Hi all,
Seems there were a lot of misunderstandings from my post :(
1st of all : Tosei, Can you please explain what you meant by
Quote:there is a way to express the PM as a function of the GBW but not of the UGB
I beleive GBW is equal to UGB of any ckt...I refer GBW commonly as UGB of the ckt...UGB == BW at which Gain is equal to1, ie, GBW product at Gain=1....But i beleive GBW product remains same for a given topology & process....It's just the gain and -3dB freq that you can alter once you fix your Topology & Process. Either my beliefs are highly mistaken, or i understood your post wrongly... Pls explain....
BuddyPoor, : POINT 1 : I said Ft is generally referrered to the Transit Frequency of a MOS....UGB on the other hand, is generally referred to the Transit Frequency of a Ckt, & both of them are usually not the same...
POINT 2 : By the word Ideal Behaviour, i meant a frequency till which you can consider opamp to have high enough gain required for your application....Don't take it quantitatively....You set the DC Gain of the opamp to be high enough to satisfy your Gain Error specs...F-3dB is a point till which Gain falls to Adc/sqrt(2) As for
Quote:The -3dB oint comes into the play only if you speak about the gain of an amplifier with feedback, because we consider this range as the "pass region" (especially for filters).
, F-3dB doesnt define the pass region for all Filters...It depends on the Filter Approx.,(like for chebyshev, we use -1dB point)...Filter cut-off is generally equal to PB ripple size..
POINT 3 : Here, of course, i didnt mean UGB decides the magnitude of PM/GM....I wanted to profess that PM is measured at UGB of the LG response...Of Course, it's decided by the Poles & Zeros of the Response Function....I am sorry here if i conveyed the wrong meaning...
thank you all,
Mayank.