Power conversion circuit applied to image sensor

Abstract

The utility model discloses a power conversion circuit applied to an image sensor, which comprises a power input end, a linear direct current voltage stabilization module, an input noise reduction module and an output noise reduction module, one end of the input noise reduction capacitor is connected with the input end of the linear DC voltage stabilization module and the power supply input end, and the other end is connected with a ground wire. The output noise reduction module comprises a plurality of output noise reduction capacitors which are connected in parallel, and the output noise reduction capacitors are connected between the output end of the linear direct current voltage stabilization module and the ground wire and used for supplying power to the image sensor. According to the utility model, the noise of the circuit can be effectively reduced, the influence of the noise on a post-stage load is reduced, and the imaging effect of the image sensor can be improved.

Description

Technical Field

[0001] This utility model relates to the field of power supply circuit technology, and in particular to a power conversion circuit applied to image sensors. Background Technology

[0002] In power supply circuits, electromagnetic interference is easily generated and difficult to avoid due to the presence of rectifier harmonics, switching frequency and its harmonics, as well as the inherent high-speed current and voltage transients during switching. This often results in ripple in the power supply output, causing the output terminal to carry glitches and noise. Especially when the power supply circuit is used to power an image sensor, excessive power supply ripple directly affects the imaging effect of the image sensor, causing problems such as horizontal stripes and water ripples in the generated image. Therefore, how to improve the stability and low noise of the power supply circuit for powering the image sensor has become an urgent problem to be solved. Utility Model Content

[0003] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a power conversion circuit for image sensors that can effectively reduce circuit noise, reduce the impact of noise on downstream loads, and help improve the imaging effect of image sensors.

[0004] In a first aspect, this utility model provides a power conversion circuit for an image sensor, comprising: a power input terminal, a linear DC voltage regulator module, an input noise reduction module, and an output noise reduction module. The input noise reduction module includes multiple input noise reduction capacitors connected in parallel, one end of each input noise reduction capacitor being connected to the input terminal of the linear DC voltage regulator module and the power input terminal, and the other end being connected to ground. The output noise reduction module includes multiple output noise reduction capacitors connected in parallel, the output noise reduction capacitors being connected between the output terminal of the linear DC voltage regulator module and ground, for supplying power to the image sensor.

[0005] The power conversion circuit for image sensors provided according to embodiments of this utility model has at least the following beneficial effects: An input noise reduction module, utilizing multiple parallel-connected input noise reduction capacitors, filters out high-frequency noise and smooths the voltage of the power supply input to the linear DC regulator module, reducing power ripple and minimizing the impact of noise on the linear DC regulator module. Meanwhile, an output noise reduction module, with multiple parallel-connected output noise reduction capacitors, further reduces the noise of the input power supply and the output noise of the linear DC regulator module, protecting the downstream image sensor from power fluctuations and noise interference, and providing a more stable and low-noise power output. Therefore, by designing input noise reduction modules and constructing a complete noise suppression system, not only can high-frequency noise from the input power supply be filtered out, but the output noise of the linear DC regulator module can also be reduced, electromagnetic interference can be reduced, circuit stability can be improved, and the power quality requirements of image sensors can be met.

[0006] According to the power conversion circuit provided in the embodiments of this utility model, the capacitance values ​​of each of the input noise reduction capacitors are different.

[0007] According to the power conversion circuit provided in this embodiment of the present invention, all the input noise reduction capacitors are connected in order of capacitance value.

[0008] According to the power conversion circuit provided in this embodiment of the present invention, the distance between the input noise reduction capacitor and the linear DC voltage regulator module increases with the increase of the capacitance value.

[0009] According to the power conversion circuit provided in the embodiments of this utility model, the capacitance values ​​of each of the output noise reduction capacitors are different.

[0010] According to the power conversion circuit provided in this embodiment of the present invention, all the output noise reduction capacitors are connected in order of capacitance value.

[0011] According to the power conversion circuit provided in this embodiment of the present invention, the distance between the output noise reduction capacitor and the linear DC voltage regulator module decreases as the capacitance value increases.

[0012] According to the power conversion circuit provided in the embodiment of this utility model, the output noise reduction module further includes a first inductor connected between the output terminal of the linear DC voltage regulator module and the output noise reduction capacitor.

[0013] According to the power conversion circuit provided in the embodiment of this utility model, the output noise reduction module further includes a magnetic bead filter element connected between the output terminal of the linear DC voltage regulator module and the output noise reduction capacitor.

[0014] The power conversion circuit provided according to the embodiment of this utility model further includes a voltage regulation module for regulating the voltage of the input power supply at the power input terminal. The power input terminal is connected to the linear DC voltage regulator module through the voltage regulation module. One end of the input noise reduction capacitor is connected to the connection point between the input terminal of the linear DC voltage regulator module and the voltage regulation module.

[0015] Other features and advantages of this invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of this invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0016] The accompanying drawings are provided to further understand the technical solution of this utility model and constitute a part of the specification. They are used together with the embodiments of this utility model to explain the technical solution of this utility model, and do not constitute a limitation on the technical solution of this utility model.

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0018] Figure 1 This is a schematic diagram of the power conversion circuit provided in an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the specific circuit connection of the power conversion circuit provided in another embodiment of this utility model. Detailed Implementation

[0020] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0021] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," "exceeding," etc. are understood to exclude the number itself, while "above," "below," "within," etc. are understood to include the number itself. "Any one" refers to one or more, and "at least one of the following" and similar expressions refer to any combination of these items, including any combination of single or multiple items. If the terms "first" and "second" are used in the description, they are only for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0022] It should be noted that the terms "setting," "installing," and "connecting" in the embodiments of this utility model should be interpreted broadly. Those skilled in the art can reasonably determine the specific meaning of the above terms in the embodiments of this utility model in conjunction with the specific content of the technical solution. For example, the term "connection" can be a mechanical connection, an electrical connection, or a connection that allows for mutual communication; it can be a direct connection or an indirect connection through an intermediate medium.

[0023] It should be noted that the technical features involved in the various embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0024] In power supply circuits, electromagnetic interference is easily generated and difficult to avoid due to the presence of rectifier harmonics, switching frequency and its harmonics, as well as the inherent high-speed current and voltage transients during switching. This often results in ripple in the power supply output, causing the output terminal to carry glitches and noise. Especially when the power supply circuit is used to power image sensors (such as dashcams, law enforcement recorders, cameras, drones, etc.), excessive power supply ripple directly affects the imaging effect of the image sensor, causing problems such as horizontal stripes and water ripples in the generated image. Therefore, how to improve the stability and low noise of the power supply circuit for image sensors has become an urgent problem to be solved.

[0025] Based on this, this utility model proposes a power conversion circuit for an image sensor. An input noise reduction module is installed at the input end of the linear DC-DC regulator module. This module, utilizing multiple parallel-connected input noise reduction capacitors, filters out high-frequency noise from the power supply input to the linear DC-DC regulator module, smooths the voltage, reduces power ripple, and minimizes the impact of noise on the linear DC-DC regulator module. Similarly, an output noise reduction module is installed at the output end of the linear DC-DC regulator module. This module, utilizing multiple parallel-connected output noise reduction capacitors, further reduces the noise of the input power supply and the output noise of the linear DC-DC regulator module, protecting the image sensor from power fluctuations and noise interference, and providing a more stable and low-noise power output. Therefore, by designing the input noise reduction module and constructing a complete noise suppression system, not only can high-frequency noise from the input power supply be filtered out, but the output noise of the linear DC-DC regulator module can also be reduced, electromagnetic interference can be reduced, circuit stability can be improved, and the power quality requirements of the image sensor can be met.

[0026] The embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0027] Reference Figure 1The first aspect of this utility model provides a power conversion circuit for an image sensor. The power conversion circuit includes a power input terminal, a linear DC regulator module, an input noise reduction module, and an output noise reduction module. The power input terminal provides power to the linear DC regulator module, which can be a low drop-out regulator (LDO). The linear DC regulator module can ensure a stable output voltage within a certain range of input voltage and load variations, providing precise and stable power to the image sensor while reducing input power ripple. However, relying solely on the linear DC regulator module to directly power the image sensor is insufficient to meet the power requirements of an image sensor sensitive to voltage ripple. Therefore, an input noise reduction module and an output noise reduction module are respectively set at the input and output terminals of the linear DC regulator module. These modules construct a complete noise suppression system, effectively filtering out high-frequency noise from the input voltage and further reducing the output noise of the linear DC regulator module. This reduces electromagnetic interference to the image sensor, improves circuit stability, and meets the high power quality requirements of the image sensor.

[0028] It is worth noting that, such as Figure 1 As shown, the power conversion circuit applied to the image sensor also includes a voltage regulation module. The voltage regulation module can refer to a DC conversion circuit, that is, in a DC circuit, electrical energy of one voltage value is converted into electrical energy of another voltage value. The voltage regulation module has the function of step-up and step-down, converting the unstable input power supply voltage into a stable intermediate voltage. The voltage regulation module is connected to the linear DC voltage regulator module through the input noise reduction module. The noise and interference signals of the intermediate voltage output by the voltage regulation module are filtered out by the input noise reduction capacitor, reducing the noise input to the linear DC voltage regulator module, so that the linear DC voltage regulator module can provide a more accurate and stable voltage.

[0029] Specifically, the input noise reduction module is located between the power input terminal and the linear DC voltage regulator module. The input noise reduction module includes multiple input noise reduction capacitors connected in parallel. One end of each input noise reduction capacitor is connected to both the input terminal of the linear DC voltage regulator module and the power input terminal, while the other end is grounded through a ground wire. By using multiple input noise reduction capacitors to short-circuit low-frequency noise and ground high-frequency noise, the impact of noise is reduced. By connecting multiple input noise reduction capacitors in parallel, noise of different frequencies can be filtered out more effectively. At the same time, the parallel-connected input noise reduction capacitors can share the voltage of the input power supply at the power input terminal, and each input noise reduction capacitor can independently filter noise, thereby increasing the filtering capability of the input noise reduction module.

[0030] Similarly, an output noise reduction module is set between the output of the linear DC regulator module and the image sensor to further reduce the output noise of the circuit, protect the noise-sensitive image sensor, and improve stability. Specifically, the output noise reduction module includes multiple output noise reduction capacitors connected in parallel. One end of the output noise reduction capacitor is connected to the output of the linear DC regulator module, and the other end is grounded. The output noise reduction capacitor has a noise bypass function, which can guide the noise to the ground wire, thereby preventing the noise from entering the image sensor. Multiple output noise reduction capacitors connected in parallel can form a wider filtering bandwidth, effectively filtering out noise of more frequencies. At the same time, connecting multiple output noise reduction capacitors in parallel at the output of the linear DC regulator module can reduce the output impedance of the power supply, which helps to reduce the voltage fluctuations generated by the power supply when the load changes, thereby further reducing the impact of noise on the image sensor.

[0031] Since noise and interference in power supply circuits are often distributed across different frequency ranges, and because the impedance of a capacitor changes with frequency, using a capacitor of a single capacitance value may not be effective in filtering out noise at all frequencies. Therefore, the input noise reduction module and the output noise reduction module are constructed using low-impedance capacitors of different capacitance values. This allows full utilization of the filtering characteristics of capacitors of different capacitance values. Large capacitance values ​​can filter out low-frequency noise, while small capacitance values ​​can reduce high-frequency noise, thereby achieving a wider frequency band filtering effect.

[0032] Reference Figure 2 , Figure 2This is a schematic diagram of the specific circuit connection of the power conversion circuit provided in this embodiment of the utility model. It can be seen that the capacitance values ​​of the input noise reduction capacitors can be different, and the capacitance values ​​of the output noise reduction capacitors can also be different. Specifically, the capacitance values ​​of the input noise reduction capacitors may or may not correspond to the capacitance values ​​of the output noise reduction capacitors. For example, the input noise reduction module includes a 10μF capacitor and a 100nF capacitor, and the capacitance values ​​of the output noise reduction capacitors correspond accordingly, i.e., the output noise reduction module includes a 10μF capacitor and a 100nF capacitor; or the input noise reduction module adopts... A 1μF capacitor is used to filter out extremely high-frequency noise, such as radio frequency interference. Simultaneously, a 100μF capacitor is connected in parallel to filter out lower-frequency noise, such as power supply harmonics. However, the capacitance values ​​of the output noise reduction capacitors do not correspond to the linear DC regulator module. To smooth the DC voltage and reduce output ripple, the output noise reduction module can use a 10μF capacitor to further filter out any high-frequency noise that may remain at the output of the linear DC regulator module. A 1000μF capacitor is also connected in parallel as an energy storage capacitor to provide stable voltage support during load transients and reduce voltage fluctuations. Therefore, by combining capacitors of different capacitance values ​​at the input and output of the linear DC regulator module, a wider-bandwidth filter is formed, effectively filtering out noise across multiple frequency bands and improving the circuit's signal-to-noise ratio. The input noise reduction module can reduce noise in subsequent circuits, improving circuit stability and reliability, while the output noise reduction module can provide a smoother DC voltage and reduce ripple, thereby improving the power supply quality to the image sensor. It should be noted that the specific capacitance values ​​of the input and output noise reduction capacitors can be adjusted according to the frequency of the power supply.

[0033] Furthermore, the input and output noise reduction capacitors can be ordered according to their capacitance values ​​and connected sequentially to the input and output terminals of the linear DC regulator module to form a multi-stage filtering network. This minimizes power supply noise and improves circuit performance. For example, the input noise reduction module can use capacitors C1 (0.1μF), C2 (1μF), C3 (10μF), and C4 (100μF), connected in parallel at the input of the linear DC regulator module in descending order of capacitance value to form a multi-stage filtering network. Similarly, the output noise reduction module can use capacitors C5 (100nF), C6 (10μF), and C7 (100μF), connected in parallel at the output of the linear DC regulator module in ascending order of capacitance value. Small-value capacitors (such as C1, C2, and C5) have reduced impedance to high-frequency noise, effectively short-circuiting high-frequency noise to ground and reducing noise in the circuit. Larger-value capacitors (such as C3, C4, C6, and C7) can absorb low- and mid-frequency noise, thus smoothing the power supply voltage. At the same time, capacitors C4 and C7 can also act as energy storage in the circuit, providing additional charge to maintain the stability of the output voltage when the load undergoes transients, thereby enhancing the stability of the circuit.

[0034] Understandably, the distance between the input noise reduction capacitors and the linear DC regulator module increases with the capacitance value. In other words, the input noise reduction capacitors are arranged between the power input terminal and the linear DC regulator module in descending order of capacitance value; the smaller the capacitance value, the closer the capacitor is to the linear DC regulator module. Figure 2 As shown, the 10μF input noise reduction capacitor is located away from the linear DC regulator module, while the 100nF input noise reduction capacitor is closer to the input terminal of the linear DC regulator module. The 1μF input noise reduction capacitor is connected in parallel between the two output noise reduction capacitors. By first placing the large-capacity input noise reduction capacitor to filter out low-frequency noise, and then connecting the small-capacity input noise reduction capacitor in parallel to reduce high-frequency noise, the small-capacity capacitor is placed closer to the linear DC regulator module to ensure that high-frequency noise is effectively filtered out before reaching the linear DC regulator module. The large-capacity capacitor, with its better energy storage capacity, is placed closer to the power input terminal, allowing for a faster response to power supply changes and reducing voltage fluctuations.

[0035] Correspondingly, the distance between the output noise reduction capacitor and the linear DC regulator module decreases as the capacitance value increases. In other words, the output noise reduction capacitors are arranged in descending order of capacitance value between the linear DC regulator module and the image sensor, the downstream load. The capacitors with larger capacitance values ​​are closer to the output terminal of the linear DC regulator module. Figure 2As shown, the 10μF output noise reduction capacitor is closer to the output terminal of the linear DC regulator module, the 100nF output noise reduction capacitor is closer to the downstream load, and the 1μF output noise reduction capacitor is connected in parallel between the two output noise reduction capacitors. Since the input power supply of the linear DC regulator module has already undergone noise filtering by the input noise reduction module, the output noise of the linear DC regulator module is relatively low. Therefore, the large-capacity capacitor prioritizes the filtering of low-frequency noise, while utilizing its energy storage capacity to ensure sufficient current buffering during transients and maintain voltage stability. The small-capacity capacitor further filters high-frequency noise from the output power supply of the linear DC regulator module, ensuring a stable power supply for the image sensor. Additionally, to ensure effective filtering of high-frequency noise, the number of small-capacity capacitors can be increased in the noise reduction output module. It is worth noting that although capacitors generate relatively little heat during operation, in high-density circuit designs, the heat dissipation of electronic components can still affect the performance of image sensors. Placing large-value capacitors near the linear DC regulator module can utilize the heat dissipation capacity of the linear DC regulator module itself to assist in heat dissipation, while placing small-value capacitors near the load can reduce the impact of capacitor heat dissipation on the image sensor.

[0036] like Figure 2 As shown, a filter element is also provided between the output terminal of the linear DC voltage regulator module and each output noise reduction capacitor. This filter element can be an inductor, specifically the first inductor. Inductors have a large impedance to high-frequency signals, effectively suppressing high-frequency noise. Simultaneously, the first inductor, in conjunction with the output noise reduction capacitors, forms an LC filter circuit, creating a high-pass filter that filters out the high-frequency noise portion of the linear DC voltage regulator module's output. Furthermore, the first inductor also functions as an energy storage and current smoother in the circuit, reducing ripple in the power supply output. When the load current changes, the first inductor can release or absorb energy, thereby stabilizing the output voltage and reducing the ripple amplitude. Therefore, by introducing the first inductor to form an LC filter circuit, the noise and interference in the power supply output can be significantly reduced, the ripple rejection ratio improved, and the image sensor protected from noise interference, thus eliminating horizontal stripes in the image caused by excessive ripple.

[0037] Alternatively, the filtering element can be a ferrite bead filter element, that is, using a ferrite bead filter element to replace the first inductor. Since horizontal stripes in the image are easily affected by interference sources such as inductors, ferrite bead filter elements not only have high resistance and low inductance values, but also act as inductive elements in the low-frequency region, resistive elements in the mid-frequency region, and capacitive elements in the high-frequency region. Therefore, using a ferrite bead filter element in combination with an output noise reduction capacitor to form an RC filter circuit can absorb high-frequency noise and convert it into heat energy, which has better anti-radiation and anti-electromagnetic interference functions, and more effectively suppresses high-frequency horizontal stripes generated by changes in brightness in the image. Since the image is constantly changing, the frequency of horizontal stripe generation will also change accordingly. Therefore, by using output noise reduction capacitors with different capacitance values, large capacitance capacitors filter out low-frequency noise, medium capacitance capacitors filter out mid-frequency noise, and small capacitance capacitors filter out high-frequency noise, a wider frequency suppression range is formed, which can more effectively suppress the appearance of horizontal stripes.

[0038] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A power conversion circuit for use in image sensors, characterized in that, include: Power input terminal; Linear DC voltage regulator module; The input noise reduction module includes multiple input noise reduction capacitors connected in parallel. One end of each input noise reduction capacitor is connected to the input terminal of the linear DC voltage regulator module and the power input terminal, respectively, and the other end is connected to the ground wire. The output noise reduction module includes multiple output noise reduction capacitors connected in parallel. The output noise reduction capacitors are connected between the output terminal of the linear DC voltage regulator module and the ground wire, and are used to supply power to the image sensor.

2. The power conversion circuit according to claim 1, characterized in that, The capacitance values ​​of the various input noise reduction capacitors are different.

3. The power conversion circuit according to claim 2, characterized in that, All input noise reduction capacitors are connected in order of capacitance value.

4. The power conversion circuit according to claim 3, characterized in that, The distance between the input noise reduction capacitor and the linear DC voltage regulator module increases with the increase of the capacitance value.

5. The power conversion circuit according to claim 1, characterized in that, The capacitance values ​​of the various output noise reduction capacitors are different.

6. The power conversion circuit according to claim 5, characterized in that, All output noise reduction capacitors are connected in order of capacitance value.

7. The power conversion circuit according to claim 6, characterized in that, The distance between the output noise reduction capacitor and the linear DC voltage regulator module decreases as the capacitance value increases.

8. The power conversion circuit according to claim 1, characterized in that, The output noise reduction module also includes a first inductor connected between the output terminal of the linear DC voltage regulator module and the output noise reduction capacitor.

9. The power conversion circuit according to claim 1, characterized in that, The output noise reduction module also includes a magnetic bead filter element connected between the output terminal of the linear DC voltage regulator module and the output noise reduction capacitor.

10. The power conversion circuit according to claim 1, characterized in that, It also includes a voltage regulation module for regulating the voltage of the input power supply at the power input terminal. The power input terminal is connected to the linear DC voltage regulator module through the voltage regulation module. One end of the input noise reduction capacitor is connected to the connection point between the input terminal of the linear DC voltage regulator module and the voltage regulation module.

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