Question

What are the important characteristics of an operational amplifier (OP-AMP)?

Answer 1

The purpose of an operational amplifier is to amplify the input signals fed to it. The working of an operational amplifier is such that in order to get best performance, it should have some characteristics like very high input impedance, very high gain, etc.

Complete answer:
An operational amplifier is a type of integrated circuit whose purpose is to amplify weak input signals into an amplified output. A basic operational amplifier looks as shown in the following diagram.

Here ${V_ + }$ and ${V_ - }$ are the input voltages, ${V_{out}}$ is the output voltage while ${V_{S + }}$ and ${V_{S - }}$ are the supply voltages.
In order to obtain good amplification from an operation amplifier, it needs to have certain necessary characteristics which are summarized as follows:
1. High input impedance: The resistance at the input terminals needs to be very large or ideally it should be infinite. Due to which, all the voltage drop will occur at the input terminals and no current will flow.
2. High gain: Gain can be defined as the ratio of the output voltage to the input voltage of the operational amplifier. The value of gain should be very large which means that we get maximum amplification from the operational amplifier.
3. Low output impedance: The resistance at the output terminals of an operational amplifier should be as low as possible or ideally it should be equal to zero. This low resistance will ensure that the output of the amplifier is not affected by the load at the output terminals.

Note:
The above mentioned characteristics are the most important characteristics of an operational amplifier. Apart from these, other characteristics of an operational amplifier include a very large bandwidth and a very large range of output voltage, very less noise, etc.