Op Amp Basic | What is an operational amplifier | operational amplifier characteristics |

Operational Amplifier ( op- Amp)

op- Amp amplifier is a linear integrated circuit. Operational amplifier is three terminal devices. two input terminal (inverting terminal and non inverting terminal) and one output terminal . negative terminal also called inverting terminal and positive terminal called Non- inverting terminal.

  • the typical operational amplifier is a high gain D.C amplifier usable from 0 TO OVER 1 MHZ. By connecting external resistor voltage gain and bandwidth can be adjusted as per requirements.
  • it is suitable for D.C as well as A.C applications.
  • the complete operational amplifier circuit, which may consists of 32 transistors and numerous resistors  along with a few semiconductor diodes is fabricated in a space of about 100 mm or so. this renders the electronic circuitry the compactness along with reliability and longer life.
  operational amplifier always work negative feed back. 

Operational amplifier Characteristics ;

an ideal case op- amp

  • Ri ( Input resistance)                                                 -               Infinite(∞)
  • R ( output)                                                                    -               0
  • Off set voltage                                                              -               0
  • Off set current                                                             -               0
  • Open loop gain                                                             -               0
  • Open loop bandwidth                                                  -               Infinite (∞)
  • CMMR ( common mode rejuction ration)               -               Infinite (∞)
  • Slow rate                                                                       -               Infinite (∞)

Practical case operational amplifier;

  • Ri ( Input resistance)                                                 -               1 M ohm - 2 M ohm
  • ( output)                                                                    -               50 Ohm -   100 Ohm
  • Off set voltage                                                              -               10 MV
  • Off set current                                                             -               10 NA
  • Open loop gain                                                             -               1000000
  • Open loop bandwidth                                                  -               1 Mhz
  • CMMR ( common mode rejuction ration)               -                 90 dB
  • Slow rate                                                                    -                   1   volt/ micro sec.

Uses of operational amplifier 

Operational  Amplifiers are devices which take a relatively weak signal as an input and produce a much stronger signal as an output. The operational amplifier (or op-amp) is a special kind of amplifier used in equipment such as stereo equipment and medical cardiographs (which amplify the heart beat).


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