AR# 37702


14.x Timing - How is total system jitter (TSJ) calculated for any particular device?


How is total system jitter (TSJ)calculated for any particular device?


When the user sets the SYSTEM_JITTER constraint, this overrides the default SYSTEM_JITTER (SJ) value.

During timing analysis, this new SYSTEM_JITTER value is applied to both the source element and the destination element.The TSJ is calculated by performing a "Root-Mean-Square" (RMS) technique between the source SJ value and the destination SJ value.

For example, if a user sets the SYSTEM_JITTER constraint to 100 ps in UCF when the SJ for the source is 100 ps and the SJ for the destination is 100 ps, then the RMS is 141 ps. This value is taken as the total system jitter (TSJ) which is used in calculation ofthe Clock Uncertainty in timing analysis.

AR# 37702
Date 12/15/2012
Status Active
Type General Article
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