Jitter Budget (SerDes) Calculator
Work out jitter budget (serdes) instantly with clear inputs, formula shown and shareable results.
About Jitter Budget (SerDes) Calculator
Total jitter combines deterministic jitter directly with random jitter scaled by a BER-dependent factor: TJ = DJ + Q x RJ, where Q is about 14 for 1e-12. Random jitter is Gaussian and unbounded, so tightening the BER target costs more eye even with no change in the hardware.
Formula
Jitter budget
TJ(pp) = DJ(pp) + Q(BER) x RJ(rms), Q = 14.07 at 1e-12 and 15.9 at 1e-16
Worked example
With the default values below, Jitter Budget (SerDes) Calculator returns Total jitter (peak to peak) of 16.05. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Random jitter (RMS)
- 0.6 ps
- Deterministic jitter (peak to peak)
- 8 ps
- Target bit error rate
- 12 1e-x
- Unit interval
- 31.25 ps
Results
- Total jitter (peak to peak)
- 16.05 ps
- Bathtub multiplier
- 13.41 x
- Jitter as share of the UI
- 51.351% %
- Remaining eye opening
- 15.20 ps
Step by step
- 1Values used
- 2Jitter budget
- 3Total jitter (peak to peak)= 16.05 ps
- 4Bathtub multiplier= 13.41 x
- 5Jitter as share of the UI= 51.351 %
- 6Remaining eye opening= 15.20 ps
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why does BER change the jitter number?
Random jitter has no bound, so the observed peak-to-peak grows with the number of bits observed. A stricter BER samples further into the Gaussian tails.
How is jitter reduced?
Better reference clocks and PLL design for random jitter; equalisation, crosstalk control and supply noise reduction for deterministic jitter.
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