Operational amplifier details
Time:2024-04-20
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Operational Amplifier (Op-Amp) is an integrated circuit, which is an important device commonly used in electronic circuits. It has the characteristics of high gain, high input impedance, low output impedance, wide bandwidth, etc., and is widely used in analog circuits and signal processing fields.
The operational amplifier has two inputs (non-inverting input and inverting input), an output and a supply. A typical op amp symbol is a triangle representing the differential input of the amplifier and an arrow pointing to the output.
Features of operational amplifiers include:
High gain: Operational amplifiers usually have very high open-loop gain, which can reach tens of thousands or even millions of times.
The operational amplifier has two inputs (non-inverting input and inverting input), an output and a supply. A typical op amp symbol is a triangle representing the differential input of the amplifier and an arrow pointing to the output.
Features of operational amplifiers include:
High gain: Operational amplifiers usually have very high open-loop gain, which can reach tens of thousands or even millions of times.
High input impedance: The input impedance of the operational amplifier is very large, so the influence of external circuits on it can be reduced.
Low output impedance: The output impedance of the operational amplifier is very small, and it can drive the load circuit without too much impact.
Adjustable gain: The gain of the operational amplifier can be adjusted through the feedback circuit.
Good stability: In the case of reasonably designed feedback circuit, the operational amplifier has good stability.
Operational amplifiers can be used in signal amplifying, filtering, integrating, differentiating, comparator and other circuits. In practical applications, it is often necessary to cooperate with other components (such as capacitors and resistors) to form various functional modules to complete specific circuit functions.
The figure below shows an ideal operational amplifier.
Low output impedance: The output impedance of the operational amplifier is very small, and it can drive the load circuit without too much impact.
Adjustable gain: The gain of the operational amplifier can be adjusted through the feedback circuit.
Good stability: In the case of reasonably designed feedback circuit, the operational amplifier has good stability.
Operational amplifiers can be used in signal amplifying, filtering, integrating, differentiating, comparator and other circuits. In practical applications, it is often necessary to cooperate with other components (such as capacitors and resistors) to form various functional modules to complete specific circuit functions.
The figure below shows an ideal operational amplifier.
The input current of the ideal op amp is 0, the gain is infinite, that is, the magnification is infinite, V+ = V- = 0, and the output impedance is also 0, which means that the load capacity is very strong, but the ideal op amp does not exist in reality.
Inverting amplifier
According to virtual short, it can be obtained: V+ = V- = 0 (1)
According to the virtual break, it can be obtained: I1 = I2 = 0 (2)
I1 = ( Vin- V-) / R1 (3)
According to the virtual break, it can be obtained: I1 = I2 = 0 (2)
I1 = ( Vin- V-) / R1 (3)
I2 = (V- - Vout) / R2 (4)
The simultaneous formula (1), (2), (3) and (4) can obtain Vout/Vin = - (R2 / R1), that is, Vout = -VIN (R2 / R1).
Assume: R2 = 10K, R1 = 1K, Vin = -0.5V, that is, Vout = 5V, that is, the Vin signal is amplified by 10 times. Note that the Vin gives a inverting voltage. When hardware is connected, connect the positive end of the power supply to the GND and the negative end of the power supply to the Vin.
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