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Measurements >> Phase Noise and Jitter Measurements >> PNoise : No crossing events detected for Jitter Calculations
https://designers-guide.org/forum/YaBB.pl?num=1247757067

Message started by rajat on Jul 16^th, 2009, 8:10am

Title: PNoise : No crossing events detected for Jitter Calculations
Post by rajat on Jul 16^th, 2009, 8:10am

Hello everyone,

I have been trying to calculate Jitter of a MM-Divider using PSS+PNoise analysis in SpectreRF. But, after the PSS analysis runs through successfully (at least I hope so), I get the following error during PNoise analysis.

PNoise analysis : No crossing events detected for Jitter Calculations.

I have no clue as to why this happens, as I can see the PSS solution converging within 3 iterations with the PSS-transient analysis results as shown in the attached pic. The threshold is set to 2.4 V and as can be seen is clearly being crossed.

The MMD is based on CML. And I have the following settings for the analysis:

PSS -
Beat Frequency = 50M (the divided output frequency)
No of Harmonics = 7
Accuracy Defaults : I tried with both conservative & moderate, but without success.
tstab = 200 ns

PNoise -
Sweep Type = relative
Relative Harmonic = 1
Sweep Range = 100Hz - 25 MHz
Sweep type = Logarithmic, Points per decade = 7
Max Sideband = 30
Output = \out & \outn, as I have the inverted divided signal also available
Input Source = none
Noise Type : Jitter
Threshold Value : 2.4 V
Crossing Dir = Rise

I would really appreciate some help on this.

Thanks in advance & Regards

Title: Re: PNoise : No crossing events detected for Jitter Calculations
Post by Ken Kundert on Jul 16^th, 2009, 8:26am

Since you are monitoring a differential signal, shouldn't the threshold be 0?

Why are you using a relative sweep in PNoise?

-Ken