The role of an operational amplifier

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Introduction: Operational amplifiers play an important role in the circuit, and their applications have extended to various fields such as automotive electronics, communications, and consumer, and will play an important role in supporting future technologies. Next, let's take a look at what the role of the op amp is.

1. The role of operational amplifiers - Introduction

An operational amplifier, referred to as an op amp, is a circuit unit with a very high amplification factor. An operational amplifier is a linear integrated circuit that is widely used. And a wide variety, in the application of not only can be used to amplify the weak signal, can also be used as an inverting, voltage follower, can add and subtract to the electrical signal, so it is called an operational amplifier. Not only is it widely used in other places, but it is also used most in terms of sound. For example, preamplifiers, buffers, headphone amplifiers, in addition to some use of discrete components, tubes, most of the use of integrated operational amplifiers. Sometimes, a voltage regulator circuit is used to make a high-precision voltage regulator filter circuit.

2. The role of the operational amplifier - structure

The operational amplifier consists of four parts: the input stage, the intermediate stage, the output stage, and the bias circuit, as shown in the following figure. It has two inputs and one output.

Input stage: Also known as the pre-stage, it is often a high-performance differential amplifier circuit with a double-ended input. Generally, the input resistance is high, the differential mode amplification is large, the ability to suppress the common mode signal is strong, and the quiescent current is small.

Intermediate stage: The main amplifier of the whole amplifying circuit, its function is to make the integrated operational amplifier have a strong amplification capability, and more commonly use a common-emitter amplifying circuit.

Output stage: It has the characteristics of wide linear range of output voltage, small output resistance and small nonlinear distortion. It uses complementary output circuits.

Bias circuit: It is used to set the static working point of the amplifier circuit of the integrated operational amplifier, and the current source circuit is often used.

3. The role of the operational amplifier

The role of an op amp is to amplify the signal. The sensor + op amp + ADC + processor is a typical application circuit of the operational amplifier. This circuit is difficult to achieve good results for the amplification of weak signals. It is difficult to achieve good results with only a single amplifier. Some special methods and sensor excitation methods must be used, and synchronous detection is used. The circuit structure can get very good measurement results. This synchronous detection circuit is similar to a lock-in amplifier structure, including a square wave excitation of a sensor, a current to voltage amplifier, and synchronous demodulation. It should be noted that the current-to-voltage amplifier needs to use an op amp with a very low input bias current.

Expand reading:

1. Have you noticed the knowledge of these operational amplifiers?

2. How to use the op amp correctly

3. Operation principle of operational amplifier

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