Current amplifier with pA-mA range
By designing a current amplifier with a pA-mA range and using readily available components and innovative circuit structures, the high cost and narrow range problems of weak current measurement in nuclear measurement instrumentation systems were solved, high-precision and wide-range current measurement was achieved, and production cycle and cost were reduced.
Patent Information
- Application Number
- CN202422704370.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-10-21
- Estimated Expiration
- 2034-11-07
AI Technical Summary
In the existing technology, the micro-current amplifiers used for weak current measurement in nuclear measurement instrument systems rely on imported components, resulting in long procurement cycles and high costs, making it difficult to achieve high-precision and wide-range current measurement.
A pA-mA range current amplifier is designed, including an input circuit, a current-voltage conversion circuit, a range control circuit, a compensation circuit, a voltage inversion circuit, and a voltage-isolated output linear amplifier circuit. Easy-to-obtain components such as Schmitt triggers and field-effect transistors are used to achieve wide-range amplification and anti-interference capabilities of current signals.
The accuracy and range of current measurement are improved, the cost of the current amplifier is reduced, and a current amplifier with strong anti-interference ability and simple structure is provided, which can process current signals in the range of 10-11 to 10-3A.
Smart Images
Figure CN223462994U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of nuclear power secondary instrument, in particular to a pA-mA range current amplifier. BACKGROUND
[0002] For a nuclear measuring instrument system in the nuclear industry field, it is very important to accurately measure a weak current output by a detector. The amount of the current output by the detector is between pA and mA, and the cross range is large. In the related art, a micro-current amplifier usually adopts a resistance feedback type for current-voltage conversion, and key elements such as an electrometer amplifier, a low-leakage-current multiplexer and a high-resistance resistor are mostly imported devices, so that the procurement cycle is long and the procurement is limited, thereby greatly increasing the measurement cost. CONTENT OF THE UTILITY MODEL
[0003] The application aims to provide a pA-mA range current amplifier, which can effectively improve the accuracy and range of current measurement, has a simple structure and can effectively reduce the cost of the current amplifier.
[0004] To achieve the above object, the application provides the following scheme.
[0005] In a first aspect, the application provides a pA-mA range current amplifier, which comprises an input circuit, a current-voltage conversion circuit, a range control circuit, a compensation circuit, a voltage reverse circuit and a voltage isolation output linear amplification circuit.
[0006] An input end of the current-voltage conversion circuit is connected with an output end of the input circuit, one end of the range control circuit and the compensation circuit respectively; an output end of the current-voltage conversion circuit is connected with an input end of the voltage reverse circuit and the other end of the range control circuit respectively; an output end of the voltage reverse circuit is connected with an input end of the voltage isolation output linear amplification circuit; and an output end of the voltage isolation output linear amplification circuit serves as an output end of the current amplifier.
[0007] Optionally, the input circuit comprises a relay K1, a relay K2, a resistor R3, a resistor R4, a resistor R7, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a triode Q1, a triode Q2, a triode Q3, a diode VD1 and a diode VD2.
[0008] One end of the resistor R10 is connected with one end of the resistor R11; one end of the resistor R10 is taken as the input end of the input circuit and is connected with the working signal Test; the other end of the resistor R10 is connected with the base of the transistor Q2; the collector of the transistor Q2 is connected with the second end of the relay K1 and the anode of the diode VD1 respectively; the first end of the relay K1 and the cathode of the diode VD1 are both connected with one end of the resistor R3; the other end of the resistor R3 is connected with 5V voltage; the emitter of the transistor Q2 is grounded; the other end of the resistor R11 is connected with the base of the transistor Q3; the collector of the transistor Q3 is connected with one end of the resistor R7 and one end of the resistor R9 respectively; the other end of the resistor R7 is connected with 5V voltage; the other end of the resistor R9 is connected with one end of the resistor R12 and the base of the transistor Q1 respectively; the collector of the transistor Q1 is connected with the second end of the relay K2 and the anode of the diode VD2 respectively; the first end of the relay K2 and the cathode of the diode VD2 are both connected with one end of the resistor R4; the other end of the resistor R4 is connected with 5V voltage; the emitter of the transistor Q3, the other end of the resistor R12 and the emitter of the transistor Q1 are all grounded; the third end of the relay K1 is connected with the test signal TMS; the third end of the relay K2 is connected with the detector signal DMS; the fourth end of the relay K1 and the fourth end of the relay K2 are connected, taken as the output end of the input circuit and connected with the current-voltage conversion circuit.
[0009] Optionally, the current-voltage conversion circuit comprises: a resistor R23, a capacitor C6, a low-noise operational amplifier U17, a resistor R19, a resistor R40, a resistor R41 and a variable resistor RP6.
[0010] One end of the resistor R23 is connected with one end of the capacitor C6, taken as the input end of the current-voltage conversion circuit and connected with the output end of the input circuit; the reverse input end of the low-noise operational amplifier U17 is connected with the other end of the resistor R23; one end of the resistor R19 is connected with the positive input end of the low-noise operational amplifier U17; the other end of the resistor R19 is grounded; the output end of the low-noise operational amplifier U17 is connected with the other end of the capacitor C6, taken as the output end of the current-voltage conversion circuit; the seventh pin of the low-noise operational amplifier U17 is connected with the tap end of the variable resistor RP6; one end of the variable resistor RP6 is connected with one end of the resistor R41; the other end of the variable resistor RP6 is connected with one end of the resistor R40; the other end of the resistor R40 and the other end of the resistor R41 are both connected with 15V voltage.
[0011] Optionally, the range control circuit comprises: a Schmitt trigger U16A, a Schmitt trigger U16B, a Schmitt trigger U16C, a Schmitt trigger U16D, a Schmitt trigger U15A, a Schmitt trigger U15B, a Schmitt trigger U15C, a Schmitt trigger U15D, a field effect transistor Q4, a field effect transistor Q5, a field effect transistor Q6, a field effect transistor Q7, a field effect transistor Q12, a field effect transistor Q13, a field effect transistor Q14, a field effect transistor Q15, a capacitor C29, a capacitor C30, a capacitor C31, a capacitor C32, a resistor R28, a resistor R29, a resistor R30, a resistor R31 and a variable resistor RP5;
[0012] The input end of the Schmitt trigger U16D is connected to the gear shifting signal Y4; the output end of the Schmitt trigger U16D is connected to the input end of the Schmitt trigger U15D and the gate of the field effect transistor Q7 respectively; the source of the field effect transistor Q7 is connected to the drain of the field effect transistor Q15, one end of the capacitor C29 and one end of the resistor R28 respectively; the output end of the Schmitt trigger U15D is connected to the gate of the field effect transistor Q15; the input end of the Schmitt trigger U16C is connected to the gear shifting signal Y5; the output end of the Schmitt trigger U16C is connected to the input end of the Schmitt trigger U15C and the gate of the field effect transistor Q6 respectively; the source of the field effect transistor Q6 is connected to the drain of the field effect transistor Q14, one end of the capacitor C30 and one end of the resistor R29 respectively; the output end of the Schmitt trigger U15C is connected to the gate of the field effect transistor Q14; the input end of the Schmitt trigger U16B is connected to the gear shifting signal Y6; the output end of the Schmitt trigger U16B is connected to the input end of the Schmitt trigger U15B and the gate of the field effect transistor Q5 respectively; the source of the field effect transistor Q5 is connected to the drain of the field effect transistor Q13 and one end of the variable resistor RP5 respectively; the other end of the variable resistor RP5, the tap end of the variable resistor RP5 and one end of the capacitor C31 are all connected to one end of the resistor R30; the output end of the Schmitt trigger U15B is connected to the gate of the field effect transistor Q13; the input end of the Schmitt trigger U16A is connected to the gear shifting signal Y7; the output end of the Schmitt trigger U16A is connected to the input end of the Schmitt trigger U15A and the gate of the field effect transistor Q4 respectively; the source of the field effect transistor Q4 is connected to the drain of the field effect transistor Q12, one end of the capacitor C32 and one end of the resistor R31 respectively; the output end of the Schmitt trigger U15A is connected to the gate of the field effect transistor Q12;
[0013] The drain of the field effect tube Q4, the drain of the field effect tube Q5, the drain of the field effect tube Q6 and the drain of the field effect tube Q7 are connected with the input end of the current-voltage conversion circuit; the source of the field effect tube Q12, the source of the field effect tube Q13, the source of the field effect tube Q14 and the source of the field effect tube Q15 are grounded; the other end of the capacitor C29, the other end of the capacitor C30, the other end of the capacitor C31, the other end of the capacitor C32, the other end of the resistor R28, the other end of the resistor R29, the other end of the resistor R30 and the other end of the resistor R31 are connected with the output end of the current-voltage conversion circuit.
[0014] Optionally, the compensation circuit comprises: a resistor R1, a resistor R3, a resistor R4, a resistor R5, a resistor R7, a variable resistor RP1, a voltage stabilizing diode D1 and a voltage stabilizing diode D2.
[0015] One end of the resistor R1 is connected with the input end of the current-voltage conversion circuit; the other end of the resistor R1 is connected with the tap end of the variable resistor RP1; one end of the variable resistor RP1 is connected with one end of the resistor R3; the other end of the resistor R3 is connected with the cathode of the voltage stabilizing diode D1 and one end of the resistor R4 respectively; the other end of the variable resistor RP1 is connected with one end of the resistor R5; the other end of the resistor R5 is connected with the anode of the voltage stabilizing diode D2 and one end of the resistor R7 respectively; the other end of the resistor R4 and the other end of the resistor R7 are connected with +15V voltage respectively; the anode of the voltage stabilizing diode D1 and the cathode of the voltage stabilizing diode D2 are grounded.
[0016] Optionally, the voltage reversing circuit comprises: a low-noise operational amplifier U4, a resistor R17, a resistor R38, a resistor R39, a capacitor C7, a capacitor C8 and a capacitor C78.
[0017] One end of the resistor R38 is connected with the output end of the current-voltage conversion circuit as the input end of the voltage reverse circuit; the other end of the resistor R38, one end of the capacitor C78 and one end of the resistor R17 are all connected with the reverse input end of the low-noise operational amplifier U4; one end of the resistor R39 is connected with the forward input end of the low-noise operational amplifier U4; the other end of the resistor R39 is grounded; the positive power supply end of the low-noise operational amplifier U4 is connected with +15V voltage and one end of the capacitor C7 respectively; the negative power supply end of the low-noise operational amplifier U4 is connected with -15V voltage and one end of the capacitor C8 respectively; the other end of the capacitor C7 and the other end of the capacitor C8 are both grounded; the other end of the capacitor C78 and the other end of the resistor R17 are both connected with the output end of the low-noise operational amplifier U4 as the output end of the voltage reverse circuit.
[0018] Optionally, the voltage isolation output linear amplification circuit comprises: an isolation operational amplifier U2, a low-noise operational amplifier U18, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R49, a capacitor C62, a capacitor C29, a capacitor C63, a capacitor C30, a capacitor C66, a capacitor C67 and a variable resistor RP7.
[0019] The VDD1 pin of the isolation operational amplifier U2 is connected with one end of the capacitor C62, one end of the capacitor C29 and 5V voltage respectively; the VIN pin of the isolation operational amplifier U2 is connected with the output end of the voltage reverse circuit; the SHTDN pin of the isolation operational amplifier U2, the GND1 pin of the isolation operational amplifier U2, the other end of the capacitor C62 and the other end of the capacitor C29 are grounded; the VDD2 pin of the isolation operational amplifier U2 is connected with one end of the capacitor C30, one end of the capacitor C63 and 5V voltage respectively; the other end of the capacitor C63 and the other end of the capacitor C30 are grounded; the OUTP pin of the isolation operational amplifier U2 is connected with one end of the resistor R58; the other end of the resistor R58 is connected with one end of the resistor R60 and the positive input end of the low-noise operational amplifier U18 respectively; the OUTN pin of the isolation operational amplifier U2 is connected with one end of the resistor R57; the other end of the resistor R57 is connected with one end of the resistor R59 and the reverse input end of the low-noise operational amplifier U18 respectively; the other end of the resistor R59 is connected with one end of the variable resistor RP7; the second pin of the low-noise operational amplifier U18 is connected with one end of the capacitor C66 and -15V voltage respectively; the fifth pin of the low-noise operational amplifier U18 is connected with one end of the capacitor C67 and +15V voltage respectively; the GND2 pin of the isolation operational amplifier U2, the other end of the resistor R60, the other end of the capacitor C66 and the other end of the capacitor C67 are grounded; the output end of the low-noise operational amplifier U18 is connected with the tap end of the variable resistor RP7, the other end of the variable resistor RP7 and one end of the resistor R49 respectively; the other end of the resistor R49 is taken as the output end of the voltage isolation output linear amplification circuit.
[0020] Optionally, the Schmidt trigger U16A, the Schmidt trigger U16B, the Schmidt trigger U16C, the Schmidt trigger U16D, the Schmidt trigger U15A, the Schmidt trigger U15B, the Schmidt trigger U15C and the Schmidt trigger U15D are all RS6G14.
[0021] Optionally, the field effect tube Q4, the field effect tube Q5, the field effect tube Q6, the field effect tube Q7, the field effect tube Q12, the field effect tube Q13, the field effect tube Q14 and the field effect tube Q15 are all NMOSFET tubes, and the model number is GL3N170FA9.
[0022] Optionally, the low-noise operational amplifier U17 is an electrometer type amplifier.
[0023] According to the specific embodiments provided in the application, the application has the following technical effects:
[0024] The application provides a pA-mA range current amplifier, through the design of an input circuit, a current-voltage conversion circuit, a range control circuit, a compensation circuit, a voltage reversing circuit and a voltage isolation output linear amplification circuit, a wide-range current amplifier required for processing a 10 -11 ~10 -3 A range current signal in a nuclear instrument system is provided, a 100% current amplifier with strong anti-interference ability, simple implementation, adjustable zero point and a measuring range of pA-mA is provided. Therefore, the pA-mA range current amplifier can effectively improve the accuracy and range of current measurement, has a simple structure and can effectively reduce the cost of the current amplifier. BRIEF DESCRIPTION OF DRAWINGS
[0025] In order to more clearly illustrate the technical solutions in the embodiments of the application or the related art, the drawings needed to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.
[0026] Figure 1 The connection relationship diagram of the pA-mA range current amplifier provided by the application is shown in the figure.
[0027] Figure 2 The connection relationship diagram of the input circuit provided by the application is shown in the figure.
[0028] Figure 3 The connection relationship diagram of the current-voltage conversion circuit and the range control circuit provided by the application is shown in the figure.
[0029] Figure 4 The connection relationship diagram of the compensation circuit provided by the application is shown in the figure.
[0030] Figure 5 The connection relationship diagram of the voltage reversing circuit provided by the application is shown in the figure.
[0031] Figure 6 The connection relationship diagram of the voltage isolation output linear amplification circuit provided by the application is shown in the figure. DETAILED DESCRIPTION
[0032] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.
[0033] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.
[0034] As shown in Figure 1 , the pA-mA range current amplifier disclosed by the present application comprises an input circuit, a current-voltage conversion circuit, a range control circuit, a compensation circuit, a voltage reversing circuit and a voltage isolation output linear amplification circuit. The input end of the current-voltage conversion circuit is connected with the input circuit, and the output end is connected with the voltage reversing circuit. The compensation circuit and the range control circuit are also connected with the current-voltage conversion circuit. The output end of the voltage reversing circuit is connected with the voltage isolation output linear amplification circuit. Specifically, as shown in Figure 1 , the input end of the current-voltage conversion circuit is connected with the output end of the input circuit, one end of the range control circuit and the compensation circuit respectively. The output end of the current-voltage conversion circuit is connected with the input end of the voltage reversing circuit and the other end of the range control circuit respectively. The output end of the voltage reversing circuit is connected with the input end of the voltage isolation output linear amplification circuit. The output end of the voltage isolation output linear amplification circuit is the output end of the current amplifier.
[0035] The present application uses a Schmidt trigger with a model number of RS6G14, an N-channel MOSFET field effect transistor with a model number of GL3N170FA9 and a precision resistor with a model number of GST4020 to build the range control circuit, and combines the easily obtained electrometer type amplifier to realize the pA-mA range current-voltage conversion circuit.
[0036] As shown in Figure 2As shown, the input circuit described in the present application is composed of relays and transistors to realize input signal switching function, specifically including: relay K1, relay K2, resistor R3, resistor R4, resistor R7, resistor R9, resistor R10, resistor R11, resistor R12, transistor Q1, transistor Q2, transistor Q3, diode VD1 and diode VD2. The base b of resistor R10 and transistor Q2 is connected, one end of relay K1 is connected to +5V, the other end is connected to the collector c of transistor Q2, the emitter e of transistor Q2 is grounded, resistor R11 is connected to the base b of transistor Q3, the collector c of transistor Q3 is connected to +5V through resistor R7, the base b of transistor Q1 is connected to resistor R9, the other end of resistor R9 is connected to the collector c of transistor Q3, one end of relay K2 is connected to +5V, the other end is connected to the collector c of transistor Q1, the emitter e of transistor Q1 is grounded.
[0037] Specifically, one end of resistor R10 is connected to one end of resistor R11. One end of resistor R10 is the input end of the input circuit and is connected to the working signal Test. The other end of resistor R10 is connected to the base of transistor Q2. The collector of transistor Q2 is connected to the second end of relay K1 and the anode of diode VD1. The first end of relay K1 and the cathode of diode VD1 are both connected to one end of resistor R3. The other end of resistor R3 is connected to 5V voltage. The emitter of transistor Q2 is grounded. The other end of resistor R11 is connected to the base of transistor Q3. The collector of transistor Q3 is connected to one end of resistor R7 and one end of resistor R9. The other end of resistor R7 is connected to 5V voltage. The other end of resistor R9 is connected to one end of resistor R12 and the base of transistor Q1. The collector of transistor Q1 is connected to the second end of relay K2 and the anode of diode VD2. The first end of relay K2 and the cathode of diode VD2 are both connected to one end of resistor R4. The other end of resistor R4 is connected to 5V voltage. The emitter of transistor Q3, the other end of resistor R12 and the emitter of transistor Q1 are all grounded. The third end of relay K1 is connected to the test signal TMS. The third end of relay K2 is connected to the detector signal DMS. The fourth end of relay K1 and the fourth end of relay K2 are connected, which is the output end of the input circuit and is connected to the current-voltage conversion circuit. When the current amplifier of the present application is in working state, the input working signal Test is low, the relay K2 is excited, and the detector signal is connected to the circuit; when the current amplifier of the present application is in test state, the input working signal Test is high, the relay K1 is excited, and the test signal is connected to the circuit.
[0038] As Figure 3As shown, the current-voltage conversion circuit and the range control circuit described in the present application are composed of electrometer type amplifier and cross resistance, which are used to convert current signal into voltage signal, wherein the range control circuit is composed of Schmitt trigger and N-channel MOSFET, and the current-voltage conversion circuit and the range control circuit specifically include: resistance R23, capacitor C6, low-noise operational amplifier U17, resistance R19, resistance R40, resistance R41, variable resistance RP6, Schmitt trigger U16A, Schmitt trigger U16B, Schmitt trigger U16C, Schmitt trigger U16D, Schmitt trigger U15A, Schmitt trigger U15B, Schmitt trigger U15C, Schmitt trigger U15D, field effect transistor Q4, field effect transistor Q5, field effect transistor Q6, field effect transistor Q7, field effect transistor Q12, field effect transistor Q13, field effect transistor Q14, field effect transistor Q15, capacitor C29, capacitor C30, capacitor C31, capacitor C32, resistance R28, resistance R29, resistance R30, resistance R31 and variable resistance RP5. The resistance R23 is connected to pin 1 of the low-noise operational amplifier U17, and pin 2 of the low-noise operational amplifier U17 is connected to the ground through the resistance R19. One end of the range control circuit is connected to the resistance R23, and the other end is connected to the cross resistance with different resistance values, such as resistance R31, resistance R30 and the like. Taking one of the paths as an example, pin 2 of the Schmitt trigger U16A is connected to pin 1 of the field effect transistor Q4 and pin 1 of the Schmitt trigger U15A, pin 2 of the field effect transistor Q4 is connected to pin 1 of the low-noise operational amplifier U17, pin 3 of the field effect transistor Q4 is connected to the resistance R31 and pin 2 of the field effect transistor Q12, pin 1 of the field effect transistor Q12 is connected to pin 2 of the Schmitt trigger U15A, and pin 2 of the field effect transistor Q12 is connected to the ground.
[0039] Specifically, one end of the resistance R23 is connected to one end of the capacitor C6, which is connected to the output end of the input circuit and the input end of the current-voltage conversion circuit. The reverse input end of the low-noise operational amplifier U17 is connected to the other end of the resistance R23. The forward input end of the low-noise operational amplifier U17 is connected to one end of the resistance R19. The other end of the resistance R19 is grounded. The output end of the low-noise operational amplifier U17 is connected to the other end of the capacitor C6, which is the output end of the current-voltage conversion circuit. The seventh pin of the low-noise operational amplifier U17 is connected to the tap end of the variable resistance RP6. One end of the variable resistance RP6 is connected to one end of the resistance R41. The other end of the variable resistance RP6 is connected to one end of the resistance R40. The other end of the resistance R40 and the other end of the resistance R41 are both connected to 15V voltage.
[0040] The input terminal of the Schmitt trigger U16D is connected to the notch signal Y4. The output terminal of the Schmitt trigger U16D is connected to the input terminal of the Schmitt trigger U15D and the gate of the field effect transistor Q7, respectively. The source of the field effect transistor Q7 is connected to the drain of the field effect transistor Q15, one end of the capacitor C29 and one end of the resistor R28, respectively. The output terminal of the Schmitt trigger U15D is connected to the gate of the field effect transistor Q15. The input terminal of the Schmitt trigger U16C is connected to the notch signal Y5. The output terminal of the Schmitt trigger U16C is connected to the input terminal of the Schmitt trigger U15C and the gate of the field effect transistor Q6, respectively. The source of the field effect transistor Q6 is connected to the drain of the field effect transistor Q14, one end of the capacitor C30 and one end of the resistor R29, respectively. The output terminal of the Schmitt trigger U15C is connected to the gate of the field effect transistor Q14. The input terminal of the Schmitt trigger U16B is connected to the notch signal Y6. The output terminal of the Schmitt trigger U16B is connected to the input terminal of the Schmitt trigger U15B and the gate of the field effect transistor Q5, respectively. The source of the field effect transistor Q5 is connected to the drain of the field effect transistor Q13 and one end of the variable resistor RP5, respectively. The other end of the variable resistor RP5, the tap terminal of the variable resistor RP5 and one end of the capacitor C31 are connected to one end of the resistor R30. The output terminal of the Schmitt trigger U15B is connected to the gate of the field effect transistor Q13. The input terminal of the Schmitt trigger U16A is connected to the notch signal Y7. The output terminal of the Schmitt trigger U16A is connected to the input terminal of the Schmitt trigger U15A and the gate of the field effect transistor Q4, respectively. The source of the field effect transistor Q4 is connected to the drain of the field effect transistor Q12, one end of the capacitor C32 and one end of the resistor R31, respectively. The output terminal of the Schmitt trigger U15A is connected to the gate of the field effect transistor Q12.
[0041] The drain of the field effect transistor Q4, the drain of the field effect transistor Q5, the drain of the field effect transistor Q6 and the drain of the field effect transistor Q7 are connected to the input terminal of the current-voltage conversion circuit. The source of the field effect transistor Q12, the source of the field effect transistor Q13, the source of the field effect transistor Q14 and the source of the field effect transistor Q15 are connected to ground. The other end of the capacitor C29, the other end of the capacitor C30, the other end of the capacitor C31, the other end of the capacitor C32, the other end of the resistor R28, the other end of the resistor R29, the other end of the resistor R30 and the other end of the resistor R31 are connected to the output terminal of the current-voltage conversion circuit. When the notch signal Y7 is low, the field effect transistor Q4 is on, the field effect transistor Q12 is off and the resistor R31 is connected to the current-voltage conversion circuit. When the notch signal Y7 is high, the field effect transistor Q4 is off, the field effect transistor Q12 is on and the resistor R31 is disconnected.
[0042] As Figure 4As shown, the compensation circuit described in the present application is composed of voltage stabilizing diodes and resistors, and specifically includes: resistors R1, R3, R4, R5, R7, variable resistor RP1, voltage stabilizing diode D1, and voltage stabilizing diode D2. One end of resistor R4 is connected to +15V, and the other end is connected to voltage stabilizing diode D1 and resistor R3. One end of resistor R3 is connected to variable resistor RP1. One end of voltage stabilizing diode D1 is connected to ground. One end of resistor R7 is connected to -15V, and the other end is connected to voltage stabilizing diode D2 and resistor R5. One end of resistor R5 is connected to variable resistor RP1. One end of voltage stabilizing diode D2 is connected to ground.
[0043] Specifically, one end of resistor R1 is connected to the input end of the current-voltage conversion circuit; the other end of resistor R1 is connected to the tap end of variable resistor RP1; one end of variable resistor RP1 is connected to one end of resistor R3; the other end of resistor R3 is connected to the cathode of voltage stabilizing diode D1 and one end of resistor R4, respectively; the other end of variable resistor RP1 is connected to one end of resistor R5; the other end of resistor R5 is connected to the anode of voltage stabilizing diode D2 and one end of resistor R7, respectively; the other end of resistor R4 and the other end of resistor R7 are both connected to +15V; the anode of voltage stabilizing diode D1 and the cathode of voltage stabilizing diode D2 are both connected to ground. The tap end of variable resistor RP1 is connected to the input end of the current-voltage conversion circuit, and by adjusting variable resistor RP1, fA or uA level current compensation can be achieved, and the overall measurement accuracy of the circuit is improved.
[0044] As shown in Figure 5 The voltage reversing circuit described in the present application is composed of low-noise operational amplifiers and resistors, and specifically includes: low-noise operational amplifier U4, resistor R17, resistor R38, resistor R39, capacitor C7, capacitor C8, and capacitor C78. The output of the current-voltage conversion circuit is a negative voltage, which is changed to a positive voltage in the range of 0-7V by the voltage reversing circuit without amplification.
[0045] One end of resistor R38 is connected to the input end of the voltage reversing circuit and connected to the output end of the current-voltage conversion circuit; the other end of resistor R38, one end of capacitor C78, and one end of resistor R17 are all connected to the inverting input end of low-noise operational amplifier U4; the non-inverting input end of low-noise operational amplifier U4 is connected to one end of resistor R39; the other end of resistor R39 is connected to ground; the positive power supply end of low-noise operational amplifier U4 is connected to +15V and one end of capacitor C7, respectively; the negative power supply end of low-noise operational amplifier U4 is connected to -15V and one end of capacitor C8, respectively; the other end of capacitor C7 and the other end of capacitor C8 are both connected to ground; the other end of capacitor C78 and the other end of resistor R17 are both connected to the output end of low-noise operational amplifier U4, serving as the output end of the voltage reversing circuit.
[0046] As shown in Figure 6As shown, the voltage isolation output linear amplification circuit described in the present application is composed of an isolation operational amplifier, a low-noise operational amplifier and a resistance capacitor, and specifically includes: an isolation operational amplifier U2, a low-noise operational amplifier U18, a resistance R57, a resistance R58, a resistance R59, a resistance R60, a resistance R49, a capacitor C62, a capacitor C29, a capacitor C63, a capacitor C30, a capacitor C66, a capacitor C67 and a variable resistance RP7. The voltage reverse circuit outputs the 2-pin of the isolation operational amplifier U2, and outputs a differential voltage after the isolation operational amplifier U2. The 7-pin of the isolation operational amplifier U2 is connected to the 3-pin of the low-noise operational amplifier U18 through the resistance R58. The 3-pin of the low-noise operational amplifier U18 is connected to the resistance R60 to the ground. The 6-pin of the isolation operational amplifier U2 is connected to the 4-pin of the low-noise operational amplifier U18 through the resistance R57. The resistance R59 is connected to the variable resistance RP7, and is connected across the 4-pin and the 1-pin of the low-noise operational amplifier U18.
[0047] Specifically, the VDD1 pin of the isolation operational amplifier U2 is connected to one end of the capacitor C62, one end of the capacitor C29 and a 5V voltage respectively. The VIN pin of the isolation operational amplifier U2 is connected to the output end of the voltage reverse circuit. The SHTDN pin of the isolation operational amplifier U2, the GND1 pin of the isolation operational amplifier U2, the other end of the capacitor C62 and the other end of the capacitor C29 are all grounded. The VDD2 pin of the isolation operational amplifier U2 is connected to one end of the capacitor C30, one end of the capacitor C63 and a 5V voltage respectively. The other end of the capacitor C63 and the other end of the capacitor C30 are both grounded. The OUTP pin of the isolation operational amplifier U2 is connected to one end of the resistance R58. The other end of the resistance R58 is connected to one end of the resistance R60 and the positive input end of the low-noise operational amplifier U18 respectively. The OUTN pin of the isolation operational amplifier U2 is connected to one end of the resistance R57. The other end of the resistance R57 is connected to one end of the resistance R59 and the negative input end of the low-noise operational amplifier U18 respectively. The other end of the resistance R59 is connected to one end of the variable resistance RP7. The second pin of the low-noise operational amplifier U18 is connected to one end of the capacitor C66 and a -15V voltage respectively. The fifth pin of the low-noise operational amplifier U18 is connected to one end of the capacitor C67 and a +15V voltage respectively. The GND2 pin of the isolation operational amplifier U2, the other end of the resistance R60, the other end of the capacitor C66 and the other end of the capacitor C67 are all grounded. The output end of the low-noise operational amplifier U18 is connected to the tap end of the variable resistance RP7, the other end of the variable resistance RP7 and one end of the resistance R49 respectively. The other end of the resistance R49 is the output end of the voltage isolation output linear amplification circuit.
[0048] In summary, the pA-mA range current amplifier provided by the application is applied to a nuclear instrument system, the measurement current range is wide, the range control circuit in the circuit provides a new idea for range switching mode, the new circuit form, the principle is simple, reliable to use, small on-resistance, and low leakage current. The pA-mA range current amplifier can convert the 10 -11 ~10 -3 A range of small direct current signals are amplified by orders of magnitude to convert into 0-10V output, and an external control unit controls the order switching according to the 0-10V feedback signal. When the feedback voltage collected by the external control unit is less than 0.9V, it is switched to a higher resistance, and when the feedback voltage collected by the external control unit is greater than 9.5V, it is switched to a low resistance.
[0049] Compared with the prior art, the pA-mA range current amplifier has the following advantages:
[0050] 1. The pA-mA range current amplifier spans 10 orders of magnitude, and the measurement current range is wide.
[0051] 2. The range switching control circuit in the pA-mA range current amplifier provides a new circuit structure, the principle is simple, reliable to use, small on-resistance, and low leakage current, the maximum is 1uA, which is lower than most multi-channel selection switch leakage current, and can solve the problem of multi-channel selection switch selection difficulty.
[0052] 3. The pA-mA range current amplifier uses easily accessible components, and the procurement period of the existing higher precision components is shorter, which can shorten the product production cycle.
[0053] 4. The pA-mA range current amplifier is adjustable, not only designed with an op-amp zero adjustment circuit, but also compensated by coarse and fine adjustment, so that the current measurement of each order is more accurate.
[0054] The technical features of the above embodiments can be combined arbitrarily, and to make the description concise, not all possible combinations of the technical features in the above embodiments are described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.
[0055] In this paper, specific examples are used to describe the principles and implementation modes of the application, and the above examples are only used to help understand the method and its core idea of the application; at the same time, for those skilled in the art, according to the idea of the application, the specific implementation mode and application range will be changed. In summary, the content of the specification should not be understood as a limitation of the application.
Claims
1. A current amplifier of pA-mA range, characterized by, The input circuit, the current-voltage conversion circuit, the range control circuit, the compensation circuit, the voltage reverse circuit and the voltage isolation output linear amplification circuit are connected. The input end of the current-voltage conversion circuit is connected with the output end of the input circuit, one end of the range control circuit and the compensation circuit respectively; the output end of the current-voltage conversion circuit is connected with the input end of the voltage reverse circuit and the other end of the range control circuit respectively; the output end of the voltage reverse circuit is connected with the input end of the voltage isolation output linear amplification circuit; and the output end of the voltage isolation output linear amplification circuit is the output end of the current amplifier. The input circuit comprises a relay K1, a relay K2, a resistor R3, a resistor R4, a resistor R7, a resistor R9, a resistor R10, a resistor R11, a resistor R12, a triode Q1, a triode Q2, a triode Q3, a diode VD1 and a diode VD2.
2. The pA-mA range current amplifier of claim 1, wherein, One end of the resistor R10 is connected with one end of the resistor R11; one end of the resistor R10 is the input end of the input circuit and is connected with a working signal Test; the other end of the resistor R10 is connected with the base of the triode Q2; the collector of the triode Q2 is connected with the second end of the relay K1 and the anode of the diode VD1 respectively; the first end of the relay K1 and the cathode of the diode VD1 are connected with one end of the resistor R3; the other end of the resistor R3 is connected with a 5V voltage; the emitter of the triode Q2 is grounded; the other end of the resistor R11 is connected with the base of the triode Q3; the collector of the triode Q3 is connected with one end of the resistor R7 and one end of the resistor R9 respectively; the other end of the resistor R7 is connected with a 5V voltage; the other end of the resistor R9 is connected with one end of the resistor R12 and the base of the triode Q1 respectively; the collector of the triode Q1 is connected with the second end of the relay K2 and the anode of the diode VD2 respectively; the first end of the relay K2 and the cathode of the diode VD2 are connected with one end of the resistor R4; the other end of the resistor R4 is connected with a 5V voltage; the emitter of the triode Q3, the other end of the resistor R12 and the emitter of the triode Q1 are grounded; the third end of the relay K1 is connected with a test signal TMS; the third end of the relay K2 is connected with a detector signal DMS; the fourth end of the relay K1 and the fourth end of the relay K2 are connected and are the output end of the input circuit and are connected with the current-voltage conversion circuit. The current-voltage conversion circuit comprises a resistor R23, a capacitor C6, a low-noise operational amplifier U17, a resistor R19, a resistor R40, a resistor R41 and a variable resistor RP6.
3. The pA-mA range current amplifier of claim 2, wherein, One end of the resistor R23 is connected with one end of the capacitor C6, as the input end of the current-voltage conversion circuit and the output end of the input circuit; the reverse input end of the low-noise operational amplifier U17 is connected with the other end of the resistor R23; the forward input end of the low-noise operational amplifier U17 is connected with one end of the resistor R19; the other end of the resistor R19 is grounded; the output end of the low-noise operational amplifier U17 is connected with the other end of the capacitor C6, as the output end of the current-voltage conversion circuit; the seventh pin of the low-noise operational amplifier U17 is connected with the tap end of the variable resistor RP6; one end of the variable resistor RP6 is connected with one end of the resistor R41; the other end of the variable resistor RP6 is connected with one end of the resistor R40; the other end of the resistor R40 and the other end of the resistor R41 are both connected with 15V voltage.
4. The pA-mA range current amplifier of claim 3, wherein, The range control circuit comprises a Schmitt trigger U16A, a Schmitt trigger U16B, a Schmitt trigger U16C, a Schmitt trigger U16D, a Schmitt trigger U15A, a Schmitt trigger U15B, a Schmitt trigger U15C, a Schmitt trigger U15D, a field effect transistor Q4, a field effect transistor Q5, a field effect transistor Q6, a field effect transistor Q7, a field effect transistor Q12, a field effect transistor Q13, a field effect transistor Q14, a field effect transistor Q15, a capacitor C29, a capacitor C30, a capacitor C31, a capacitor C32, a resistor R28, a resistor R29, a resistor R30, a resistor R31 and a variable resistor RP5. The input end of the Schmitt trigger U16D is connected with the gear shifting signal Y4; the output end of the Schmitt trigger U16D is connected with the input end of the Schmitt trigger U15D and the gate of the field effect transistor Q7 respectively; the source of the field effect transistor Q7 is connected with the drain of the field effect transistor Q15, one end of the capacitor C29 and one end of the resistor R28 respectively; the output end of the Schmitt trigger U15D is connected with the gate of the field effect transistor Q15; the input end of the Schmitt trigger U16C is connected with the gear shifting signal Y5; the output end of the Schmitt trigger U16C is connected with the input end of the Schmitt trigger U15C and the gate of the field effect transistor Q6 respectively; the source of the field effect transistor Q6 is connected with the drain of the field effect transistor Q14, one end of the capacitor C30 and one end of the resistor R29 respectively; the output end of the Schmitt trigger U15C is connected with the gate of the field effect transistor Q14; the input end of the Schmitt trigger U16B is connected with the gear shifting signal Y6; the output end of the Schmitt trigger U16B is connected with the input end of the Schmitt trigger U15B and the gate of the field effect transistor Q5 respectively; the source of the field effect transistor Q5 is connected with the drain of the field effect transistor Q13 and one end of the variable resistor RP5 respectively; the other end of the variable resistor RP5, the tap end of the variable resistor RP5 and one end of the capacitor C31 are connected with one end of the resistor R30; the output end of the Schmitt trigger U15B is connected with the gate of the field effect transistor Q13; the input end of the Schmitt trigger U16A is connected with the gear shifting signal Y7; the output end of the Schmitt trigger U16A is connected with the input end of the Schmitt trigger U15A and the gate of the field effect transistor Q4 respectively; the source of the field effect transistor Q4 is connected with the drain of the field effect transistor Q12, one end of the capacitor C32 and one end of the resistor R31 respectively; the output end of the Schmitt trigger U15A is connected with the gate of the field effect transistor Q12; The drain of the field effect transistor Q4, the drain of the field effect transistor Q5, the drain of the field effect transistor Q6 and the drain of the field effect transistor Q7 are connected with the input end of the current-voltage conversion circuit; the source of the field effect transistor Q12, the source of the field effect transistor Q13, the source of the field effect transistor Q14 and the source of the field effect transistor Q15 are grounded; the other end of the capacitor C29, the other end of the capacitor C30, the other end of the capacitor C31, the other end of the capacitor C32, the other end of the resistor R28, the other end of the resistor R29, the other end of the resistor R30 and the other end of the resistor R31 are connected with the output end of the current-voltage conversion circuit.
5. The pA-mA range current amplifier of claim 4, wherein, The compensation circuit comprises the resistor R1, the resistor R3, the resistor R4, the resistor R5, the resistor R7, the variable resistor RP1, the stabilizing diode D1 and the stabilizing diode D2; One end of the resistor R1 is connected with the input end of the current-voltage conversion circuit; the other end of the resistor R1 is connected with the tap end of the variable resistor RP1; one end of the variable resistor RP1 is connected with one end of the resistor R3; the other end of the resistor R3 is connected with the cathode of the stabilizing diode D1 and one end of the resistor R4 respectively; the other end of the variable resistor RP1 is connected with one end of the resistor R5; the other end of the resistor R5 is connected with the anode of the stabilizing diode D2 and one end of the resistor R7 respectively; the other end of the resistor R4 and the other end of the resistor R7 are both connected with +15V voltage; the anode of the stabilizing diode D1 and the cathode of the stabilizing diode D2 are both grounded.
6. The pA-mA range current amplifier of claim 5, wherein, The voltage reverse circuit comprises a low-noise operational amplifier U4, a resistor R17, a resistor R38, a resistor R39, a capacitor C7, a capacitor C8 and a capacitor C78; One end of the resistor R38 is connected with the output end of the current-voltage conversion circuit as the input end of the voltage reverse circuit; the other end of the resistor R38, one end of the capacitor C78 and one end of the resistor R17 are all connected with the reverse input end of the low-noise operational amplifier U4; the forward input end of the low-noise operational amplifier U4 is connected with one end of the resistor R39; the other end of the resistor R39 is grounded; the positive power supply end of the low-noise operational amplifier U4 is connected with +15V voltage and one end of the capacitor C7 respectively; the negative power supply end of the low-noise operational amplifier U4 is connected with -15V voltage and one end of the capacitor C8 respectively; the other end of the capacitor C7 and the other end of the capacitor C8 are both grounded; the other end of the capacitor C78 and the other end of the resistor R17 are both connected with the output end of the low-noise operational amplifier U4 as the output end of the voltage reverse circuit.
7. The pA-mA range current amplifier of claim 6, wherein, The voltage isolation output linear amplification circuit comprises an isolation operational amplifier U2, a low-noise operational amplifier U18, a resistor R57, a resistor R58, a resistor R59, a resistor R60, a resistor R49, a capacitor C62, a capacitor C29, a capacitor C63, a capacitor C30, a capacitor C66, a capacitor C67 and a variable resistor RP7; The VDD1 pin of the isolation operational amplifier U2 is connected with one end of the capacitor C62, one end of the capacitor C29 and 5V voltage respectively; the VIN pin of the isolation operational amplifier U2 is connected with the output end of the voltage reverse circuit; the SHTDN pin of the isolation operational amplifier U2, the GND1 pin of the isolation operational amplifier U2, the other end of the capacitor C62 and the other end of the capacitor C29 are grounded; the VDD2 pin of the isolation operational amplifier U2 is connected with one end of the capacitor C30, one end of the capacitor C63 and 5V voltage respectively; the other end of the capacitor C63 and the other end of the capacitor C30 are grounded; the OUTP pin of the isolation operational amplifier U2 is connected with one end of the resistor R58; the other end of the resistor R58 is connected with one end of the resistor R60 and the positive input end of the low-noise operational amplifier U18 respectively; the OUTN pin of the isolation operational amplifier U2 is connected with one end of the resistor R57; the other end of the resistor R57 is connected with one end of the resistor R59 and the reverse input end of the low-noise operational amplifier U18 respectively; the other end of the resistor R59 is connected with one end of the variable resistor RP7; the second pin of the low-noise operational amplifier U18 is connected with one end of the capacitor C66 and -15V voltage respectively; the fifth pin of the low-noise operational amplifier U18 is connected with one end of the capacitor C67 and +15V voltage respectively; the GND2 pin of the isolation operational amplifier U2, the other end of the resistor R60, the other end of the capacitor C66 and the other end of the capacitor C67 are grounded; the output end of the low-noise operational amplifier U18 is connected with the tap end of the variable resistor RP7, the other end of the variable resistor RP7 and one end of the resistor R49 respectively; the other end of the resistor R49 is taken as the output end of the voltage isolation output linear amplification circuit.
8. The pA-mA range current amplifier of claim 4, wherein, The Schmidt trigger U16A, the Schmidt trigger U16B, the Schmidt trigger U16C, the Schmidt trigger U16D, the Schmidt trigger U15A, the Schmidt trigger U15B, the Schmidt trigger U15C and the Schmidt trigger U15D are RS6G14.
9. The pA-mA range current amplifier of claim 4, wherein, The field effect tube Q4, the field effect tube Q5, the field effect tube Q6, the field effect tube Q7, the field effect tube Q12, the field effect tube Q13, the field effect tube Q14 and the field effect tube Q15 are NMOSFET tubes, and the model number is GL3N170FA9.
10. The pA-mA range current amplifier of claim 3, wherein, The low-noise operational amplifier U17 is an electrometer type amplifier.