Pre-amplifier

Abstract

The embodiment of the invention relates to the technical field of circuit devices except for detectors, in particular to a pre-amplifier, which is suitable for amplifying an output signal of a fission ionization chamber, and comprises an anode receiving and amplifying circuit used for receiving and amplifying an output signal of a high-voltage end of the fission ionization chamber; the cathode receiving and amplifying circuit is used for receiving and amplifying an output signal of the grounding end of the fission ionization chamber; a differential amplification circuit which receives the signals amplified by the anode reception amplification circuit and the cathode reception amplification circuit and reduces noise in the signals; the differentiating circuit is connected with the output end of the differential amplification circuit and is used for receiving and adjusting an output signal of the differential amplification circuit; and a power supply. The preamplifier can amplify the output signals of the high-voltage end and the grounding end of the fission ionization chamber, it is ensured that the output signals can be normally recognized and read, the signal-to-noise ratio and the resolution ratio can be improved, the accuracy and definition of the output signals can be improved, and the actual operation condition in a reactor can be accurately monitored.

Description

Technical Field

[0001] Embodiments of the present application relate to the technical field of circuit devices other than detectors, and more particularly to a preamplifier. Background Art

[0002] The statements herein merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] To monitor the operation of a reactor core, fission ionization chambers are usually arranged near the core to monitor the neutron flux in the core. Different detectors are used to measure the changes in neutron flux in the source range, intermediate range, and power range. However, due to the high temperature in the reactor core, the electronic devices for identifying and processing detector signals cannot work in close proximity. The output signals received by the detectors need to be led out through long cables, during which they are vulnerable to various interferences and noises, resulting in the output signals being unable to reflect the actual operating conditions in the core. Summary of the Invention

[0004] A brief overview of the present application is given below to provide a basic understanding of certain aspects of the present application. It should be understood that this overview is not an exhaustive overview of the present application. It is not intended to identify the key or important parts of the present application, nor is it intended to limit the scope of the present application. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0005] Embodiments of the present application provide a preamplifier suitable for amplifying the output signals of fission ionization chambers, which includes: an anode receiving and amplifying circuit configured such that its input terminal is connected to the high-voltage terminal of the fission ionization chamber for receiving and amplifying the output signal of the high-voltage terminal of the fission ionization chamber; a cathode receiving and amplifying circuit configured such that its input terminal is connected to the grounded terminal of the fission ionization chamber for receiving and amplifying the output signal of the grounded terminal of the fission ionization chamber; a differential amplifying circuit configured to be respectively connected to the output terminals of the anode receiving and amplifying circuit and the cathode receiving and amplifying circuit, receiving the signals amplified by the anode receiving and amplifying circuit and the cathode receiving and amplifying circuit, and reducing the noise in the signals; a differentiating circuit configured to be connected to the output terminal of the differential amplifying circuit for receiving and adjusting the output signal of the differential amplifying circuit; and a power supply for providing operating voltages for the anode receiving and amplifying circuit, the cathode receiving and amplifying circuit, the differential amplifying circuit, and the differentiating circuit.

[0006] The preamplifier in the embodiments of the present application amplifies the output signals of the high-voltage end and the grounded end of the fission ionization chamber through the anode receiving amplifier circuit and the cathode receiving amplifier circuit respectively, ensuring that they can be normally recognized and read. Moreover, the differential amplifier circuit is used to denoise the amplified output signals to improve the signal-to-noise ratio, and the differentiating circuit is used to adjust the denoised signals to further improve the signal-to-noise ratio and resolution, enhancing the accuracy and clarity of the output signals. Thus, accurate monitoring of the actual operating conditions inside the reactor is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Other objects and advantages of the present application will become apparent and help to provide a comprehensive understanding of the present application through the description of the embodiments of the present application with reference to the accompanying drawings below.

[0008] Figure 1 is a schematic structural diagram of a preamplifier according to an embodiment of the present application;

[0009] Figure 2 is a schematic structural diagram of the anode receiving amplifier circuit and the cathode receiving amplifier circuit according to an embodiment of the present application;

[0010] Figure 3 is a schematic structural diagram of a differential amplifier circuit according to an embodiment of the present application.

[0011] DESCRIPTION OF THE REFERENCE NUMERALS:

[0012] 1. Fission ionization chamber; 101. High-voltage end; 102. Grounded end;

[0013] 10. Anode receiving amplifier circuit; 11. Input circuit; 111. First field-effect transistor; 112. First resistor; 113. First capacitor; 12. Amplifier circuit; 121. Second triode; 122. Second resistor; 123. Third resistor; 124. Second capacitor; 125. Third capacitor; 13. Constant current source circuit; 131. Third triode; 132. Fourth resistor; 133. Fifth resistor; 14. Follower circuit; 141. Fourth triode; 142. Sixth resistor; 15. Feedback circuit; 151. Fourth capacitor; 152. Seventh resistor; 16. Operational amplifier circuit; 161. First amplifier; 162. Eighth resistor; 163. Ninth resistor; 164. Tenth resistor; 165. Fifth capacitor; 166. Sixth capacitor;

[0014] 20. Cathode receiving amplifier circuit; 30. Differential amplifier circuit; 31. Second amplifier; 32. Eleventh resistor; 33. Twelfth resistor; 40. Differentiating circuit; 50. Power supply.

[0015] It should be noted that the drawings are not necessarily drawn to scale, but are only shown in a schematic manner that does not affect the understanding of the reader. Detailed implementation manners

[0016] In the following, exemplary embodiments of the present application will be described in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual implementation manners are described in the specification. However, it should be understood that many implementation-specific decisions must be made during the development of any such actual embodiment in order to achieve the specific goals of the developer, for example, to comply with those limitations related to the system and business, and such limitations may vary with different implementation manners. In addition, it should also be understood that although the development work may be very complex and time-consuming, for those skilled in the art who benefit from the content of the present application, such development work is only a routine task.

[0017] Here, it should also be noted that, in order to avoid obscuring the present application due to unnecessary details, only the device structures and / or processing steps closely related to the solution according to the present application are shown in the drawings, while other details less related to the present application are omitted.

[0018] The inventors of the present application have found that the output signal of the fission ionization chamber needs to be transmitted to the signal recognition and processing device through a cable with a length of dozens to more than one hundred meters, introducing a large input capacitance, which is likely to cause problems such as the signal being unable to be read out normally. Moreover, due to the complex electromagnetic environment inside the reactor and in the nuclear island, the signal is vulnerable to interference and noise during transmission, resulting in problems such as a decrease in the accuracy and clarity of the signal, and thus it is difficult to accurately monitor the operating conditions of the reactor.

[0019] Based on this, the embodiments of the present application provide a preamplifier, which is suitable for amplifying the output signal of the fission ionization chamber, as Figure 1 and Figure 2 shown, Figure 1 showing a schematic structural diagram of the preamplifier according to an embodiment of the present application, Figure 2Schematic diagram showing the structure of the anode receiving and amplifying circuit and the cathode receiving and amplifying circuit according to an embodiment of the present application. The preamplifier includes: an anode receiving and amplifying circuit 10, the anode receiving and amplifying circuit 10 is arranged such that its input terminal is connected to the high-voltage terminal 101 of the fission ionization chamber 1, and is used to receive and amplify the output signal of the high-voltage terminal 101 of the fission ionization chamber 1; a cathode receiving and amplifying circuit 20, the cathode receiving and amplifying circuit 20 is arranged such that its input terminal is connected to the grounded terminal 102 of the fission ionization chamber 1, and is used to receive and amplify the output signal of the grounded terminal 102 of the fission ionization chamber 1; a differential amplifying circuit 30, the differential amplifying circuit 30 is arranged to be respectively connected to the output terminals of the anode receiving and amplifying circuit 10 and the cathode receiving and amplifying circuit 20, receives the signals amplified by the anode receiving and amplifying circuit 10 and the cathode receiving and amplifying circuit 20, and reduces the noise in the signals; a differentiating circuit 40, the differentiating circuit 40 is arranged to be connected to the output terminal of the differential amplifying circuit 30, and is used to receive and adjust the output signal of the differential amplifying circuit 30; a power supply 50, the power supply 50 provides operating voltages for the anode receiving and amplifying circuit 10, the cathode receiving and amplifying circuit 20, the differential amplifying circuit 30, and the differentiating circuit 40.

[0020] The preamplifier provided by the embodiment of the present application amplifies the output signals of the high-voltage terminal and the grounded terminal of the fission ionization chamber respectively through the anode receiving and amplifying circuit 10 and the cathode receiving and amplifying circuit 20 to ensure that they can be normally recognized and read; and, the differential amplifying circuit 30 is used to denoise the amplified output signals to improve the signal-to-noise ratio, and the differentiating circuit 40 is used to adjust the denoised signals to further improve the signal-to-noise ratio and resolution, and improve the accuracy and clarity of the output signals. Thus, accurate monitoring of the actual operating conditions inside the reactor is achieved.

[0021] In some embodiments, the anode receiving and amplifying circuit 10 and the cathode receiving and amplifying circuit 20 have the same structure to respectively amplify the output signals of the high-voltage terminal 101 and the grounded terminal 102 of the fission ionization chamber 1.

[0022] Such as Figure 2As shown, in some embodiments, the anode receiving and amplifying circuit 10 and the cathode receiving and amplifying circuit 20 include: an input circuit 11, an amplifying circuit 12, a constant current source circuit 13, a follower circuit 14, a feedback circuit 15, and an operational amplifier circuit 16. The input end of the input circuit 11 is connected to the high-voltage end 101 or the ground end 102 of the fission ionization chamber 1. The input circuit 11 is configured to have two output ends. Among them, one output end is connected to the input end of the amplifying circuit 12, and the other output end is connected to the input end of the feedback circuit 15. The output end of the amplifying circuit 12 is connected to the input end of the constant current source circuit 13, and the output end of the constant current source circuit 13 is connected to the input end of the follower circuit 14. The feedback circuit 15 is configured to have two output ends, and the operational amplifier circuit 16 is configured to have two input ends. The output end of the follower circuit 14 is connected to one output end of the feedback circuit 15 and one input end of the operational amplifier circuit 16. The other output end of the feedback circuit 15 is connected to the other input end of the operational amplifier circuit 16. The output end of the operational amplifier circuit 16 is connected to the input end of the differential amplifying circuit 30. The input circuit 11, the amplifying circuit 12, the constant current source circuit 13, the follower circuit 14, and the operational amplifier circuit 16 are connected to a power supply.

[0023] In this embodiment, the output signal of the high-voltage end 101 or the ground end 102 of the fission ionization chamber is input from the input end of the input circuit 11. Utilizing the characteristics of the large input impedance and good noise characteristics of the input circuit 11, and on the premise of ensuring signal integrity, the signal is quickly input to the amplifying circuit 12 and the feedback circuit 15. The amplifying circuit 12 amplifies the signal and outputs it to the constant current source circuit 13 to increase the open-loop gain and ensure the stability of signal output. The follower circuit 14 receives the output signal of the constant current source circuit 13, which provides good impedance transformation for the circuit. The operational amplifier circuit 16 receives the signals output by the follower circuit 14 and the feedback circuit 15 to further amplify the signal and reduce the signal fall time. The two output ends of the feedback circuit 15 are respectively connected to the two input ends of the operational amplifier circuit 16 to increase the closed-loop gain of the circuit and adjust and optimize the amplification effect of the signal.

[0024] As Figure 2 shown, in some embodiments, the input circuit 11 may include: a first field-effect transistor 111, a first resistor 112, and a first capacitor 113. The first field-effect transistor 111 is provided with a first end, a second end, and a third end. One end of the first capacitor 113 is connected to the high-voltage end 101 or the ground end 102 of the fission ionization chamber 1, and the other end is connected to the input end of the feedback circuit 15 and the third end of the first field-effect transistor 111. The first end of the first field-effect transistor 111 is grounded. The second end of the first field-effect transistor 111 is connected to one end of the first resistor 112 and the input end of the amplifying circuit 12. The other end of the first resistor 112 is connected to the power supply 50.

[0025] In this embodiment, a first capacitor 113 is provided to achieve DC blocking. The first capacitor 113 is connected to the third terminal of the first field-effect transistor 111 to reduce the noise slope and ensure the integrity and stability of signal transmission. The first resistor 112 is connected to the second terminal of the first field-effect transistor 111 to provide an appropriate current for changing the gate-drain of the first field-effect transistor 111.

[0026] In some embodiments, multiple first field-effect transistors 111 in the input circuit 11 can be provided. The multiple first field-effect transistors 111 are connected in parallel to significantly increase the transconductance, further reduce the noise slope, and ensure signal integrity.

[0027] As Figure 2 shown, in some embodiments, the amplifier circuit 12 may include: a second triode 121, a second resistor 122, a third resistor 123, a second capacitor 124, and a third capacitor 125. The second triode 121 is provided with a first terminal, a second terminal, and a third terminal; the second terminal of the second triode 121 is connected to the second terminal of the first field-effect transistor 111, the first terminal of the second triode 121 is connected to one end of the second resistor 122, one end of the third resistor 123, and one end of the third capacitor 125. The other end of the second resistor 122 is connected to the power supply 50, the other ends of the third resistor 123 and the third capacitor 125 are grounded, the third terminal of the second triode 121 is connected to one end of the second capacitor 124 and the input terminal of the constant current source circuit 13, and the other end of the second capacitor 124 is grounded. The amplifier circuit 12 is configured as a common-base amplifier circuit, which has good frequency response characteristics to facilitate signal amplification.

[0028] In this embodiment, by setting the second triode 121 to be connected to the second terminal of the first field-effect transistor 111, and setting the second resistor 122 and the third resistor 123 to be connected to the second triode 121, the drain potential of the first field-effect transistor 111 is fixed at a certain value through the voltage division of the second resistor 122 and the third resistor 123.

[0029] As Figure 2 shown, in some embodiments, the constant current source circuit 13 may include: a third triode 131, a fourth resistor 132, and a fifth resistor 133. The third triode 131 is provided with a first terminal, a second terminal, and a third terminal; the first terminal of the third triode 131 is connected to one end of the second capacitor 124 and one end of the fourth resistor 132, the second terminal of the third triode 131 is connected to the other end of the fourth resistor 132, one end of the fifth resistor 133, and the input terminal of the follower circuit 14. The other end of the fifth resistor 133 and the third terminal of the third triode 131 are connected to the power supply 50. To increase the dynamic resistance of the amplifier circuit 12, thereby increasing the open-loop gain and ensuring the stability of signal output.

[0030] AsFigure 2 As shown, in some embodiments, the follower circuit 14 may include: a fourth triode 141 and a sixth resistor 142. The fourth triode is provided with a first end, a second end, and a third end; the first end of the fourth triode 141 is connected to the second end of the third triode 131, the second end of the fourth triode 141 is connected to an output end of the feedback circuit 15, an input end of the operational amplifier circuit 16, and one end of the sixth resistor 142, and the third end of the fourth triode 141 and the other end of the sixth resistor 142 are connected to the power supply 50. To serve as a buffer stage and an isolation stage, providing better buffering and impedance transformation for the circuit, and to a certain extent avoiding signal loss caused by a relatively high output impedance and a relatively small input impedance of the next stage.

[0031] As Figure 2 shown, in some embodiments, the feedback circuit 15 may include: a fourth capacitor 151 and a seventh resistor 152. One end of the fourth capacitor 151 is connected to the other end of the first capacitor 113 and one end of the seventh resistor 152, the other end of the fourth capacitor 151 is connected to the second end of the fourth triode 141 and an input end of the operational amplifier circuit 16, and the other end of the seventh resistor 152 is connected to the other input end of the operational amplifier circuit 16. So that the feedback circuit 15 is respectively connected to the output end of the first capacitor 113 of the input circuit 11 and the two input ends of the operational amplifier circuit 16, thereby increasing the closed-loop gain of the circuit and adjusting and optimizing the amplification effect of the signal.

[0032] In some embodiments, the fourth capacitor 151 is arranged before the operational amplifier circuit 16, and the seventh resistor 152 is arranged after the operational amplifier circuit 16 to reduce the output signal fall time and improve the charge sensitivity at the same time. Specifically, the amplification factor of the operational amplifier circuit 16 is G. At this time, the voltage drop across the seventh resistor 152 is G times the voltage drop across the fourth capacitor 151, that is, the discharge current on the seventh resistor 152 is G times the discharge current on the fourth capacitor 151. The signal fall time constant can be reduced to 1 / G of the original without inserting a pole-zero cancellation circuit, and no new noise is introduced, while improving the charge sensitivity.

[0033] The fourth capacitor 151 may adopt a low-temperature drift capacitor to reduce the influence of temperature change on the performance of the fourth capacitor 151. By way of example, a low-temperature drift capacitor with a capacitance value of 51 pF may be adopted to improve the stability of signal transmission through a long cable at the same time.

[0034] The seventh resistor 152 may adopt a low-temperature drift resistor to avoid the influence of temperature change on the stability of the resistance value of the seventh resistor 152. The seventh resistor 152 may adopt a resistor with a resistance value range of 100 kΩ to 1 MΩ to avoid the signal recovering to the baseline state with a relatively slow time constant due to an excessive resistance value under the condition that the noise characteristics meet the predetermined requirements. By way of example, a 500 kΩ resistor may be adopted.

[0035] As Figure 2 shown, in some embodiments, the operational amplifier circuit 16 may include: a first amplifier 161, an eighth resistor 162, a ninth resistor 163, a tenth resistor 164, a fifth capacitor 165, and a sixth capacitor 166. The first amplifier 161 includes a first terminal, a second terminal, a third terminal, a fourth terminal, and a fifth terminal. The second terminal of the first amplifier 161 is connected to the second terminal of the fourth transistor 141 and the other end of the fourth capacitor 151. The first terminal of the first amplifier 161 is connected to one end of the eighth resistor 162 and one end of the ninth resistor 163. The other end of the ninth resistor 163 is grounded. The third terminal of the first amplifier 161 is connected to one end of the fifth capacitor 165 and the power supply 50. The other end of the fifth capacitor 165 is grounded. The fourth terminal of the first amplifier 161 is connected to the other end of the eighth resistor 162 and one end of the tenth resistor 164. The other end of the tenth resistor 164 is connected to the input terminal of the differential amplifier circuit 30. The fifth terminal of the first amplifier 161 is connected to one end of the sixth capacitor 166 and the power supply 50. The other end of the sixth capacitor 166 is grounded. In this way, the operational amplifier circuit 16 is configured as a high-speed current-feedback operational amplifier, thereby further reducing the fall time of the output signal and improving the charge sensitivity.

[0036] Specifically, in order to further reduce the fall time of the output signal and improve the charge sensitivity, it is necessary to increase the gain of the operational amplifier circuit 16. Since the gain and bandwidth of a high-speed current-feedback operational amplifier are independent of each other, and the feedback resistor value determines the -3dB bandwidth and cutoff frequency of the operational amplifier, using a high-speed current-feedback operational amplifier can achieve high gain without affecting the bandwidth.

[0037] The resistance value of the eighth resistor 162 can be selected according to the recommended value in the data sheet to ensure the closed-loop bandwidth and the stability of the circuit. The resistance value of the ninth resistor 163 is set according to the resistance value of the eighth resistor 162 and the predetermined gain.

[0038] As Figure 3 shown, Figure 3A schematic structural diagram of a differential amplifier circuit showing an embodiment of the present application. In some embodiments, the differential amplifier circuit 30 includes: a second amplifier 31, an eleventh resistor 32, and a twelfth resistor 33. The second amplifier 31 includes a first terminal, a second terminal, a third terminal, a fourth terminal, a fifth terminal, a sixth terminal, a seventh terminal, and an eighth terminal. The first terminal of the second amplifier 31 is connected to the other end of the tenth resistor 164 of the anode receiving amplifier circuit 10. The eighth terminal of the second amplifier 31 is connected to the other end of the tenth resistor 164 of the cathode receiving amplifier circuit 20. The second terminal, the third terminal, and the seventh terminal of the second amplifier 31 are connected to the power supply 50. The fifth terminal of the second amplifier 31 is connected to one end of the eleventh resistor 32 and one end of the twelfth resistor 33. The fourth terminal of the second amplifier 31 is connected to the other end of the eleventh resistor 32 and grounded. The sixth terminal of the second amplifier 31 is connected to the other end of the twelfth resistor 33 and the differential circuit 40. The differential amplifier circuit 30 is set as an integrated operational amplifier, and its high slew rate is used to quickly achieve voltage conversion, which is convenient for suppressing the common-mode signal generated during transmission, reducing the electromagnetic interference received by the signal, and further improving the signal-to-noise ratio.

[0039] In some embodiments, the differential circuit may include an inductor, a variable resistor, and a variable capacitor, which are used to adjust the signal before it is output from the differential circuit to filter out unwanted low-frequency or high-frequency interference, whiten the noise, so as to retain the required frequency components in the output signal and reduce the falling edge length of the output signal at the same time.

[0040] In some embodiments, the preamplifier may further include a voltage amplification circuit, which is set to be connected to the output terminal of the differential circuit 40, and is used to receive and adjust the output signal of the differential circuit 40 to improve the load-carrying capacity of the preamplifier, ensure the accuracy and stability of the output signal even when the load changes, and ensure the isolation and shielding effect of the signal output to the next connection system.

[0041] In some embodiments, an impedance matching resistor is further included, which is set to be connected to the output terminal of the voltage amplification circuit and is used to receive and adjust the output signal of the voltage amplification circuit to avoid the reflection of noise signals and cause signal oscillation.

[0042] For the embodiments of the present application, it should also be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0043] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. The protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A preamplifier, which is suitable for amplifying the output signal of a fission ionization chamber, characterized in that: It includes: an anode receiving amplifier circuit, wherein the anode receiving amplifier circuit is configured to have an input end connected to the high voltage end of the fission ionization chamber, and is used to receive and amplify an output signal of the high voltage end of the fission ionization chamber; a cathode receiving amplifier circuit, wherein the cathode receiving amplifier circuit is configured such that an input end thereof is connected to a ground end of the fission ionization chamber, and is used for receiving and amplifying an output signal of the ground end of the fission ionization chamber; A differential amplifier circuit, wherein the differential amplifier circuit is configured to be connected to the output ends of the anode receiving amplifier circuit and the cathode receiving amplifier circuit respectively, receive the signals amplified by the anode receiving amplifier circuit and the cathode receiving amplifier circuit, and reduce noise in the signals; a differential circuit, the differential circuit being arranged to be connected to the output end of the differential amplifier circuit, and being used to receive and adjust the output signal of the differential amplifier circuit; A power supply, wherein the power supply provides operating voltage for the anode receiving amplifier circuit, the cathode receiving amplifier circuit, the differential amplifier circuit and the differential circuit.

2. The preamplifier according to claim 1, characterized in that: The anode receiving amplifier circuit has the same structure as the cathode receiving amplifier circuit.

3. The preamplifier according to claim 1 or 2, characterized in that: The anode receiving amplifier circuit and the cathode receiving amplifier circuit include: an input circuit, an amplifier circuit, a constant current source circuit, a follower circuit, a feedback circuit and an operational amplifier circuit. The input end of the input circuit is connected to the high voltage end or the ground end of the fission ionization chamber, and the input circuit is configured to have two output ends, wherein one output end is connected to the input end of the amplifier circuit, and the other output end is connected to the input end of the feedback circuit; The output end of the amplifier circuit is connected to the input end of the constant current source circuit, and the output end of the constant current source circuit is connected to the input end of the follower circuit; The feedback circuit is configured to have two output terminals, the operational amplifier circuit is configured to have two input terminals, the output terminal of the follower circuit is connected to an output terminal of the feedback circuit and an input terminal of the operational amplifier circuit, the other output terminal of the feedback circuit is connected to the other input terminal of the operational amplifier circuit, and the output terminal of the operational amplifier circuit is connected to the input terminal of the differential amplifier circuit; The input circuit and the amplifier circuit are connected to the power supply, and the constant current source circuit, the follower circuit and the operational amplifier circuit are connected to the power supply.

4. The preamplifier according to claim 3, characterized in that: The input circuit comprises: a first field effect transistor, a first resistor and a first capacitor, wherein the first field effect transistor is provided with a first end, a second end and a third end, One end of the first capacitor is connected to the high voltage end or the ground end of the fission ionization chamber, and the other end is connected to the input end of the feedback circuit and the third end of the first field effect transistor. The first end of the first field effect transistor is grounded, the second end of the first field effect transistor is connected to one end of the first resistor and the input end of the amplifier circuit, and the other end of the first resistor is connected to the power supply.

5. The preamplifier according to claim 4, characterized in that: The amplifying circuit comprises: a second triode, a second resistor, a third resistor, a second capacitor and a third capacitor, wherein the second triode is provided with a first end, a second end and a third end, The second end of the second transistor is connected to the second end of the first field effect transistor, A first end of the second transistor is connected to one end of the second resistor, one end of the third resistor and one end of the third capacitor, the other end of the second resistor is connected to the power supply, and the other end of the third resistor and the other end of the third capacitor are grounded. The third end of the second transistor is connected to one end of the second capacitor and the input end of the constant current source circuit, and the other end of the second capacitor is grounded.

6. The preamplifier according to claim 5, characterized in that: The constant current source circuit comprises: a third triode, a fourth resistor and a fifth resistor, wherein the third triode is provided with a first end, a second end and a third end, The first end of the third transistor is connected to one end of the second capacitor and one end of the fourth resistor, the second end of the third transistor is connected to the other end of the fourth resistor, one end of the fifth resistor and the input end of the follower circuit, and the other end of the fifth resistor and the third end of the third transistor are connected to the power supply.

7. The preamplifier according to claim 6, characterized in that: The follower circuit comprises: a fourth transistor and a sixth resistor, wherein the fourth transistor is provided with a first end, a second end and a third end, The first end of the fourth transistor is connected to the second end of the third transistor, the second end of the fourth transistor is connected to an output end of the feedback circuit, an input end of the operational amplifier circuit and one end of the sixth resistor, and the third end of the fourth transistor and the other end of the sixth resistor are connected to the power supply.

8. The preamplifier according to claim 7, characterized in that: The feedback circuit comprises: a fourth capacitor and a seventh resistor, One end of the fourth capacitor is connected to the other end of the first capacitor and one end of the seventh resistor, the other end of the fourth capacitor is connected to the second end of the fourth transistor and an input end of the operational amplifier circuit, and the other end of the seventh resistor is connected to the other input end of the operational amplifier circuit.

9. The preamplifier according to claim 8, characterized in that: The operational amplifier circuit comprises: a first amplifier, an eighth resistor, a ninth resistor, a tenth resistor, a fifth capacitor and a sixth capacitor, wherein the first amplifier includes a first end, a second end, a third end, a fourth end and a fifth end, The second end of the first amplifier is connected to the second end of the fourth transistor and the other end of the fourth capacitor, the first end of the first amplifier is connected to one end of the eighth resistor and one end of the ninth resistor, the other end of the ninth resistor is grounded, the third end of the first amplifier is connected to one end of the fifth capacitor and the power supply, the other end of the fifth capacitor is grounded, The fourth end of the first amplifier is connected to the other end of the eighth resistor and one end of the tenth resistor, the other end of the tenth resistor is connected to the input end of the differential amplifier circuit, the fifth end of the first amplifier is connected to one end of the sixth capacitor and the power supply, and the other end of the sixth capacitor is grounded.

10. The preamplifier according to claim 9, characterized in that: The differential amplifier circuit comprises: a second amplifier, an eleventh resistor and a twelfth resistor, wherein the second amplifier includes a first end, a second end, a third end, a fourth end, a fifth end, a sixth end, a seventh end and an eighth end, The first end of the second amplifier is connected to the other end of the tenth resistor of the anode receiving amplifier circuit, the eighth end of the second amplifier is connected to the other end of the tenth resistor of the cathode receiving amplifier circuit, the second end, the third end and the seventh end of the second amplifier are connected to the power supply, the fifth end of the second amplifier is connected to one end of the eleventh resistor and one end of the twelfth resistor, the fourth end of the second amplifier is connected to the other end of the eleventh resistor and is grounded, and the sixth end of the second amplifier is connected to the other end of the twelfth resistor and the differential circuit.

11. The preamplifier according to claim 1, characterized in that: It also includes a voltage amplifier circuit, The voltage amplifying circuit is configured to be connected to the output end of the differential circuit, and is used to receive and adjust the output signal of the differential circuit.

12. The preamplifier according to claim 11, characterized in that It also includes impedance matching resistors, The impedance matching resistor is configured to be connected to the output end of the voltage amplifier circuit, and is used to receive and adjust the output signal of the voltage amplifier circuit.

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