An operational amplifier is a DC-coupled high-gain electronic voltage amplifier amplifier that has high gain, differential input, high input resistance, and low output resistance.
The symbol of an OP-AMP is as shown
Usually, there are five pins in one OP-AMP
Positive Supply/Bias voltage pin
Negative Supply Voltage/Ground pin
Dual power supply:
Most of the OP-AMP need to a DC power supply. The +Vs and -Vs are power supply terminal.
the +ve terminal of OP-AMP is connected to positive terminal of source and -ve terminal is connected to negative terminal of source.
Ideally, the OP-AMP amplifies the input differential voltage (potential difference between inverting and non-inverting pin).
The gain of an OP-AMP is controllable. External resistor controls the gain of OP-AMPs. If there is no feedback, the gain is called open-loop gain, if the feedback is present the gain is called closed-loop gain.
If there is even a small differential voltage at the input, it will cause an output voltage equal to the almost supply voltage. It is due to the large gain of the amplifier. In open-loop gain, an operational amplifier acts as a comparator (compares the inverting and non-inverting voltage). If non-inverting voltage is greater than the inverting voltage, the output will be almost equal to the supply voltage because
If feedback is present then the gain is called closed-loop gain. Now, there are two configurations for the operational amplifier
Inverting operational amplifier
Inverting amplifier is the one which amplifies the signal and also inverts the signal. Its gain formula is
Non-Inverting Operational Amplifier:
A non-Inverting amplifier is the one that amplifies the signal without inverting it. Its gain formula is
Ideal Operational Amplifier
The ideal OP-AMP is the one that has the following characteristics.
- Infinite open-loop gain
- Infinite input resistance
- Zero output resistance
- Zero input offset voltage
No real OP-AMP is ideal because the real OP-AMP does not satisfy the above conditions.
Applications of Operational Amplifier:
In various electronic circuits OP-AMPs are present.
- Differential Amplifier
- Differentiators and Integrators
- Oscillators and waveform generators
- Precision rectifiers
- Voltage clamping
- Analog to digital converters
- Digital to analog converters