When I run a slave small signal noise analysis subjected to a master large signal driven PSS(Periodical Steady State) Analysis of a simple Hysteresis Inverter in attached figure, biggest contributor about phase noise at Vout is "MN3".

Do you think my result is reasonable ?

Anyway output phase noise of this Hysteresis Inverter is fairly worse compared to conventional inverter.

Do you think Hysteresis Inverter could produce larger phase noise ?

You are applying a small signal analysis to a circuit which is significant in its large signal effects.

Plus small signal is not wisely applied to switching circuits - stay with  PSS type techniques.

Also, hysterisys is a sense introduces a phase shift a a function of bias point and may not be the way to analyze the circuit.

Attached figure shows time domain waveform for input and output.
I also show gradient of output.
As you can see, if width of hysteresis is wider, gradient of output is larger and sideband noise is also larger.

Mayank wrote on Sep 17^th, 2010, 2:34am:
There is no reason why Large signal Steady State analysis can't capture transition effect, although I don't know what you mean by "two types of transition".

This is a small signal noise analysis averaged over one period which include both rise and fall edge's contributions.
See "deriv(out)" in http://www.designers-guide.org/Forum/Attachments/Hysteresis_2.png

Mayank wrote on Sep 17^th, 2010, 2:34am:
What do you mean by "their corresponding Large Signal Solutions" ?

vp1953 wrote on Sep 18^th, 2010, 8:44am:
There is no such noise.
It is "USB Noise" not "USB Phase Noise".
See http://www.designers-guide.org/Forum/YaBB.pl?num=1274422891

Also see http://www.designers-guide.org/Forum/YaBB.pl?num=1280323054
Basically same as a link although this Hysteresis Buffer case is driven circuit not autonomous circuit.

vp1953 wrote on Sep 18^th, 2010, 8:44am:
Biggest contributor to output noise is a fricker noise of MN3 not thermal noise.

If size of MN3 is larger and then width of hysteresis is wider, sideband noise from MN3 is larger.
However total fricker noise of MN3 itself is smaller for larger MN3.

See "deriv(out)" in http://www.designers-guide.org/Forum/Attachments/Hysteresis_2.png
If a transition is sharper, output noise will be smaller generally.

But it is not true for my Hysteresis Buffer case.
I will survey about this more.

vp1953 wrote on Sep 18^th, 2010, 8:44am:
Such thing is natural and common effect.
Consider "Bias dependent Noise" and then "Cyclostationary Noise".

Effects of periodical varying bias points are surely taken into Slave small signal noise analysis subjected to master large signal steady state analysis.

I think we can never escape fairly large degradation of phase noise if we implement Hysteresis characteristics having meaningful Hysteresis width.

I can see many cases where external TCXO signal is inputed via Hysteresis buffer for reference clock of PLL Synthesizer.
However could it cause very serious degradation of phase noise of PLL Synthesizer ?

pancho_hideboo wrote on Sep 15^th, 2010, 8:29am:

vp1953 wrote on Sep 19^th, 2010, 10:32am:
Surely read following.
pancho_hideboo wrote on Sep 18^th, 2010, 12:37pm:

vp1953 wrote on Sep 19^th, 2010, 12:23pm:
Again, biggest contributor is fricker noise not channel noise.

I think large value of deriv(out) causes enhancement of cotribution to out from MN3's fricker noise.

vp1953 wrote on Sep 19^th, 2010, 12:23pm:
I can't understand what you want to mean.

MN1 and MN2 are formig common source stage.
MP1 and MP2 are also forming common source stage.

MN3 and MP3 are forming source follower stage.

Do you understand a working mechanism of this Hysteresis Inverter correctly ?

For fixed NN, increasing MM results in smaller output noise.
In this case, gain as inverter is also larger for larger MM.

On the other hand, for fixed MM, increasing NN results in larger output noise.
Also in this case, gain as inverter is larger for larger NN regardless of feedback.

vp1953 wrote on Sep 19^th, 2010, 2:23pm:
Do you understand a mechanism of contribution of fricker noise to sideband noise correctly ?

Contribution of fricker noise to sideband noise could be larger for sharp transition since conversion gain is larger.

Again do you understand a working mechanism of this Hysteresis Inverter correctly ?

BTW, have you been able to resolve the following ?
http://www.designers-guide.org/Forum/YaBB.pl?num=1283902372