transistor devices

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