Introduction
The term operational amplifier or "op-amp" refers to a class of high-gain DC coupled amplifiers with two inputs and a single output. The modern integrated circuit version is typified by the famous 741 op-amp. Some of the general characteristics of the IC version are:

   • High gain, on the order of a million
   • High input impedance, low output impedance
   • Used with split supply, usually +/- 15V
   • Used with feedback, with gain determined by the feedback network.