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What is the difference between UGF and GBW in OPAMP ?

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lhlbluesky

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what is gbw and ugf

i have a question,for opamp,there are two parameters: UGF and GBW,are they the same?or are there some difference between them?and what,s the exact mean of UGF and GBW?Besides,in spectre,how to measure the two parameters(UGF and GBW)in caculator? thanks.
 

Re: a simple question

Here is a short explanation:
1:) UGB=unity gain bandwidth (example: 1 MHz) is identical to the frequency for which gain=1 (0 dB)
2.) GBW=gain-bandwidth-product equals the product Amax (gain at DC) times 3-dB-corner frequency fc. Example: GBW=Amax*fc=1E5*10=1E6=1MHz

Both are identical for universal compensated opamps which exhibit a gain slope of -20 dB/Dec in the active region (gain>0dB).
 

a simple question

it is just the case of how many poles lie within ugb... if only one pole falls in that range then they r same....
 

Re: a simple question

hi lhlbluesky,

if non-dominant poles are much larger than UGB, in general ten times or above, UGB is equal to GBW. otherwise UGB is smaller than GBW.
 

a simple question

The users' jiangxb and A.Anand Srinivasan responses are quite misleading for me.Can anyone of you two point out the difference which you guys have posted.

Sorry for not able to understand it properly.

regards
santom
 

Re: a simple question

Well, both contributors are right and they have repeated my explanations from my first reply with other words and parameters. Perhaps you are confused on the word "pole".
In this context, "pole" means nothing else than "corner frequency" with the consequence that the amplitude response gets steeper by 20 dB.
Try to examine a BODE plot for a lowpass system of -let´s say - third order (that means with three poles).
 

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