阅读说明：本技术 一种用于测氚电离室的大动态范围电流转换电路及方法 (Large-dynamic-range current conversion circuit and method for tritium measurement ionization chamber ) 是由 林奎成 付军 秦驰 王中成 于 2019-09-16 设计创作，主要内容包括：本发明公开了一种用于测氚电离室的大动态范围电流转换电路及方法,该电路包括依次连接的电离室、跨阻放大电路、ADC电路、微处理器和信号输出端,以及与微处理器和跨阻放大电路连接的跨阻切换电路；所述方法包括电离室输出电流信号；跨阻放大电路进行I-V转换；ADC电路将电压信号转换为数字信号,并将数字信号输出到微处理器中；微处理器将接收到的数字信号转换为数字电流值,同时微处理器控制跨阻切换电路切换接入跨阻放大电路中的跨阻；信号输出端输出经微处理器进行数字化滤波、降低信号噪声处理后得到的数字电流值。通过上述方案,本发明达到了实现了现有电离室电流信号处理需求的目的,具有很高的实用价值和推广价值。(The invention discloses a large dynamic range current conversion circuit and a method for measuring a tritium ionization chamber, wherein the circuit comprises the ionization chamber, a transimpedance amplification circuit, an ADC (analog to digital converter) circuit, a microprocessor, a signal output end and a transimpedance switching circuit, wherein the ionization chamber, the transimpedance amplification circuit, the ADC circuit, the microprocessor and the signal output end are sequentially connected; the method includes ionizing a chamber output current signal; the trans-impedance amplifying circuit performs I-V conversion; the ADC circuit converts the voltage signal into a digital signal and outputs the digital signal to the microprocessor; the microprocessor converts the received digital signal into a digital current value, and controls the transimpedance switching circuit to switch into the transimpedance in the transimpedance amplifying circuit; the signal output end outputs a digital current value obtained by carrying out digital filtering and signal noise reduction processing by the microprocessor. Through the scheme, the invention achieves the purpose of meeting the current signal processing requirement of the existing ionization chamber, and has very high practical value and popularization value.)

1. A large dynamic range current conversion circuit for a tritium measuring ionization chamber is characterized by comprising an ionization chamber for generating a weak current signal, a transimpedance amplification circuit for receiving current generated by the ionization chamber, an ADC (analog to digital converter) circuit which is connected with the transimpedance amplification circuit and has high precision, a microprocessor which is connected with the ADC circuit, a transimpedance switching circuit which is connected with the microprocessor and returns a signal to the transimpedance amplification circuit, and a signal output end which is connected with the microprocessor; the transimpedance switching circuit comprises an amplifier ADA4530-1ARZ chip, a relay K1 and a high-resistance resistor R11, wherein the output end of the amplifier ADA4530-1ARZ chip is connected with a microprocessor, one end of the relay K1 and the other end of the relay R11 are connected with the negative input end of the ADA4530-1ARZ chip after being connected in series, one end of the high-resistance resistor R8 is simultaneously connected with the negative input end of the relay K1 and the negative input end of the ADA4530-1ARZ chip, the other end of the high-resistance resistor R8 is connected with the output end of the ADA4530-1ARZ chip, the positive input end of the ADA4530-1 AR.

2. The large dynamic range current conversion circuit for tritium measurement ionization chamber according to claim 1, wherein the current output by the ionization chamber spans 7 orders of magnitude, and wherein switching of the measurement range is realized by controlling the connection of a high resistance value resistor R11 in the transimpedance amplification circuit through a microprocessor.

3. The large dynamic range current-to-voltage conversion circuit for a tritium-measuring ionization chamber of claim 2, wherein the transimpedance amplification circuit is a current-to-voltage conversion circuit.

4. The large dynamic range current conversion circuit for tritium measuring ionization chamber according to claim 3, wherein the ADC circuit employs a 24-bit analog-to-digital conversion chip ADS1255, wherein the ADC circuit is used for collecting the voltage signal converted by the transimpedance amplification circuit.

5. A method for a large dynamic range current transformation circuit for a tritium ionization chamber according to any one of claims 1 to 4, comprising the steps of:

(S1) the ionization chamber outputting a current signal between 10fA and 100 nA;

(S2) the transimpedance amplification circuit converts the current signal output from the ionization chamber into a voltage signal;

(S3) the ADC circuit converting the voltage signal into a digital signal and outputting the digital signal to the microprocessor;

(S4) the microprocessor converts the received digital signal into a digital current value, and simultaneously controls the transimpedance switching circuit to switch into the transimpedance in the transimpedance amplifying circuit;

(S5) the signal output end outputs a digital current value obtained by carrying out digital filtering and signal noise reduction processing by the microprocessor.

Technical Field

The invention belongs to the technical field of electronics, and particularly relates to a large-dynamic-range current conversion circuit and method for a tritium measuring ionization chamber.

Background

The intensity of the current generated by the ionization chamber in the tritium measuring instrument is usually between 1fA and 100nA, the requirement on the dynamic range of a corresponding ionization chamber current conversion circuit is high, the requirement on the sensitivity is also high, and the generated signal is easily influenced by external factors such as electromagnetic interference and the like due to low current lower line, so that the current conversion circuit is required to have good noise resistance.

In the conventional ionization chamber current signal processing method, in order to realize large dynamic range measurement, a multi-stage amplification method is generally adopted. Because the noise is introduced into the multistage amplifier, and the noise at the front stage is easily amplified by the rear stage, the measurement lower line is limited, the magnitude of 100fA is usually achieved, and the measurement lower limit and the measurement sensitivity of the tritium measuring instrument are directly influenced. Therefore, it is difficult to simultaneously implement the measurement of the switching of the weak circuit with large dynamic range and lower limit by the multi-stage amplification method, and therefore, how to solve the problems existing in the prior art is a problem that needs to be solved urgently by those skilled in the art.

Disclosure of Invention

The invention aims to provide a large dynamic range current conversion circuit and method for a tritium measurement ionization chamber, and mainly solves the problem that the conventional ionization chamber signal processing method in the prior art is difficult to realize large dynamic range and current conversion measurement simultaneously through a multi-stage amplification method.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a large dynamic range current conversion circuit for a tritium measuring ionization chamber comprises an ionization chamber, a transimpedance amplification circuit, an ADC (analog to digital converter) circuit, a microprocessor, a transimpedance switching circuit and a signal output end, wherein the ionization chamber is used for generating weak current signals; the transimpedance switching circuit comprises an amplifier ADA4530-1ARZ chip with an output end connected with a microprocessor, a relay K1 and a high-resistance resistor R11, wherein one end of the relay K1 and the other end of the relay R11 are connected with the negative input end of the ADA4530-1ARZ chip after being connected in series, one end of the relay K1 and the negative input end of the ADA4530-1ARZ chip are connected, the other end of the relay K1 and the high-resistance resistor R8 are connected with the output end of the ADA4530-1ARZ chip, the positive input end of the ADA4530-1ARZ chip is grounded, and the output end of the ADA4530-1ARZ chip is connected with the.

Further, the current output by the ionization chamber spans 7 orders of magnitude, wherein the switching of the measuring range is realized by controlling a high-resistance resistor R11 in the transimpedance amplification circuit through a microprocessor.

Further, the transimpedance amplification circuit is a current-voltage conversion circuit.

Specifically, the ADC circuit adopts a 24-bit analog-to-digital conversion chip ADS1255, wherein the ADC circuit is configured to collect a voltage signal converted by the transimpedance amplification circuit.

A method for measuring a large dynamic range current switching circuit of a tritium ionization chamber, comprising the steps of:

(S1) the ionization chamber outputting a current signal between 10fA and 100 nA;

(S2) the transimpedance amplification circuit converts the current signal output from the ionization chamber into a voltage signal;

(S3) the ADC circuit converting the voltage signal into a digital signal and outputting the digital signal to the microprocessor;

(S4) the microprocessor converts the received digital signal into a digital current value, and simultaneously controls the transimpedance switching circuit to switch into the transimpedance in the transimpedance amplifying circuit;

(S5) the signal output end outputs a digital current value obtained by carrying out digital filtering and signal noise reduction processing by the microprocessor.

Compared with the prior art, the invention has the following beneficial effects:

the invention carries out current-voltage conversion on the current generated by the ionization chamber through the transimpedance amplification circuit, the converted voltage is converted into a digital signal by the ADC circuit, the digital signal is converted into a digital current value through the microprocessor, meanwhile, the microprocessor carries out digital filtering and signal noise reduction processing and then passes through a digital current value at the signal output end, and the microprocessor simultaneously controls the transimpedance of the transimpedance switching circuit to be connected into the transimpedance amplification circuit, thereby switching the measuring range of the output current of the ionization chamber. The large dynamic range current conversion circuit and the conversion method for signal processing of the ionization chamber, which are provided by the invention, can automatically realize current measurement of 10 fA-100 nA level, can meet the current signal processing requirement of the existing ionization chamber, and have stronger practicability.

Drawings

Fig. 1 is a schematic block diagram of the circuit of the present invention.

Fig. 2 is a flow chart of the operation of the present invention.

Fig. 3 is a schematic diagram of a transimpedance switching and amplifying circuit according to the present invention.

Fig. 4 is a schematic diagram of an ADC circuit of the present invention.

FIG. 5 is a comparison graph of the current conversion circuit results of the circuit of the present invention and a TYNE 7045 type tritium measuring instrument.

Detailed Description

The present invention is further illustrated by the following examples and figures, and embodiments of the present invention include, but are not limited to, the following examples.