Products > Test Equipment
Pocket-Sized 6 GHz 1 TS/s ET Scope
joeqsmith:
1GHz oscillator attached to the 6400 using a 6dB attenuator:
https://www.minicircuits.com/WebStore/dashboard.html?model=BW-S6-2W263A%2B
Both systems are using 80/20. 6400 was allowed to warmup about an hour. Rj is more than triple with the 6400.
joeqsmith:
Zooming in and increasing the resolution and samples per CDF has no effect (resetting cursors after adjustments).
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Updated plot to include P-P@ 1e-3&1e-2 BER.
SJL-Instruments:
The 6400 reports total RMS jitter, and cannot automatically currently isolate the Rj contribution.
The histogram at the bottom looks double-peaked (before the image was updated). The 1 sigma deviation for one of the features looks like ~6 ps RMS. This should be closer to Rj.
At 13 ns, your specific unit has ~4.7 ps RMS intrinsic trigger jitter that adds in quadrature (calculated from Section 2.3 and the calibration sheet). Subtracting this contribution gives 3-4 ps RMS as an estimate for Rj.
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We can extract the Rj(δδ) and Dj(δδ) contributions assuming the dual-Dirac model. This will be implemented in the next update. There is no way to further decompose Dj(δδ) with this architecture.
joeqsmith:
Using your 85ps @ BER 1e-3, @ BER 1e-12 is about 185 ps p-p vs 48ps measured.
https://www.analog.com/media/en/technical-documentation/app-notes/hfan0402-converting-between-rms-and-peaktopeak-jitter-at-a-specified-ber.pdf
SJL-Instruments:
--- Quote from: joeqsmith on March 10, 2024, 05:26:52 pm ---Using your 85ps @ BER 1e-3, @ BER 1e-12 is about 185 ps p-p vs 48ps measured.
https://www.analog.com/media/en/technical-documentation/app-notes/hfan0402-converting-between-rms-and-peaktopeak-jitter-at-a-specified-ber.pdf
--- End quote ---
Both the 85 ps and 48 ps measurements are correct - they're just measuring different things.
The conversion you quoted is valid only in the absence of Dj(δδ). It assumes a Gaussian jitter distribution. Since in your case there is visible double-edging, the Dj(δδ) contribution is a significant factor.
Since you're looking at the 12th transition after the trigger, likely the Dj(δδ) of the transition you're looking at is roughly 12x larger than the Dj(δδ) inherent to the clock (which is what was reported by your clock analyzer). (This assumes the Dj correlation timescale is ~10 ns or longer - in general the true Dj spectrum can be complicated.)
The appropriate alpha (equal to 2*Q_BER in below reference) for 1e-2 BER is 4.652.
https://people.engr.tamu.edu/spalermo/ecen689/jitter_dual_dirac_agilent.pdf
Eyeballing your plot, it looks like Dj(δδ) ~ 20 ps. Taking Rj(δδ) ~ 6 ps (effective, due to trigger jitter), this gives ballpark estimates:
TJ(BER = 1e-2) = 20 + 4.652*6 = 48 ps
TJ(BER = 1e-3) = 20 + 6.180*6 = 57 ps.
The reported measurements are larger than this since the selected analysis window has a significant vertical extent compared to the slope of the signal.
The PP jitter measurements reported in our software are the "true" PP jitter and do not assume the dual-Dirac model. When we implement Rj(δδ) and Dj(δδ) decomposition, we will also add TJ(δδ) measurements at BER down to 1e-12.
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