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Simulators >> RF Simulators >> Pnoise analysis of PFD+Charge Pump
https://designers-guide.org/forum/YaBB.pl?num=1244545623

Message started by sanjay on Jun 9^th, 2009, 4:07am

Title: Pnoise analysis of PFD+Charge Pump
Post by sanjay on Jun 9^th, 2009, 4:07am

Hi,
I am doing pnoise analysis for PFD+Charge pump.
Setup is as shown in fig(1):

and commands used are:
TT_pss pss fund=10M harms=5 errpreset=moderate
+ tstab=2u annotate=status
TT_pn pnoise sweeptype=relative oprobe=V7
+ start=100 stop=10G maxsideband=5 annotate=status

But, when I am plotting phase noise, it is giving following error:
*Error* quotient: can't handle (nil / 1.414214)
Can any one help me?
Thanks...

Title: Re: Pnoise analysis of PFD+Charge Pump
Post by pancho_hideboo on Jun 9^th, 2009, 5:03am

sanjay wrote on Jun 9^th, 2009, 4:07am:

I am doing pnoise analysis for PFD+Charge pump.
But, when I am plotting phase noise, it is giving following error:
*Error* quotient: can't handle (nil / 1.414214)

What vendor's simulator do you use ?
There are many simulators which have analysis called as Pnoise.

I assume Pnoise of Cadence Spectre under Cadence ADE.

Show me output equation.
You can get it by enabling "Add Output" if you use Direct Plot Form of ADE,

Title: Re: Pnoise analysis of PFD+Charge Pump
Post by sanjay on Jun 9^th, 2009, 6:25am

I am using spectreRF for simulation & ocean script to plot phase noise as below:
openResults("test.raw")
pn=phaseNoise(1 "pss_fd" ?result "pnoise")
plot(pn)

Thank you...

Title: Re: Pnoise analysis of PFD+Charge Pump
Post by pancho_hideboo on Jun 9^th, 2009, 6:44am

Try to modify analysis statements like following.

Quote:

TT_pss pss fund=10M harms=1 maxacfreq=100M errpreset=moderate
+ tstab=2u annotate=status outputtype=all

TT_pn pnoise oprobe=V7 maxsideband=7
+ sweeptype=relative relharmnum=1
+ start=100 stop=10G dec=5 annotate=status

Title: Re: Pnoise analysis of PFD+Charge Pump
Post by sanjay on Jun 9^th, 2009, 7:45am

Pancho,
Thank you for your precious time.
I tried the code you mentioned but it is giving the same error....

Title: Re: Pnoise analysis of PFD+Charge Pump
Post by pancho_hideboo on Jun 9^th, 2009, 8:12am

sanjay wrote on Jun 9^th, 2009, 7:45am:

I tried the code you mentioned but it is giving the same error....

Try to change current probe "V7" to "CCVS".
Then observe output as node voltage.

Title: Re: Pnoise analysis of PFD+Charge Pump
Post by lunren on Aug 6^th, 2009, 9:34am

I think the sweettype should be "absolute", not "relative". When we simulate VCO, we use "relative" because we want to get the phase noise of VCO. Concerning PFD+Charge Pump, we want to get noise current, which is not relative to fun frequency.

Title: Re: Pnoise analysis of PFD+Charge Pump
Post by Forum Administrator on Aug 10^th, 2009, 10:05am

The error message does not look like it is from Spectre, meaning it is probably from Ocean. Since is is complaining about data that is 'nil', it likely means that the data does not exist for some reason. Check the simulation log file and make sure the simulation completed without error and the results were produced.

-Ken