Friday, July 23, 2010

Operational Amplifiers (Op-Amps)

An operational amplifier (Op-Amp) is a differential amplifier that amplifies the difference of voltages applied to its two input terminals (differential input), and provides a single-ended output. The operational amplifier is an extremely efficient and versatile device. Its applications span the broad electronic industry filling requirements for signal conditioning, special transfer functions, analog instrumentation, analog computation, and special systems design.
Originally, the term, “Operational Amplifier,” was used in the computing field to describe amplifiers that performed various mathematical operations. It was found that the application of negative feedback around a high gain DC amplifier would produce a circuit with a precise gain characteristic that depended only on the feedback used. By the proper selection of feedback components, operational amplifier circuits could be used to add, subtract, average, integrate, and differentiate.
An ideal Op-Amp is basically a 3-terminal device that consists of two high impedance inputs, one an Inverting input marked with a negative sign, ("-") and the other a Non-inverting input marked with a positive plus sign ("+").

Learn more about Operational Amplifiers
I am going to provide some valuable resources available online on Op-Amp theory and applications. Check these out:

  • Op-Amps for Everyone: This reference guide from Texas Instruments is my all time favorite. You must read it.
  • Theory of Operational Amplifiers: This link I provided here is of application note AN165 from Philips semiconductors. The title of the note is "Integrated operational amplifier theory" and it describes all the basic terminologies of an opamp.
  • Handbook of Operational Amplifier Applications: The purpose of this handbook is to provide a single source of information covering the proper design of circuits employing the versatile modem operational amplifier. This manual from Texas Instruments will be helpful to the experienced user of operational amplifiers, as well as the new user, in extending the range of potential applications in which these devices can be used to advantage.
  • Basic Op-Amp Applications: A hand book from California Institute of Technology designed for Sophomore Physics Laboratory.
  • A Single Supply Op-Amp Circuit Collection: Op-Amps usually require both positive and negative power supplies. Here is a collection of single supply Op-amp circuits from Texas Instruments.


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