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How do I simulate a 3 stage Ring Oscillator? [Virtuoso]

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catalin560

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Hello Forum! I need some guidance. Please follow the screenshots in the attachments.
So first I made the schematic for the inverter, then I've setup the symbol for it and using that symbol I've quickly put together a 3 stage ring oscillator. I've got here using information found on google, however for the next part I'm completely lost. I need a transient analysis for the simulation of the circuit, a PSS analysis to determine the frequency of oscillation and a PNOISE analysis to determine the phase noise of the designed ring oscillator. Can someone please explain how do I approach all of these?
1a-schema-inversor.png1b-schema-inversor.png1c-schema-inversor.png2-simbol-inversor.png3-schema-oscilator-3etaje.png
 

catalin560 said:
I need a transient analysis for the simulation of the circuit,
a PSS analysis to determine the frequency of oscillation
and a PNOISE analysis to determine the phase noise of the designed ring oscillator.
Click to expand...
Your tasks are very very easy to do.
So no one can know what you are embarassing to do them.

Simply do Transient Analysis and PSS Analysis with Pnoise Analysis.
 

I might have left out the fact that I'm totally dumb when it comes to electronics... I'm a beginner so please don't make fun of me...
 

yeah... I totally forgot about that... anyway

Cadence Virtuoso is giving me a headache, its so clunky and I can't even find parts that I see in online tutorials...

Can someone recommend a great FREE circuit simulator? One in which I can easily manage the three analysis I've mentioned in post #1.
 

catalin560 said:
One in which I can easily manage the three analysis I've mentioned in post #1.
Click to expand...
What do you want to mean ?

Pnoise Analysis is slave analysis subjected to master PSS Analysis.

You can do similar analyses in any vendor's simulators, such as Synopsys HSPICE, Mentor eldo, Keysight ADSsim, Keysight GoldenGate, AWR Microwave Office, Ansys Nexim, etc.

If you prefer free tool, you can do Transient Analysis using LTspice
https://www.linear.com/designtools/software/#LTspice
 
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Thanks I'll give it a try...

I'll also need to do the PSS and the Phase Noise...can these be approached with LTspice?
 

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pancho_hideboo said:
Describe correctly.
Click to expand...

I need to do a PSS analysis to determine the frequency of oscillation and the influence of parameters such as supply voltage, temperature or load capacitance over the oscillation frequency, a transient analysis for the simulation of the circuit and a PNOISE analysis to determine the phase noise of the designed ring oscillator.

pancho_hideboo said:
Pnoise is not an abbreviation of "Phase Noise".
Click to expand...

Since its used to determine the phase noise I've assumed that its also its full name...
 

catalin560 said:
yeah... I totally forgot about that... anyway
Click to expand...
We are all very surprised that you can not learn anything at all during full one year.
If you are proffesional, you will lose job.

catalin560 said:
Since its used to determine the phase noise I've assumed that its also its full name...
Click to expand...
Learn correct terminologies.

Simply do Transient Analysis and Autonomous-PSS/Pnoise Analysis.
Nothing is difficult at all.
 
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pancho_hideboo said:
We are all very surprised that you can not learn anything at all during full one year.
If you are proffesional, you will lose job.
Click to expand...

HAHAHAHAHAHAHAA OMG I've almost died of laughter! I'm far from professional, I'm just a poor student just starting out to learn engineering... there is very much information that I have to assimilate and put together by myself...

Anyway I'll try your suggestions from post #6 and come back with pertinent feedback...
 

So I've tried your suggestion and used a step pulse for vdd (1.2V) and got a oscillation frequency of ~16GHz and a phase noise of -68 dBc/Hz...
Is this normal? I think there is something wrong...
The inverters have 120nM and 100nM each...
 

I don't know how to show you the netlist...

the width and length of transistors...
 

well that's a bit harsh... I'm only seeking advice here... maybe someone else can provide feedback if you don't want to help... thank you for your feedback so far but I think I'll try @Audioguru suggestion and hope for better frequencies...
 

Ok so I'm back with cadence unfortunately... so I remade my circuit, I do the tran analysis, its oscillating around 1.2GHz which is great but for some reason I can't do a damn PSS analysis... I keep getting this error for my MOSFET's:

ERROR (SPCRTRF-15177): PSS analysis doesn't support behavioral module components with hidden states found in component 'nfet_ahdl'. Skipped.
ERROR (SPCRTRF-15177): PSS analysis doesn't support behavioral module components with hidden states found in component 'pfet_ahdl'. Skipped.

I used the cmhv7sf library since its the only one on my faculty server which has MOSFET's with 4 terminals... any suggestions? I need help please!

Picture1.pngPicture2.png
 

catalin560 said:
Ok so I'm back with cadence unfortunately
Click to expand...
It does not make sense.
Use correct terminologies.

catalin560 said:
I used the cmhv7sf library
Click to expand...
Show us cmhv7sf.
Maybe it is IBM device model.
We can not know whether true hidden states are included in their Verilog-A modules, 'nfet_ahdl' and 'pfet_ahdl'.

If you use Cadence Spectre and hidden states of 'nfet_ahdl' and 'pfet_ahdl' are not true but faik, add following in them.
Code: 
(* ignore_hidden_state *)

No one can help, as far as you can not show netlist.
Cose this thread.
 

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