A leakage current measuring wide range weak current amplifier, device and method

Abstract

The application discloses a weak current amplifier with leakage current measurement, a device and a method, relates to the technical field of amplifier and circuit device, and input signal switching circuit of the amplifier is used for switching different amplification circuits; the first amplification circuit is used for amplifying high gas pressure ionization chamber output signals and leakage current signals in a low range; the second amplification circuit is used for amplifying high gas pressure ionization chamber output signals and leakage current signals in a high range and a middle range and output signal switching; the switching logic drive circuit is used for realizing logic drive of range switching and leakage current measurement; and the output signal processing circuit is used for switching selection, low-pass filtering and series matching processing of output amplified signals. The application can realize rapid and accurate switching among a high range, a middle range and a low range, and improves the accuracy of actual gamma dose rate in a measurement environment.

Description

Technical Field

[0001] This application relates to the field of amplifier and circuit device technology, and in particular to a wide-range weak current amplifier, device and method with leakage current measurement. Background Technology

[0002] To assess the potential radiation impact of natural or artificial radionuclides on the public, environmental radiation monitoring agencies generally use high-pressure ionization chambers (HPICs) to continuously monitor atmospheric gamma radiation dose. HPICs have sufficient sensitivity and a fairly wide range, with an output current of 1pA to 0.1mA, and the dose rate measured spans eight orders of magnitude.

[0003] Traditional HPIC low-current wide-range amplifiers switch measurement ranges by using reed relays and analog switches to switch between three high-precision resistors of different values, typically categorized as high, medium, and low ranges. During measurement, at the low range, electronic leakage current significantly impacts the measurement lower limit, and traditional low-current amplifier circuits do not actively compensate for this after measurement to lower the measurement lower limit. Furthermore, traditional HPIC low-current wide-range amplifiers are not designed to account for the varying leakage currents of the reed relays and analog switches at different ranges, and this leakage current increases with usage. Assuming that after long-term use, the leakage current at the medium range, after low-current amplification, may exceed the measurement lower limit of the medium range, preventing the switch to the low range when environmental conditions change, thus failing to accurately reflect the actual gamma dose rate in the measurement environment. Summary of the Invention

[0004] The purpose of this application is to provide a wide-range weak current amplifier, device, and method for measuring leakage current, which can achieve rapid and accurate switching between high, medium, and low ranges, thereby improving the accuracy of the actual gamma dose rate in the measurement environment.

[0005] To achieve the above objectives, this application provides the following solution.

[0006] In a first aspect, this application provides a wide-range weak current amplifier with leakage current measurement, which includes the following circuit structure.

[0007] The input signal switching circuit is connected to the high-voltage end of the high-pressure ionization chamber at its input terminal, and is used to switch between different amplifier circuits.

[0008] The first amplification circuit has its input terminal connected to the first output terminal of the input signal switching circuit, and is used to amplify the output signal of the high-pressure ionization chamber and the corresponding leakage current signal at a low-range amplification level.

[0009] The second amplifier circuit has its input terminal connected to the second output terminal of the input signal switching circuit. It is used to amplify the output signal of the high-pressure ionization chamber and the corresponding leakage current signal at a high-range amplification level or a medium-range amplification level.

[0010] A switching logic drive circuit is connected to the input signal switching circuit, the first amplifier circuit, and the second amplifier circuit, respectively, to realize the logic drive for range switching and leakage current measurement.

[0011] The output signal processing circuit is connected to the output terminals of the first amplifier circuit and the second amplifier circuit, respectively, and is used to perform switching selection, low-pass filtering and series matching processing on the amplified signals output by the first amplifier circuit and the second amplifier circuit.

[0012] Optionally, the input signal switching circuit includes: a first reed relay, a second reed relay, a first reed relay coil, and a second reed relay coil.

[0013] The coil of the first reed relay is used to control the on / off state of the first reed relay.

[0014] The coil of the second reed relay is used to control the on / off state of the second reed relay.

[0015] When the first reed relay is turned on, the high-pressure ionization chamber output signal is measured at the low-range amplification level; when the first reed relay is turned off, the leakage current signal is measured at the low-range amplification level.

[0016] When the second reed relay is turned on, the high-pressure ionization chamber output signal is measured at the medium-range amplification level or the high-range amplification level. When the second reed relay is turned off, the leakage current signal is measured at the medium-range amplification level or the high-range amplification level.

[0017] Optionally, the input signal switching circuit further includes a first resistor.

[0018] The first resistor is a metal film resistor with a resistance range of 1MΩ to 50MΩ.

[0019] Optionally, the first amplifier circuit includes: a first operational amplifier, a second resistor, and a first capacitor.

[0020] The input terminal of the first operational amplifier is connected to the output terminal of the first reed relay, one end of the second resistor is connected to the output terminal of the first operational amplifier, the other end of the second resistor is connected to the inverting input terminal of the first operational amplifier, and the first capacitor is connected in parallel with the second resistor.

[0021] Optionally, the second amplifier circuit includes: a second operational amplifier, a third resistor, a second capacitor, a fourth resistor, a third capacitor, and a first two-to-one analog electronic switch.

[0022] The input terminal of the second operational amplifier is connected to the output terminal of the second reed relay; one end of the third resistor is connected to the input terminal of the second operational amplifier, and the other end of the third resistor is grounded; the second capacitor is connected in parallel with the third resistor; one end of the fourth resistor is connected to the output terminal of the second operational amplifier, and the other end of the fourth resistor is connected to the inverting input terminal of the second operational amplifier; the third capacitor is connected in parallel with the fourth resistor; the input terminal of the first two-to-one analog electronic switch is connected to the output terminal of the second operational amplifier.

[0023] Optionally, the switching logic drive circuit includes: a first MOSFET, a second MOSFET, a first NOT gate, a fifth resistor, a sixth resistor, and a second two-to-one analog electronic switch.

[0024] The gate of the first MOSFET is connected to an external device for outputting standard TTL or CMOS level signals through the fifth resistor. The source of the first MOSFET is grounded, and the drain of the first MOSFET is connected to one end of the coil of the first reed relay. The other end of the coil of the first reed relay is connected to a power supply. The fifth resistor is a current-limiting resistor.

[0025] The gate of the second MOSFET is connected to the output of the first NOT gate through the sixth resistor. The source of the second MOSFET is grounded, and the drain of the second MOSFET is connected to one end of the coil of the second reed relay. The other end of the coil of the second reed relay is connected to the power supply. The input of the first NOT gate is connected to an external device for outputting standard TTL or CMOS level signals. The sixth resistor is a current-limiting resistor.

[0026] The control terminal of the second 2-to-1 analog electronic switch is connected to the output terminal of the first NOT gate, or the control terminal of the second 2-to-1 analog electronic switch is connected to an external device for outputting standard TTL or CMOS level signals. The input terminals of the second 2-to-1 analog electronic switch are respectively connected to the first amplifier circuit and the second amplifier circuit, and the output terminal of the second 2-to-1 analog electronic switch is connected to the output signal processing circuit.

[0027] Optionally, the amplified signal output value of the output signal processing circuit is used for A / D sampling to obtain A / D sample value. The A / D sample value is used to subtract the leakage current component in the output signal of the high-pressure ionization chamber to achieve leakage current compensation, thereby reducing the lower limit of γ dose rate measurement.

[0028] Optionally, the A / D sampled value can also be used as a range switching reference.

[0029] When the A / D sampling value corresponding to the current amplification level is greater than the maximum value of the A / D conversion, the system switches to the higher amplification level; when the A / D sampling value corresponding to the current amplification level is less than or equal to the leakage current signal A / D sampling value corresponding to the current amplification level, the system switches to the lower amplification level.

[0030] Secondly, this application provides a wide-range weak current amplification device, which includes: a signal input and switching module, a leakage current measurement module, a control and processing module, and the wide-range weak current amplifier with leakage current measurement described in the first aspect.

[0031] The signal input and switching module is used to receive external weak current signals and selectively turn on or off the signal path; the weak current signals include: the output signal of the high-pressure ionization chamber.

[0032] The wide-range weak current amplifier with leakage current measurement is connected to the signal input and switching module. The wide-range weak current amplifier with leakage current measurement is used to switch different amplification levels based on the signal path, amplify the weak current signal according to the corresponding range, and output an amplified signal.

[0033] The leakage current measurement module is connected to the signal input and switching module and the wide-range weak current amplifier with leakage current measurement, respectively. The leakage current measurement module is used to measure the electronic leakage current signal at each of the amplification levels and obtain the measurement result.

[0034] The control and processing module is connected to the signal input and switching module, the wide-range weak current amplifier with leakage current measurement, and the leakage current measurement module, respectively. The control and processing module is used to perform leakage current compensation on the amplified signal according to the measurement result to reduce the measurement lower limit; and to control the wide-range weak current amplifier with leakage current measurement to switch between different amplification levels based on the leakage current measurement value at each amplification level.

[0035] Thirdly, this application provides a wide-range weak current amplification method, which is implemented based on the wide-range weak current amplification device described in the second aspect, and includes the following steps.

[0036] It receives weak current signals from the outside and selectively turns the signal path on or off; the weak current signals include: the output signal of the high-pressure ionization chamber.

[0037] By switching different amplification levels based on the signal path, the weak current signal is amplified according to the corresponding range, and an amplified signal is output.

[0038] Based on each of the aforementioned amplification levels, the electronic leakage current signal at each amplification level is measured to obtain the measurement results.

[0039] Based on the measurement results, leakage current compensation is performed on the amplified signal to reduce the measurement lower limit, and the leakage current measurement value at each amplification level is used as a reference to control the switching of different amplification levels.

[0040] According to the specific embodiments provided in this application, this application has the following technical effects.

[0041] This application provides a wide-range, low-current amplifier, apparatus, and method for measuring leakage current. On one hand, a precise switching of different amplification circuits is achieved through an input signal switching circuit, ensuring that signals are directed to the corresponding amplification circuit and that signals of different ranges are amplified and processed accordingly. On the other hand, the first and second amplification circuits correspond to different amplification levels—low, medium, and high—effectively amplifying the output signal and leakage current signal of the high-pressure ionization chamber within the corresponding ranges. Combined with the processing of the output signal processing circuit, the accuracy and stability of the amplified signal are guaranteed. Furthermore, a switching logic drive circuit enables the logic drive for range switching and leakage current measurement, effectively reducing the lower limit of gamma dose rate measurement while simultaneously resolving the error problem in the range switching logic of traditional amplifiers. Therefore, this application integrates the input signal switching circuit, the first amplifier circuit, the second amplifier circuit, the switching logic drive circuit, and the output signal processing circuit into the same amplifier. Through the synergistic effect of the above multiple circuits, it can achieve rapid and accurate switching between high, medium, and low ranges, effectively improving the accuracy of the actual gamma dose rate in the measurement environment. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the structure of a wide-range weak current amplifier with leakage current measurement provided in an embodiment of this application.

[0044] Figure 2 This is a schematic diagram of the input signal switching circuit provided in an embodiment of this application.

[0045] Figure 3 This is a schematic diagram of the structure of a first amplifier circuit provided in an embodiment of this application.

[0046] Figure 4 This is a schematic diagram of the structure of a second amplifier circuit provided in an embodiment of this application.

[0047] Figure 5 This is a schematic diagram of a reed relay and electronic analog switch control circuit structure provided in an embodiment of this application.

[0048] Figure 6 This is a schematic diagram of a wide-range, low-current amplification device provided in an embodiment of this application.

[0049] Figure 7 This is a flowchart illustrating a wide-range, low-current amplification method according to an embodiment of this application.

[0050] Reference numerals: 1. High-pressure ionization chamber; 101. Negative high-pressure module; 102. First standard TTL or CMOS level signal; 103. Second standard TTL or CMOS level signal; 104. Third standard TTL or CMOS level signal; 10. Input signal switching circuit; 11. First resistor; 12. First reed relay; 13. Second reed relay; 14. First reed relay coil; 15. Second reed relay coil; 20. First amplifier circuit; 21. First operational amplifier; 22. Second resistor; 23. First capacitor; 30. Second amplifier circuit; 31. Second operational amplifier; 32. Third resistor; 33. Second capacitor; 34. Fourth resistor; 35. Third capacitor; 36. First two-to-one analog electronic switch; 40. Switching logic drive circuit; 41. First MOSFET; 42. Second MOSFET; 43. First NOT gate; 44. Fifth resistor; 45. Sixth resistor; 46. Second two-to-one analog electronic switch; 50. Output signal processing circuit. Detailed Implementation

[0051] 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.

[0052] Currently, the output current signal of the high-pressure ionization chamber is weak to the pA level, making it susceptible to interference and noise. Examples include reed relay leakage current shot noise, operational amplifier input leakage current shot noise, electronic analog switch leakage current shot noise, and high-resistance thermal noise; these are collectively referred to as leakage current noise. To lower the measurement limit for detecting gamma dose rate in the high-pressure ionization chamber, leakage current noise must be compensated for; otherwise, environmental-grade measurement requirements will not be met. Furthermore, at zero input in different ranges, the leakage current, after being amplified by a weak current amplifier, will not have a zero output value. For example, at zero input in the medium range, the voltage value of the leakage current amplified by the weak current amplifier in the medium range is not zero. This prevents the medium range from switching to the low range, resulting in consistently overestimated measurement results and errors that fail to accurately reflect the actual gamma dose rate in the measurement environment.

[0053] This application proposes a wide-range weak current amplifier, device, and method with leakage current measurement, applicable to the application scenario of output signal amplification in high-pressure ionization chambers. The aim is to add electronic leakage current measurement function to a traditional weak current amplifier, which not only effectively reduces the measurement lower limit of gamma dose rate by subtracting the leakage current, but also solves the problem of logic error in switching between high, medium, and low ranges in traditional wide-range weak current amplifiers. In particular, when the leakage current in the medium range is larger than the maximum input signal current in the low range, the current gamma dose rate meter cannot switch to the low range, resulting in an excessively large measured value and false alarms.

[0054] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] like Figure 1 As shown in the figure, this embodiment proposes a wide-range weak current amplifier with leakage current measurement, which includes the following circuit structure.

[0056] The input signal switching circuit 10 is connected to the high-voltage terminal of the high-pressure ionization chamber 1. It is used to receive the output signal of the high-pressure ionization chamber and control the on / off state of each internal reed relay according to the externally input first standard TTL or CMOS level signal 102 to realize the switching of different amplification circuits and to make the output signal of the high-pressure ionization chamber pass to the corresponding amplification circuit. Each amplification circuit corresponds to an amplification level, which includes, in order of increasing range, a low-range amplification level, a medium-range amplification level, and a high-range amplification level.

[0057] The first amplifier circuit 20, corresponding to the low-range amplification level, has its input terminal connected to the first output terminal of the input signal switching circuit 10. It is used to amplify the high-pressure ionization chamber output signal and the corresponding leakage current signal within the low-range range under the low-range amplification level.

[0058] The second amplification circuit 30, corresponding to the medium-range amplification level and the high-range amplification level, has its input terminal connected to the second output terminal of the input signal switching circuit 10. It is used to amplify the high-pressure ionization chamber output signal and the corresponding leakage current signal within the high-range and medium-range ranges in the medium-range or high-range amplification level, and has an output signal switching function. The output signal switching function includes: measurement switching between the high-pressure ionization chamber output signal and the leakage current signal, and output switching between amplified signals of different ranges.

[0059] The switching logic drive circuit 40 is connected to the input signal switching circuit 10, the first amplifier circuit 20 and the second amplifier circuit 30 respectively. It is used to control the on / off state of each internal analog electronic switch and each reed relay inside the input signal switching circuit 10 according to the externally input second standard TTL or CMOS level signal 103 and third standard TTL or CMOS level signal 104, so as to realize the logic drive for range switching and leakage current measurement.

[0060] The output signal processing circuit 50 is connected to the output terminals of the first amplifier circuit 20 and the second amplifier circuit 30, respectively, and is used to perform switching selection, low-pass filtering and series matching processing on the amplified signals output by the first amplifier circuit 20 and the second amplifier circuit 30.

[0061] In this embodiment, the input signal switching circuit 10 adopts a dual reed relay input signal switching circuit, specifically including: a first reed relay 12, a second reed relay 13, a first reed relay coil 14, and a second reed relay coil 15.

[0062] The first reed relay coil 14 is used to control the on / off state of the first reed relay 12.

[0063] The second reed relay coil 15 is used to control the on / off state of the second reed relay 13.

[0064] When the first reed relay 12 is turned on, the high-pressure ionization chamber output signal is measured under the low-range amplification setting. When the first reed relay 12 is turned off, the leakage current signal is measured under the low-range amplification setting.

[0065] When the second reed relay 13 is turned on, the high-pressure ionization chamber output signal is measured at the medium-range amplification level or the high-range amplification level. When the second reed relay 13 is turned off, the leakage current signal is measured at the medium-range amplification level or the high-range amplification level.

[0066] In this embodiment, the input signal switching circuit 10 further includes a first resistor 11. The first resistor 11 can be a metal film resistor, preferably a low-temperature drift metal film resistor, with a resistance value ranging from 1MΩ to 50MΩ.

[0067] In this embodiment, the first amplifier circuit 20 adopts a low-range weak current amplifier circuit (corresponding to the low-range amplification level, used to realize amplification processing under the low-range amplification level), specifically including: a first operational amplifier 21, a second resistor 22 and a first capacitor 23.

[0068] The input terminal of the first operational amplifier 21 is connected to the output terminal of the first reed relay 12, one end of the second resistor 22 is connected to the output terminal of the first operational amplifier 21, the other end of the second resistor 22 is connected to the inverting input terminal of the first operational amplifier 21, and the first capacitor 23 is connected in parallel with the second resistor 22.

[0069] In this embodiment, the second amplifier circuit 30 adopts a high-medium range weak current amplification and output signal switching circuit (corresponding to the medium range amplification level and the high range amplification level, used to realize the amplification processing under the medium range amplification level or the high range amplification level, and has the function of output signal switching), specifically including: a second operational amplifier 31, a third resistor 32, a second capacitor 33, a fourth resistor 34, a third capacitor 35, and a first two-to-one analog electronic switch 36.

[0070] The input terminal of the second operational amplifier 31 is connected to the output terminal of the second reed relay 13; one end of the third resistor 32 is connected to the input terminal of the second operational amplifier 31, and the other end of the third resistor 32 is grounded; the second capacitor 33 is connected in parallel with the third resistor 32; one end of the fourth resistor 34 is connected to the output terminal of the second operational amplifier 31, and the other end of the fourth resistor 34 is connected to the inverting input terminal of the second operational amplifier 31; the third capacitor 35 is connected in parallel with the fourth resistor 34; the input terminal of the first two-to-one analog electronic switch 36 is connected to the output terminal of the second operational amplifier 31.

[0071] In this embodiment, the switching logic drive circuit 40 adopts a range and leakage current measurement switching logic drive circuit, specifically including: a first MOSFET 41, a second MOSFET 42, a first NOT gate 43, a fifth resistor 44, a sixth resistor 45, and a second two-to-one analog electronic switch 46.

[0072] The gate of the first MOSFET 41 is connected to an external device for outputting standard TTL or CMOS level signals (including the first standard TTL or CMOS level signal 102, the second standard TTL or CMOS level signal 103, and the third standard TTL or CMOS level signal 104) through the fifth resistor 44. The source of the first MOSFET 41 is grounded, and the drain of the first MOSFET 41 is connected to one end of the first reed relay coil 14. The other end of the first reed relay coil 14 is connected to a power supply. The fifth resistor 44 is a current-limiting resistor.

[0073] The gate of the second MOSFET 42 is connected to the output terminal of the first NOT gate 43 through the sixth resistor 45. The source of the second MOSFET 42 is grounded, and the drain of the second MOSFET 42 is connected to one end of the second reed relay coil 15. The other end of the second reed relay coil 15 is connected to the power supply. The input terminal of the first NOT gate 43 is connected to an external device for outputting standard TTL or CMOS level signals (including the first standard TTL or CMOS level signal 102, the second standard TTL or CMOS level signal 103, and the third standard TTL or CMOS level signal 104). The sixth resistor 45 is a current-limiting resistor.

[0074] The control terminal of the second two-to-one analog electronic switch 46 is connected to the output terminal of the first NOT gate 43, or the control terminal of the second two-to-one analog electronic switch 46 is connected to an external device for outputting standard TTL or CMOS level signals (including the first standard TTL or CMOS level signal 102, the second standard TTL or CMOS level signal 103, and the third standard TTL or CMOS level signal 104). The input terminal of the second two-to-one analog electronic switch 46 is connected to the first amplifier circuit 20 and the second amplifier circuit 30, respectively. The output terminal of the second two-to-one analog electronic switch 46 is connected to the output signal processing circuit 50.

[0075] In this embodiment, the output signal processing circuit 50 employs an output signal switching, low-pass filtering, and series matching circuit (used for switching, low-pass filtering, and series matching processing of the output amplified signal). The output value of the amplified signal is used for A / D sampling to obtain A / D sampled values. The A / D sampled values ​​are used to subtract the leakage current component in the output signal of the high-pressure ionization chamber to achieve leakage current compensation, thereby reducing the lower limit of γ dose rate measurement.

[0076] In this embodiment, the A / D sampled value is also used as a reference for range switching.

[0077] When the A / D sampling value corresponding to the current amplification level is greater than the maximum value of the A / D conversion, the system switches to the higher amplification level; when the A / D sampling value corresponding to the current amplification level is less than or equal to the leakage current signal A / D sampling value corresponding to the current amplification level, the system switches to the lower amplification level.

[0078] To make the wide-range weak current amplifier with leakage current measurement proposed in this application clearer, the specific structure of the wide-range weak current amplifier with leakage current measurement will be described in detail below by way of example.

[0079] like Figure 1 As shown, the wide-range weak current amplifier with leakage current measurement includes: an input signal switching circuit 10; the outer shell of the high-pressure ionization chamber 1 is connected to the negative high-voltage module 101; the high-voltage end of the high-pressure ionization chamber 1 is connected to the input end of the input signal switching circuit 10; the first standard TTL or CMOS level signal 102 input externally controls the first reed relay 12 and the second reed relay 13 to be turned on or off, allowing the output signal of the high-pressure ionization chamber 1 to enter the input end of the first amplifier circuit 20 or the second amplifier circuit 30; the amplified output voltage signal of the first amplifier circuit 20 and the second amplifier circuit 30 enters the output signal processing circuit 50, which is controlled by the switching logic drive circuit 40.

[0080] The wide-range, low-current amplifier with leakage current measurement provided in this embodiment controls the first reed relay 12 or the second reed relay 13 to close or open via an externally input first standard TTL or CMOS level signal 102. The ionization chamber output signal and leakage current signal enter the input terminal of the first amplifier circuit 20 or the second amplifier circuit 30 and are amplified. The amplified output value can be directly sampled by an A / D converter. The sampled value can be subtracted to reduce the lower limit of the high-pressure ionization chamber gamma dose rate measurement. When the measured value of the current amplification level is higher than the maximum value of the A / D conversion, resulting in an overload signal, the system can switch to a higher range. The leakage current signal A / D sampled value can be used as a reference value for switching from a high range to a low range. When the measured value of the current amplification level is less than or equal to the leakage current signal sampled value, the system can switch to a lower range via a first two-to-one analog electronic switch 36 or a second two-to-one analog electronic switch 46, ensuring the accuracy of the measurement results and truly reflecting the actual gamma dose rate in the environment.

[0081] In one exemplary embodiment, such as Figure 2 As shown, an input signal switching circuit structure is provided. The input signal switching circuit 10 includes: a first resistor 11, a first reed relay 12, a second reed relay 13, a first reed relay coil 14, and a second reed relay coil 15. The first resistor 11 can be a low-temperature drift metal film resistor, typically with a value between 1MΩ and 50MΩ, to avoid the signal recovering to the baseline state with a slow time constant due to excessive resistance while ensuring that the noise characteristics meet the predetermined requirements. For example, a 10MΩ resistor can be used. The first reed relay 12 and the second reed relay 13 can be glass-sealed reed relays with a contact resistance <100mΩ and an insulation resistance >10¹²Ω. Otherwise, if the insulation resistance is low, leakage current will affect the measurement lower limit and range switching. When the first reed relay 12 is turned on, it realizes the measurement of low-range HPIC signal; when it is turned off, it realizes the measurement of low-range leakage current. The first reed relay coil 14 realizes the turning on and off of the first reed relay 12. When the second reed relay 13 is turned on, it realizes the measurement of high and medium-range HPIC signal; when it is turned off, it realizes the measurement of high and medium-range leakage current. The second reed relay coil 15 realizes the turning on and off of the second reed relay 13.

[0082] In one exemplary embodiment, such as Figure 3 and Figure 4As shown, the first amplifier circuit 20 and the second amplifier circuit 30 have basically the same structure, amplifying the current signals at the output terminals of the first reed relay 12 and the second reed relay 13, respectively; the first operational amplifier 21 and the second operational amplifier 31 can be operational amplifiers with ultra-low input bias current and high input impedance; the second resistor 22 can be a vacuum micro-current glass glaze film ultra-high resistance resistor, for example, a 500GΩ resistor; the first capacitor 23 is a frequency compensation capacitor, which can be a polytetrafluoroethylene capacitor with ultra-low leakage current, for example, a 12pF capacitor; the third resistor 32 and the fourth resistor 34 can be low-temperature drift metal film resistors, for example, 2.2GΩ and 10MΩ resistors; the second capacitor 33 and the third capacitor 35 can be polypropylene capacitors, for example, 180pF and 400pF capacitors.

[0083] In one exemplary embodiment, an output signal processing circuit structure is provided, such as... Figure 5 As shown, in this circuit structure, the switching logic drive circuit 40 includes a first MOSFET 41 and a second MOSFET 42, which are N-channel enhancement-type MOSFETs in a SOT23 surface-mount package. The first two-to-one analog electronic switch 36 and the second two-to-one analog electronic switch 46 can be electronic analog switches with low on-resistance, high bandwidth, and low leakage current; for example, a DG413 chip can be used. The first two-to-one analog electronic switch 36 is connected to the second operational amplifier 31, the third resistor 32, and the fourth resistor 34, and receives an externally input second standard TTL or CMOS level signal 103. The second two-to-one analog electronic switch 46 is connected to the first amplifier circuit 20, the second amplifier circuit 30, and the output signal processing circuit 50, and receives an externally input third standard TTL or CMOS level signal 104.

[0084] In one exemplary embodiment, a low-pass filter is used to filter out unwanted high-frequency interference, ensuring the accuracy and stability of the output signal; a series matching circuit is used to receive and adjust the output signal of the weak current amplifier circuit to avoid noise signal reflection, which could cause signal oscillation.

[0085] This embodiment proposes a wide-range, low-current amplifier with leakage current measurement, suitable for amplifying, switching, and measuring the wide-range low-current signal output from a high-pressure ionization chamber (HPIC). It includes: a wide-range low-current amplifier circuit for receiving and amplifying the HPIC output signal; the core amplification circuit employs an operational amplifier with ultra-low input bias current and high input impedance, and low-noise, high-precision, high-value resistors; a range switching circuit that controls a reed relay and an electronic analog switch using standard TTL or CMOS level signals; and a leakage current measurement circuit for receiving and amplifying the electronic leakage current signal, controlling the reed relay and electronic analog switch with standard TTL or CMOS level signals to achieve leakage current measurement at different ranges. The measured values ​​are used to lower the detection limit and enable rapid switching between different ranges. The wide-range weak current amplifier with leakage current measurement in this application can separately amplify the weak current signal output by HPIC and the electronic leakage current signal through a drive circuit to achieve reed relay switching selection, ensuring that they can be correctly identified and read. Since online measurement of electronic leakage current is realized, the lower limit of gamma dose rate measurement can be effectively reduced after subtraction. By measuring the weak current of electronic leakage current in high, medium and low ranges, accurate switching between the three ranges can be effectively achieved, with rapid and efficient switching. This method enables accurate monitoring of the actual gamma dose rate in the environment.

[0086] Based on the same inventive concept, this application also provides a wide-range weak current amplification device based on the aforementioned wide-range weak current amplifier with leakage current measurement. The solution provided by this device is similar to the solution described in the aforementioned wide-range weak current amplifier with leakage current measurement. Therefore, the specific limitations in the embodiments of the wide-range weak current amplification device provided below can be found in the above-described limitations of the wide-range weak current amplifier with leakage current measurement, and will not be repeated here.

[0087] In one exemplary embodiment, such as Figure 6 As shown, a wide-range weak current amplification device is provided, which includes: a signal input and switching module, a leakage current measurement module, a control and processing module, and the wide-range weak current amplifier with leakage current measurement.

[0088] The signal input and switching module is used to receive external weak current signals and selectively turn on or off the signal path; the weak current signals include: the output signal of the high-pressure ionization chamber.

[0089] The wide-range weak current amplifier with leakage current measurement is connected to the signal input and switching module. The wide-range weak current amplifier with leakage current measurement is used to switch different amplification levels based on the signal path, amplify the weak current signal according to the corresponding range, and output an amplified signal.

[0090] The leakage current measurement module is connected to the signal input and switching module and the wide-range weak current amplifier with leakage current measurement, respectively. The leakage current measurement module is used to measure the electronic leakage current signal at each of the amplification levels and obtain the measurement result.

[0091] The control and processing module is connected to the signal input and switching module, the wide-range weak current amplifier with leakage current measurement, and the leakage current measurement module, respectively. The control and processing module is used to perform leakage current compensation on the amplified signal according to the measurement result to reduce the measurement lower limit; and to control the wide-range weak current amplifier with leakage current measurement to switch between different amplification levels based on the leakage current measurement value at each amplification level.

[0092] Based on the same inventive concept, this application also provides a wide-range weak current amplification method based on the wide-range weak current amplification device mentioned above. The solution provided by this wide-range weak current amplification method is similar to the solution described in the wide-range weak current amplifier with leakage current measurement described above. Therefore, the specific limitations in the embodiments of the wide-range weak current amplification method provided below can also refer to the limitations of the wide-range weak current amplifier with leakage current measurement described above, and will not be repeated here.

[0093] In one exemplary embodiment, such as Figure 7 As shown, a wide-range weak current amplification method is provided. The wide-range weak current amplification method is implemented based on the wide-range weak current amplification device and includes the following steps.

[0094] S1: Receives external weak current signals and selectively turns the signal path on or off; the weak current signals include: the output signal of the high-pressure ionization chamber.

[0095] S2: Based on the signal path, switch different amplification levels to amplify the weak current signal according to the corresponding range and output an amplified signal.

[0096] S3: Based on each of the aforementioned amplification levels, measure the electronic leakage current signal at each of the aforementioned amplification levels to obtain the measurement results.

[0097] S4: Based on the measurement results, leakage current compensation is performed on the amplified signal to reduce the measurement lower limit, and the leakage current measurement value under each amplification level is used as a reference to control the switching of different amplification levels.

[0098] This application provides a wide-range, low-current amplifier, apparatus, and method for leakage current measurement. On one hand, an input signal switching circuit receives the output signal from a high-pressure ionization chamber and controls the on / off state of a reed relay based on an externally input first standard TTL or CMOS level signal, achieving precise switching between different amplification circuits and directing the signal to the corresponding amplification circuit, ensuring that signals of different ranges can be amplified and processed accordingly. On the other hand, the first and second amplification circuits correspond to different amplification levels, effectively amplifying the high-pressure ionization chamber output signal and leakage current signal of the corresponding range. Combined with the processing of the output signal processing circuit, the accuracy and stability of the amplified signal are guaranteed. Furthermore, the switching logic drive circuit controls the analog electronic switch and reed relay based on externally input second and third standard TTL or CMOS level signals, realizing the logic drive for range switching and leakage current measurement. Combined with the measurement and subtraction of the leakage current signal, this effectively reduces the lower limit of gamma dose rate measurement and solves the problem of logic errors in the range switching of traditional amplifiers. Therefore, this application integrates the input signal switching circuit, the first amplifier circuit, the second amplifier circuit, the switching logic drive circuit, and the output signal processing circuit into the same amplifier. Through the synergistic effect of the above multiple circuits, it can achieve rapid and accurate switching between high, medium, and low ranges, effectively improving the accuracy of the actual gamma dose rate in the measurement environment.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A wide-range, low-current amplifier with leakage current measurement, characterized in that, include: The input signal switching circuit is connected to the high-voltage end of the high-pressure ionization chamber at its input terminal, and is used to switch between different amplifier circuits. The input signal switching circuit includes: a first reed relay, a second reed relay, a first reed relay coil, and a second reed relay coil; The coil of the first reed relay is used to control the on / off state of the first reed relay; The coil of the second reed relay is used to control the on / off state of the second reed relay; When the first reed relay is turned on, it realizes the measurement of the output signal of the high-pressure ionization chamber under the low-range amplification setting; when the first reed relay is turned off, it realizes the measurement of the leakage current signal under the low-range amplification setting. When the second reed relay is turned on, it realizes the measurement of the high-pressure ionization chamber output signal under the medium-range amplification range or the high-range amplification range; when the second reed relay is turned off, it realizes the measurement of the leakage current signal under the medium-range amplification range or the high-range amplification range. The first amplification circuit has its input terminal connected to the first output terminal of the input signal switching circuit, and is used to amplify the output signal of the high-pressure ionization chamber and the leakage current signal of the corresponding range at a low range amplification level. The second amplifier circuit has its input terminal connected to the second output terminal of the input signal switching circuit, and is used to amplify the output signal of the high-pressure ionization chamber and the corresponding leakage current signal at a high-range amplification level or a medium-range amplification level. A switching logic drive circuit is connected to the input signal switching circuit, the first amplifier circuit, and the second amplifier circuit respectively, and is used to realize the logic drive for range switching and leakage current measurement. An output signal processing circuit is connected to the output terminals of the first amplifier circuit and the second amplifier circuit, respectively, and is used to switch, select, low-pass filter and series match the amplified signals output by the first amplifier circuit and the second amplifier circuit. The amplified signal output value of the output signal processing circuit is used for A / D sampling to obtain A / D sample value. The A / D sample value is used to subtract the leakage current component in the output signal of the high-pressure ionization chamber to achieve leakage current compensation and reduce the measurement lower limit of γ dose rate. The A / D sampled value is also used as a reference for range switching; When the A / D sampling value corresponding to the current amplification level is greater than the maximum value of the A / D conversion, the system switches to the higher amplification level; when the A / D sampling value corresponding to the current amplification level is less than or equal to the leakage current signal A / D sampling value corresponding to the current amplification level, the system switches to the lower amplification level.

2. The wide-range, low-current amplifier with leakage current measurement according to claim 1, characterized in that, The input signal switching circuit further includes: a first resistor; The first resistor is a metal film resistor with a resistance range of 1MΩ to 50MΩ.

3. The wide-range, low-current amplifier with leakage current measurement according to claim 1, characterized in that, The first amplifier circuit includes: a first operational amplifier, a second resistor, and a first capacitor; The input terminal of the first operational amplifier is connected to the output terminal of the first reed relay, one end of the second resistor is connected to the output terminal of the first operational amplifier, the other end of the second resistor is connected to the inverting input terminal of the first operational amplifier, and the first capacitor is connected in parallel with the second resistor.

4. The wide-range, low-current amplifier with leakage current measurement according to claim 1, characterized in that, The second amplifier circuit includes: a second operational amplifier, a third resistor, a second capacitor, a fourth resistor, a third capacitor, and a first two-to-one analog electronic switch; The input terminal of the second operational amplifier is connected to the output terminal of the second reed relay; one end of the third resistor is connected to the input terminal of the second operational amplifier, and the other end of the third resistor is grounded; the second capacitor is connected in parallel with the third resistor; one end of the fourth resistor is connected to the output terminal of the second operational amplifier, and the other end of the fourth resistor is connected to the inverting input terminal of the second operational amplifier; the third capacitor is connected in parallel with the fourth resistor; the input terminal of the first two-to-one analog electronic switch is connected to the output terminal of the second operational amplifier.

5. The wide-range, low-current amplifier with leakage current measurement according to claim 1, characterized in that, The switching logic drive circuit includes: a first MOSFET, a second MOSFET, a first NOT gate, a fifth resistor, a sixth resistor, and a second 2-to-1 analog electronic switch; The gate of the first MOSFET is connected to an external device for outputting standard TTL or CMOS level signals through the fifth resistor. The source of the first MOSFET is grounded, and the drain of the first MOSFET is connected to one end of the coil of the first reed relay. The other end of the coil of the first reed relay is connected to a power supply. The fifth resistor is a current-limiting resistor. The gate of the second MOSFET is connected to the output of the first NOT gate through the sixth resistor. The source of the second MOSFET is grounded, and the drain of the second MOSFET is connected to one end of the coil of the second reed relay. The other end of the coil of the second reed relay is connected to the power supply. The input of the first NOT gate is connected to an external device for outputting standard TTL or CMOS level signals. The sixth resistor is a current-limiting resistor. The control terminal of the second 2-to-1 analog electronic switch is connected to the output terminal of the first NOT gate, or the control terminal of the second 2-to-1 analog electronic switch is connected to an external device for outputting standard TTL or CMOS level signals. The input terminals of the second 2-to-1 analog electronic switch are respectively connected to the first amplifier circuit and the second amplifier circuit, and the output terminal of the second 2-to-1 analog electronic switch is connected to the output signal processing circuit.

6. A wide-range, low-current amplification device, characterized in that, The wide-range weak current amplification device includes: a signal input and switching module, a leakage current measurement module, a control and processing module, and a wide-range weak current amplifier with leakage current measurement as described in any one of claims 1-5. The signal input and switching module is used to receive external weak current signals and selectively turn on or off the signal path; the weak current signals include: the output signal of the high-pressure ionization chamber; The wide-range weak current amplifier with leakage current measurement is connected to the signal input and switching module. The wide-range weak current amplifier with leakage current measurement is used to switch different amplification levels based on the signal path, amplify the weak current signal according to the corresponding range, and output an amplified signal. The leakage current measurement module is connected to the signal input and switching module and the wide-range weak current amplifier with leakage current measurement respectively. The leakage current measurement module is used to measure the electronic leakage current signal at each of the amplification levels and obtain the measurement result. The control and processing module is connected to the signal input and switching module, the wide-range weak current amplifier with leakage current measurement, and the leakage current measurement module, respectively. The control and processing module is used to perform leakage current compensation on the amplified signal according to the measurement result to reduce the measurement lower limit; and to control the wide-range weak current amplifier with leakage current measurement to switch between different amplification levels based on the leakage current measurement value at each amplification level.

7. A wide-range, low-current amplification method, characterized in that, The wide-range weak current amplification method is implemented based on the wide-range weak current amplification device as described in claim 6, and the wide-range weak current amplification method includes: It receives weak current signals from the outside and selectively turns the signal path on or off; the weak current signals include: the output signal of the high-pressure ionization chamber; Based on the signal path, different amplification levels are switched to amplify the weak current signal according to the corresponding range, and an amplified signal is output. Based on each of the aforementioned amplification levels, the electronic leakage current signal at each of the aforementioned amplification levels is measured to obtain the measurement results; Based on the measurement results, leakage current compensation is performed on the amplified signal to reduce the measurement lower limit, and the leakage current measurement value at each amplification level is used as a reference to control the switching of different amplification levels.

Images