R/E/P > Dan Lavry

Proper Gain Staging Considerations?

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Barish:
Yes, Dan, please carry on. We've read so many books about opamps and gain staging but no one has ever explained it from this point of view before. Thank you for sparing your time and opening up your expertise for public domain here, that's really appreciated and respected.

Eagerly looking forward to the second installment.

Regards,

Mahcem Ozturk

wireline:
Quote:
Again, noise is not really additive


OK, this I understand...but is distortion additive, multiplicative, exponential, or what?  

Say you have .005% distortion coming from gain stage A...which is sent to gain stage B, which adds its own .005% distortion...

Is the distortion at that point .010%?  .025%?

danlavry:
wireline wrote on Thu, 07 October 2004 15:00
Quote:
Again, noise is not really additive


OK, this I understand...but is distortion additive, multiplicative, exponential, or what?  

Say you have .005% distortion coming from gain stage A...which is sent to gain stage B, which adds its own .005% distortion...

Is the distortion at that point .010%?  .025%?




I am sure we will talk about distortion more. But unlike noise, you really can relay on distortion figures to predict anything about how distortion will "accumulate". You will have to know more then just the distortion figures. In fact, distortion may add in some cases, and cancel out in other cases. The circuit designer often "weaves the circuits" to do exactly that, cancel distortions.

I hope I did not confuse anyone talking about noise. I was talking a bout the noise generated by the circuits themselves (resistor noise, semiconductor noise...). This is not about the noise you get when your mic picks up say a car driving by. The car noise is a signal. Circuit noise is random and unpredictable. There are no recognizable patterns in it...

BR
Dan Lavry
   

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