CN222736125U - An operational amplifier input protection circuit - Google Patents
An operational amplifier input protection circuit Download PDFInfo
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- CN222736125U CN222736125U CN202420678532.XU CN202420678532U CN222736125U CN 222736125 U CN222736125 U CN 222736125U CN 202420678532 U CN202420678532 U CN 202420678532U CN 222736125 U CN222736125 U CN 222736125U
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- protection circuit
- clamping diode
- input
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Abstract
本实用新型涉及一种运算放大器输入保护电路，输入保护电路包括过压保护电路、静电保护电路、运算放大器Ⅰ、运算放大器Ⅱ；静电保护电路包括电阻R1、电容C；所述的过压保护电路输入端与电压输入端IN连接，过压保护电路经电阻R1与运算放大器Ⅰ输入端连接，运算放大器Ⅰ输出端与运算放大器Ⅱ连接，运算放大器Ⅱ输出端经电容C连接至电阻R1与运算放大器Ⅰ输入端之间。静电保护电路与过压保护电路之间的电性连接，可以确保电流的稳定和正常分配。在电路设计过程中考虑到灵活性和便利性，以满足各种使用需求，具有极好的防护效果和稳定性，大大提高了运算放大器的使用效率和寿命。
The utility model relates to an operational amplifier input protection circuit, the input protection circuit includes an overvoltage protection circuit, an electrostatic protection circuit, an operational amplifier I, and an operational amplifier II; the electrostatic protection circuit includes a resistor R1 and a capacitor C; the input end of the overvoltage protection circuit is connected to the voltage input end IN, the overvoltage protection circuit is connected to the input end of the operational amplifier I via the resistor R1, the output end of the operational amplifier I is connected to the operational amplifier II, and the output end of the operational amplifier II is connected between the resistor R1 and the input end of the operational amplifier I via the capacitor C. The electrical connection between the electrostatic protection circuit and the overvoltage protection circuit can ensure the stability and normal distribution of the current. Flexibility and convenience are taken into consideration in the circuit design process to meet various usage requirements, with excellent protection effect and stability, which greatly improves the use efficiency and life of the operational amplifier.
Description
Technical Field
The utility model belongs to the field of electronic information, and particularly relates to an operational amplifier input protection circuit.
Background
An operational amplifier is a key component widely applied to various electronic devices, and is used for amplifying electric signals to realize various signal processing tasks, such as filtering, amplifying, analog quantity integration, distinguishing, addition and the like. Operational amplifiers have very high input impedance, low output impedance, wide bandwidth, and highly flexible gain adjustment characteristics, and thus play an important role in analog electronic circuits.
Although operational amplifiers have many advantages as an analog signal processing component, they are not without drawbacks. For example, the input terminal of the operational amplifier may be damaged by exposing to excessive voltage or electrostatic shock, and thus the semiconductor element inside the operational amplifier needs to be protected correspondingly.
In the fields of communication, instruments, biomedicine and the like, detection of weak signals is a common requirement. These signals, in the form of voltages, currents, or optoelectronics, typically require amplification by an amplifier, followed by subsequent signal analysis and processing. Since these signals are very weak, the amplifier itself is required to have characteristics of low noise, high input impedance, high common mode rejection ratio, and low power consumption to ensure that the amplified signal is not covered by noise or interference.
Disclosure of Invention
The utility model effectively protects the sensitive part of the operational amplifier to input, avoids the damage of the internal elements of the operational amplifier caused by over high input voltage or electrostatic impact, has simple structure and quick response, and can quickly respond and protect the input voltage when the input voltage is over high instantly or the electrostatic impact so as to improve the reliability and the stability of the operational amplifier and the whole circuit system.
The input protection circuit comprises an overvoltage protection circuit, an electrostatic protection circuit, an operational amplifier I and an operational amplifier II, wherein the overvoltage protection circuit, the electrostatic protection circuit, the operational amplifier I and the operational amplifier II are electrically connected;
The input end of the overvoltage protection circuit is connected with the voltage input end IN, the overvoltage protection circuit is connected with the input end of the operational amplifier I through the resistor R1, the output end of the operational amplifier I is connected with the operational amplifier II, and the output end of the operational amplifier II is connected between the resistor R1 and the input end of the operational amplifier I through the capacitor C.
In one scheme, the overvoltage protection circuit comprises a current limiting resistor Rin, a clamping diode D1 and a clamping diode D2, wherein the electrostatic protection circuit comprises a resistor R1 and a capacitor C;
One end of the current limiting resistor Rin is electrically connected with the voltage input end IN, and the other end of the current limiting resistor Rin is electrically connected with one end of the resistor R1 and the anode of the clamping diode D1;
The anode of the clamping diode D1 is electrically connected with the cathode of the clamping diode D2, the cathode of the clamping diode D1 is electrically connected with the power VCC end, and the clamping diode D2 is electrically connected with the power VSS end;
The other end of the resistor R1 is electrically connected with the positive input port of the operational amplifier I, and the output port of the operational amplifier I is electrically connected with the negative input port of the operational amplifier II;
The output end of the operational amplifier II is connected with the positive input port of the operational amplifier I through a capacitor C.
In one aspect, the input protection circuit further includes an adjustable resistor R2, and the output port of the operational amplifier I is electrically connected to the negative input port of the operational amplifier II through the adjustable resistor R2.
In one scheme, the input protection circuit further comprises a clamping diode D3 and a clamping diode D4, wherein the output end of the operational amplifier II is electrically connected with the cathode of the clamping diode D3 and the anode of the clamping diode D4 through a capacitor C, and the anode of the clamping diode D3 is electrically connected with the cathode of the clamping diode D4 and then is connected with the positive input port of the operational amplifier I.
The utility model has the beneficial effects that:
The utility model has the beneficial effects that the input protection circuit of the operational amplifier is designed, wherein the input protection circuit comprises an overvoltage protection circuit and an electrostatic protection circuit, the overvoltage protection circuit can effectively limit the input voltage, the damage of internal elements of the operational amplifier caused by overhigh voltage is avoided, and the electrostatic protection circuit effectively inhibits the influence of static electricity on the operational amplifier and prevents the amplifier from being damaged by the static electricity. The comprehensive protection design can enhance the reliability and the safety of the operational amplifier and the whole circuit system, improves the working stability of the operational amplifier and the whole circuit system, has simple integral structure and easy realization, and greatly improves the service life and the safety performance of the electronic equipment.
Drawings
FIG. 1 is a schematic circuit diagram of an example of the present utility model;
Fig. 2 is a schematic circuit diagram provided by another example of the present utility model.
Detailed Description
Embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While embodiments of the present application are illustrated in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.
In one example, as shown in fig. 1, the input protection circuit includes an overvoltage protection circuit, an electrostatic protection circuit, an operational amplifier I, and an operational amplifier II. The overvoltage protection circuit, the electrostatic protection circuit, the operational amplifier I and the operational amplifier II are electrically connected, and the electrostatic protection circuit comprises a resistor R1 and a capacitor C;
The input end of the overvoltage protection circuit is connected with the voltage input end IN, the overvoltage protection circuit is connected with the input end of the operational amplifier I through the resistor R1, the output end of the operational amplifier I is connected with the operational amplifier II, and the output end of the operational amplifier II is connected between the resistor R1 and the input end of the operational amplifier I through the capacitor C.
In another example, the overvoltage protection circuit comprises a current limiting resistor Rin, a clamping diode D1 and a clamping diode D2;
One end of the current limiting resistor Rin is electrically connected with the voltage input end IN, and the other end of the current limiting resistor Rin is electrically connected with one end of the resistor R1 and the anode of the clamping diode D1;
The anode of the clamping diode D1 is electrically connected with the cathode of the clamping diode D2, the cathode of the clamping diode D1 is electrically connected with the power VCC end, and the clamping diode D2 is electrically connected with the power VSS end;
the other end of the resistor R1 is electrically connected with the positive input port of the operational amplifier I. Preferably, the input protection circuit further includes an adjustable resistor R2, and the output port of the operational amplifier I is electrically connected to the negative input port of the operational amplifier II through the adjustable resistor R2.
Preferably, as shown in fig. 2, the input protection circuit further includes a clamping diode D3 and a clamping diode D4, wherein the output end of the operational amplifier II is electrically connected with the cathode of the clamping diode D3 and the anode of the clamping diode D4 through a capacitor C, and the anode of the clamping diode D3 is electrically connected with the cathode of the clamping diode D4 and then is connected with the positive input port of the operational amplifier I.
The operational amplifier I and the operational amplifier II are in a negative feedback working mode, the negative input end of the operational amplifier I is directly and electrically connected with the output end, and the negative input end of the operational amplifier II is electrically connected with the output end through a resistor R3.
The current limiting resistor Rin is used for limiting the current and protecting the subsequent circuit from being damaged by excessive current. The clamping diodes D1 and D2 are used for clamping the voltage to prevent the input voltage from being too high, and play a role in overvoltage protection. Clamping diodes D3 and D4 are connected in the circuit to ensure that the input impedance of the preamplifier is not influenced by the electrostatic protection circuit.
The resistor R1 is used to form a high-pass filter circuit in cooperation with the capacitor C, and is used to remove the dc component in the input signal. The capacitor C is used for forming a high-pass filter circuit by matching with the resistor R1 and removing direct current components in an input signal, and is connected with the output end of the operational amplifier II and used for blocking direct current and transmitting alternating current signals. The adjustable resistor R2 is used for adjusting negative feedback of the operational amplifier and changing the amplification factor.
The parameters were selected to be rin=5kΩ, r1=100deg.kΩ, r2=1kΩ adjustable resistance, c=0.001 uF. The amplitude of the analog electrostatic signal applied at the input IN during the test is 4000V, 10ns on rising and 200ns duration.
The operational amplifier I is used for amplifying an input signal, and the operational amplifier II is used for further amplifying the signal to form a two-stage amplifying circuit. The operational amplifier II is connected with the negative feedback of the operational amplifier I, so that the amplification factor can be stabilized, and the linearity can be improved.
In the working principle of the utility model, in an overvoltage protection circuit, if the input voltage is too high, the overvoltage can be transmitted to the inside of the circuit through a current limiting resistor Rin, when the voltage reaches a certain level, the clamping diodes D1 and D2 start to conduct, and the voltage can be clamped at a certain value, so that the damage of the overvoltage to the input voltage is prevented.
The electrostatic protection circuit is used for preventing interference of static electricity, when current passes through the current limiting resistor Rin, the resistor R1 and the capacitor C start to work, and the static electricity is grounded, so that damage of the static electricity to the operational amplifier is prevented.
The operational amplifier I and the operational amplifier II are core signal amplification links, signals connected to the positive input port of the operational amplifier I can be amplified through electrical connection between the operational amplifier I and the operational amplifier II, and amplified signals are amplified again by the operational amplifier II through the capacitor C and the negative input port of the operational amplifier II, so that larger signals are output.
The adjustable resistor R2 plays a role in adjusting the amplification factor, and the amplification factor of a signal input to the negative input port of the operational amplifier II can be changed by adjusting the adjustable resistor R2, so that the use requirement is better met. Clamping diodes D3 and D4 are connected in the circuit to ensure that the input impedance of the preamplifier is not affected by the electrostatic protection circuit.
The foregoing description of embodiments of the application has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described. The terminology used herein was chosen in order to best explain the principles of the embodiments, the practical application, or the improvement of technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (4)
1. The operational amplifier input protection circuit is characterized by comprising an overvoltage protection circuit, an electrostatic protection circuit, an operational amplifier I and an operational amplifier II, wherein the overvoltage protection circuit, the electrostatic protection circuit, the operational amplifier I and the operational amplifier II are electrically connected;
The input end of the overvoltage protection circuit is connected with the voltage input end IN, the overvoltage protection circuit is connected with the input end of the operational amplifier I through the resistor R1, the output end of the operational amplifier I is connected with the operational amplifier II, and the output end of the operational amplifier II is connected between the resistor R1 and the input end of the operational amplifier I through the capacitor C.
2. The operational amplifier input protection circuit according to claim 1, wherein the overvoltage protection circuit comprises a clamping diode D1, a clamping diode D2 and a current limiting resistor Rin;
The anode of the clamping diode D1 is electrically connected with the cathode of the clamping diode D2, the cathode of the clamping diode D1 is electrically connected with the power VCC end, and the clamping diode D2 is electrically connected with the power VSS end;
One end of the current limiting resistor Rin is electrically connected with the voltage input end IN, the other end of the current limiting resistor Rin is connected between the anode of the clamping diode D1 and the cathode of the clamping diode D2, and the anode of the clamping diode D1 is also connected with one end of the resistor R1, the other end of the resistor R1 is electrically connected with the same-direction input end of the operational amplifier I, the reverse input end of the operational amplifier I is connected with the output end of the operational amplifier I, and the output end of the operational amplifier I is electrically connected with the reverse input end of the operational amplifier II;
The output end of the operational amplifier II is connected with the homodromous input end of the operational amplifier I through a capacitor C.
3. The operational amplifier input protection circuit according to claim 1, wherein an adjustable resistor R2 is provided between the output terminal of the operational amplifier I and the inverting input terminal of the operational amplifier II.
4. The operational amplifier input protection circuit according to claim 1, further comprising a clamping diode D3 and a clamping diode D4, wherein the output end of the operational amplifier II is electrically connected with the cathode of the clamping diode D3 and the anode of the clamping diode D4 through a capacitor C, and the anode of the clamping diode D3 is electrically connected with the cathode of the clamping diode D4 and then is connected with the positive input port of the operational amplifier I.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202420678532.XU CN222736125U (en) | 2024-04-03 | 2024-04-03 | An operational amplifier input protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202420678532.XU CN222736125U (en) | 2024-04-03 | 2024-04-03 | An operational amplifier input protection circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN222736125U true CN222736125U (en) | 2025-04-08 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202420678532.XU Active CN222736125U (en) | 2024-04-03 | 2024-04-03 | An operational amplifier input protection circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN222736125U (en) |
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2024
- 2024-04-03 CN CN202420678532.XU patent/CN222736125U/en active Active
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| Date | Code | Title | Description |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20250819 Address after: 071000 Hebei Province, Tang County, Renhou Town, Yuanzi Village, No. 57 Patentee after: Li Mi Country or region after: China Patentee after: Qin Honghua Patentee after: Zhao Yahui Address before: 610039 Chengdu City, Jinniu District Province, North Bridge Road, No. Patentee before: XIHUA University Country or region before: China |
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| TR01 | Transfer of patent right |