Number of Op Amp: Limit for Amplifying Signals?

[nadersb]

hello,
Is there a limit for the numbers of op amp we use to amplify a signal?! I mean is there a problem if I use 3 or more op amp to amplify a signal?!

 

[yungman]

Absolutely yes. Op-amp have noise, offset, offset drift and distortion. The first two cases they multiply.

The key for low noise design is to put as high gain as possible on the first stage and still have the frequency respond that you need. This is because the higher the closed loop gain, the lower the frequency response. Then use the second stage to make up the required gain.

For precision circuit where offset is the problem, the reasoning is the same as above, use the lowest offset op-amp for the first stage and set it to the highest gain and still meet the frequency requirement, then make up the gain by the following stages.

For HiFi and guitar amp, you want as few stages as possible because each stage add distortion. You can really tell by your ear. I am into both and I can tell you it is obvious.

 

[nadersb]

thank you :)