Sensor and electronic device

Abstract

The invention provides a sensor and electronic equipment, and the sensor comprises a signal conversion module which is used for converting a sensing signal into a voltage signal; the noise elimination module comprises N gain modules, the ith gain module is used for gaining ripple noise output by the (i-1) th gain module, the noise elimination module is used for obtaining first ripple noise and outputting second ripple noise after gaining of the N gain modules, N is larger than or equal to 2, and i is larger than or equal to 2 and smaller than or equal to N; and the analog-to-digital conversion module is connected with the signal conversion module and the noise elimination module, and is used for receiving the voltage signal and the second ripple noise and generating a digital signal. The sensor provided by the invention can suppress ripple noise in the sensor.

Description

Technical Field

[0001] This application relates to the field of sensor technology, specifically to a sensor and an electronic device. Background Technology

[0002] Ripple noise refers to the periodic fluctuations or ripples in the alternating current (AC) power supply, typically caused by the rectification and filtering processes. This noise can negatively impact the performance of certain sensors, especially those requiring high precision and stability. For example, image sensors consist of a pixel array and a readout circuit. The pixel array converts light signals into electrical signals. When ripple noise exists in the pixel array's power supply, this ripple, after gain attenuation and phase delay, acts on the pixel array's output voltage signal, which is then sampled and quantized by the readout circuit, affecting the quality of the final image generated by the system. Therefore, measures are needed to suppress ripple noise in the sensor. Summary of the Invention

[0003] This application provides a sensor and an electronic device capable of suppressing ripple noise in the sensor.

[0004] In a first aspect, a sensor is provided, comprising: a signal conversion module for converting a sensing signal into a voltage signal; a noise cancellation module comprising N gain modules, wherein the i-th gain module is used to amplify the ripple noise output by the (i-1)-th gain module, and the noise cancellation module is used to acquire a first ripple noise and output a second ripple noise after amplification by the N gain modules, where N≥2, 2≤i≤N; and an analog-to-digital conversion module connected to the signal conversion module and the noise cancellation module for receiving the voltage signal and the second ripple noise and generating a digital signal.

[0005] The sensor provided in this application includes a noise cancellation module, which comprises multiple gain modules. By amplifying the first ripple noise using the gain modules, ripple noise similar to that in the voltage signal output by the signal conversion module can be generated. This ripple noise is then canceled out by the analog-to-digital conversion module, reducing the impact of ripple noise on sensor performance.

[0006] It should be understood that when the noise cancellation module includes only one gain module, a large gain factor needs to be set for that gain module when the first ripple noise is large. In this case, the gain module itself will generate significant noise, affecting the sensor's performance. The sensor provided in this application includes a noise cancellation module comprising multiple gain modules. Each gain module, except for the first one, can amplify the ripple noise output by the previous gain module. This results in a relatively small gain factor for each gain module, generating less additional noise and having virtually no impact on the sensor's performance.

[0007] In conjunction with the first aspect, in some implementations of the first aspect, the N gain modules include a first gain module, the first gain module including a feedback resistor loop and a first resistor, the first gain module being used to selectively set part or all of the first resistor in the feedback resistor loop, the feedback resistor loop including a loop composed of a first amplifier and a first transistor.

[0008] The first gain module is used to adjust the gain value of the first gain module by selectively setting part or all of the first resistor in the feedback resistor loop to adjust the total resistance of the feedback resistor loop.

[0009] It should be understood that the resistance value of the first resistor in the feedback resistor loop is positively correlated with the gain value of the first gain module. Typically, the gain value of the first gain module is greater than 1. This first resistor can also be referred to as a voltage divider resistor.

[0010] For example, the feedback resistor loop includes a loop connecting the input terminal of the first amplifier, the first transistor, and the output terminal of the first amplifier, with some or all of the first resistor disposed in the feedback resistor loop. One input terminal of the amplifier is used to input the first ripple noise or the ripple noise output from the previous gain module, and the other input terminal of the amplifier is connected to the source or drain of the first transistor through the first resistor. The output terminal of the amplifier is connected to the gate of the first transistor. It should be understood that the two input terminals of the amplifier have a virtual short characteristic, that is, the voltage difference between the two input terminals approaches zero.

[0011] In the sensor provided in this application, the noise cancellation module includes a gain module, and the gain value of the gain module can be adjusted by means of resistance feedback. This adjustment method is not sensitive to circuit parasitics and has better process, voltage, temperature, and PVT performance.

[0012] In conjunction with the first aspect, in some implementations of the first aspect, the N gain modules further include a second gain module, the input terminal of the second gain module being connected to the output terminal of the first gain module, the second gain module including a second transistor and a second resistor, the second resistor being connected to the second transistor, and the first transistor being connected to the second transistor.

[0013] The second gain module is connected to the first gain module. The second gain module is used to increase the ripple noise output of the first gain module by P1 times before outputting it. P1 = R2 × k1 / R1, where R1 is the resistance value of the first resistor, R2 is the resistance value of the second resistor, and the value of k1 is determined by the size ratio of the second transistor and the first transistor.

[0014] In some possible implementations, the value of k1 is related to the width-to-length ratio of the second transistor and the first transistor. When the lengths of the second and first transistors are the same, the value of k1 can be controlled by adjusting the width ratio of the second and first transistors. When the widths of the second and first transistors are the same, the value of k1 can be controlled by adjusting the length ratio of the second and first transistors.

[0015] The first resistor converts the voltage-divided ripple noise into a current signal, which flows through the first transistor to the second transistor. The second transistor replicates the current signal from the first transistor; the value of k1 can be used to change the ratio of the replicated current signal to the current signal flowing through the first transistor. After current replication is complete, the replicated current in the second transistor can be converted into a voltage signal across the second resistor. In some possible applications, the second resistor can be referred to as the load resistor.

[0016] For example, N=2, the noise cancellation module includes a first gain module and a second gain module. The first gain module obtains the first ripple noise. The first ripple noise is amplified by the first gain module to obtain the fourth ripple noise. The fourth ripple noise is amplified by the second gain module to obtain the second ripple noise.

[0017] The sensor provided in this application includes a noise cancellation module, which comprises multiple gain modules. By amplifying the first ripple noise using the gain modules, a ripple noise similar to that in the voltage signal output by the signal conversion module can be generated. This ripple noise is then canceled out by the analog-to-digital conversion module, reducing the impact of ripple noise on sensor performance. Furthermore, this application employs resistive feedback to adjust the gain value of the gain modules. This adjustment method is insensitive to circuit parasitics and exhibits superior PVT performance.

[0018] In conjunction with the first aspect, in some implementations of the first aspect, the N gain modules include a third gain module, the third gain module including a feedback capacitor loop, a capacitor array and a third resistor, the third gain module being used to selectively place some or all of the capacitors in the capacitor array in the feedback capacitor loop, the feedback capacitor loop including a loop composed of a second amplifier and a third transistor, and the third resistor being connected to the third transistor.

[0019] The third gain module is used to adjust the gain value of the third gain module by selectively placing some or all of the capacitors in the capacitor array into the feedback capacitor loop, thereby adjusting the total capacitance of the feedback capacitor loop.

[0020] It should be understood that the total capacitance of the capacitors in the feedback capacitor loop is positively correlated with the gain value of the third gain module. Typically, the gain value of the third gain module is greater than 1.

[0021] For example, the feedback capacitor loop includes a loop connecting the input terminal of the second amplifier, the second transistor, and the output terminal of the second amplifier. Some or all of the capacitors in the capacitor array are located within the feedback capacitor loop. One input terminal of the amplifier is used to input the first ripple noise or the ripple noise output from the previous gain module. The other input terminal of the amplifier is connected to the source or drain of the third transistor via the capacitor array, and the output terminal of the amplifier is connected to the gate of the third transistor. It should be understood that the two input terminals of the amplifier have a virtual short characteristic, meaning the voltage difference between the two input terminals approaches zero.

[0022] The feedback capacitor loop can adjust the gain value of the third gain module by setting some or all of the capacitors in the capacitor array in the feedback capacitor loop through the corresponding switch of the capacitor.

[0023] In the sensor provided in this application, the noise cancellation module includes a gain module that can use capacitive feedback to adjust the gain value of the gain module, thereby generating ripple noise similar to the ripple noise in the voltage signal output by the signal conversion module. The ripple noise in the voltage signal output by the signal conversion module is then canceled by the analog-to-digital conversion module, reducing the impact of ripple noise on the sensor performance.

[0024] In conjunction with the first aspect, in some implementations of the first aspect, the N gain modules further include a fourth gain module, the input terminal of which is connected to the output terminal of the third gain module, the fourth gain module including a fourth transistor and a fourth resistor, the fourth resistor being connected to the fourth transistor, and the third transistor being connected to the fourth transistor.

[0025] The fourth gain module is used to increase the ripple noise output of the third gain module by P2 times before outputting it. P2 = R4 × k2 / R3, where R3 is the resistance value of the third resistor, R4 is the resistance value of the fourth resistor, and the value of k2 is determined by the size ratio of the fourth transistor and the third transistor.

[0026] In some possible implementations, the value of k2 is related to the width-to-length ratio of the fourth and third transistors. When the lengths of the fourth and third transistors are the same, the value of k2 can be controlled by adjusting the width ratio of the fourth and third transistors. When the widths of the fourth and third transistors are the same, the value of k2 can be controlled by adjusting the length ratio of the fourth and third transistors.

[0027] The third resistor converts the voltage-divided ripple noise into a current signal, which flows through the third transistor to the fourth transistor. The fourth transistor replicates the current signal from the third transistor; the value of k2 can be used to change the ratio of the replicated current signal to the current signal flowing through the third transistor. After current replication is complete, the replicated current in the fourth transistor can be converted into a voltage signal across the fourth resistor. In some possible applications, the third and fourth resistors can be referred to as load resistors.

[0028] For example, N=2, the noise cancellation module includes a third gain module and a fourth gain module. The third gain module obtains the first ripple noise, the first ripple noise is amplified by the third gain module to obtain the fifth ripple noise, and the fifth ripple noise is amplified by the fourth gain module to obtain the second ripple noise.

[0029] In the sensor provided in this application, the noise cancellation module includes a gain module that can use capacitive feedback to adjust the gain value of the gain module, thereby generating ripple noise similar to the ripple noise in the voltage signal output by the signal conversion module. The ripple noise in the voltage signal output by the signal conversion module is then canceled by the analog-to-digital conversion module, reducing the impact of ripple noise on the sensor performance.

[0030] In conjunction with the first aspect, in some implementations of the first aspect, the second ripple noise is equal to the first ripple noise gain Av times, where Av = G1 × G2 × … × GN, and Gi is the gain value corresponding to the i-th gain module.

[0031] The i-th gain module is used to increase the ripple noise output of the (i-1)-th gain module by a factor of Gi, where Gi is usually greater than 1.

[0032] The sensor provided in this application includes a noise cancellation module, which comprises multiple gain modules. Each gain module, except for the first gain module, can amplify the ripple noise output by the previous gain module. Thus, the gain factor of each gain module is relatively small, resulting in less additional noise and having virtually no impact on the sensor's performance.

[0033] In conjunction with the first aspect, in some implementations of the first aspect, the analog-to-digital conversion module includes a comparator for receiving the voltage signal and the second ripple noise.

[0034] In conjunction with the first aspect, in some implementations of the first aspect, the sensor is an image sensor, the signal conversion module is a pixel array, and the pixel array is used to convert the optical signal into the voltage signal.

[0035] The pixel array comprises multiple pixel rows and pixel columns, and each pixel includes a photodetector circuit for recording the pixel signal level corresponding to a certain amount of light exposed during the exposure window.

[0036] This image sensor can be used in various electronic devices that include camera functions, such as mobile phones, laptops, security equipment, automobiles, drones, and medical endoscopes.

[0037] The image sensor provided in this application includes a noise cancellation module, which comprises multiple gain modules. This module generates ripple noise similar to the ripple noise in the voltage signal output by the signal conversion module and cancels the ripple noise in the voltage signal output by the signal conversion module through an analog-to-digital conversion module. This reduces the impact of ripple noise on the performance of the image sensor and improves the imaging quality of the image sensor.

[0038] In conjunction with the first aspect, in some implementations of the first aspect, the power supply rejection ratio (PSRR) of the pixel array is less than or equal to a preset threshold.

[0039] PSRR is a metric that measures a circuit's ability to suppress power supply noise. PSRR is commonly used to describe how well a circuit resists noise from its power supply. PSRR is usually expressed in decibels (dB). It represents the ratio between the change in output signal caused by a change in the input power supply (usually an AC signal) and the change in output signal caused by the same magnitude change applied directly to the circuit input. A higher PSRR value indicates a stronger ability to suppress power supply noise.

[0040] It should be understood that when the noise cancellation module includes only one gain module, if the PSRR of the pixel array is less than or equal to a preset threshold, a large gain factor needs to be set for that gain module. In this case, the gain module itself will generate significant noise, affecting the sensor's performance. The sensor provided in this application includes a noise cancellation module comprising multiple gain modules. Each gain module, except for the first one, can amplify the ripple noise output by the previous gain module. This results in a relatively small gain factor for each gain module, generating less additional noise and having virtually no impact on the sensor's performance.

[0041] In conjunction with the first aspect, in some implementations of the first aspect, the preset threshold is -20dB.

[0042] In conjunction with the first aspect, in some implementations of the first aspect, the digital signal includes image data.

[0043] The sensor provided in this application includes a noise cancellation module, which comprises multiple gain modules. By amplifying the first ripple noise using the gain modules, ripple noise similar to that in the voltage signal output by the signal conversion module can be generated. This ripple noise is then canceled out by the analog-to-digital conversion module, reducing the impact of ripple noise on sensor performance and improving the imaging quality of the image sensor.

[0044] In a second aspect, an electronic device is provided, including the sensor described in the first aspect and any possible implementation thereof.

[0045] The sensor can be a pressure sensor, an optical sensor, a temperature sensor, an acceleration sensor, a sound sensor, or an image sensor. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the ripple noise path of an image sensor provided in an embodiment of this application.

[0047] Figure 2 This is a schematic diagram of the structure of a sensor provided in an embodiment of this application.

[0048] Figure 3 This is a schematic diagram of the structure of an image sensor provided in an embodiment of this application.

[0049] Figure 4 This is a schematic diagram of another image sensor provided in an embodiment of this application.

[0050] Figure 5 This is a schematic diagram of another image sensor provided in an embodiment of this application. Detailed Implementation

[0051] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort should fall within the scope of protection of this application.

[0052] In the embodiments of this application, the words "exemplary," "for example," etc., are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the term "exemplary" is intended to present the concept in a concrete manner.

[0053] The business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0054] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0055] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0056] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related 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 single or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0057] Ripple noise refers to the periodic fluctuations or ripples in the alternating current (AC) power supply, typically caused by the rectification and filtering processes. This noise can negatively impact the performance of certain sensors, especially those requiring high precision and stability. For example, for pressure sensors, ripple noise can cause fluctuations in the output signal, affecting measurement accuracy and stability; for optical sensors, ripple noise can introduce signal interference, potentially affecting the accuracy of optical measurements; for temperature sensors, some types are sensitive to electromagnetic interference in the environment, and ripple noise can affect temperature measurement results; for accelerometers, ripple noise can interfere with the output signal, leading to errors or unstable measurement results; for sound sensors, some types can interfere with sound signal acquisition and analysis; and for image sensors, ripple noise can affect the quality of the final generated image.

[0058] Figure 1 This is a schematic diagram of the ripple noise path of an image sensor provided in an embodiment of this application.

[0059] An image sensor consists of a pixel array and a readout circuit. The pixel array converts light signals into electrical signals. The ripple noise present in the pixel array power supply can be called power supply ripple noise. When power supply ripple noise exists in the pixel array power supply, it is attenuated by a certain gain and phase delay, and then acts on the output voltage signal of the pixel array. It is then sampled and quantized by the readout circuit, affecting the quality of the final generated image.

[0060] The pixel array comprises multiple pixel rows and pixel columns, and each pixel includes a photodetector circuit for recording the pixel signal level corresponding to a certain amount of light exposed during the exposure window.

[0061] The circuitry in the pixel array includes photodiodes (PDs), floating diffusion regions (FDs), transfer transistors (TXs), source followers (SFs), and selectors (SELs). The pixel array is powered via an analog voltage domain (AVDD), which includes ripple noise.

[0062] Ripple noise can manifest as striped noise in the horizontal or vertical direction of an image, typically appearing as periodic brightness variations. This noise affects image sharpness and quality, and is more easily observed, especially in low-light conditions or high-contrast scenes.

[0063] Figure 2 This is a schematic diagram of the structure of a sensor provided in an embodiment of this application.

[0064] The sensor 200 includes a signal conversion module 210, a noise cancellation module 220, and an analog-to-digital conversion module 230. The analog-to-digital conversion module 230 is connected to both the signal conversion module 210 and the noise cancellation module 220.

[0065] The signal conversion module 210 is powered by a supply voltage signal, which includes a first ripple noise. The signal conversion module 210 converts the sensing signal into a voltage signal. During this conversion, the signal conversion module 210 is affected by the first ripple noise, which includes a third ripple noise. The sensing signal can be a light signal, sound signal, pressure signal, electromagnetic signal, etc.

[0066] The noise cancellation module 220 includes N gain modules, wherein the i-th gain module is used to amplify the ripple noise output by the (i-1)-th gain module. The noise cancellation module 220 is used to acquire the first ripple noise, and after amplification by the N gain modules, output the second ripple noise, wherein the similarity between the second ripple noise and the third ripple noise is less than a first preset threshold, N≥2, 2≤i≤N.

[0067] The second ripple noise is equal to the first ripple noise gain Av times, Av = G1 × G2 × … × GN, Gi is the gain value corresponding to the i-th gain module, the i-th gain module is used to increase the ripple noise output of the (i-1)-th gain module by Gi times, and Gi is usually greater than 1.

[0068] The analog-to-digital conversion module 230 is used to receive the voltage signal output by the signal conversion module 210 and the second ripple noise output by the noise cancellation module 220, and to use the second ripple noise to cancel the third ripple noise in the voltage signal.

[0069] The sensor provided in this application embodiment includes a noise cancellation module 220, which includes multiple gain modules that can generate a second ripple noise similar to the third ripple noise output by the signal conversion module 210, in order to cancel the third ripple noise in the voltage signal output by the signal conversion module 210 and reduce the impact of ripple noise on the sensor performance.

[0070] In the following embodiments, sensor 200 is used as an image sensor as an example to specifically describe the ripple noise suppression scheme in the sensor. Other types of sensors are similar to image sensors, and will not be described again in this application.

[0071] Figure 3 This is a schematic diagram of the structure of an image sensor provided in an embodiment of this application.

[0072] The image sensor 300 includes a pixel array 310, a noise cancellation module 320, and an analog-to-digital conversion module 330. The noise cancellation module 320 provided in this embodiment can improve the power supply rejection ratio (PSRR) of the pixel array 310.

[0073] The pixel array 310 includes multiple pixel rows and columns, and each pixel includes a photodetector circuit for recording a pixel signal level corresponding to a certain amount of light exposed during an exposure window. The pixel array 310 is powered by AVDD, which includes first ripple noise. During the process of converting the light signal into a voltage signal, the pixel array 310 is affected by the first ripple noise, resulting in the generation of a third ripple noise in the voltage signal.

[0074] The noise cancellation module 320 includes a first gain module 321 and a second gain module 322.

[0075] The first gain module 321 includes a feedback resistor loop and a first resistor R1. The first gain module 321 is used to adjust the gain value of the first gain module 321 by selectively setting part or all of the first resistor R1 in the feedback resistor loop to adjust the total resistance of the feedback resistor loop. The first resistor R1 can also be referred to as a voltage divider resistor.

[0076] For example, the feedback resistor loop may include a loop consisting of a first amplifier A1 and a first transistor M1. One input terminal of the first amplifier A1 is used to input the first ripple noise, and the other input terminal of the first amplifier A1 is connected to the source or drain of the first transistor M1 through the first resistor R1. The output terminal of the first amplifier A1 is connected to the gate of the first transistor M1. It should be understood that the two input terminals of the first amplifier A1 have virtual short characteristics, that is, the voltage difference between the two input terminals approaches zero.

[0077] For example, the gain value of the first gain module 321 is denoted as Gain1. In the first gain module 321, the resistance of the first resistor outside the feedback resistor loop is R1 / Gain1, and the resistance of the first resistor in the feedback resistor loop is (Gain1-1)×R1 / Gain1. It should be understood that the resistance value of the first resistor in the feedback resistor loop is positively correlated with the gain value of the first gain module 321. Typically, the gain value of the first gain module 321 is greater than 1. By changing the resistance value of the first resistor in the feedback resistor loop, the gain value of the first gain module 321 can be adjusted.

[0078] It should be understood that in amplifier circuits, feedback is a technique used to control the amplifier's gain. The feedback point of an amplifier is a point in the connection path from the output to the input, where a feedback element (such as a resistor) is introduced to adjust the amplification factor. Typically, by adjusting the resistance value of the feedback element or changing the feedback method, the nature of the feedback network can be altered, thereby changing the amplifier's gain. In this case, by changing the amplifier's feedback point, different voltage division ratios can be achieved, thus adjusting the gain value, i.e., the amplification factor.

[0079] The second gain module 322 includes a second transistor M2 and a second resistor R2. The second transistor M2 is connected to the first transistor M1, and the second transistor M2 is connected to the second resistor R2. The amplification factor of the second transistor M2 and the first transistor M1 is k1. The value of k1 can be used to change the amplification factor of the ripple noise reproduced by the second transistor M2 and the ripple noise flowing through the first transistor M1. The ripple noise can be in the form of a current signal or a voltage signal.

[0080] In some possible implementations, the value of k1 is related to the width-to-length ratio of the second transistor M2 and the first transistor M1. When the lengths of the second transistor M2 and the first transistor M1 are the same, the value of k1 can be controlled by adjusting the width ratio of the second transistor M2 and the first transistor M1. When the widths of the second transistor M2 and the first transistor M1 are the same, the value of k1 can be controlled by adjusting the length ratio of the second transistor M2 and the first transistor M1.

[0081] For example, the first resistor R1 in the feedback resistor loop converts the first ripple noise after voltage division into a current signal, which flows through the first transistor M1. The second transistor M2 in the second gain module 322 replicates the current signal flowing through the first transistor M1 and amplifies it by a factor of k1. The current signal replicated and amplified in the second transistor M2 is converted into a voltage signal across the second resistor R2, which is the second ripple noise.

[0082] In some possible implementations, 1 / 1000 ≤ k1 ≤ 10.

[0083] The gain value of the second gain module 322 is P1, P1 = R2 × k1 / R1, where R1 is the resistance value of the first resistor R1, R2 is the resistance value of the second resistor R2, and k1 is the amplification factor of the second transistor M2 and the first transistor M1.

[0084] The noise amplification factor formula for the noise cancellation module 320 is: Av1=Gain1·R2·k1 / R1, where Av1 represents the noise amplification factor at the output of the noise cancellation module 320.

[0085] The analog-to-digital conversion module 330 is connected to the pixel array 310 and the noise cancellation module 320. It is used to receive the voltage signal output by the pixel array 310 and the second ripple noise output by the noise cancellation module 320, and use the second ripple noise to cancel the third ripple noise in the voltage signal, thereby reducing the impact of ripple noise on the performance of the image sensor and improving the imaging quality of the image sensor.

[0086] For example, the analog-to-digital conversion module 330 includes a comparator (CM) 331, which subtracts the voltage signal output by the pixel array 310 from the second ripple noise output by the noise cancellation module 320 at the comparator 331, thereby canceling the third ripple noise in the voltage signal.

[0087] In this embodiment, by changing the gain value Gain1 and amplification factor k1 of the first gain module 321, the second ripple noise output by the noise cancellation module 320 and the third ripple noise output by the pixel array 310 can be kept as consistent as possible. After being subtracted by the comparator 331, the ripple noise in the output voltage signal of the pixel array 310 can be basically eliminated, thereby improving the PSRR of the pixel array 310.

[0088] The sensor provided in this application uses a resistive feedback method to adjust the gain value of the gain module. This adjustment method is not sensitive to circuit parasitics and has better process, voltage, temperature, and PVT performance.

[0089] It should be understood that when the noise cancellation module 320 includes only one gain module, if the first ripple noise is large, for example, if the PSRR of the pixel array 310 is less than or equal to a preset threshold (e.g., -20dB), a large gain factor needs to be set for the gain module. In this case, the gain module itself will generate significant noise, affecting the performance of the image sensor. In the image sensor provided in this application, the noise cancellation module 320 includes multiple gain modules. Each gain module, except for the first gain module, can amplify the ripple noise output by the previous gain module. Thus, the gain factor of each gain module is relatively small, and under the same PSRR, the additional noise generated is less, and it has virtually no impact on the performance of the image sensor.

[0090] Figure 4 This is a schematic diagram of another image sensor provided in an embodiment of this application.

[0091] The image sensor 400 includes a pixel array 410, a noise cancellation module 420, and an analog-to-digital conversion module 430. The noise cancellation module 420 provided in this embodiment can improve the PSRR of the pixel array 410.

[0092] The pixel array 410 includes multiple pixel rows and columns, and each pixel includes a photodetector circuit for recording a pixel signal level corresponding to a certain amount of light exposed during an exposure window. The pixel array 410 is powered by AVDD, which includes first ripple noise. During the process of converting the light signal into a voltage signal, the pixel array 410 is affected by the first ripple noise, resulting in the generation of a third ripple noise in the voltage signal.

[0093] The noise cancellation module 420 includes a third gain module 423 and a fourth gain module 424.

[0094] The third gain module 423 includes a feedback capacitor loop and a capacitor array C. fb The third gain module 423 is used to selectively gain the capacitor array C fb Some or all of the capacitors are placed in the feedback capacitor loop to adjust the gain value of the third gain module 423 by adjusting the total capacitance of the feedback capacitor loop.

[0095] It should be understood that the total capacitance of the capacitors in the feedback capacitor loop is positively correlated with the gain value of the third gain module 423. Typically, the gain value of the third gain module 423 is greater than 1.

[0096] For example, the feedback capacitor loop may include a second amplifier A2 and a third transistor M3, one input terminal of the second amplifier A2 is used to input the first ripple noise, and the other input terminal of the second amplifier A2 passes through the capacitor array C.fb The second amplifier A2 is connected to either the source or drain of the third transistor M3, and its output is connected to the gate of the third transistor M3. It should be understood that the two inputs of the second amplifier A2 have a virtual short characteristic, meaning the voltage difference between the two inputs approaches zero.

[0097] The feedback capacitor loop can switch the capacitor array C through the corresponding capacitor. fb Some or all of the capacitors are placed in the feedback capacitor loop to adjust the gain value of the third gain module 423 by adjusting the total capacitance of the feedback capacitor loop.

[0098] The third gain module 423 also includes a resistor R. fb Voltage divider capacitor C di And the third resistor R3, resistor R fb Parallel connection in capacitor array C fb The voltage divider capacitor C at both ends di The third resistor R3 is connected to the capacitor array C. fb The two ends are connected. The third resistor R3 can be called the load resistor, and the third resistor R3 is connected to the source or drain of the third transistor M3.

[0099] In the third gain module 423, through resistor R fb The path establishes the DC operating point of the second amplifier A2, through the capacitor array C. fb With voltage divider capacitor C di The voltage divider is used to divide the ripple noise signal, thereby changing the gain value of the third gain module 423.

[0100] The gain value Gain2 of the third gain module 423 is equal to (C fb +C di ) / C fb C fb For the capacitor array C set in the feedback capacitor loop fb The capacitance value, C di For the voltage divider capacitor C di The capacitance value.

[0101] The fourth gain module 424 includes a fourth transistor M4 and a fourth resistor R4. The fourth transistor M4 is connected to the third transistor M3, and the fourth transistor M4 and the fourth resistor R4 are also connected. The amplification factor of the fourth transistor M4 and the third transistor M3 is k2. This k2 value can be used to change the ratio of the ripple noise replicated by the fourth transistor M4 to the ripple noise flowing through the third transistor M3. This ripple noise can be in the form of a current signal or a voltage signal. The fourth resistor R4 can be referred to as the load resistor.

[0102] The ripple noise flowing through the third transistor M3 is equal to the first ripple noise multiplied by Gain2.

[0103] In some possible implementations, the value of k2 is related to the width-to-length ratio of the fourth transistor M4 and the third transistor M3. When the lengths of the fourth transistor M4 and the third transistor M3 are the same, the value of k2 can be controlled by adjusting the ratio of their widths. Conversely, when the widths of the fourth transistor M4 and the third transistor M3 are the same, the value of k2 can be controlled by adjusting the ratio of their lengths.

[0104] For example, the capacitor array C located in the feedback capacitor loop fb The first ripple noise can be gained to a fifth ripple noise, which is equal to the first ripple noise multiplied by Gain2. The third resistor R3 converts the fifth ripple noise into a current signal, which flows through the third transistor M3. The fourth transistor M4 in the fourth gain module 424 replicates the current signal flowing through the third transistor M3 and amplifies it by k2 times. The current signal replicated and amplified in the fourth transistor M4 is converted into a voltage signal across the fourth resistor R4, which is the second ripple noise.

[0105] In some possible implementations, 1 / 1000 ≤ k2 ≤ 10.

[0106] The gain value of the fourth gain module 424 is P2, P2 = R4 × k2 / R3, where R3 is the resistance value of the third resistor R3, R4 is the resistance value of the fourth resistor R4, and k2 is the amplification factor of the fourth transistor M4 and the third transistor M3.

[0107] The noise amplification factor formula for the noise cancellation module 420 is: Av2=Gain2·R4·k2 / R3, where Av2 represents the noise amplification factor at the output of the noise cancellation module 420.

[0108] The analog-to-digital conversion module 430 is connected to the pixel array 410 and the noise cancellation module 420. It is used to receive the voltage signal output by the pixel array 410 and the second ripple noise output by the noise cancellation module 420, and use the second ripple noise to cancel the third ripple noise in the voltage signal, thereby reducing the impact of ripple noise on the performance of the image sensor and improving the imaging quality of the image sensor.

[0109] For example, the analog-to-digital conversion module 430 includes a comparator 431, which subtracts the voltage signal output by the pixel array 410 from the second ripple noise output by the noise cancellation module 420 at the comparator 431, thereby canceling the third ripple noise in the voltage signal.

[0110] In this embodiment, by changing the gain value Gain2 and the amplification factor k2 of the third gain module 423, the second ripple noise output by the noise cancellation module 420 and the third ripple noise output by the pixel array 410 can be kept as consistent as possible. After subtraction by the comparator 431, the ripple noise in the output voltage signal of the pixel array 410 can be basically eliminated, thereby improving the PSRR of the pixel array 410.

[0111] In the sensor provided in this application, capacitive feedback is used to adjust the gain value of the gain module. It should be understood that when the noise cancellation module 420 includes only one gain module, if the first ripple noise is large, for example, if the PSRR of the pixel array 410 is less than or equal to a preset threshold (e.g., -20dB), a large gain factor needs to be set for that gain module. In this case, the gain module itself will generate significant noise, affecting the performance of the image sensor. In the image sensor provided in this application, the noise cancellation module 420 includes multiple gain modules. Each gain module, except for the first one, can amplify the ripple noise output by the previous gain module. Thus, the gain factor of each gain module is relatively small, resulting in less additional noise at the same PSRR, and having virtually no impact on the performance of the image sensor.

[0112] Figure 5 This is a schematic diagram of another image sensor provided in an embodiment of this application.

[0113] In the sensor provided in this application, the noise cancellation module 320 and the noise cancellation module 420 can also be connected together, that is, the first ripple noise is output as the second ripple noise after being gained by the first gain module 321, the second gain module 322, the third gain module 423 and the fourth gain module 424 in sequence.

[0114] op-amp input capacitor C in Connected between noise cancellation module 320 and noise cancellation module 420, it is used to block the DC power output by noise cancellation module 320 and allow only the AC power output by noise cancellation module 320 to pass through.

[0115] Optionally, in the sensor provided in this application, multiple noise cancellation modules 320 can be connected together, multiple noise cancellation modules 420 can be connected together, or multiple noise cancellation modules 320 and multiple noise cancellation modules 420 can be connected together. This application does not limit the specific structure of the gain module included in the noise cancellation module.

[0116] This application also provides an electronic device, including, as in the following embodiments: Figure 2 , Figure 3 , Figure 4 or Figure 5The sensor shown can be an electronic device such as a mobile phone, laptop, security device, car, drone, medical endoscope, etc.

[0117] The sensor provided in this application includes a noise cancellation module, which comprises multiple gain modules that can generate a second ripple noise similar to the third ripple noise output by the signal conversion module, thereby canceling the third ripple noise in the voltage signal output by the signal conversion module and reducing the impact of ripple noise on the sensor performance.

[0118] It should be understood that when the noise cancellation module includes only one gain module, a large gain factor needs to be set for that gain module when the first ripple noise is large. In this case, the gain module itself will generate significant noise, affecting the sensor's performance. The sensor provided in this application includes a noise cancellation module comprising multiple gain modules. Each gain module, except for the first one, can amplify the ripple noise output by the previous gain module. This results in a relatively small gain factor for each gain module, generating less additional noise and having virtually no impact on the sensor's performance.

[0119] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A sensor, characterized in that, include: The signal conversion module is used to convert the sensing signal into a voltage signal; The noise cancellation module includes N gain modules, wherein the i-th gain module is used to amplify the ripple noise output by the (i-1)-th gain module, and the noise cancellation module is used to obtain the first ripple noise and output the second ripple noise after amplification by the N gain modules, where N≥2, 2≤i≤N; An analog-to-digital conversion module, connected to the signal conversion module and the noise cancellation module, is used to receive the voltage signal and the second ripple noise, and generate a digital signal.

2. The sensor according to claim 1, characterized in that, The N gain modules include a first gain module, which includes a feedback resistor loop and a first resistor. The first gain module is used to selectively place part or all of the first resistor in the feedback resistor loop, which includes a loop composed of a first amplifier and a first transistor.

3. The sensor according to claim 2, characterized in that, The N gain modules further include a second gain module, the input terminal of which is connected to the output terminal of the first gain module. The second gain module includes a second transistor and a second resistor, the second resistor being connected to the second transistor, and the first transistor being connected to the second transistor.

4. The sensor according to any one of claims 1 to 3, characterized in that, The N gain modules include a third gain module, which includes a feedback capacitor loop, a capacitor array, and a third resistor. The third gain module is used to selectively place some or all of the capacitors in the capacitor array into the feedback capacitor loop. The feedback capacitor loop includes a loop composed of a second amplifier and a third transistor, and the third resistor is connected to the third transistor.

5. The sensor according to claim 4, characterized in that, The N gain modules further include a fourth gain module, the input of which is connected to the output of the third gain module. The fourth gain module includes a fourth transistor and a fourth resistor, the fourth resistor being connected to the fourth transistor, and the third transistor being connected to the fourth transistor.

6. The sensor according to any one of claims 1 to 5, characterized in that, The second ripple noise is equal to the first ripple noise gain Av times, where Av = G1 × G2 × … × GN, and Gi is the gain value corresponding to the i-th gain module.

7. The sensor according to any one of claims 1 to 6, characterized in that, The analog-to-digital conversion module includes a comparator for receiving the voltage signal and the second ripple noise.

8. The sensor according to any one of claims 1 to 7, characterized in that, The sensor is an image sensor, and the signal conversion module is a pixel array, which is used to convert the light signal into the voltage signal.

9. The sensor according to claim 8, characterized in that, The power supply rejection ratio (PSRR) of the pixel array is less than or equal to a preset threshold.

10. The sensor according to claim 9, characterized in that, The preset threshold is -20dB.

11. The sensor according to any one of claims 8 to 10, characterized in that, The digital signal includes image data.

12. An electronic device, characterized in that, Includes the sensor as described in any one of claims 1 to 11.

Images