The basic working principle of an operational amplifier is to distribute the input voltage to two internal resistors and control the output voltage by changing the voltage difference between the two resistors. In which one resistor (input resistor) is connected to the input terminal and the other resistor (output resistor) is connected to the output terminal. The internal circuit of the operational amplifier amplifies the input signal by amplifying the voltage difference between the two resistors.
An operational amplifier has two inputs: a positive input (V+) and a negative input (V-). These two ports are usually used for control and adjustment in circuit design.
The positive input terminal is usually called "positive" terminal or "polarity" terminal, and the negative input terminal is usually called "negative" terminal or "inverting" terminal.
The operational amplifier has extremely high gain, can amplify tiny input signals, and has good linear characteristics.
Operational amplifiers can also be used to build various circuits, such as amplifiers, filters, shapers, comparators, integrators, differentiators and so on.
Operational amplifiers can be divided into two categories.
voltage amplifier
current amplifier
These two usage scenarios are mainly different, and they need to be judged and selected in combination with actual needs when used in applications.