System and method for testing analog-to-digital conversion circuit of infrared detector

Abstract

The invention provides a test system and method for an analog-to-digital conversion circuit of an infrared detector, and the system comprises a signal generation module which is used for outputting an analog signal according to the parameters of the infrared detector and the tested analog-to-digital conversion circuit; the signal injection module is used for synchronously injecting analog signals into a plurality of analog input channels of the analog-to-digital conversion circuit; the analog-to-digital conversion circuit performs analog-to-digital conversion and data processing on the analog signal and then outputs video data; and the analysis module is used for analyzing the video data to obtain a test result of the analog-to-digital conversion circuit. According to the invention, the performance test efficiency of the analog-to-digital conversion circuit is effectively improved, and the test cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of circuit testing technology, specifically relating to a testing system and method for an infrared detector analog-to-digital conversion circuit. Background Technology

[0002] Currently, cooled infrared detectors primarily output analog signals. Users need to design dedicated analog-to-digital converter (AD) circuits to match the analog signal from the infrared detector to the AD analog input via operational amplifier circuits, thereby converting it into an equivalent digital signal for FPGA image processing. The design of analog circuits presents challenges such as dynamic range matching issues and the introduction of interference and noise. These problems severely impact the imaging performance of the infrared detector, as well as performance metrics like NETD (Net-Temperature Difference) and MRTD (Minimum Resolvable Temperature Difference). Typical debugging requires connecting the infrared detector for testing and adjustments; however, infrared detectors are expensive and have a short lifespan, significantly increasing debugging costs and time. Summary of the Invention

[0003] The purpose of this invention is to provide a testing system and method for an infrared detector analog-to-digital conversion circuit, which can achieve the testing of the analog-to-digital conversion circuit without using an infrared detector.

[0004] To address the aforementioned technical problems, this invention provides a testing system for an infrared detector analog-to-digital conversion circuit, comprising: The signal generation module is used to output analog signals based on the parameters of the infrared detector and the analog-to-digital converter circuit under test. The signal injection module is used to synchronously inject analog signals into multiple analog input channels of the analog-to-digital converter circuit; the analog-to-digital converter circuit performs analog-to-digital conversion and data processing on the analog signals and then outputs video data. The analysis module is used to analyze video data and obtain test results of the analog-to-digital conversion circuit.

[0005] According to the above scheme, the analog signal is a triangular wave signal. The analysis module draws a grayscale distribution curve based on the video data. The test results are obtained by comparing the grayscale distribution curve with the waveform image of the triangular wave signal. Alternatively, the analog signal is a DC level signal, and the analysis module obtains the equivalent noise temperature difference of the analog-to-digital conversion circuit based on the video data.

[0006] According to the above scheme, the upper and lower limits of the amplitude and the frequency of the triangular wave signal are determined based on the low-level voltage and high-level voltage of the infrared detector.

[0007] According to the above scheme, the DC level signal includes two DC levels with different voltages within a set voltage range.

[0008] According to the above scheme, the two DC levels with different voltages in the DC level signal correspond to the quarter-well and three-quarter-well of the infrared detector, respectively.

[0009] According to the above scheme, the signal injection module is a one-to-many cable.

[0010] According to the above scheme, for a certain analog input channel, if the two extreme values ​​of the grayscale distribution curve cannot completely cover the image dynamic range of the infrared detector, or if the grayscale distribution curve is inconsistent with the waveform of the triangular wave signal, then the analog input channel is determined to be abnormal.

[0011] According to the above scheme, when the equivalent noise temperature difference corresponding to a certain analog input channel is greater than a set threshold, the analog input channel is determined to be abnormal.

[0012] This invention also provides a test method for an infrared detector analog-to-digital conversion circuit, comprising: S1. Input the parameters of the infrared detector and the analog-to-digital converter circuit under test into the signal generation module to obtain the analog signal; S2. Simultaneously inject the analog signal into multiple analog input channels of the analog-to-digital converter circuit to obtain the video data output by the analog-to-digital converter circuit; the analog-to-digital converter circuit performs analog-to-digital conversion and data processing on the analog signal and then outputs the video data. S3. Input the video data into the analysis module for analysis to obtain the test results of the analog-to-digital conversion circuit.

[0013] According to the above scheme, the analog signal is a triangular wave signal. The analysis module draws a grayscale distribution curve based on the video data. The test results are obtained by comparing the grayscale distribution curve with the waveform image of the triangular wave signal. Alternatively, the analog signal is a DC level signal, and the analysis module obtains the equivalent noise temperature difference of the analog-to-digital conversion circuit based on the video data.

[0014] Beneficial effects This invention, by incorporating a signal generation module, can accurately output analog signals based on the parameters of the infrared detector and the analog-to-digital converter circuit under test. This eliminates the need for expensive and short-lived infrared detectors, effectively avoiding the high costs associated with their use and preventing the impact of detector wear on testing. The signal injection module can simultaneously inject analog signals into multiple analog input channels of the analog-to-digital converter circuit, enabling synchronous testing across multiple channels.

[0015] Furthermore, by setting the analog signal to a triangular wave or a DC level signal, a more targeted testing method is provided for the analog-to-digital converter (ADC) circuit. When the analog signal is a triangular wave, the analysis module plots a grayscale distribution curve based on the video data. By comparing this curve with the waveform image of the triangular wave, the response of the ADC circuit to dynamic signals and its conversion accuracy can be intuitively and accurately determined. This clearly identifies potential issues such as waveform distortion and dynamic range mismatch during signal transmission and conversion. When the analog signal is a DC level signal, the analysis module uses the video data to obtain the equivalent noise temperature difference of the ADC circuit, effectively quantifying the noise interference level of the circuit and accurately reflecting its stability and anti-interference capability during static signal processing. The two analog signal settings and corresponding analysis methods complement each other, allowing the test to comprehensively cover the core performance indicators of the ADC circuit from the two key dimensions of dynamic response and static noise. This significantly improves the comprehensiveness and reliability of the test, providing accurate and valuable reference for circuit optimization and improvement, and further ensuring the imaging effect and overall performance of the ADC circuit when applied to infrared detection systems. Attached Figure Description

[0016] Figure 1 This is a flowchart of a test method for an infrared detector analog-to-digital conversion circuit according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a triangular wave waveform according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the analog signal flow according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the data interaction between the AD and FPGA according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the clock and data of the AD and FPGA according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a frame of video data according to an embodiment of the present invention; Figure 7 This is an embodiment of the present invention. Figure 6 A schematic diagram of the corresponding grayscale distribution curve. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0018] This embodiment provides a test system for an infrared detector analog-to-digital conversion circuit, including: The signal generation module is used to output analog signals based on the parameters of the infrared detector and the analog-to-digital converter circuit under test. The signal injection module is used to synchronously inject analog signals into multiple analog input channels of the analog-to-digital converter circuit; the analog-to-digital converter circuit performs analog-to-digital conversion and data processing on the analog signals and then outputs video data. The analysis module is used to analyze video data and obtain test results of the analog-to-digital conversion circuit.

[0019] Specifically, see Figure 3 In this embodiment, the analog-to-digital converter circuit under test includes a differential operational amplifier circuit, an analog-to-digital converter (AD), and an FPGA connected in sequence. The differential operational amplifier circuit includes differential operational amplifiers with the same number of analog input channels as the AD. After an analog signal is input to the differential operational amplifier, it is output from the differential operational amplifier to one analog input channel of the AD, then input from the AD to the FPGA, and finally input from the FPGA to the analysis module.

[0020] In this embodiment, the AD model is SAD6445MC, which supports 4 analog channels, each channel having a 14-bit digitization level; the FPGA model is XC7K325T, the DDR3 capacity is 2 MT41J256M16 chips, and the FLASH model is MT25QL01G.

[0021] See Figure 4 , Figure 5 The analog-to-digital conversion and data processing processes of AD and FPGA specifically include: 1) The AD is configured in a mode (AD mode is configured via SPI), which converts the input analog signal into serial data (digital signal) and outputs a differential synchronous clock (7 times the clock frequency) based on the external input AD differential sampling clock.

[0022] 2) The FPGA generates a 14x frequency AD sampling clock based on the differential synchronization clock, acquires 4 channels of differential data, and latches 14 bits of parallel data through the differential synchronization clock.

[0023] 3) Parallel data from the 4 channels is written to the FIFO buffer at a 14x frequency AD sampling clock. The FPGA generates a 4x frequency AD sampling clock and reads the FIFO data in a fixed order to complete the sorting of the 4 channels.

[0024] 4) Generate video data streams and line and field signals based on the sorted data, and package them into Cameralink video (i.e., video data) and send them to the analysis module.

[0025] In this embodiment, the main clock frequency MC of the infrared detector is 9MHz (i.e., the AD differential sampling clock), the resolution is 640*512, each analog signal is digitally quantized to 14 bits, and the serial data clock frequency is expressed as follows:

[0026] The clock frequency for 4-channel parallel data is expressed as:

[0027] The line frequency of an image is represented as:

[0028] Since the signal generation module injects two triangular waves into each line of the image, the frequency of the signal generator is 112.5 kHz. See the triangular wave waveform below. Figure 2 .

[0029] Furthermore, the analog signal is a triangular wave signal. The analysis module plots a grayscale distribution curve based on the video data (plotting a grayscale distribution curve based on each line of video data in the image). The test results are obtained by comparing the grayscale distribution curve with the waveform image of the triangular wave signal. Alternatively, the analog signal is a DC level signal, and the analysis module obtains the equivalent noise temperature difference of the analog-to-digital conversion circuit based on the video data.

[0030] Specifically, see Figure 6 , Figure 7 The analysis module calculates the dynamic range of the triangular wave input from each analog input channel. The dynamic range of the 14-bit image is [0-16383]. The minimum and maximum values ​​in the image are counted. If both maximum and minimum values ​​completely cover [0-16383], it indicates that the high and low levels of the signal generator accurately map to the entire dynamic range of the 14-bit image. The input triangular wave waveform and grayscale distribution curve of each analog channel are compared sequentially. The two waveforms should be approximately identical. If the grayscale distribution curve of a certain analog input channel is abnormal, it indicates that the analog channel is abnormal.

[0031] Furthermore, the upper and lower limits of the amplitude and the frequency of the triangular wave signal are determined based on the low-level voltage and high-level voltage of the infrared detector.

[0032] Furthermore, the DC level signal includes two different DC levels within a set voltage range.

[0033] Specifically, the DC voltage value is determined according to the user manual of the infrared detector.

[0034] In this embodiment, the low-level voltage of the infrared detector to be simulated is vl=1.35V, and the high-level voltage is vh=3V. Therefore, the amplitude of the triangular wave signal is expressed as follows:

[0035] The DC bias of a triangular wave is expressed as:

[0036] Furthermore, the two different DC levels in the DC level signal correspond to the quarter-well and three-quarter-well of the infrared detector, respectively.

[0037] Specifically, the voltage values ​​of the two DC levels are expressed as follows:

[0038]

[0039] The host computer calculates the NETD value of the DC level according to the GB17444-2013 Infrared Focal Plane Array Parameter Test Method. This parameter characterizes the noise fluctuation of the analog circuit; the smaller the value, the lower the analog noise of the circuit itself. The NETD values ​​of the four channels are measured separately. If the NETD of a certain channel is significantly larger, it indicates that the analog channel is abnormal.

[0040] Furthermore, the signal injection module is a one-to-many cable.

[0041] Specifically, in this embodiment, the signal injection module is a 1-to-4 cable, which corresponds to the four analog input channels of the AD converter.

[0042] Furthermore, for a certain analog input channel, if the two extreme values ​​of the grayscale distribution curve cannot completely cover the image dynamic range of the infrared detector, or if the grayscale distribution curve is inconsistent with the waveform of the triangular wave signal, then the analog input channel is determined to be abnormal.

[0043] Furthermore, when the equivalent noise temperature difference corresponding to a certain analog input channel is greater than a set threshold, the analog input channel is determined to be abnormal.

[0044] See Figure 1 This embodiment also provides a test method for an infrared detector analog-to-digital conversion circuit, including: S1. Input the parameters of the infrared detector and the analog-to-digital converter circuit under test into the signal generation module to obtain the analog signal; S2. Simultaneously inject the analog signal into multiple analog input channels of the analog-to-digital converter circuit to obtain the video data output by the analog-to-digital converter circuit; the analog-to-digital converter circuit performs analog-to-digital conversion and data processing on the analog signal and then outputs the video data. S3. Input the video data into the analysis module for analysis to obtain the test results of the analog-to-digital conversion circuit.

[0045] Furthermore, the analog signal is a triangular wave signal. The analysis module plots a grayscale distribution curve based on the video data, and obtains the test results by comparing the grayscale distribution curve with the waveform image of the triangular wave signal. Alternatively, the analog signal is a DC level signal, and the analysis module obtains the equivalent noise temperature difference of the analog-to-digital conversion circuit based on the video data.

[0046] The method of this invention has been verified in engineering, and quantitative tests are performed on the dynamic range and noise of analog circuits. This technology can effectively improve circuit debugging efficiency, reduce debugging costs, and realize independent verification at the analog circuit board level.

[0047] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.

[0048] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A test system for an infrared detector analog-to-digital conversion circuit, characterized in that, include: The signal generation module is used to output analog signals based on the parameters of the infrared detector and the analog-to-digital converter circuit under test. The signal injection module is used to synchronously inject analog signals into multiple analog input channels of the analog-to-digital converter circuit; the analog-to-digital converter circuit performs analog-to-digital conversion and data processing on the analog signals and then outputs video data. The analysis module is used to analyze video data and obtain test results of the analog-to-digital conversion circuit.

2. The test system for the infrared detector analog-to-digital conversion circuit according to claim 1, characterized in that, The analog signal is a triangular wave signal. The analysis module plots a grayscale distribution curve based on the video data. The test results are obtained by comparing the grayscale distribution curve with the waveform image of the triangular wave signal. Alternatively, the analog signal is a DC level signal, and the analysis module obtains the equivalent noise temperature difference of the analog-to-digital conversion circuit based on the video data.

3. The test system for the infrared detector analog-to-digital conversion circuit according to claim 2, characterized in that, The amplitude upper and lower limits and frequency of the triangular wave signal are determined based on the low-level voltage and high-level voltage of the infrared detector.

4. The test system for the infrared detector analog-to-digital conversion circuit according to claim 2, characterized in that, A DC level signal includes two different DC levels within a set voltage range.

5. The test system for the infrared detector analog-to-digital conversion circuit according to claim 4, characterized in that, In the DC level signal, the two different DC levels correspond to the quarter-well and three-quarter-well of the infrared detector, respectively.

6. The test system for the infrared detector analog-to-digital conversion circuit according to claim 4, characterized in that, The signal injection module is a one-to-many cable.

7. The test system for the infrared detector analog-to-digital conversion circuit according to claim 2, characterized in that, If the two extreme values ​​of the grayscale distribution curve corresponding to a certain analog input channel cannot completely cover the image dynamic range of the infrared detector, or if the grayscale distribution curve is inconsistent with the waveform of the triangular wave signal, then the analog input channel is determined to be abnormal.

8. The test system for the infrared detector analog-to-digital conversion circuit according to claim 2, characterized in that, When the equivalent noise temperature difference corresponding to a certain analog input channel is greater than a set threshold, the analog input channel is determined to be abnormal.

9. A test method for an infrared detector analog-to-digital conversion circuit, characterized in that, include: S1. Input the parameters of the infrared detector and the analog-to-digital converter circuit under test into the signal generation module to obtain the analog signal; S2. Simultaneously inject analog signals into multiple analog input channels of the analog-to-digital converter circuit to obtain the video data output by the analog-to-digital converter circuit; The analog-to-digital converter circuit performs analog-to-digital conversion and data processing on the analog signal before outputting video data; S3. Input the video data into the analysis module for analysis to obtain the test results of the analog-to-digital conversion circuit.

10. The test method for the infrared detector analog-to-digital conversion circuit according to claim 9, characterized in that, The analog signal is a triangular wave signal. The analysis module plots a grayscale distribution curve based on the video data. The test results are obtained by comparing the grayscale distribution curve with the waveform image of the triangular wave signal. Alternatively, the analog signal is a DC level signal, and the analysis module obtains the equivalent noise temperature difference of the analog-to-digital conversion circuit based on the video data.

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