What is operational amplifier? basics concepts

• Automatic battery charger using op amp

Symbol: 

The symbol of an OP-AMP is as shown

Usually, there are five pins in one OP-AMP
Inverting pin
Non-Inverting pin
Output pin
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.

Operation:

Ideally, the OP-AMP amplifies the input differential voltage (potential difference between inverting and non-inverting pin).

Vout = A_OL(V₊ – V_–)where A_OL is the open-loop gain of the operational amplifier, V₊ is the non-inverting input voltage and V_– is the inverting input voltage.
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. This 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

(V₊ – V_–) > 0So, the output will be positive and equal to supply voltage while if inverting voltage is greater than the non-inverting voltage, the output will be almost equal to the negative supply voltage or ground.

If feedback is present then the gain is called closed-loop gain. Now, there are two configurations for the operational amplifier
1-inverting OP-AMP
2-non-inverting OP-AMP

Inverting operational amplifier

Inverting amplifier is the one which amplifies the signal and also inverts the signal. Its gain formula is

A_V = -(Rf/Rin)The negative sign shows that the signal gets inverted.

Non-Inverting Operational Amplifier:

A non-Inverting amplifier is the one that amplifies the signal without inverting it. Its gain formula is

A_V = 1 + (R2/R1)

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
• Filters
• Oscillators and waveform generators
• Precision rectifiers
• Voltage clamping
• Analog to digital converters
• Digital to analog converters

OP-AMP tutorial:

Triangle Wave Generator using OPAMP