The OPerational AMPlifier or OPAMP is a versatile analog Integrated Circuit (IC) that is capable of producing a very high gain. An amplifier is a circuit that receives a signal at its input and delivers an undistorted larger version of the signal at its output. The operational amplifier is a high gain amplifier to which feedback is added to control its overall response characteristic. In closed loop connection, an external resistance is connected between the output and the negative (inverting) input terminal as a negative feedback. Here, the gain can be controlled by changing the values of the resistors.