“The integrated operational Amplifier is an Electronic circuit with a certain function by using a certain manufacturing process to make a large number of semiconductor triodes, resistors, Capacitors and other components and the connections between them ON the same small piece of monocrystalline silicon chip.

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The integrated operational amplifier is an electronic circuit with a certain function by using a certain manufacturing process to make a large number of Semiconductor triodes, resistors, capacitors and other components and the connections between them on the same small piece of monocrystalline silicon chip.

This article focuses on the Linear application of operational amplifiers. Linear applications focus on mastering the transmission characteristics of integrated operational amplifiers, the characteristics of ideal operational amplifiers, as well as basic non-inverting amplifiers, inverting amplifiers, addition circuits, subtraction circuits, integrating circuits and differential circuits.

**1. The transmission characteristics of the op amp**

The transmission characteristic curve of the operational amplifier is as follows:

The linear region satisfies:

Because the voltage gain value of the operational amplifier is very high, it is easy to cause unstable circuit performance, and the linear region is very narrow. In order to make the various application circuits composed of the integrated operational amplifier work in the linear region steadily, negative feedback must be introduced.

If the op amp is in an open loop or positive feedback state, the op amp works in the non-linear region, then it can be used as a comparator:

**2. Fictitious and fictitious**

The characteristics of an ideal op amp are:

The open loop Voltage gain is regarded as infinite;

The input resistance is regarded as infinite;

The output resistance is regarded as zero.

Therefore, when the operational amplifier is working in the linear region, the voltage at the same direction input terminal and the reverse input terminal can be regarded as equal, which is called “virtual short”.

Since the input resistance is also regarded as infinite, the input current can be regarded as zero, which is called “virtual disconnection”.

Notice:

The word “virtual” is not a real short circuit or open circuit, but in the calculation, the voltage is regarded as equal and the current is regarded as zero. In reality, there is no short circuit or open circuit.

In addition, only when the op amp works in the linear region can it have “virtual short” characteristics.

**3. Typical arithmetic circuit**

The arithmetic circuit is that the operational amplifier introduces deep negative feedback. At this time, the operational amplifier works in the linear region and has the two major characteristics of “virtual short” and “virtual disconnection”. This is also the basic starting point for analyzing arithmetic circuits.

Everyone is familiar with the following basic arithmetic circuits, which will help solve complex arithmetic circuits.

The integrated operational amplifier is an electronic circuit with a certain function by using a certain manufacturing process to make a large number of semiconductor triodes, resistors, capacitors and other components and the connections between them on the same small piece of monocrystalline silicon chip.

This article focuses on the linear application of operational amplifiers. Linear applications focus on mastering the transmission characteristics of integrated operational amplifiers, the characteristics of ideal operational amplifiers, as well as basic non-inverting amplifiers, inverting amplifiers, addition circuits, subtraction circuits, integrating circuits and differential circuits.

**1. The transmission characteristics of the op amp**

The transmission characteristic curve of the operational amplifier is as follows:

The linear region satisfies:

Because the voltage gain value of the operational amplifier is very high, it is easy to cause unstable circuit performance, and the linear region is very narrow. In order to make the various application circuits composed of the integrated operational amplifier work in the linear region steadily, negative feedback must be introduced.

If the op amp is in an open loop or positive feedback state, the op amp works in the non-linear region, then it can be used as a comparator:

**2. Fictitious and fictitious**

The characteristics of an ideal op amp are:

The open loop voltage gain is regarded as infinite;

The input resistance is regarded as infinite;

The output resistance is regarded as zero.

Therefore, when the operational amplifier is working in the linear region, the voltage at the same direction input terminal and the reverse input terminal can be regarded as equal, which is called “virtual short”.

Since the input resistance is also regarded as infinite, the input current can be regarded as zero, which is called “virtual disconnection”.

Notice:

The word “virtual” is not a real short circuit or open circuit, but in the calculation, the voltage is regarded as equal and the current is regarded as zero. In reality, there is no short circuit or open circuit.

In addition, only when the op amp works in the linear region can it have “virtual short” characteristics.

**3. Typical arithmetic circuit**

The arithmetic circuit is that the operational amplifier introduces deep negative feedback. At this time, the operational amplifier works in the linear region and has the two major characteristics of “virtual short” and “virtual disconnection”. This is also the basic starting point for analyzing arithmetic circuits.

Everyone is familiar with the following basic arithmetic circuits, which will help solve complex arithmetic circuits.

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