Page "Operational amplifier" Paragraph 52

The use of op-amps as circuit blocks is much easier and clearer than specifying all their individual circuit elements ( transistors, resistors, etc.

), whether the amplifiers used are integrated or discrete.

In the first approximation op-amps can be used as if they were ideal differential gain blocks ; at a later stage limits can be placed on the acceptable range of parameters for each op-amp.