The IC op-amp µA 741:
The µA 741 IC op-amp introduced by Fairchild Semiconductor in year of 1966, is now extensively recognized as the most popular and general purpose op-amp.
The design of µA 741 is depend upon a two stage architecture illustrated in Figure
Figure: Simplified Op-amp Circuit
A simplified schematic of µA 741 depend upon this architecture is illustrated in above Figure
Here the input stage is a differential input transconductance amplifier (consisting of Q1 - Q4) along an active load (comprising of the current mirror Q5 - Q6), the intermediate stage is a buffered inverting amplifier built from Q8 (with buffer consisting Q7 in emitter follower connection) and the output stage is a complementary class AB amplifier built from Q9 and Q10. A complete expanded form of this schematic is illustrated in Figure
Figure: The Internal Circuit of µA 741 Op-amp