Infrared signal conditioning and acquisition circuit

Abstract

The application discloses an infrared signal conditioning and collecting circuit, and relates to the technical field of infrared imaging.The circuit comprises a preamplification circuit, which is used for amplifying and enhancing the driving capacity of the signal output by an infrared detector, and obtaining an amplified signal.A single-ended-to-differential circuit is used for signal conversion of the amplified signal according to the anti-interference requirement of signal transmission, and a differential signal with a matched common-mode voltage is obtained.A passive filter circuit is used for filtering processing of the differential signal with the matched common-mode voltage, and a filtered signal is obtained.A high-speed sampling circuit is used for converting the filtered signal into a digital signal, so as to meet the requirement of subsequent processing circuit for infrared gray-scale image processing, realize high-bandwidth and low-noise signal processing, meet the requirement of large-area array high-frame-frequency infrared imaging, and meet the requirement of 2K area array infrared image with a frame frequency of not less than 50Hz, and the circuit has the advantages of small volume and low noise.

Description

Technical Field

[0001] This application relates to the field of infrared imaging technology, and in particular to an infrared signal conditioning and acquisition circuit. Background Technology

[0002] Currently, in the field of infrared imaging, with the increasingly mature manufacturing processes of front-end infrared sensors and the pursuit of high-resolution infrared images, infrared imaging arrays are evolving from traditional 320×256 and 640×512 arrays to 1K or even higher resolution arrays. This places higher demands on infrared signal conditioning and acquisition circuits, as traditional conditioning and sampling circuits are insufficient to meet the requirements of current infrared imaging terminals for high-speed processing capabilities and miniaturization. Utility Model Content

[0003] This application provides an infrared signal conditioning and acquisition circuit that addresses the shortcomings of existing infrared signal conditioning and acquisition circuits that cannot meet the requirements of large-area array high frame rate infrared imaging terminals. It achieves high bandwidth and low noise signal processing to meet the needs of area array high frame rate infrared imaging.

[0004] This application provides an infrared signal conditioning and acquisition circuit, including:

[0005] It includes a preamplifier circuit, a single-ended to differential circuit, a passive filter circuit, and a high-speed sampling circuit connected in series.

[0006] The preamplifier circuit is used to receive the infrared analog signal output by the infrared detector, amplify it and enhance its driving capability to obtain an amplified signal, and send the amplified signal to the single-ended to differential circuit.

[0007] The single-ended to differential circuit is used to convert the amplified signal according to the anti-interference requirements of signal transmission to obtain a differential signal with a matching common-mode voltage, and send the differential signal with the matching common-mode voltage to the passive filter circuit.

[0008] The passive filtering circuit is used to filter the differential signal with matched common-mode voltage to obtain a filtered signal, and then send the filtered signal to the high-speed sampling circuit.

[0009] The high-speed sampling circuit is used to convert the filtered signal into a digital signal to meet the requirements of subsequent processing circuits for infrared grayscale image processing.

[0010] According to the infrared signal conditioning and acquisition circuit, the preamplifier circuit includes a rail-to-rail operational amplifier and a feedback network.

[0011] The rail-to-rail operational amplifier is used to receive the infrared analog signal output by the infrared detector and amplify it to obtain the amplified signal.

[0012] The feedback network works in conjunction with the rail-to-rail operational amplifier to stabilize the amplitude of the amplified signal and adjust the signal gain to ensure that the signal remains stable and undistorted during amplification.

[0013] According to the infrared signal conditioning and acquisition circuit, the rail-to-rail operational amplifier is an SGM80582.

[0014] According to the infrared signal conditioning and acquisition circuit, the single-ended to differential circuit includes:

[0015] Differential amplifier and resistor divider network;

[0016] The differential amplifier is used to receive the amplified signal output from the preamplifier circuit and convert it into a differential signal.

[0017] The resistor divider network is used to set the common-mode voltage of the differential signal to obtain a differential signal with a matched common-mode voltage, so as to ensure the symmetry of the differential signal and simultaneously achieve the matching of input impedance and output impedance.

[0018] According to the infrared signal conditioning and acquisition circuit, the differential amplifier is ZJA3100.

[0019] According to the infrared signal conditioning and acquisition circuit, the passive filtering circuit includes a high-pass filter and a low-pass filter. The cutoff frequency of the high-pass filter is below 1 kHz and is used to filter out DC components. The cutoff frequency of the low-pass filter is above 30 MHz and is used to filter out high-frequency noise.

[0020] According to the infrared signal conditioning and acquisition circuit, the high-speed sampling circuit includes a high-speed ADC, which has a 4-channel simultaneous sampling function and a sampling frequency of not less than 150MHz.

[0021] According to the infrared signal conditioning and acquisition circuit described above, the high-speed ADC is AD9653. This application also provides an infrared signal conditioning and acquisition circuit, including the aforementioned infrared signal conditioning and acquisition circuit.

[0022] The infrared signal conditioning and acquisition circuit and system provided by this utility model have the following advantages compared with the prior art:

[0023] This application discloses an infrared signal conditioning and acquisition circuit, relating to the field of infrared imaging technology. The circuit includes a preamplifier circuit for amplifying and enhancing the driving capability of the signal output from the infrared detector to obtain an amplified signal. A single-ended to differential converter circuit is used to convert the amplified signal according to the anti-interference requirements of signal transmission, obtaining a differential signal with a matched common-mode voltage. A passive filter circuit is used to filter the differential signal with the matched common-mode voltage to obtain a filtered signal. A high-speed sampling circuit is used to convert the filtered signal into a digital signal to meet the requirements of subsequent processing circuits for infrared grayscale image processing. This achieves high-bandwidth, low-noise signal processing, meeting the requirements of large-area array high-frame-rate infrared imaging, and can meet the frame rate of no less than 50Hz for 2K area array infrared images. It also has advantages such as small size and low noise. Attached Figure Description

[0024] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of an optional infrared signal conditioning and acquisition circuit provided in an embodiment of this application. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Currently, in the field of infrared imaging, with the increasingly mature manufacturing processes of front-end infrared sensors and the pursuit of high-resolution infrared images, infrared imaging arrays are evolving from traditional 320×256 and 640×512 arrays to 1K or even higher resolution arrays. This places higher demands on infrared signal conditioning and acquisition circuits, as traditional conditioning and sampling circuits are insufficient to meet the requirements of current infrared imaging terminals for high-speed processing capabilities and miniaturization.

[0028] This invention proposes an infrared signal conditioning and acquisition circuit, comprising a preamplifier circuit, a single-ended to differential converter circuit, a passive filter circuit, and a high-speed sampling circuit. The preamplifier circuit amplifies the signal output from the infrared detector and enhances its driving capability, improving the signal-to-noise ratio. The single-ended to differential converter circuit converts the single-ended signal into a differential signal, improving the anti-interference capability of signal transmission and enabling interface matching between the single-channel signal output from the front-end detector and the input of the subsequent high-speed sampling circuit. The passive filter circuit filters the infrared analog signal. The high-speed sampling circuit converts the analog signal into a digital signal, enabling subsequent processing circuits to perform image processing and output an infrared grayscale image. This circuit has a bandwidth of not less than 150MHz, which can meet the frame rate of not less than 50Hz for 2K area array infrared images, and also has the advantages of small size and low noise.

[0029] This application provides an infrared signal conditioning and acquisition circuit. Figure 1 This application provides a schematic diagram of an infrared signal conditioning and acquisition circuit structure, as shown in the embodiment of the present application. Figure 1 As shown, the device includes a preamplifier circuit, a single-ended to differential circuit, a passive filter circuit, and a high-speed sampling circuit connected in series.

[0030] The preamplifier circuit is used to receive the infrared analog signal output by the infrared detector, amplify it and enhance its driving capability, improve the signal-to-noise ratio, obtain the amplified signal, and send the amplified signal to the single-ended to differential circuit.

[0031] A single-ended to differential circuit is used to convert amplified signals according to the anti-interference requirements of signal transmission, to obtain differential signals with matched common-mode voltage, and then send the differential signals with matched common-mode voltage to a passive filter circuit.

[0032] A passive filter circuit is used to filter differential signals with matched common-mode voltages to obtain a filtered signal, and then send the filtered signal to a high-speed sampling circuit.

[0033] The high-speed sampling circuit is used to convert the filtered signal into a digital signal to meet the needs of subsequent processing circuits for infrared grayscale image processing.

[0034] Specifically, when the infrared radiation from an object in space is focused onto the photosensitive surface of an infrared detector by an infrared optical system, the infrared detector performs charge integration and outputs a specified infrared analog signal under bias voltage and timing control.

[0035] After receiving the infrared analog signal output by the infrared detector, the preamplifier circuit amplifies the infrared analog signal by an appropriate factor and enhances its driving capability to obtain the amplified signal, and then sends the amplified signal to the single-ended to differential circuit.

[0036] The single-ended to differential circuit converts the amplified signal according to the anti-interference requirements of signal transmission, converting the single-ended signal into a differential signal with a suitable common-mode voltage, and sends the differential signal with the matched common-mode voltage to the passive filter circuit.

[0037] After receiving a differential signal with a matched common-mode voltage, the passive filter circuit filters the differential signal with the matched common-mode voltage to obtain a filtered signal, and then sends the filtered signal to the high-speed sampling circuit.

[0038] The high-speed sampling circuit converts the filtered signal into a digital signal, realizing the analog-to-digital conversion of the infrared analog signal, and converting the analog signal into a digital signal that can be processed by the subsequent processor to meet the needs of the subsequent processing circuit for infrared grayscale image processing.

[0039] The infrared signal conditioning and acquisition circuit provided by this utility model has the advantages of high bandwidth and low noise. It can be used for infrared signal conditioning and acquisition at the front end of infrared imaging components, realizing the application of infrared imaging in large-area array high frame rate scenarios. It is of great significance for improving the environmental adaptability of infrared combat equipment.

[0040] In an optional embodiment, the preamplifier circuit in the infrared signal conditioning and acquisition circuit proposed in this embodiment of the present invention includes a rail-to-rail operational amplifier and a feedback network.

[0041] The rail-to-rail operational amplifier is used to receive the infrared analog signal output by the infrared detector and amplify it to obtain the amplified signal.

[0042] The feedback network works in conjunction with the rail-to-rail operational amplifier to stabilize the amplitude of the amplified signal and adjust the signal gain to ensure that the signal remains stable and undistorted during amplification.

[0043] Specifically, the infrared signal radiated by the target in space is focused onto the photosensitive surface of the detector by an infrared optical system. Under bias and timing control, the detector outputs an analog signal. The preamplifier circuit amplifies the original infrared analog signal output from the detector and achieves impedance matching with the subsequent stage. It then further amplifies the signal to obtain the amplified signal. Through cooperation with a feedback network, the amplitude of the amplified signal is stabilized, and the signal gain is adjusted to ensure that the signal remains stable and distortion-free during amplification, thus guaranteeing signal integrity. The key design points of the preamplifier circuit are: firstly, selecting a suitable high-bandwidth, low-offset rail-to-rail operational amplifier to ensure the integrity of the signal path; and secondly, using a suitable feedback network to achieve an appropriate amplification factor and ensure impedance matching.

[0044] Optionally, the preamplifier circuit uses the SGM80582 op-amp. This op-amp features high bandwidth and low offset voltage characteristics and can operate in a rail-to-rail range. With an appropriate feedback network, a suitable amplification factor (e.g., 2x or 4x) can be achieved while ensuring input-output impedance matching (e.g., 50Ω matching), thereby guaranteeing signal integrity and transmission efficiency.

[0045] High-bandwidth, low-offset-voltage rail-to-rail operational amplifiers ensure signal path integrity and reduce signal distortion. A suitable feedback network achieves appropriate amplification while ensuring impedance matching, thus improving signal transmission efficiency. This invention enhances the performance of the preamplifier circuit, thereby improving the signal quality and processing capabilities of the entire infrared signal conditioning and acquisition circuit.

[0046] In an optional embodiment, the single-ended to differential circuit in the infrared signal conditioning and acquisition circuit proposed in this embodiment includes:

[0047] Differential amplifier and resistor divider network;

[0048] The differential amplifier is used to receive the amplified signal output from the preamplifier circuit and convert it into a differential signal.

[0049] The resistor divider network is used to set the common-mode voltage of the differential signal to obtain a differential signal with a matched common-mode voltage, so as to ensure the symmetry of the differential signal and simultaneously achieve the matching of input impedance and output impedance.

[0050] Specifically, after being amplified by the preamplifier circuit, the signal enters the single-ended to differential converter circuit. This circuit converts the single-ended voltage signal from the infrared detector into a differential voltage signal to enhance signal anti-interference capability and ensure the symmetry of the differential signal. A resistor divider network is used to set the common-mode voltage of the differential signal, achieving impedance matching and optimal performance between the input and output. When designing a single-ended differential circuit, attention must be paid to impedance matching and common-mode voltage setting to ensure that the converted differential voltage signal is not distorted.

[0051] Optionally, the single-ended to differential circuit uses the ZJA3100 differential amplifier. Impedance matching can be achieved during design by precisely calculating and selecting appropriate resistor values ​​(e.g., 50Ω input impedance, 100Ω differential output impedance). The common-mode voltage can be set at an appropriate level using a resistor divider network (e.g., ±1V range with 1.65V as the center point). The ZJA3100 features high gain and bandwidth characteristics, capable of handling signals up to hundreds of MHz, meeting the demands of high-speed signal processing.

[0052] Proper impedance matching reduces signal reflection and improves signal transmission efficiency. Appropriate common-mode voltage settings ensure the symmetry of differential signals and improve signal quality. High-gain, high-bandwidth differential amplifiers can handle signals over a wider frequency range, increasing the overall bandwidth of the circuit. This invention improves the performance of the single-ended to differential circuit, thereby enhancing the signal quality and anti-interference capability of the entire infrared signal conditioning and acquisition circuit.

[0053] In an optional embodiment, the passive filtering circuit in the infrared signal conditioning and acquisition circuit proposed in this embodiment includes a high-pass filter and a low-pass filter. The cutoff frequency of the high-pass filter is below 1 kHz and is used to filter out DC components; the cutoff frequency of the low-pass filter is above 30 MHz and is used to filter out high-frequency noise.

[0054] Passive filters can be constructed using resistors and capacitors. For example, a low-pass filter can be constructed using a 1kΩ resistor and a 160nF capacitor, forming an RC low-pass filter circuit with a cutoff frequency of approximately 1kHz. A high-pass filter can be constructed using a 5.3Ω resistor and a 1nF capacitor, forming an RC high-pass filter circuit with a cutoff frequency of approximately 30MHz. Such designs can effectively filter out DC components and high-frequency noise while preserving the desired signal frequency range.

[0055] Low-pass filters can effectively remove the dark current of the detector and the DC component generated by the offset voltage of the preamplifier single-channel and differential circuit devices, improving signal purity. High-pass filters can remove high-frequency noise generated by the circuit itself, further improving signal quality. This invention, by reasonably setting the cutoff frequency, can remove interference to the greatest extent while retaining the useful signal, thereby improving the signal-to-noise ratio of the entire system.

[0056] In an optional embodiment, the high-speed sampling circuit in the infrared signal conditioning and acquisition circuit proposed in this embodiment includes a high-speed ADC, which has a 4-channel simultaneous sampling function and a sampling frequency of not less than 150MHz.

[0057] The high-speed sampling circuit can utilize the AD9653 high-speed ADC. The AD9653 is a 14-bit, 4-channel, 250MSPS analog-to-digital converter. Its 14-bit high resolution provides 16384 quantization levels, ensuring fine signal sampling. The four channels can simultaneously sample four independent signals, significantly improving the system's parallel processing capabilities. The 250MSPS sampling rate far exceeds the minimum requirement of 150MHz, meeting the requirement of a minimum 50Hz frame rate for 2K area array infrared images, and even providing margin for higher frame rates. The subsequent processor processes the digital signal output from the ADC, ultimately outputting an infrared grayscale image.

[0058] A resolution of 14 bits or higher can provide finer signal quantization, improving the accuracy of digital signals. Simultaneous 4-channel sampling allows for the processing of multiple signals at the same time, enhancing the system's parallel processing capabilities. A sampling frequency of at least 150MHz ensures the system can process high-frequency signals, meeting the requirements of large-area, high-frame-rate infrared imaging. This invention improves the performance of the high-speed sampling circuit, thereby enhancing the data acquisition capability and accuracy of the entire infrared signal conditioning and acquisition circuit.

[0059] In summary, the infrared signal conditioning and acquisition circuit proposed in this utility model has a bandwidth of not less than 150MHz, which can meet the frame rate of not less than 50Hz for 2K area array infrared images, and also has the advantages of small size and low noise.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] Furthermore, the terms "first," "second," etc., used in the embodiments of this utility model are for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of technical features indicated in this embodiment. Therefore, features defined with terms such as "first" and "second" in the embodiments of this utility model can explicitly or implicitly indicate that the embodiment includes at least one of those features. In the description of this utility model, the word "multiple" means at least two or more, such as two, three, four, etc., unless otherwise explicitly specified in the embodiments.

[0062] In this utility model, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing" appearing in the embodiments should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two components, or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific implementation.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An infrared signal conditioning and acquisition circuit, characterized in that, include: It includes a preamplifier circuit, a single-ended to differential circuit, a passive filter circuit, and a high-speed sampling circuit connected in series. The preamplifier circuit receives the infrared analog signal output from the infrared detector, amplifies it, and enhances its driving capability to obtain an amplified signal. The amplified signal is then sent to the single-ended to differential circuit. The preamplifier circuit includes a rail-to-rail operational amplifier and a feedback network. The rail-to-rail operational amplifier receives the infrared analog signal output from the infrared detector and amplifies it to obtain an amplified signal. The feedback network works in conjunction with the rail-to-rail operational amplifier to stabilize the amplitude of the amplified signal and adjust the signal gain to ensure that the signal remains stable and undistorted during amplification. The single-ended to differential circuit is used to convert the amplified signal according to the anti-interference requirements of signal transmission to obtain a differential signal with a matching common-mode voltage, and send the differential signal with the matching common-mode voltage to the passive filter circuit. The single-ended to differential circuit includes a differential amplifier and a resistor divider network. The differential amplifier is used to receive the amplified signal output from the preamplifier circuit and convert it into a differential signal. The resistor divider network is used to set the common-mode voltage of the differential signal to obtain a differential signal with a matched common-mode voltage, so as to ensure the symmetry of the differential signal and simultaneously achieve the matching of input impedance and output impedance. The passive filtering circuit is used to filter the differential signal with matched common-mode voltage to obtain a filtered signal, and then send the filtered signal to the high-speed sampling circuit. The high-speed sampling circuit is used to convert the filtered signal into a digital signal to meet the requirements of subsequent processing circuits for infrared grayscale image processing; the high-speed sampling circuit includes a high-speed ADC, which has a 4-channel simultaneous sampling function and a sampling frequency of not less than 150MHz.

2. The infrared signal conditioning and acquisition circuit according to claim 1, characterized in that, The rail-to-rail operational amplifier is an SGM80582.

3. The infrared signal conditioning and acquisition circuit according to claim 1, characterized in that, The differential amplifier is ZJA3100.

4. The infrared signal conditioning and acquisition circuit according to claim 1, characterized in that, The passive filter circuit includes a high-pass filter and a low-pass filter. The cutoff frequency of the high-pass filter is below 1 kHz and is used to filter out DC components. The cutoff frequency of the low-pass filter is above 30 MHz and is used to filter out high-frequency noise.

5. The infrared signal conditioning and acquisition circuit according to claim 1, characterized in that, The high-speed ADC is AD9653.

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