I simulated a simple LC oscillator noise ( PSS+PNOISE) at the oscillator output ( IC5141, .sub-version 126.96.36.1992.isr5).
I have also saw the topic "Explain the differences between the 4 noisetype settings for pnoise". But it could not answer what I want.
I used Shooting Method for PSS. I actually wanted to find the AM Noise & PM noise component separately. For total output noise I used PSS+PNOISE analysis. The noise power in db10 looks ok as it is matching the analysis. And it is a Single Sided PSD.
I have attached the waveform of it as Total-Noise.png
However, when I tried to plot AM noise component and PM Noise component separately I faced a really horrible experience. It is really confusing !!
Could anybody please clarify the following. It will be really helpful not only for me but also for many other designers.
First of all the plot form format in pnoise -source-modulated is very different form.
a) Power is being plotted in absolute value? why not in db10 like Pnoise ( is it because of IC5141 )
b) dBV option is there unlike PNOISE form. Why ?
c) USB, LSB, AM & PM
What is USB:-
is it total noise (AM+PM) in Fcenter + Fif ? ( is it Single sided or double sided PSD )
What is LSB :-
is it total noise in Fcenter - Fif ? ( is it Single sided or double sided PSD )
What is AM:-
Is it only AM noise component ?
is it ( Single-Sided or Double Sided PSD ) As there is dbV I suspect it is all Single Sided PSD ) ?
is it possible to plot AM Noise in Fcenter + Fif band & Fcenter - Fif band ?
What is PM:-
Is it only PM noise component ?
Is it ( Single-Sided or Double Sided PSD ) ?
Is it possible to plot AM Noise in Fcenter + Fif band & Fcenter - Fif band ?
When I plotted the AM noise ( I have captured it in the figure as AM-Noise_dBV.png ), It didn't match the analysis in the lower frequncy range. I plotted in dBV as when I Plotted it gives me -ve value also below 1MHz ( attached as AM-Noise-Power.png).
Beyond 10MHz it was matching with analysis. Also I am finding a NOTCH in the AM-PSD why is this ?
When I plotted the PM noise ( I have captured it in the figure as PM-Noise_dBV.png ), itis exactly folllowing the total -power as drawn in pnoise analysis but with around 3-dB less
AM-Noise_dBV.png is attached here
In reply to RFStuff:
AM-Noise_Power..PNG is attached here
PM-Noise-dBV.png Attached here
Hi RF Stuff,
This sort of thing should really be addressed by contacting Cadence Customer Support (http://support.cadence.com ) rather than on the forum.
I cannot answer these questions at the moment (I have my "day job" to attend to! <grin>) but I strongly recommend that you look at the MMSIM12.1.1 SpectreRF documentation on Cadence Online Support. It is really thorough and explains a lot of these terms.
A link to this is:
Sr. Staff Support AE, Global Customer Support
Cadence Design Systems, Inc.