Why are there so many op-amp ICs?

If all op-amp have same functional principle then why are there so many op-amp ICs and can I use any op-amp IC to amplify signals like audio signals.

Same reasons that there are so many cars or washing machines or anything else. Mainly, they aren’t all the same, they can have all sorts of different features and parameters. So while in many cases there will be quite a few different ones that will work equally well there will also be others that don’t work so well for your specific purpose.


an I use any op-amp IC to amplify signals like audio signals.

Yes that is one use for opamps... I personally like the BurrBrown ones for audio.

There are at least 20 important parameters for opamp selection, its a massive design space.

For starters the very basic things:

noise (voltage, current, flicker)
output drive
input bias current
common-mode range
output voltage range
supply voltage
recovery time from saturation
open loop gain
power consumption

can I use any op-amp IC to amplify signals like audio signals.

Many, yes, but not all. For instance the LM358 maxes out at a few kHz for full output swing,
so its a poor choice.

You might need rail-to-rail output for a 5V circuit for instance, most audio targeted
opamps don't like that.

I've been playing with some OPA1612's recently, 0.00001% distortion or something like that,
but pricey...

  • and of course another issue in the real world is companies produce new improved devices
    on a regular basis to stay competitive, but have to keep making older designs to support
    existing markets

For completeness it should probably be pointed out the various different uses for opamps
these days.

low speed sensor measurements, often need boosting before an ADC, low bandwidth, accuracy
and CMRR most important, very large gain may be needed, as in strain-gauge amps.

Audio - low distortion over the audio range, low noise most important.

Video and RF amplifiers - bandwidths upto GHz, often asymmetric inputs and impedances and
for video phase distortion/ringing is a major issue. Video amps are becoming less important
as digital is taking over.

And many more specialized uses.