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What is an operational amplifier?

Latest Updated:03/01/2007

Question:

What is an operational amplifier?

Answer:

"Op Amp" is an abbreviation for operational amplifier. Ideally, this is a differential amplifier with the following characteristics:

  • Gain: infinite
  • Input impedance: infinite
  • Output impedance: 0
  • Delay from input to output: 0

By negative feedbackNote application, it can be used as an amplifier and for various types of analog signal processing (addition, subtraction, differentiation, integration, etc.).

[Operational amplifier description]
Represented as a triangle, comprises a total of 5 pins, as follows: + input (VN: non-inverting input => This means that the polarities of the applied input signal and the signal obtained as the output are identical), - input (VI: inverting input: This means that the polarities of the applied input signal and the signal obtained as the output are exactly the opposite (-180°)), output (VO), and power supplies (V+, V-).



The most common usage example is that of an amplification circuit, as follows.



In this example, the input signal is amplified by (1 + R2/R1) times.
If R1 = 1 kΩ and R2 = 10 kΩ, the amplifier will have a gain of x11.
Therefore, the gain can be freely set simply by changing the resistance value. In the above circuit, the signal is being input via the + pin, so the input and output are in-phase (non-inverting amplifier); however, if the signal is input on the R1 side, the output is inverted (inverting amplifier).

Note Negative feedback means the output signal is fed back to the - input via a resistor, capacitor, diode, or transistor connected between the output and - input.

Suitable Products
Operational Amplifiers
USB3.0 Host Controller
UPD720202
UPD720201
UPD720200A
UPD720200
USB2.0 Host Controller
UPD720102
UPD720101
UPD720100A