Block Diagram of op-Amp:
The input stage is the dual input balanced output differential amplifier provides most of the voltage gain Intermediate stage provides additional gain Level shifter shifts the de level of the output to Zero volt with respect to ground. The output stage increases current output voltage swing and provides low output resistance.
Block Diagram:
The OP-AMP is basically a different amplifier i.e. it will amplify the voltage which is differentially present between its input terminals.
1.Input stage: The input stage is a dual-input, balanced output differential. The two inputs are inverting and non-inverting input terminals. This stage provides most of the voltage gain of the OP-AMP and decides the input resistance value R1.
2.Intermediate stage: This is usually another differential amplifier. It is driven by the output of the input stage. This stage is a dual-input unbalanced output (single ended output) differential amplifier.
3.Level shifting stage: Due to the direct coupling between the first two stages, the input of level shifting stage is an amplified signal with some non-zero dc level. Level shifting stage is used to bring this dc level to zero volts with respect to ground.
4.Output stage: this stage is normally a complementary output stage. It increases the OPAMP. It also provides a low output resistance.