阅读说明：本技术 一种红外模拟信号调理采集电路 (Infrared analog signal conditioning and collecting circuit ) 是由 祁海军 吴鹤 魏洪苗 赵金博 于 2021-08-11 设计创作，主要内容包括：本申请涉及一种红外模拟信号调理采集电路,其属于微弱信号采集技术领域,包括电源模块、数字处理模块和低噪声电路处理模块；电源模块用于提供电压；低噪声电路处理模块连接数字处理模块,用于输出稳定基准电压和降低电路噪声；低噪声电路处理模块包括基准电压单元、滤波单元和负反馈单元；基准电压单元用于输出稳定基准电压,滤波单元连接基准电压单元；负反馈单元连接滤波单元,用于降低电路噪声并增大电路驱动能力。本申请具有提高了采集信号过程中的降噪效果的效果。(The application relates to an infrared analog signal conditioning and collecting circuit, which belongs to the technical field of weak signal collection and comprises a power module, a digital processing module and a low-noise circuit processing module; the power supply module is used for supplying voltage; the low-noise circuit processing module is connected with the digital processing module and used for outputting stable reference voltage and reducing circuit noise; the low-noise circuit processing module comprises a reference voltage unit, a filtering unit and a negative feedback unit; the reference voltage unit is used for outputting stable reference voltage, and the filtering unit is connected with the reference voltage unit; the negative feedback unit is connected with the filtering unit and used for reducing circuit noise and increasing circuit driving capacity. The method and the device have the effect of improving the noise reduction effect in the signal acquisition process.)

1. The utility model provides an infrared analog signal conditioning acquisition circuit, is applied to infrared detector which characterized in that: the device comprises a power supply module (3), a digital processing module (4) and a low-noise circuit processing module (1);

the power supply module (3) is used for providing voltage;

the low-noise circuit processing module (1) is connected with the digital processing module (4) and is used for outputting stable reference voltage and reducing circuit noise;

the low-noise circuit processing module (1) comprises a reference voltage unit (11), a filtering unit (12) and a negative feedback unit (13);

the reference voltage unit (11) is used for outputting a stable reference voltage, and the filtering unit (12) is connected with the reference voltage unit (11);

the negative feedback unit (13) is connected with the filtering unit (12) and is used for reducing circuit noise and increasing circuit driving capacity.

2. The infrared analog signal conditioning and collecting circuit of claim 1, wherein: and a resistor for voltage division is also connected in series between the reference voltage unit (11) and the filter unit (12).

3. The infrared analog signal conditioning and collecting circuit of claim 2, wherein: the filtering unit (12) comprises an RC low-pass filter (121).

4. The infrared analog signal conditioning and collecting circuit of claim 2, wherein: the reference voltage unit (11) comprises an ADR4540 chip.

5. The infrared analog signal conditioning and collecting circuit of claim 3, wherein: the negative feedback unit (13) includes a non-inverting amplifier (131).

6. The infrared analog signal conditioning and collecting circuit of claim 5, wherein: further comprising a conversion unit (14); the conversion unit (14) is connected with the reference voltage unit (11).

7. The infrared analog signal conditioning and collecting circuit of claim 6, wherein: the conversion unit (14) comprises an LTC2263-14 chip.

8. The infrared analog signal conditioning and collecting circuit of claim 1, wherein: the detector also comprises a signal acquisition and conditioning module (2), wherein the signal acquisition and conditioning module (2) is used for providing bias voltage for the detector; the signal acquisition conditioning module (2) is connected with the digital processing module (4);

the signal acquisition conditioning module (2) comprises a digital-to-analog conversion unit (21) and an operational amplifier unit (22); one end of the operational amplifier unit (22) is connected with the detector and receives an original analog signal which is sent by the detector and can be amplified or attenuated; the digital-to-analog conversion unit (21) is connected to the other end of the operational amplifier unit (22) and is used for conditioning an original analog signal.

9. The infrared analog signal conditioning and collecting circuit of claim 1, wherein: the power module (3) comprises a reverse connection protection unit (31), an overvoltage and overcurrent protection unit (32), a filtering and noise reduction unit (33), a surge suppression unit (34) and an isolation unit (35);

the overvoltage and overcurrent protection unit (32) is connected with a reverse connection protection unit (31), and the reverse connection protection unit (31) and the overvoltage and overcurrent unit are used for protecting the power module (3);

the filtering and noise reducing unit (33) is connected with the overvoltage and overcurrent protection unit (32), the surge suppression unit (34) is connected with the filtering and noise reducing unit (33), and the isolation unit (35) is connected with the surge suppression unit (34).

10. The infrared analog signal conditioning and collecting circuit of claim 1, wherein: the zoom lens further comprises a motor control module (5), and the motor control module (5) is used for controlling a motor on the lens of the detector to achieve continuous zooming.

Technical Field

The application relates to the technical field of weak signal acquisition, in particular to an infrared analog signal conditioning and acquiring circuit.

Background

The infrared detector is a device for converting an incident infrared radiation signal into an electric signal and outputting the electric signal; infrared radiation is electromagnetic waves with a wavelength between visible light and microwaves, and cannot be detected by human eyes; therefore, the signals output by the infrared detector need to be collected and processed by the collecting circuit.

At present, a high-speed large-dynamic-range infrared analog signal acquisition circuit with publication number CN107870593A may be referred to as an acquisition circuit in the related art, which refers to a high-speed large-dynamic-range infrared analog signal acquisition circuit including a signal conditioning circuit, a filter network, and a digital-to-analog conversion circuit; the signal conditioning circuit comprises an operational amplifier, a relevant chip, a plurality of resistors and a plurality of capacitors; the filter network comprises a plurality of resistors and capacitors; the digital-to-analog conversion circuit comprises a relevant chip, a plurality of bias capacitors and a plurality of resistors, and the acquisition and processing of signals output by the infrared detector are realized through the circuit, so that noise introduced in the signal acquisition process is reduced.

With respect to the related art in the above, the inventors found that: the noise reduction effect is poor in the process of using the acquisition circuit to acquire signals.

Disclosure of Invention

In order to improve the noise reduction effect of the signal acquisition process, the application provides an infrared analog signal conditioning and acquisition circuit.

The application provides an infrared analog signal conditioning acquisition circuit adopts following technical scheme:

an infrared analog signal conditioning and collecting circuit comprises a power supply module, a digital processing module and a low-noise circuit processing module;

the power supply module is used for providing voltage;

the low-noise circuit processing module is connected with the digital processing module and is used for outputting stable reference voltage and reducing circuit noise;

the low-noise circuit processing module comprises a reference voltage unit, a filtering unit and a negative feedback unit;

the reference voltage unit is used for outputting stable reference voltage, and the filtering unit is connected with the reference voltage unit;

the negative feedback unit is connected with the filtering unit and used for reducing circuit noise and increasing circuit driving capacity.

Through adopting above-mentioned technical scheme, circuit structure is simple on the one hand, and is compared in the complicated circuit among the correlation technique, and the cost is reduced has reduced circuit structure, and on the other hand passes through the cooperation between filtering unit and the negative feedback unit, has reduced the circuit noise, has improved the noise reduction effect of gathering the signal in-process.

The present application may be further configured in a preferred example to: and a resistor for voltage division is also connected in series between the reference voltage unit and the filtering unit.

The present application may be further configured in a preferred example to: the filtering unit includes an RC low pass filter.

The present application may be further configured in a preferred example to: the reference voltage unit comprises an ADR4540 chip.

The present application may be further configured in a preferred example to: the negative feedback unit includes a non-inverting amplifier.

The present application may be further configured in a preferred example to: the device also comprises a conversion unit; the conversion unit is connected with the reference voltage unit.

The present application may be further configured in a preferred example to: the conversion unit comprises an LTC2263-14 chip.

The present application may be further configured in a preferred example to: the device also comprises a signal acquisition and conditioning module, wherein the signal acquisition and conditioning module is used for providing bias voltage for the detector; the signal acquisition conditioning module is connected with the digital processing module;

the signal acquisition conditioning module comprises a digital-to-analog conversion unit and an operational amplifier unit; one end of the operational amplifier unit is connected with the detector and receives an original analog signal which is sent by the detector and can be amplified or attenuated; the digital-to-analog conversion unit is connected to the other end of the operational amplifier unit and is used for conditioning an original analog signal.

The present application may be further configured in a preferred example to: the power module comprises a reverse connection protection unit, an overvoltage and overcurrent protection unit, a filtering and noise reduction unit, a surge suppression unit and an isolation unit;

the overvoltage and overcurrent protection unit is connected with the reverse connection protection unit, and the reverse connection protection unit and the overvoltage and overcurrent unit are used for protecting the power supply module;

the filtering and noise reducing unit is connected with the overvoltage and overcurrent protection unit, the surge suppression unit is connected with the filtering and noise reducing unit, and the isolation unit is connected with the surge suppression unit.

The present application may be further configured in a preferred example to: the zoom lens further comprises a motor control module which is used for controlling a motor on the lens of the detector to achieve continuous zooming.

In summary, the present application includes at least one of the following beneficial technical effects:

compared with the circuits in the related technology, the circuit in the application has the advantages that the structure is simple, the use cost is reduced by using the circuit in the application, and meanwhile, the maintenance cost of the circuit is reduced; compared with the circuit in the related technology, the circuit in the application reduces more noise influence and improves the noise reduction effect in the signal conversion process.

Drawings

Fig. 1 is a schematic diagram of an overall system structure of an infrared analog signal conditioning and collecting circuit in an embodiment of the present application.

Fig. 2 is a block diagram of a power module in an infrared analog signal conditioning and collecting circuit in an embodiment of the present application.

Fig. 3 is a schematic circuit structure diagram of a low-noise circuit processing module in an infrared analog signal conditioning and collecting circuit according to an embodiment of the present application.

Fig. 4 is a block diagram of a signal acquisition and conditioning module in an infrared analog signal conditioning and acquisition circuit according to an embodiment of the present application.

Description of reference numerals: 1. a low noise circuit processing module; 11. a reference voltage unit; 12. a filtering unit; 121. an RC low-pass filter; 13. a negative feedback unit; 131. a non-inverting amplifier; 14. a conversion unit; 2. a signal acquisition and conditioning module; 21. a digital-to-analog conversion unit; 22. an operational amplifier unit; 3. a power supply module; 31. a reverse connection protection unit; 32. an overvoltage and overcurrent protection unit; 33. a filtering and noise reducing unit; 34. a surge suppression unit; 35. an isolation unit; 4. a digital processing module; 5. and a motor control module.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The embodiments of the present application will be described in further detail with reference to the drawings attached to the specification.

The medium-wave infrared 640X512 HgCdTe detector is mainly used for realizing conversion of target infrared signals and electric signals and comprises an HgCdTe array detector chip, a CMOS read-out circuit chip, a metal Dewar and a Stirling refrigerator.

The center spacing of the detector pixels is 15 mu m, the corresponding wave band is 3.7-4.8 mu m, a Focal Plane Array (FPA) consists of 512 rows by 640 columns of pixels, and the center spacing of the transverse and longitudinal pixels is 15 mu m; the detector can realize imaging of the following modes: windowing in the range of 640 × 512, 640 × 480, 512 × 512, and 640 × 512.

The detector is also provided with different reading modes, and the reading modes can select reading after integration or reading at the same time of integration.

In addition, the detector also has the functions of programmable integration time, window mode, horizontal and vertical turnover imaging and the like, and a user can select different working modes according to application requirements.

The detector adopts a SHARAN 6 of Xilinx as a main processing chip, and can complete the functions of 50HZ imaging frame frequency, non-uniform correction, image enhancement and the like.

The embodiment of the application discloses an infrared analog signal conditioning and collecting circuit. Referring to fig. 1, an infrared analog signal conditioning and collecting circuit comprises a power module 3, a digital processing module 4, a low-noise circuit processing module 1, a signal collecting and conditioning module 2 and a motor control module 5; the power supply module 3 is used for supplying voltage; the digital processing module 4 is connected with the power supply module 3; the low-noise circuit processing module 1 is connected with the digital processing module 4 and is used for acquiring and conditioning analog signals output by the detector; the signal acquisition conditioning module 2 is connected with the digital processing module 4 and is used for providing bias voltage for the detector; the motor control module 5 is connected with the digital processing module 4 and is used for controlling a motor on a lens of the detector to realize continuous zooming; through the cooperation between the above-mentioned modules, the noise reduction effect in the signal acquisition process has been improved.

Referring to fig. 2, the power module 3 is used to provide a stable reference voltage, and in order to meet the application of different systems, the power is designed to be input in a wide range of 18V-36V, and needs to meet the functions of electric switch control, reverse connection protection, overvoltage and overcurrent protection, surge suppression, etc.; therefore, the power module 3 in the embodiment of the present application includes a reverse connection protection unit 31, an overvoltage and overcurrent protection unit 32, a filtering and noise reduction unit 33, a surge suppression unit 34 and an isolation unit 35, where the reverse connection protection unit 31 is connected to an electric switch control unit, the overvoltage and overcurrent protection unit 32 is connected to the reverse connection protection unit 31, the filtering and noise reduction unit 33 is connected to the overvoltage and overcurrent protection unit 32, the surge suppression unit 34 is connected to the filtering and noise reduction unit 33, and the isolation unit 35 is connected to the surge suppression unit 34; the reverse connection protection unit 31 and the overvoltage and overcurrent unit are both used for protecting the power module 3.

When the power module 3 is used, external power supply voltage firstly passes through the electric switch control unit, the reverse connection protection unit 31, the overvoltage and overcurrent protection unit 32, the filtering and noise reduction unit 33, the surge suppression unit 34 and the isolation unit 35 to generate voltage for the imaging circuit and the refrigerator circuit; in the embodiment of the present application, the detector refrigerant may generate strong PWM electromagnetic interference when operating, so that the isolation unit 35 is required to isolate the power supply of the imaging circuit from the power supply of the refrigerator circuit, thereby reducing the interference of the refrigerator circuit to the imaging circuit, and enabling the imaging circuit to output a stable image; in the embodiment of the present application, the isolation unit 35 uses a DCDC power supply chip.

In the embodiment of the application, the noise is reduced through RC filtering, then the operational amplifier forms an active filter, the power supply noise is reduced, meanwhile, the operational amplifier can also increase the driving capability of a circuit, and then voltage conversion is carried out through the LT3042 ultra-low noise LDO, so that the ripple noise brought by a front-end DCDC power supply chip is effectively inhibited.

Referring to fig. 3, the low noise circuit processing module 1 includes a reference voltage unit 11, a filtering unit 12, a negative feedback unit 13, and a converting unit 14; the reference voltage unit 11 is used for outputting a stable reference voltage, the filtering unit 12 is connected with the reference voltage unit 11, and the negative feedback unit 13 is connected with the filtering unit 12 and used for reducing circuit noise; the conversion unit 14 is connected to the reference voltage unit 11.

The conversion unit 14 includes an LTC2263-14 chip, which is an AD conversion chip, the sampling precision is 14-bit precision, the sampling range is 2Vp-p, and the range of the voltage signal output by the detector is 1.4-3.0V, so that a single-ended voltage signal output by the detector needs to be converted into a differential voltage signal meeting the sampling range of the AD conversion chip, and excessive noise cannot be introduced in the signal conversion process, so that the above requirements are met by the reference voltage unit 11, the filtering unit 12, and the negative feedback unit 13.

The reference voltage unit 11 is used for outputting a stable reference voltage, which changes with time or temperature; according to the noise transfer theory, since the reference voltage unit 11 is the first stage of the circuit, the smaller the noise coefficient is, the better the noise coefficient is; the reference voltage unit 11 is therefore selected from 3 aspects of long-term stability, temperature stability and output noise; the reference voltage unit 11 in the embodiment of the present application includes an ADR4540 chip.

The filtering unit 12 comprises two identical RC low-pass filters 121, and circuit noise can be effectively reduced through RC filtering; the output end of the reference voltage unit 11 is connected to the two RC low pass filters 121 respectively, and a resistor R1 and a resistor R2 are connected in series between the reference voltage unit 11 and the RC low pass filters 121; the RC low pass filter 121 includes a resistor and a capacitor connected in parallel with the resistor; the RC low-pass filter 121 is connected in parallel in the circuit of the low-noise circuit processing module 1 and is used for attenuating high-frequency signals; the negative feedback unit 13 includes two identical non-inverting amplifiers 131, a non-inverting input terminal of the non-inverting amplifier 131 is connected to the output terminal of the RC low pass filter 121, and an inverting input terminal of the non-inverting amplifier 131 is connected to the input terminal of the non-inverting amplifier 131, so that the complexity of the circuit structure is reduced and the circuit noise is reduced by using the non-inverting amplifier 131.

When the module 1 is processed by using the low-noise circuit, firstly, the reference voltage unit 11 outputs a voltage, and then the voltage is divided by the resistors R1 and R2 to obtain a target voltage; the target voltage is filtered by the RC low-pass filter 121 and then buffered by the non-inverting amplifier 131 to obtain an ideal bias voltage; for example, the output voltage is 12V, the required ideal voltage is 2.5V, and according to the voltage division theory, the voltage ratio of R1/R2 is 19/5; in the embodiment of the present application, the above process can be understood as that the operational amplifier forms an active filter, which reduces power supply noise, and at the same time, the operational amplifier can also increase the driving capability of the circuit.

In the embodiment of the present application, the resistance in the RC low-pass filter 121 is 1.6M Ω, the capacitance is μ F, and the cutoff frequency is 0.1 Hz; the non-inverting amplifier 131 employs LT 6202.

The non-inverting amplifier LTC6202 can perform single-ended differential signal transmission to increase the anti-interference capability of analog signals, and because the ADC input voltage range is 0-4.096V, signals output by the detector can be amplified through the fully differential amplifier ADA4940, and voltage signals meeting the sampling range of an AD conversion chip are output by taking 2.048 as common-mode voltage.

Referring to fig. 4, it can be understood that, the infrared detector pixel array operates at a temperature of 80K, and simultaneously needs to provide a certain voltage and a pulse signal to perform photoelectric conversion on external infrared radiation to form a photocurrent, and a CMOS readout circuit performs photocurrent integration to form and output a voltage signal; therefore, the detector driving circuit mainly provides bias voltage and time sequence signals required by the operation of the detector, wherein the fixed bias voltage can be directly supplied by a power supply chip, and the rest parts except the fixed bias voltage are adjustable bias voltages which need to be adjusted according to actual conditions.

In the embodiment of the application, a signal acquisition and conditioning module 2 is arranged to realize the requirements; the signal acquisition conditioning module 2 comprises a digital-to-analog conversion unit 21 and an operational amplifier unit 22; the digital-to-analog conversion unit 21 is connected with the operational amplifier unit 22, and the operational amplifier unit 22 is connected with the detector; the operational amplifier unit 22 receives an original analog signal which can be amplified or attenuated and is sent by the detector, and the digital-to-analog conversion unit 21 is used for conditioning the original analog signal; in the embodiment of the present application, the operational amplifier unit 22 includes an operational amplifier and a fully differential amplifier, when the operational amplifier unit 22 receives an original analog signal, the operational amplifier first performs single-ended to differential conversion on the original analog signal, and then sends the original analog signal to the digital-to-analog conversion unit 21 after being conditioned by the fully differential amplifier; the cooperation of the digital-to-analog conversion unit 21 and the operational amplifier unit 22 realizes the power supply and bias voltage supply for the detector, so that the working voltage of the detector is kept at the optimal working voltage.

In the embodiment of the present application, the digital processing module 4 adopts an FPGA digital processing circuit, and the motor control module 5 is configured to control a motor on a lens of the detector to achieve continuous zooming.

The foregoing description is only exemplary of the preferred embodiments of the invention and is provided for the purpose of illustrating the general principles of the technology. It will be appreciated by those skilled in the art that the scope of the disclosure herein is not limited to the particular combination of features described above, but also encompasses other arrangements formed by any combination of the above features or their equivalents without departing from the spirit of the disclosure. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.