Q. Explain basic working of Ideal operational amplifier?

The operational amplifier, known also as op amp, consists of several transistors, diodes, capacitors, and resistors. It is available in integrated-circuit form for less than one U.S. dollar. Being inexpensive, compact, and versatile, operational amplifiers are used in a variety of simple circuits.

Op-amp circuits, as we will see later, usually contain negative feedback. Op-amp circuits themselves can be regarded as building blocks. These blocks are characterized by their input resistance, output resistance, and open-circuit voltage amplification. The symbol for the op amp is shown in Figure. Two terminals labeled + and - are available for inputs. The voltages of these terminals are labeled with respect to the common terminal,

denoted by a ground symbol. The output voltage is related to the difference between the two input voltages as

v_o = A(v_p - v_n)

where A is the open-loop voltage gain. Thus, the op amp is basically a form of differential amplifier, in which the difference v_p - v_n is amplified. For an output voltage on the order of 12 V, the difference voltage vd is on the order of 0.12 mV, or 120 µV. The input impedance Z_i is on the order of 1 M, while the output impedance Z_o is on the order of 100  to 1k.