What are operational amplifiers primarily used for?

Question

also... if u compare an ideal op-amp's performance to that of a practical what would the outcome be?

Answer 1

operational amplifiers primarily provide a high input impedance and a very high voltage gain which are both essential for an electronic circuit. Also the output of the op-amp can be controlled by the feedback (either positive or negative) depending upon the output required. With two inputs it can also be used as a comparator/differentiator or simply as an amplifier of the signal by keeping one input gnd.

      The ideal op-amp has several characteristics like infinite gain, infinite bandwidth, infinite input impedance, zero o/p imp., etc.,  but with practical op-amps, there is always a finite gain, finite BW, High I/P imp., and a non-zero o/p imp., Performance of an ideal op-amp is just used as refernce measure for hte purpose of calculations so as to come to the outcome of the practical op-amps.

Answer 2

When you use an OpAmp, the formulas you use for calculating system gain, impedances, bandwidths, etc. are all based on if the op-amp was ideal.

What you actually get in real life, then, is errors to those numbers.  Gain error -- instead of a system gain of 10.0000 with an ideal amp, you get a gain of 9.999999, or whatever.  Instead of an input impedance of Rin to the negative input, you get Rin in parallel with 10 Megohms (or whatever) which is less than Rin by a small amount.  You get the idea.

Add to this the fact that real op-amps have offset voltages, offset currents, bias currents, changes in parameters due to temperature, power supply voltage, time/drift, etc. etc. and your 'ideal' system can all-of-a-sudden have a whole bunch of errors.

Real designers must take these things into account when designing a real amplifier.  Depending on the application, either these errors won't affect things that matter, or (in a precision application) you need to take *everything* into account to get a proper design.

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Answer 3

OP-AMPs are used in:

audio- and video-frequency pre-amplifiers and buffers

voltage comparators

differential amplifiers

differentiators and integrators

filters

precision rectifiers

precision peak detectors

voltage and current regulators

analog calculators

analog-to-digital converters

digital-to-analog converter

voltage clamps

oscillators and waveform generators

"Real op-amps can only approach this ideal: in addition to the practical limitations on slew rate, bandwidth, offset and so forth. real op-amp parameters are subject to drift over time and with changes in temperature, input conditions, etc. Modern integrated FET or MOSFET op-amps approximate more closely the ideal op-amp than bipolar ICs where large signals must be handled at room temperature over a limited bandwidth; input impedance, in particular, is much higher, although the bipolar op-amps usually exhibit superior (i.e., lower) input offset drift and noise characteristics."