ac & dc isolation in amplifier circuit

[Disha Karnataki]

we know that when there is a small signal applied to the base of transistor then the o/p (i.e from the collector) the waveform got will be inverted this is very basic so that is why we say this amplifier is a inverting one...
now suppose if we want a non-inverting one then i will have to feed the o/p of first amplifier stage to the i/p of next amplifier stage & the o/p got will be again inverted by the 2nd amplifier stage so the out coming signal has made a 360deg phase shift compared to the initial i/p signal such amplifiers are nothing but non-inverting amplifier... hope this convinced u why i have said out of phase...
so now can u please tell me whether i am correct in what i have written before i.e post #19???

 

[LvW]

we know that when there is a small signal applied to the base of transistor then the o/p (i.e from the collector) the waveform got will be inverted this is very basic so that is why we say this amplifier is a inverting one...
now suppose if we want a non-inverting one then i will have to feed the o/p of first amplifier stage to the i/p of next amplifier stage & the o/p got will be again inverted by the 2nd amplifier stage so the out coming signal has made a 360deg phase shift compared to the initial i/p signal such amplifiers are nothing but non-inverting amplifier... hope this convinced u why i have said out of phase...
so now can u please tell me whether i am correct in what i have written before i.e post #19???

Your phrase "out of phase" is rather confusing. I`ve got the impression that you mean "phase shift of 0 resp. 360 deg". Therefore, please be as exact as possible to avoid misunderstandings?
As mentioned already in my post #16 there are only two distinct cases which matter for oscillator applications: Inverting and non-inverting.
However, in any case, we need a loop gain with a total phase shift of 360 deg (resp. 0 deg).

 

[skamthey]

in amplifier circuits usually we pass small ac signals and then pass through various transistor biasing circuits and finally get an amplified o/p.
..

Hi Disha,
In case of Amplifiers say single-CS-stage (MOS) amplifier. Once we bias the opamp in saturation region. The simulator makes an linear-model of mosfets (opamp) and apply ac signal over it. So now even if we change the ac signal amplitude say 1V, the Mosfets will not see this variation as their bias-voltage is changing. Linear model just took the ac input, multiply with gain and gives output.
So if we are using 1V as a input ac signal the Output of opamp is nothing but its Gain which we want to find out.
Gain = Vout/Vin =Vout/1V=Vout