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