Operational amplifier (OP – AMP)
Linear integrated circuits are being used in a number of
electronic applications, such as in the fields like communication,
medical electronics, instrumentation control etc. An important linear
IC is an operational amplifier.
OP-AMP is a solid state device capable of sensing and amplifying
dc and ac input signals. OP-AMP is an amplifier with two inputs
(differential inputs) and a single output. OP-AMP consists of 20
transistors, 11 resistors and one capacitor. It usually requires a
positive and negative power supply (dual power supply). This allows the
output voltage to swing positive and negative with respect to ground
The most important characteristics of OP-AMP are : (i) very high
input impedance or even infinity which produces negligible current at
the inputs, (ii) very high gain, (iii) very low output impedance or even
zero, so as not to affect the output of the amplifier by loading.
An OP-AMP is so named, because it was originally designed to
perform mathematical operations such as addition, subtraction,
multiplication, division, integration, differentiation etc in analog
computer. Nowdays OP-AMPs are used in analog computer operations
and in timing circuits.