Operational Amplifier (Op-amp) Characteristics and Applications

  Operational Amplifier (Op-amp)

What is an Operational Amplifier (Op-amp)?

An operational amplifier is an integrated circuit that can amplify weak electric signals. An operational amplifier has two input pins and one output pin. Its basic role is to amplify and output the voltage difference between the two input pins.

An operational amplifier (op amp) is an analog circuit block that takes a differential voltage input and produces a single-ended voltage output.

Pin configuration

  • V+: non-inverting input
  • V−: inverting input
  • Vout: output
  • VS+: positive power supply
  • VS−: negative power supply

Operational Amplifier Clasifications

There are four ways to classify operational amplifiers:

  • Voltage amplifiers take voltage in and produce a voltage at the output.
  • Current amplifiers receive a current input and produce a current output.
  • Transconductance amplifiers convert a voltage input to a current output.
  • Transresistance amplifiers convert a current input and produces a voltage output.

Op-amp characteristics

  • Infinite open-loop gain G = vout / v. in
  • Infinite input impedance Rin, and so zero input current.
  • Zero input offset voltage.
  • Infinite output voltage range.
  • Infinite bandwidth with zero phase shift and infinite slew rate.
  • Zero output impedance R. out
  • Zero noise.
  • Infinite common-mode rejection ratio (CMRR)

Characteristics Of Ideal Op-amp

  • Infinite input impedance(about 2Mohm)
  • Low output impedance(about 200 ohm)
  • Very large voltage gain at low frequency
  • Thus,small changes in voltages can be amplified byusing an op-amp
  • Infinte bandwidth(all frequencies are amplified by same factor
  • Infinite Common-mode rejection ratio
  • Infinite Power supply rejection ratio.

Characteristics of non ideal op-amp

  • Finite open-loop gain that causes gain error
  • Finite input impedance
  • Non zero output impedance
  • Finite CMRR
  • Common-mode input resistance
  • Finite bandwidth
  • Finite power supply rejection ratio.

Advantages Of An Op-amp

  • Op-amp is an universal amplifier.
  • Voltage comparators.
  • Precision rectifiers.
  • Anologue to digital converters.
  • Digital to analogue converters.
  • Filters.
  • Diffrentiators and integrators.
  • Voltage and current regulator.
  • Analogue to computers.

Disadvantages Of An Op-amp

  • Most Op-amp are designed to for lower power operation.
  • For high output is desired then the opam Specifically Designed for that purpose must be seen.
  • Most commercial Op-amp shuts off when the load resistance is below a specific level.

Applications of Op-Amps

  • Simple Amplifiers
  • Summers
  • Comparators
  • Integrators
  • Differentiators
  • Analog to Digital Converters
  • A to D Converters
  • Power source
  • Zero Crossing Detector (ZCD)