Basics of Operational Amplifiers (Op-Amps)

Operational Amplifiers, or Op-Amps, are a type of integrated circuit widely used in electronic devices.
It is a high-gain electronic voltage amplifier with a differential input, which means it amplifies the voltage difference between two inputs.
The two inputs of an Op-Amp are known as the inverting (negative) and non-inverting (positive) inputs.

Characteristics of Op-Amps

Operational amplifiers have very high input impedance, which means they draw very little current from the input source.
They also typically have low output impedance, implying they can drive (transfer power to) a range of loads.
The open-loop gain of an Op-Amp is the gain without any external feedback from output to input.
The gain of an Op-Amp is usually quite high - at least 100,000 times in many common Op-Amps.
The output voltage of an op-amp is the product of the difference between the input voltages and the gain.

Types of Op-Amps

Voltage follower (buffer) Op-Amps provide no amplification of the signal. The output voltage directly follows the input voltage.
Inverting Op-Amps amplify the input voltage with a 180-degree phase shift.
Non-Inverting Op-Amps amplify the input voltage without a phase shift.
Differential Op-Amps amplify the difference between two input voltages and ignore any voltages common to both inputs.

Applications of Op-Amps

Op-Amps are used extensively in signal processing, controls systems, and feedback amplifier circuits.
They are often used to create active filters, oscillators, voltage regulators, and instrumentation amplifiers.
Other applications include audio and video processing, radar, power electronics, and optical communication.

Special Mention: Limitations of Op-Amps

Input offset voltage is the voltage that must be applied between the two input terminals of an op-amp to null the output.
Op-Amps are not ideal; there is always some amount of input bias current and input offset current.
Limited bandwidth - The frequency response of an op-amp may not be infinite. The gain decreases as the frequency increases.
Operational amplifiers may have a limited output voltage swing and may not be able to output a large enough signal for some applications.

Understanding the functionality of operational amplifiers - their characteristics, types, applications, and limitations - is key to their effective use in various electronic circuits.