2-6-order multistage tapped ultra-low noise supply system applied to bias voltage of visual detector

Abstract

The invention provides a 2-6-order multi-stage tapped ultra-low noise supply system applied to the bias voltage of a visual detector, and relates to the technical field of signal processing. Comprising a processing unit, a digital-to-analog conversion processing unit interacting with the processing unit, a voltage reference unit interacting with the digital-to-analog conversion processing unit, and a plurality of filtering units receiving data sent by the digital-to-analog conversion processing unit. The detector is connected with the filtering units, the low-noise power supply unit is used for supplying power to the digital-to-analog conversion processing unit and the filtering units, and the multiple filtering units comprise a first-stage second-order filtering unit, a second-stage first-order filtering unit, a third-stage second-order filtering unit and a fourth-stage first-order filtering unit which are connected in sequence. The system has the advantages of low circuit noise, small size, low power consumption and the like. The system can be widely applied to various types of visual detector bias voltage supply occasions and has high function expandability, and the noise can be as low as 3 uV by using 2-6-order multi-stage tapped ultra-low noise supply designed by the invention.

Description

Technical Field

[0001] The invention relates to the technical field of signal processing, and in particular provides a 2-6-order multi-stage tap type ultra-low noise supply system applied to a bias voltage of a visual detector. Background Art

[0002] The imaging system is a system that uses an optical system and a visual detector to receive the radiation or reflection of the target object and displays the radiation / reflection distribution diagram in a way that can be observed by the human eye. The imaging processing circuit function of the imaging system mainly includes providing power, bias voltage and drive signal to the detector to enable the detector to work normally. The weakest signal that the imaging system can detect is limited by its noise. By consulting the data sheet of the infrared focal plane detector, it can be obtained that the performance requirements for the bias voltage of the relevant detector readout circuit are as follows: Fig.10 The noise of the bias voltage source will cause the output noise of the detector to increase, thereby increasing the noise of the system and reducing the performance of the imaging system. Fig.10 It can be seen that the performance requirements for the key bias voltages of several readout circuits are relatively high, all in the order of 100 μV or lower. Summary of the invention

[0003] The purpose of the present application is to provide a 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage, which can be applied to various types of visual detector bias voltage supply occasions.

[0004] In order to achieve the above-mentioned object, the present invention adopts the following technical scheme: a 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage, the system comprising a processing unit, a digital-to-analog conversion processing unit interacting with the processing unit, a voltage reference unit interacting with the digital-to-analog conversion processing unit, a plurality of filtering units receiving data sent by the digital-to-analog conversion processing unit, a detector connected to the filtering unit, and a low-noise power supply unit for powering the digital-to-analog conversion processing unit and the filtering unit.

[0005] The plurality of filter units include a first-stage second-order filter unit, a second-stage first-order filter unit, a third-stage second-order filter unit and a fourth-stage first-order filter unit which are connected in sequence.

[0006] The 2-6-stage multi-stage tap-type ultra-low noise supply system for visual detector bias voltage provided by the present invention also has the following technical features: the first-stage and second-stage filter units include two carbon film resistors R1 and R2, two ceramic capacitors C1 and C2, an operational amplifier U1 and a voltage regulator V1,

[0007] The precision of carbon film resistor R1 is 1%, and the resistance is 10Ω to 50KΩ; the precision of carbon film resistor R2 is 1%, and the resistance is 1KΩ to 5MΩ; the precision of ceramic capacitor C1 is 5%, and the capacitance is 1nF to 330uF; the precision of ceramic capacitor C2 is 5%, and the capacitance is 1nF to 20uF; the voltage noise of operational amplifier U1 is <10nv / √Hz,

[0008] The -3dB cutoff bandwidth of the first-stage second-order filtering unit is 8.93 Hz.

[0009] The 2-6-order multi-stage tap-type ultra-low noise supply system for visual detector bias voltage provided by the present invention also has the following technical features: the two-stage first-order filtering unit includes a carbon film resistor R3 with a precision of 10Ω to 50KΩ and a ceramic capacitor C3 with a precision of 1nF to 20uF X7R material and a precision of 5%. The -8.93dB cutoff bandwidth of the two-stage first-order filtering unit is 5Hz.

[0010] The 2-6-stage multi-stage tap-type ultra-low noise supply system for visual detector bias voltage provided by the present invention also has the following technical features: the three-stage second-order filter unit includes two carbon film resistors R4 and R5, two ceramic capacitors C4 and C5, an operational amplifier U2 and a voltage regulator V2,

[0011] The precision of carbon film resistor R4 is 1%, and the resistance is 10Ω to 50KΩ; the precision of carbon film resistor R5 is 1%, and the resistance is 1KΩ to 5MΩ; the precision of ceramic capacitor C4 is 5%, and the capacitance is 1nF to 330uF; the precision of ceramic capacitor C5 is 5%, and the capacitance is 1nF to 20uF; the voltage noise of operational amplifier U2 is <10nv / √Hz,

[0012] The -3dB cutoff bandwidth of the three-stage second-order filtering unit is 7.6 Hz.

[0013] The 2-6-stage multi-stage tap-type ultra-low noise supply system for visual detector bias voltage provided by the present invention also has the following technical features: the four-stage first-order filtering unit includes a carbon film resistor R6 with a precision of 10Ω to 50KΩ and a ceramic capacitor C6 with a precision of 1nF to 20uF X7R material with a precision of 5%, and the -3dB cutoff bandwidth of the four-stage first-order filtering unit is 7.6Hz.

[0014] The 2-6-order multi-tap type ultra-low noise supply system for visual detector bias voltage provided by the present invention also has the following technical features: the first-order second-order filter unit, the second-order first-order filter unit and the third-order second-order filter unit are all provided with an output terminal directly connected to the detector.

[0015] The 2-6-stage multi-stage tap-type ultra-low noise supply system for visual detector bias voltage provided by the present invention also has the following technical characteristics: the voltage reference unit includes an LTC6655 voltage reference chip.

[0016] Beneficial Effects

[0017] The 2-6-stage multi-stage tap type ultra-low noise supply system for visual detector bias voltage provided by the present invention has the advantages of low circuit noise, small size, low power consumption, etc. It can work normally under wide temperature (-55℃~+70℃) conditions, and can be widely used in various types of visual detector bias voltage supply occasions, with strong functional scalability. The 2-6-stage multi-stage tap type ultra-low noise supply designed by the present invention can reduce the noise to 3uV.

[0018] The system provided by the present invention provides an extremely low frequency cutoff, the cutoff frequency is less than 10Hz and can be adjusted; a second-order unit gain low-pass filter non-inverting structure of the Sallen-Key topology is adopted, which can tolerate an input signal with a positive offset circuit; it can operate under a single power supply voltage, reducing the complexity of system design; a low input bias current operational amplifier is adopted; a low voltage drop linear regulator LDO is adopted to power each unit; and the order of magnitude of peripheral resistors and capacitors can be flexibly configured to reduce the generated thermal noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is a structural block diagram of a 2- to 6-stage multi-stage tap type ultra-low noise supply system for visual detector bias voltage provided in this application;

[0021] Figure 2 It is a 2 to 6-stage multi-stage tap type ultra-low noise bias voltage supply circuit;

[0022] Figure 3 To configure the circuit of the digital-to-analog converter through SPI and I2C bus by using GA / MCU / DSP;

[0023] Figure 4 It is a second-order Sallen-Key filter circuit;

[0024] Figure 5 It is a first-order RC filter circuit;

[0025] Figure 6Gain diagram for 2 to 6-stage multi-stage tap type ultra-low noise bias voltage supply circuit;

[0026] Figure 7 Phase diagram of a 2 to 6-stage multi-stage tap type ultra-low noise bias voltage supply circuit;

[0027] Figure 8 The total noise figure of the 2 to 6-stage multi-stage tap type ultra-low noise bias voltage supply circuit;

[0028] Fig. 9 The signal-to-noise ratio diagram of the 2- to 6-stage multi-stage tap type ultra-low noise bias voltage supply circuit;

[0029] Fig.10 Performance requirements table for detector bias voltage. DETAILED DESCRIPTION

[0030] The present application is further described in detail below in conjunction with the accompanying drawings and examples, but it should be noted that these implementation methods are not limitations of the present application, and equivalent changes or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these implementation methods are all within the scope of protection of the present application.

[0031] In the description of the embodiments of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the creation of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the creation of the present application.

[0032] In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0033] The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention of this application can be understood by specific circumstances.

[0034] like Figure 1-9 As shown, the embodiment of the present application provides a 2-6-stage multi-stage tap type ultra-low noise supply system for a visual detector bias voltage, the system comprising a processing unit, a digital-to-analog conversion processing unit interacting with the processing unit, a voltage reference unit interacting with the digital-to-analog conversion processing unit, a plurality of filter units receiving data sent by the digital-to-analog conversion processing unit, a detector connected to the filter unit, and a low-noise power supply unit for powering the digital-to-analog conversion processing unit and the filter unit.

[0035] The plurality of filter units include a first-stage second-order filter unit, a second-stage first-order filter unit, a third-stage second-order filter unit and a fourth-stage first-order filter unit which are connected in sequence.

[0036] In the above embodiment, the processing unit is an FPGA / MCU / DSP processing unit. The system is suitable for linear cooled infrared detectors, array cooled infrared detectors, array uncooled infrared detectors, visible light CMOS detectors, etc. It uses FPGA / MCU / DSP to configure the output voltage of the digital-to-analog converter through buses such as SPI / I2C, outputs an ultra-low noise bias voltage after passing through a 2nd to 6th order filtering circuit, and designs a multi-tap output mechanism, which can flexibly select 2 to 6 orders of output according to the actual engineering situation.

[0037] In some embodiments, the first-order second-order filter unit includes two carbon film resistors R1 and R2, two ceramic capacitors C1 and C2, an operational amplifier U1 and a voltage regulator V1, forming a Sallen-Key topology second-order unit gain low-pass filter non-inverting structure.

[0038] The precision of carbon film resistor R1 is 1%, and the resistance is 10Ω to 50KΩ; the precision of carbon film resistor R2 is 1%, and the resistance is 1KΩ to 5MΩ; the precision of ceramic capacitor C1 is 5%, and the capacitance is 1nF to 330uF; the precision of ceramic capacitor C2 is 5%, and the capacitance is 1nF to 20uF; the voltage noise of operational amplifier U1 is <10nv / √Hz, and ceramic capacitors C1 and C2 are made of X7R material,

[0039] The -3dB cutoff bandwidth of the first-stage second-order filtering unit is 8.93 Hz.

[0040] In some embodiments, the secondary first-order filter unit includes a 1% precision 10Ω to 50KΩ carbon film resistor R3 and a 5% precision 1nF to 20uF X7R material ceramic capacitor C3, forming a first-order RC filter circuit, and the -8.93dB cutoff bandwidth of the secondary first-order filter unit is 5Hz.

[0041] In some embodiments, the three-stage second-order filter unit includes two carbon film resistors R4 and R5, two ceramic capacitors C4 and C5, an operational amplifier U2 and a voltage regulator V2, forming a Sallen-Key topology second-order unit gain low-pass filter non-inverting structure.

[0042] The precision of carbon film resistor R4 is 1%, and the resistance is 10Ω to 50KΩ; the precision of carbon film resistor R5 is 1%, and the resistance is 1KΩ to 5MΩ; the precision of ceramic capacitor C4 is 5%, and the capacitance is 1nF to 330uF; the precision of ceramic capacitor C5 is 5%, and the capacitance is 1nF to 20uF; the voltage noise of operational amplifier U2 is <10nv / √Hz,

[0043] The -3dB cutoff bandwidth of the three-stage second-order filtering unit is 7.6 Hz.

[0044] In some embodiments, the four-stage first-order filter unit includes a 1% precision 10Ω to 50KΩ carbon film resistor R6 and a 5% precision 1nF to 20uF X7R material ceramic capacitor C6, forming a first-order RC filter circuit, and the -3dB cutoff bandwidth of the four-stage first-order filter unit is 7.6Hz.

[0045] In some embodiments, the first-stage second-order filtering unit, the second-stage first-order filtering unit and the third-stage second-order filtering unit are all provided with an output terminal directly connected to the detector.

[0046] In some embodiments, the tap output can be flexibly selected according to the actual engineering application situation. The second-order Sallen-Key filter circuit uses the tap Vout1 output, and the R3 resistor is not welded at this time; the tap output can be flexibly selected according to the actual engineering application situation. The third-order Sallen-Key+RC filter circuit uses the tap Vout2 output, and the R4 resistor is not welded at this time; the tap output can be flexibly selected according to the actual engineering application situation. The fifth-order Sallen-Key+RC+Sallen-Key filter circuit uses the tap Vout3 output, and the R6 resistor is not welded at this time; the tap output can be flexibly selected according to the actual engineering application situation. The sixth-order Sallen-Key+RC+Sallen-Key+RC filter circuit uses the tap Vout4 output.

[0047] In some embodiments, a low dropout linear regulator LDO such as LT3045 / LT3042 is used to power each unit.

[0048] In some embodiments, the voltage reference unit includes an LTC6655 voltage reference chip.

[0049] In some embodiments, FPGA / MCU / DSP is used to configure the digital-to-analog converter via SPI and I2C buses so that the output voltage can be adjusted in real time.

[0050] In some embodiments, a 2-6-order multi-stage tap-type ultra-low noise supply system for a visual detector bias voltage is provided, which adopts a four-stage passive filtering structure:

[0051] The first-order second-order Sallen-Key filter circuit is composed of R1, R2, C1, C2, U1, and V1, and its -3dB cutoff bandwidth is 8.93Hz; R1 is a 27.4kΩ 1% carbon film resistor, R2 is a 196kΩ 1% carbon film resistor, C1 is a 470nF 5% X7R ceramic capacitor, C2 is a 100nF 5% X7R ceramic capacitor, U1 uses an operational amplifier model OPA374, and V1 uses a LT3045 low-dropout linear regulator LDO;

[0052] The two-stage first-order RC filter circuit is composed of R3 and C3, and its -3dB cut-off bandwidth is 8.93Hz. R3 is a 9.31kΩ 1% carbon film resistor, and C3 is a 470nF 5% X7R ceramic capacitor to further suppress high-frequency interference.

[0053] The three-stage second-order Sallen-Key filter circuit is composed of R4, R5, C4, C5, U2 and V2, and its -3dB cut-off bandwidth is 7.6Hz; R4 is a 27.4kΩ 1% carbon film resistor, R5 is a 196kΩ 1% carbon film resistor, C4 is a 470nF 5% X7R ceramic capacitor, C5 is a 100nF 5% X7R ceramic capacitor, U2 uses an operational amplifier model OPA374, and V2 uses a LT3045 low-dropout linear regulator LDO;

[0054] The two-stage first-order RC filter circuit is composed of R5 and C6, and its -3dB cut-off bandwidth is 7.6Hz. R5 is a 50Ω 1% carbon film resistor, and C6 is a 470nF 5% X7R ceramic capacitor to further suppress high-frequency interference.

[0055] The tap output can be flexibly selected according to the actual engineering application. The second-order Sallen-Key filter circuit uses the tap Vout1 output, and the R3 resistor is not welded at this time; the third-order Sallen-Key+RC filter circuit uses the tap Vout2 output, and the R4 resistor is not welded at this time; the fifth-order Sallen-Key+RC+Sallen-Key filter circuit uses the tap Vout3 output, and the R6 resistor is not welded at this time; the sixth-order Sallen-Key+RC+Sallen-Key+RC filter circuit uses the tap Vout4 output;

[0056] Use low dropout linear regulators (LDOs) such as LT3045 / LT3042 to power each unit;

[0057] The LTC6655 voltage reference chip is used to provide a voltage base for the digital-to-analog converter;

[0058] FPGA / MCU / DSP is used to configure the digital-to-analog converter through SPI and I2C buses, so that the output voltage can be adjusted in real time.

[0059] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage, characterized in that: The system includes a processing unit, a digital-to-analog conversion processing unit interacting with the processing unit, a voltage reference unit interacting with the digital-to-analog conversion processing unit, a plurality of filter units receiving data sent by the digital-to-analog conversion processing unit, a detector connected to the filter unit, and a low-noise power supply unit for supplying power to the digital-to-analog conversion processing unit and the filter unit. The plurality of filter units include a first-stage second-order filter unit, a second-stage first-order filter unit, a third-stage second-order filter unit and a fourth-stage first-order filter unit which are connected in sequence.

2. The 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage according to claim 1, characterized in that: The first-order second-order filtering unit includes two carbon film resistors R1 and R2, two ceramic capacitors C1 and C2, an operational amplifier U1 and a voltage regulator V1. The precision of carbon film resistor R1 is 1%, and the resistance is 10Ω to 50KΩ; the precision of carbon film resistor R2 is 1%, and the resistance is 1KΩ to 5MΩ; the precision of ceramic capacitor C1 is 5%, and the capacitance is 1nF to 330uF; the precision of ceramic capacitor C2 is 5%, and the capacitance is 1nF to 20uF; the voltage noise of operational amplifier U1 is <10nv / √Hz, The -3dB cutoff bandwidth of the first-stage second-order filtering unit is 8.93 Hz.

3. The 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage according to claim 1, characterized in that: The two-stage first-order filter unit includes a 1% precision carbon film resistor R3 of 10Ω to 50KΩ and a 5% precision ceramic capacitor C3 of 1nF to 20uF X7R material. The -8.93dB cutoff bandwidth of the two-stage first-order filter unit is 5Hz.

4. The 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage according to claim 1, characterized in that: The three-stage second-order filtering unit includes two carbon film resistors R4 and R5, two ceramic capacitors C4 and C5, an operational amplifier U2 and a voltage regulator V2. The precision of carbon film resistor R4 is 1%, and the resistance is 10Ω to 50KΩ; the precision of carbon film resistor R5 is 1%, and the resistance is 1KΩ to 5MΩ; the precision of ceramic capacitor C4 is 5%, and the capacitance is 1nF to 330uF; the precision of ceramic capacitor C5 is 5%, and the capacitance is 1nF to 20uF; the voltage noise of operational amplifier U2 is <10nv / √Hz, The -3dB cutoff bandwidth of the three-stage second-order filtering unit is 7.6 Hz.

5. The 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage according to claim 1, characterized in that: The four-stage first-order filter unit includes a 1% precision carbon film resistor R6 of 10Ω to 50KΩ and a 5% precision ceramic capacitor C6 of 1nF to 20uF X7R material. The -3dB cutoff bandwidth of the four-stage first-order filter unit is 7.6Hz.

6. The 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage according to claim 1, characterized in that: The first-stage second-order filtering unit, the second-stage first-order filtering unit and the third-stage second-order filtering unit are all provided with an output terminal directly connected to the detector.

7. The 2-6-stage multi-tap type ultra-low noise supply system for visual detector bias voltage according to claim 1, characterized in that: The voltage reference unit includes an LTC6655 voltage reference chip.

Images