Operational Amplifiers – Complete Theory
Page 1 – Introduction to Operational Amplifier
An Operational Amplifier (Op-Amp) is a high gain differential amplifier designed to amplify the difference between two input voltages.
It is one of the most important components in Analog Electronics and widely used in:
- Signal amplification
- Filters
- Oscillators
- Analog computation
- Instrumentation systems
Basic Structure
An Op-Amp has three main terminals:
- Non-inverting input (+)
- Inverting input (−)
- Output terminal
The output voltage depends on the difference between the input voltages.
Vo = A (V+ − V−)
Where- A = Open loop gain
- V+ = Non-inverting input voltage
- V− = Inverting input voltage
Ideal Op-Amp Characteristics
- Infinite open loop gain (A → ∞)
- Infinite input resistance
- Zero output resistance
- Infinite bandwidth
- Infinite CMRR
- Infinite slew rate
Important Concept
Because gain is extremely large:
V+ ≈ V−
This is called the Virtual Short Concept.GATE Important Points
- Op-Amp is a differential amplifier
- Output depends on difference of input voltages
- Virtual short concept is used in circuit analysis
- Open loop gain is extremely large (10⁵ – 10⁶)
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