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Why are there multitude of operational amplifier, why not type size fits all

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Advanced Member level 2
Apr 17, 2011
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This question is about op-amps and may look strange at first. Basically my question is that since, operational amplifier is a device which has 2 inputs and one output. One of the two inputs is inverting while the other is non-inverting. The output is equal to the difference between the inputs multiply by open loop gain that may be like a million.

Real op-amps come close to this ideal but have some leakage currents for biasing purpose and have slew rate.

I want to know, why isn't there a single all-purpose op-amp. All we need is a device with ultra low leakage current, ultra high slew rate, use single supply and not become badly effected by temperature. Why does an all-purpose op-amp not then exist?

Putting it in other words, we take the best of all different op-amps and put it all into one op-amp and name it all purpose op-amp. Why has this not been done?

On a side note, how to op-amps advertised for "audio" and "video" applications differ from other operational amplifiers? I mean all there is, is a device that has a huge open-loop gain and two inputs. I don't see why there should be an op-amp for audio applications and another for video e.t.c.

All you want is everything that matters to you. Simple.

So implicitly you would not care if your do-all op amp
consumed an ampere or two of supply current or had
to be built from transistors which do not exist?

Slew rate can't be divorced from supply current in a
given technology. Gain and input bias neither.

If it's so easy, download yourself a foundry PDK and
have yourself a time.

More likely you'll end up better understanding how
transistor attributes limit circuit attributes, and how
transistor attributes themselves must be traded against
material-system limits (fT, gm, ro, BV).

Not seeing why, has to do with the wearing of blinders.
Things do matter which you do not consider or list here.
If not to you, to others who make the market.
The lousy 741 opamp has many problems because it was one of the first opamps released 47 years ago.
The LM324 and lM358 have crossover distortion ansd trouble with freq OOPS

Continued in this Edit: and trouble with frequencies above only 2000H, because they are also old and are one of the first low power multiple opamps.
Manufacturers of OP-amps make them to sell at a profit so they have to design a product at a price the market can afford. So they optimise their amplifiers for say, high gain and good DC stability for instrumentation, but not a very good frequency ersponse, Low noise, high gain, low distortion and reasonable frequency response for audio use and very high speed for video applications. Its the same reason that there are so many different forms of road vehicles, each one is designed for a different market segment. No one expects a furniture van to have the speed and handling of a Ferrari!

why not type size fits all

you can ask this question to almost any thing: cellular phones, food, cars, colors, people, pencils, schools, movies, forums, boxes...

isn´t it funny to think of a cellular phone that has all functions you can imagine, with no power consumption, in water, in space, no weight, stretch it to the perfect size and back...

or a teacher who he knows all and everything...

..a perfect world?... not for me. For me this sounds very booring and the same time scary..

If everything was made to be PERFECT then they would cost too much for applications that do not need the extreme features.

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