Operational Amplifier(op-amp)

An operational amplifier is a high gain amplifier usually consisting of one or more differential amplifier and usually followed by a level translator and an output stage.

The op-amp is a versatile device that can be used to amplify dc as well as ac input signal and was originally designed for performing mathematical operations such as addition ,subtraction,multiplication and integration.Thus the name operational amplifier stems from its original use for these mathematical operations and is abbreviated to op-amp.The first op-amp was introduced by Fairchild semiconductor in 1963,its μA 702 which set the stage for development of other IC op-amps

Internal Block Schematic of op-amp

The input stage is the dual input balanced output differential amplifier.This stage generally provides most of the voltage gain of the amplifier and also establishes the input resistance of the op-amp.The intermediate stage is usually another differential amplifier,which is driven by the output of the first stage.On most amplifiers,the intermediate stage is dual input,unbalanced output. Because of direct coupling,the dc voltage at the output of the intermediate stage is well above ground potential.Therefore,the level translator(shifting)circuits is used after the intermediate stage downwards to zero volts with respect to ground.The final stage is usually a push pull complementary symmetry amplifier output stage.The output stage increases the voltage swing and raises the ground supplying capabilities of the op-amp.a well designed output stage also provides low output resistance.

Written by John on September 26th, 2008 with 1 comment.
Read more articles on Linear Integrated Circuits and op-amp.

Related articles

• Op-amp in closed loop configuration (October 15th, 2008)
• Open Loop Op-Amp Configurations (October 14th, 2008)
• Ideal Voltage Transfer Curve (October 14th, 2008)
• The Ideal Op-amp (October 13th, 2008)
• Op-amp Parameters (October 13th, 2008)