Phase shift issue in Dominant Pole Compensation strategy....

[LvW]

what I realized from your post 26 is that...in electronics one cannot be absolute...like there is nothing certain.
.

I don`agree. This conclusion cannot be drawn from my post#26

actually if something is true at a certain condition..doesn't necessarily mean that it would be true at other conditions as well...

...philosophical rule of thumb? Do you have an example?

 

[brainbaby]

I don`agree. This conclusion cannot be drawn from my post#26

sorry its a typo..I meant post 16 not 26...

...philosophical rule of thumb? Do you have an example?

earlier I use to think that roll off happens only at a rollover frequency...wp=1/RC...which I previously thought to be certain...but in your following quote you told me a fact that actually the decrease of amplitude takes place at very low frequency (f=1E-12 Hz) though hard to measure... so that's why I thought that one cannot be absolutely certain at all times..it mere conditional...(depends upon condition)

remember the simple RC lowpass with a pole at wp=1/RC. The decrease of amplitude with a corresponding phase shift will start already for f=1E-12 Hz (and even below).

 

[LvW]

earlier I use to think that roll off happens only at a rollover frequency...wp=1/RC...which I previously thought to be certain...but in your following quote you told me a fact that actually the decrease of amplitude takes place at very low frequency (f=1E-12 Hz) though hard to measure... so that's why I thought that one cannot be absolutely certain at all times..it mere conditional...(depends upon condition)

I rather think, it depends not on certain conditions but on the degree of simplification one is able to accept.
To make it clear: At the pole frequency "starts" the roll-off of the asymptotic line that is used as an aid for constructing a much more realsitic curve of the phase response (which begins to deviate from the starting value much earlier).

 

[jim hardy]

earlier I use to think that roll off happens only at a rollover frequency...wp=1/RC...which I previously thought to be certain...but in your following quote you told me a fact that actually the decrease of amplitude takes place at very low frequency (f=1E-12 Hz) though hard to measure...

that's the trouble with umpteen-digit calculators
by slide rule it's obvious from the t or srt scale when phase has got so close to its asymptote as to 'have arrived'
but the calculator goes out probably beyond twelve digits ,
one has to 'think analog' to realize the number has effectively quit changing.

 

[LvW]

.in electronics one cannot be absolute...like there is nothing certain.
actually if something is true at a certain condition..doesn't necessarily mean that it would be true at other conditions as well...

I don`t know if I completely understood the meaning of these sentences - but It could be the truth replacing "certain" by "absolutely correct".
Let me explain: In electronics nothing is absolutely "correct" (formulas, explanations) because we always make simplifications and neglect some minor influences. This makes sense and is necessary - otherwise we would arrive at formulas which cannot be handled and evaluated. The most simple example is a resistive voltage divider which - of course - has some capacitive and inductive influences. However, as long as these influences are smaller than parts tolerances or other unwanted and/or unknown influences from other sources it makes much sense to treat the divider as "pure resistive".
However, there my be other situations ("conditions" as you say) where some simplifications are not allowed anymore.
Another example: We must know within which limits we can treat an operational amplifier as ideal. Otherwise, it can happen that an opamp-based circuit suddenly behaves unexpected or even begins to oscillate.
Summary: Each formula or function contains simplifications - and it is the task of a good engineer to know under which operating conditions these simplifications are allowed and will cause errors/deviations which are within acceptable limits.