A dynamic range measurement circuit and method for radiation dose measurement

Abstract

The present invention relates to the technical field of radiation dose measurement, and specifically discloses a dynamic range measurement circuit and a measurement method applied to radiation dose determination. The measurement circuit includes a buffer module, a pre-sampling module, a signal conditioning module, a measurement module, and a main control module. The pre-sampling module obtains the signal amplitude prior to the measurement module and dynamically adjusts the signal parameters through the signal conditioning module. The measurement module measures the signal synchronously buffered in the buffer module, and finally processes and superimposes the parameters of the signal conditioning module in the main control module to obtain the final measurement result. The present invention can achieve fewer gear settings and higher sensitivity in the case of a wide measurement range, and can accurately measure pulse signals in the dynamic buffer mode.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation dose measurement, and in particular to a dynamic range measurement circuit and a measurement method for radiation dose measurement. Background Art

[0002] In the field of radiation dose measurement, a large measurement range is usually required to meet the radiation measurement requirements. Currently, all common ADC (Analog to Digital Converter) architectures need to perform binary comparison and quantization on the input signal with a reference voltage. Therefore, when the resolution of the ADC and the reference voltage parameter are determined, the larger the measurement range, the larger the value of the least significant bit (1LSB), which means a reduction in measurement accuracy.

[0003] The measurement scheme of the designed dosimeter usually uses an operational amplifier cascaded with an ADC to amplify and measure the signal. This scheme needs to use the following formula to evaluate the measurement accuracy:

[0004]

[0005]

[0006]

[0007]

[0008] In the formula, FSR is the full-scale range of the ADC, which is equivalent to the measurement range of the dosimeter; V REF is the reference voltage value input to the ADC; A is the gain of the operational amplifier for the input signal; 1LSB is the least significant bit, representing the smallest unit of the full-scale input range; n is the ADC resolution; Sensitivity is the ADC sensitivity, which is proportional to the measurement accuracy and is the main performance index determining the measurement accuracy; The formula (4) obtained by combining formula (1), formula (2) and formula (3) can intuitively present the influence of the measurement range and the PGA gain on the ADC sensitivity, and reflect their influence on the accuracy of the dosimeter.

[0009] As shown in formula (4), in order to achieve higher measurement accuracy, the dosimeter usually uses a larger operational amplifier gain. However, as shown in formula 1, a larger operational amplifier gain greatly reduces the full-scale range of the ADC, thereby greatly reducing the measurement range of the dosimeter. Therefore, in order to achieve a larger measurement range, the measurement accuracy often needs to be sacrificed. Some products on the market use a programmable operational amplifier to switch to a high gain at a low range to obtain higher accuracy, but at a high range, the gain still needs to be reduced to sacrifice the measurement accuracy to meet the measurement range requirements of the ADC. Summary of the Invention

[0010] In view of the above problems, the purpose of the present invention is to provide a dynamic range measurement circuit and a measurement method for radiation dose measurement, which can achieve fewer gear settings and higher sensitivity in a wide measurement range, and can accurately measure pulse signals in the dynamic buffer mode. The technical solutions are as follows:

[0011] A dynamic range measurement circuit for radiation dose measurement, comprising a buffer module, a pre-sampling module, a signal conditioning module, a measurement module and a main control module;

[0012] A plurality of buffer structures including buffer capacitors are connected in parallel in the buffer module, and the signal is buffered by controlling the charge and discharge of the buffer capacitors;

[0013] The pre-sampling module includes an operational amplifier circuit A1 and an ADC1 connected in cascade. The operational amplifier circuit A1 amplifies the input signal so that the ADC1 can quickly and roughly sample the signal within the full range, and sends the rough sampling result to the main control module;

[0014] The signal conditioning module includes a voltage conversion circuit composed of an operational amplifier circuit A3, an operational amplifier circuit A2 and a DAC; the main control module controls the DAC and the operational amplifier circuit A2 to output an offset voltage according to the measurement result of the pre-sampling module; the offset voltage and the buffered signal output by the buffer module are input to the operational amplifier circuit A3 to realize voltage level conversion of the buffered signal;

[0015] The measurement module includes an operational amplifier circuit A4 and an ADC2 connected in cascade. The operational amplifier circuit A4 amplifies the input converted signal and outputs it to the ADC2 for accurate measurement, and outputs the accurate measurement value to the main control module for processing to obtain the final measurement result.

[0016] Further, a variable resistor R is connected in series at the output end of the operational amplifier of the operational amplifier circuit A2 G3 and a resistor R L , and a switch S is connected in parallel at both ends of the variable resistor R G3 . When attenuation is required, the switch S w is disconnected to control the resistance value of the variable resistor R w to attenuate the DAC output voltage to obtain an offset voltage. When S G3 is closed, the DAC output is not attenuated to obtain an offset voltage; w The operational amplifier circuit A3 includes a differential operational amplifier, a variable resistor R

[0017] G1 and R G2 ; the offset voltage output by the operational amplifier circuit A2 is input to the negative-phase input end of the differential operational amplifier through the variable resistor R G1 , and the buffered signal output by the buffer module is also input through the variable resistor R G2 to the negative-phase input terminal of the differential operational amplifierInput to the non-inverting input terminal of the differential operational amplifier, and the gain is controlled by adjusting the variable resistors R G1 and R G2 The voltage difference between the buffered signal and the offset voltage is amplified to obtain the conversion signal;

[0018] One end of the variable resistor R G2 far from the differential operational amplifier is grounded through the switch S A . The switch S A is used to close when the output of the buffer module is turned off, so that the non-inverting input terminal of the differential operational amplifier is connected to the reference zero potential. At this time, the differential voltage at the input terminal of the differential operational amplifier is equal to the offset voltage, which is amplified to obtain the conversion signal. The measurement module measures this signal with the high-precision ADC2 and then processes it by the main control module to obtain the accurate offset voltage value. After the offset voltage measurement is completed, the switch S A is disconnected.

[0019] Furthermore, the buffer module includes a signal input switch S IN , a signal output switch S OUT , a buffer switch S N1 , a discharge switch S N0 and a buffer capacitor C N . The input signal is input through the signal input switch S IN . One end of the buffer switch S N1 is connected between the signal input switch S IN and the signal output switch S OUT , and the other end is grounded through the buffer capacitor C N . One end of the discharge switch S N0 is connected between the buffer switch S N1 and the buffer capacitor C N , and the other end is grounded through the discharge resistor R N .

[0020] A dynamic range measurement method applied to radiation dose measurement, comprising the following steps:

[0021] Step 1: The pre-sampling module uses the high-speed ADC1 to coarsely sample the signal amplified by its pre-stage operational amplifier and sends the coarse sampling result to the main control module; meanwhile, the buffer module closes the signal input switch S IN and the buffer switch S N1 , and disconnects the signal output switch S OUT , and disconnects the discharge switch S N of the buffer capacitor C N0 ;

[0022] Step 2: When the buffering of the buffer capacitor C N , that is, when the charging is completed, the signal input switch S IN and the buffer switch S N1 are disconnected to complete the signal buffering;

[0023] Step 3: The main control module processes the amplitude of the input signal obtained from the coarse sampling value of the pre-sampling module. Based on this, the main control module controls the DAC in the signal conditioning module to output a specified voltage, which is amplified by the operational amplifier circuit A2 and then output as an offset voltage to the voltage level conversion circuit composed of the operational amplifier circuit A3;

[0024] Step 4: The buffer module closes the signal output switch S OUT and the buffer switch S N1 to output the buffered signal to the signal conditioning module to superimpose the offset voltage to obtain a conversion signal that meets the input requirements of the measurement module;

[0025] Step 5: The pre-stage operational amplifier circuit A4 in the measurement module amplifies the conversion signal and then outputs it to the ADC2 for precise measurement, and outputs the precise measurement value to the main control module for processing to obtain the final measurement result;

[0026] Step 6: After the measurement module completes the measurement, the buffer module disconnects the signal output switch S OUT and the buffer switch S N1 , and closes the discharge switch S N0 to discharge the buffer capacitor to the discharge resistor R N ; after the electrical energy of the buffer capacitor C N is emptied, the discharge switch S N0 is disconnected and waits for the next signal buffering.

[0027] Further, in the step 3, the signal conditioning module introduces the feedback measurement of the offset voltage to solve the error introduced by the operational amplifier circuit A2. A switch S A is introduced in the operational amplifier circuit A3 for closing when the output of the buffer module is turned off; the feedback measurement of the offset voltage is performed in the step of adjusting the parameters of the signal conditioning module in the dynamic range mode measurement process, and the switch S A is disconnected when the offset voltage measurement is completed.

[0028] Furthermore, in the step 1, the sampling action of the pre-sampling module is synchronized with the sequential buffering actions of the buffer structure, that is, while the pre-sampling module samples, a specified buffer structure is designated to buffer the signal at the current sampling moment, and when the pre-sampling module performs the next sampling, it switches to the next specified buffer structure to buffer the signal at the new sampling moment

[0029] The beneficial effects of the present invention are:

[0030] 1) The present invention introduces a signal conditioning module of a voltage level conversion circuit: a relatively large measurement range of a dosimeter often requires reducing the gain at the expense of measurement accuracy. By using a voltage level conversion circuit to superimpose an offset voltage, the signal amplitude can be converted to an appropriate range to meet the measurement requirements of the subsequent ADC. The main control module can obtain an accurate result by adding the influence of this offset voltage during the processing of the final measurement result. Therefore, the advantage of the present invention is that it can still use a relatively high gain when achieving a wide measurement range, thereby obtaining a relatively high sensitivity in this case.

[0031] 2) Introduce a buffer module: The purpose of introducing a buffer module is to solve the delay problem of the signal conditioning module by buffering the signal. That is, in the case of no buffer structure, the overvoltage signal has entered the measurement module ADC through the conditioning module before the signal conditioning module completes its operation, and accurate measurement of pulse signals can be achieved in the dynamic buffer mode. Description of the Drawings

[0032] Figure 1 is the schematic diagram of the dynamic range measurement circuit of the present invention.

[0033] Figure 2 is the schematic diagram of the operational amplifier circuit A2.

[0034] Figure 3 is the schematic diagram of the operational amplifier circuit A3.

[0035] Figure 4 is the flow chart of the dynamic range mode measurement of the present invention.

[0036] Figure 5 is the flow chart of the dynamic buffer measurement. Detailed Embodiment

[0037] The following further describes the present invention in detail with reference to the drawings and specific embodiments. A dynamic range measurement circuit applied to radiation dose measurement is as Figure 1 shown. Each module is controlled by the main control module. The input signal is first roughly sampled by the pre-sampling module and buffered by the buffer module, then undergoes voltage level conversion in the signal conditioning module, and finally the accurate value is obtained by the measurement module. Among them, the operational amplifier circuit A1 in the pre-sampling module is cascaded with ADC1 for rapid rough sampling; the main control module includes a control chip and its related circuits for module control and data processing, and the control chip includes chips with control and operation capabilities such as FPGA, MCU, DSP, etc.; in the buffer module, multiple are connected in parallel, including buffer switch S N1 , discharge switch S N0 , discharge resistor R N and buffer capacitor C NThe buffer structure realizes the buffering of signals by controlling the charging and discharging of the buffer capacitor; the signal conditioning module includes a voltage conversion circuit composed of an operational amplifier circuit A3, an operational amplifier circuit A2, and a DAC to realize the voltage level conversion of the buffered signal; the measurement module includes an operational amplifier circuit A4 and an ADC2 to accurately measure the signal after voltage conversion.

[0038] The operational amplifier circuit refers to the general term including the operational amplifier and its related amplification circuits. The operational amplifier includes programmable operational amplifiers PGA, differential operational amplifiers, precision operational amplifiers, etc. with the function of amplifying analog signals.

[0039] The operational amplifier circuit A1 is an amplification circuit composed of a precision operational amplifier, and its function is to amplify the input signal so that ADC1 can sample the signal within the full scale range.

[0040] The operational amplifier circuit A4 is an ADC drive circuit composed of a precision operational amplifier, and its function is to amplify or buffer the input signal so that ADC2 can accurately sample the converted signal.

[0041] The operational amplifier circuit A2 is composed of a precision operational amplifier such as Figure 2 the attenuation circuit shown, and R G3 is a variable resistor used to adjust the attenuation coefficient. When attenuation is required, S w is disconnected to control R G3 to attenuate the DAC output voltage to obtain an offset voltage. When S w is closed, the DAC output is not attenuated to obtain the offset voltage. The reason for adding a series resistor to the operational amplifier circuit A2 for attenuation voltage division is to reduce the influence of the DAC linear error in the small range. For example, for a 12-bit DAC with a 4.096V reference voltage, when the DAC outputs a 10mV voltage, if its linear error is 4LSB, its output range is 10mV ± 4mV, and the output error caused by the DAC linear error is as high as 40%. If the DAC outputs 1000mV and then attenuates it by 100 times, the output error caused by the DAC linear error is less than 0.4%. Note that the positions of R G3 and R L can be interchanged.

[0042] The operational amplifier circuit A3 is composed of a differential operational amplifier circuit as shown in Figure 3 . The main control module controls the DAC and the operational amplifier circuit A2 to output an offset voltage to the negative input terminal of the differential operational amplifier according to the measurement result of the pre-sampling module. The buffered signal is input to the positive input terminal of the differential operational amplifier. By controlling the variable resistors R G1 and R G2Implement gain control. The voltage difference between the buffered signal and the offset voltage is amplified to obtain a conversion signal. By dynamically controlling the offset voltage to match the buffered signal, the amplified conversion signal at a higher gain meets the input requirements of the measurement module, achieving an increase in the measurement range at the same high gain. As proven by Equation 4, a higher gain brings higher measurement sensitivity, thus improving measurement accuracy. The increase in the measurement range at the same high gain means that an overall gain increase can be achieved within a larger measurement range of the dosimeter, so higher measurement accuracy can be brought. To improve measurement accuracy, the conditioning module introduces feedback measurement of the offset voltage. Therefore, a switch S is introduced into the operational amplifier circuit A3. A It is used to close when the output of the buffer module is turned off, so that the non-inverting input terminal of the differential operational amplifier is connected to the reference zero potential. At this time, the differential voltage at the input terminal of the differential operational amplifier is equal to the conversion signal obtained after the offset voltage is amplified. The high-precision ADC of the measurement module measures this signal and then processes it by the main control module to obtain the accurate offset voltage value. After the offset voltage measurement is completed, the switch S A is disconnected.

[0043] The present invention can still use a higher gain when achieving a wide measurement range, thus obtaining higher sensitivity in this case. Assuming that the effective resolution of the ADC is 0.1, the traditional scheme uses a gain of 1000 at a low measurement range to achieve a sensitivity of 0.0001 (effectively measuring to the fourth decimal place), but uses a gain of 10 at a high measurement range, and its sensitivity is 0.01 (effectively measuring to the second decimal place). The present invention cancels through the DAC and then amplifies, so a larger gain can be used at a high measurement range. For example, if a gain of 1000 is used, the sensitivity is 0.0001, and if a gain of 100 is used, the sensitivity is 0.001, achieving a higher comprehensive sensitivity relative to the traditional scheme. Especially in the medium and high measurement ranges, the present invention has a higher gain relative to it, that is, a relatively higher sensitivity is achieved.

[0044] The key of the present invention lies in the introduction of the pre-sampling module, the buffer module, and the signal conditioning module. The following is a detailed description of the functions of introducing these modules.

[0045] Dynamic range mode:

[0046] As described above, a larger measurement range often requires reducing the gain and sacrificing measurement accuracy. The present invention proposes a variable range mode based on the above circuit structure to solve this contradiction. By dynamically superimposing the offset voltage, signal conditioning at a high gain is achieved to meet the input requirements of the subsequent ADC2, thereby expanding the high-precision measurement range of the dosimeter.

[0047] As Figure 4 shown, during the measurement process, the pre-sampling module uses the high-speed ADC1 to coarsely sample the signal amplified by its previous-stage operational amplifier and sends the coarse sampling result to the main control module. At the same time, the buffer module closes the signal input switch S IN and the buffer switch SN1 and disconnect the signal output switch S OUT and the specified buffer capacitor C N discharge switch S N0 , and disconnect the signal input switch S when the buffer capacitor finishes buffering, i.e., when charging is completed IN and the buffer switch S N to complete signal buffering; The main control module processes the amplitude of the input signal obtained from the coarse sampling value of the pre-sampling module, and the main control module controls the DAC in the signal conditioning module to output a specified voltage accordingly. After being amplified by the next-stage operational amplifier circuit A2, it is output as an offset voltage to the voltage level conversion circuit composed of the operational amplifier circuit A3; Subsequently, the buffer module closes the signal output switch S OUT and the buffer switch S N1 to output the buffered signal to the signal conditioning module to superimpose the offset voltage to obtain a conversion signal that meets the input requirements of the measurement module; The pre-stage operational amplifier circuit A4 in the measurement module amplifies the conversion signal and then outputs it to ADC2 for precise measurement, and outputs the precise measurement value to the main control module for processing to obtain the final measurement result; After the measurement module completes the measurement, the buffer module will disconnect the signal output switch S OUT and the buffer switch S N1 and close the discharge switch S N0 to discharge the buffer capacitor to the discharge resistor R N , and after the electrical energy of the buffer capacitor is emptied, disconnect the discharge switch S N0 to wait for the next signal buffering.

[0048] To improve the measurement accuracy, the signal conditioning module introduces feedback measurement of the offset voltage to solve the error introduced by the operational amplifier circuit A2. A switch S is introduced in the operational amplifier circuit A3 A for closing when the buffer module closes the output, so that the positive input terminal of the differential operational amplifier is connected to the reference zero potential. At this time, the differential voltage at the input terminal of the differential operational amplifier is equal to the conversion signal obtained after the offset voltage is amplified. The high-precision ADC of the measurement module precisely measures this conversion signal, and the main control module can obtain the precise value of the offset voltage after processing. The feedback measurement of the offset voltage is executed in the step of adjusting the parameters of the signal conditioning module in the dynamic range mode measurement process. When the measurement of the offset voltage is completed, the switch S A is disconnected.

[0049] Dynamic buffering:

[0050] The buffer module is paralleled with multiple buffer structures each containing a buffer switch S N1 , a discharge switch S N0 , a discharge resistor R N and a buffer capacitor C N , and by controlling the multiple buffer structures to buffer the input signal in sequence, multi-point buffering of the signal within a certain period of time can be realized.

[0051] As shown Figure 5 in the figure, the sampling operation of the pre-sampling module is synchronized with the sequential buffering operations of the buffer structure. That is, while the pre-sampling module samples, a buffer structure is designated to buffer the signal at the current sampling moment. The next sampling of the pre-sampling module then switches to the next designated buffer structure to buffer the signal at the new sampling moment, and so on in a loop until the measurement condition is met and the signal conditioning module and measurement module at the subsequent stage are entered for precise measurement.

[0052] Explanation of the measurement condition: The measurement condition refers to the judgment condition for the rough sampling result of the pre-measurement module to exit the loop buffering of the buffer structure. A typical measurement condition is to find the peak value, that is, when it is judged that the peak value appears in the rough sampling result, the loop buffering is stopped and the signal conditioning module and measurement module are called to obtain the precise result.

[0053] The measurement discrimination is implemented by adopting a discriminant shifting scheme to replace the buffer module, that is, the ADC measurement result is discriminated. When the measurement result is close to the threshold value of the current gear (different gears correspond to different preset parameters of the conditioning module, that is, different amplification coefficients and offset voltage values), the gear is switched. Further, a prediction model can be established for discrimination, and the gear is shifted in advance if the prediction model is satisfied.

[0054] The buffering scheme has higher accuracy than the discriminant shifting scheme and will not have incorrect gear shifting (incorrect gear shifting may occur at the signal peak point, resulting in reduced accuracy after gear shifting). At the same time, this alternative scheme is compatible with the scheme proposed in the present invention. When all the buffer switches S N are disconnected and the signal input switch S IN and the output switch S OUT are closed, the buffering function of the buffer module fails and the above scheme can be executed. When the alternative scheme captures a pulse width that is relatively narrow, if a single ADC measurement is used (that is, the pre-measurement structure is cancelled), a high-cost high-speed and high-precision ADC needs to be selected. If a pre-sampling module including a low-cost high-speed ADC is introduced as in this scheme, there will be a problem of delay in that the overvoltage signal has entered the ADC of the measurement module through the conditioning module before the signal conditioning module completes its operation without a buffer module. Therefore, the dosimeter introducing the buffer module and the pre-sampling module has the advantages of lower cost and simpler delay control.

Claims

1. A dynamic range measurement circuit applied to radiation dose measurement, characterized in that, It includes a buffer module, a pre-sampling module, a signal conditioning module, a measurement module and a main control module; A plurality of buffer structures including buffer capacitors are connected in parallel in the buffer module, and the buffer of the signal is realized by controlling the charging and discharging of the buffer capacitors; The pre-sampling module includes an operational amplifier circuit A1 and an ADC1 connected in cascade. The operational amplifier circuit A1 amplifies the input signal so that the ADC1 can quickly and coarsely sample the signal within the full range, and sends the coarse sampling result to the main control module; The signal conditioning module includes a voltage conversion circuit composed of an operational amplifier circuit A3, an operational amplifier circuit A2 and a DAC. The main control module controls the DAC and the operational amplifier circuit A2 to output an offset voltage according to the measurement result of the pre-sampling module; the offset voltage and the buffered signal output by the buffer module are input to the operational amplifier circuit A3 to realize the voltage level conversion of the buffered signal; The measurement module includes an operational amplifier circuit A4 and an ADC2 connected in cascade. The operational amplifier circuit A4 amplifies the input converted signal and outputs it to the ADC2 for precise measurement, and outputs the precise measurement value to the main control module for processing to obtain the final measurement result; A variable resistor R is connected in series at the output terminal of the operational amplifier of the operational amplifier circuit A2 G3 and resistor R L . A switch S G3 is connected in parallel across both ends of the variable resistor R w . When attenuation is required, the switch S w is opened to control the resistance value of the variable resistor R G3 to attenuate the DAC output voltage to obtain an offset voltage. When S w is closed, the DAC output is not attenuated to obtain an offset voltage; The operational amplifier circuit A3 includes a differential operational amplifier and variable resistors R G1 and R G2 ; the offset voltage output by the operational amplifier circuit A2 is input to the negative-phase input terminal of the differential operational amplifier through the variable resistor R G1 , and the buffer signal output by the buffer module is input to the positive-phase input terminal of the differential operational amplifier through the variable resistor R G2 . By controlling the variable resistors R G1 and R G2 , gain control is achieved, and the voltage difference between the buffer signal and the offset voltage is amplified to obtain a conversion signal; Variable resistor R G2 One end far from the differential operational amplifier is grounded through the switch S A The switch S A Is used to close when the buffer module turns off the output, so that the non-inverting input terminal of the differential operational amplifier is connected to the reference zero potential. At this time, the differential voltage at the input terminal of the differential operational amplifier is equal to the offset voltage amplified to obtain the conversion signal. The high-precision ADC2 of the measurement module measures this signal and then processes it by the main control module to obtain the accurate offset voltage value. After the offset voltage measurement is completed, the switch S A Is disconnected.

2. The dynamic range measurement circuit applied to radiation dose measurement according to claim 1, characterized in that The buffer module includes a signal input switch S IN , a signal output switch S OUT , a buffer switch S N1 , a discharge switch S N0 and a buffer capacitor C N ; The input signal is input through the signal input switch S IN . One end of the buffer switch S N1 is connected between the signal input switch S IN and the signal output switch S OUT , and the other end is grounded through the buffer capacitor C N ; One end of the discharge switch S N0 is connected between the buffer switch S N1 and the buffer capacitor C N , and the other end is grounded through the discharge resistor R N .

3. A measurement method for a dynamic range measurement circuit applied to radiation dose measurement according to claim 2, characterized in that It includes the following steps: Step 1: The pre-sampling module uses the high-speed ADC1 to coarsely sample the signal amplified by its pre-stage operational amplifier and sends the coarse sampling result to the main control module; meanwhile, the buffer module closes the signal input switch S IN and the buffer switch S N1 , and disconnects the signal output switch S OUT , and disconnects the discharge switch S N of the buffer capacitor C N0 ; Step 2: At the buffer capacitor C N When the buffering is completed, i.e., the charging is completed, disconnect the signal input switch S IN and the buffer switch S N1 Complete the signal buffering; Step 3: The main control module processes the amplitude of the input signal obtained according to the coarse sampling value of the pre-sampling module. Based on this, the main control module controls the DAC in the signal conditioning module to output a specified voltage, which is amplified by the operational amplifier circuit A2 and then output as an offset voltage to the voltage level conversion circuit composed of the operational amplifier circuit A3; Step 4: Buffer module closing signal output switch S OUT and buffer switch S N1 Output the buffer signal to the signal conditioning module to superimpose an offset voltage to obtain a conversion signal that meets the input requirements of the measurement module; Step 5: The pre-stage operational amplifier circuit A4 in the measurement module amplifies the converted signal and then outputs it to the ADC2 for precise measurement, and outputs the precise measurement value to the main control module for processing to obtain the final measurement result; Step 6: After the measurement module completes the measurement, the buffer module will disconnect the signal output switch S OUT and the buffer switch S N1 , and close the discharge switch S N0 to discharge the buffer capacitor to the discharge resistor R N ; after the electrical energy of the buffer capacitor C N is emptied, disconnect the discharge switch S N0 and wait for the next signal buffering.

4. The measuring method according to claim 3, characterized in that In step 3, the signal conditioning module introduces the feedback measurement of the offset voltage to solve the error caused by introducing the operational amplifier circuit A2, and a switch S is introduced into the operational amplifier circuit A3 A which is used to close when the buffer module shuts down the output; the feedback measurement of the offset voltage is performed in the step of adjusting the parameters of the signal conditioning module in the dynamic range mode measurement process, and the switch S is disconnected when the offset voltage measurement is completed A .

5. The measuring method according to claim 3, characterized in that, In the step 1, the sampling action of the pre-sampling module is synchronized with the sequential buffering actions of the buffer structures, that is, while the pre-sampling module samples, a specified buffer structure is designated to buffer the signal at the current sampling moment, and the next sampling of the pre-sampling module switches to the next specified buffer structure to buffer the signal at the new sampling moment.

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