Related to "How to specify phase noise as an instance parameter in spectre sources (e.g. vsource, isource, port)"

You're not running transient noise (or a pnoise/hbnoise analysis), so you won't see any noise generated by this source.

With noisefmax=fin*10 (say) on the transient analysis, the noise is generated - although you're unlikely to see it as it's small - in reality you'd have to do an DFT of the results, in which case you'd want to set strobeperiod and ensure that the DFT sampling interval coincides with the strobeperiod.

Of course, if you do this, you'll also get the thermal noise from the resistor and the 50 ohms in the port - and any other devices in the real circuit. Note that the isnoisy=yes on the port is redundant because noise is enabled on sources by default, just doesn't appear in a non-noise-related analysis.

Andrew

Thank you Andrew for your response.
When I enable transient noise, I indeed see the difference between noisy and non noisy source. 
To remove the impact of 50 ohms in the port, I changed the source to vsource keeping all other parameters same. With -100 dBc/Hz phase noise floor and fin = 20 MHz, I expect an rms jitter of 355 ps, but evaluation using calculator function 'rms_jitter' (integrated from 1 to 10M) yields number in the ballpark of 250 ps (with noisefmax swept from fin*5 to fin*20 and 1k-10k fin cycles). Why these two numbers are differing?

Hi,

I am trying to specify the phase noise as an instance parameter of spectre component vsource. I can verify the applied phase noise profile in pss-pnoise is correct but when I enable transient noise, I do not see expected integrated rms jitter. With -100 dBc/Hz phase noise floor and fin = 20 MHz, I expect integrated rms jitter of 355 ps, but evaluation using calculator function 'rms_jitter' (integrated from 1 to 10M) yields 246 ps. Why are these two numbers differing? I am using cadence-icadvm-/20.10.340 and spectre 23.10.538.isr10. Attached is the netlist of the testbench.

// Point Netlist Generated on: Aug 14 17:12:45 2024

// Generated for: spectre

// Design Netlist Generated on: Aug 14 17:12:44 2024

// Design library name: AAA_AA

// Design cell name: pn_modelling_tb

// Design view name: schematic

simulator lang=spectre

global 0

parameters fin=20M k=10k noisefmax=fin*100 tstop=k/fin

// Library name: AAA_AA

// Cell name: pn_modelling_tb

// View name: schematic

R0 (clk 0) resistor r=50

R14 (ideal_clk 0) resistor r=50

V1 (clk 0) vsource type=sine val0=-500m val1=500.0m period=1/fin rise=100f \

        fall=100f width=0.5*(1/fin) freq=fin ampl=1 sinedc=0 \

        noisetype=ssbphasenoise noisevec=[ 1K -100 10K -100 100K -100 1M \

        -100 10M -100 20M -100 ]

V0 (ideal_clk 0) vsource type=sine freq=fin ampl=1 sinedc=0

simulatorOptions options psfversion="1.4.0" reltol=1e-3 vabstol=1e-6 \

    iabstol=1e-12 temp=27 tnom=27 scalem=1.0 scale=1.0 gmin=1e-12 rforce=1 \

    maxnotes=5 maxwarns=5 digits=5 cols=80 pivrel=1e-3 \

    sensfile="../psf/sens.output" checklimitdest=psf

tran tran stop=tstop noisefmax=noisefmax noiseseed=1 write="spectre.ic" \

    writefinal="spectre.fc" annotate=status maxiters=5

finalTimeOP info what=oppoint where=rawfile

modelParameter info what=models where=rawfile

element info what=inst where=rawfile

outputParameter info what=output where=rawfile

designParamVals info what=parameters where=rawfile

primitives info what=primitives where=rawfile

subckts info what=subckts where=rawfile

save ideal_clk clk

saveOptions options save=allpub

Thank you!

Please don't ask the same question more than once (see Guidelines for the Custom IC Design Forum) otherwise this confuses where the answer should be given (if at all).

Also, if this is urgent, you should contact customer support (submit a support case after logging in). I'd been hoping to reply but haven't had a chance to investigate due to the day job getting in the way (answering here is not part of my role at Cadence - we do so in our spare time, which has been lacking this week!)

Andrew