11©2016 Integra ted Device Technolo gy, Inc June 30, 2 016
843441 Data Sheet
Peak-to-Peak Jitter Calculations
A standard dev iation of a sta tistica l populat ion or data set is the
square root of its va ri anc e. A standar d dev ia ti on is used to cal cu la te
the probability of an anomaly or to predict a failure. Many times, the
term "root mean s quare " (RM S) is used syno nymou sly f or s tanda rd
deviation. Thi s is accurat e when refe rring to th e square roo t of the
mean squared devi ation of a si gnal from a gi ven baseli ne and the
data set co ntain s a Gaussi an d istri bution with no deter minis tic
components. A low standard de viation indicate s that the da ta set
tends to be clos e to the mean with littl e var iatio n. A larg e stan dard
deviation indi cates tha t the data set is spread out and has a lar ge
variation f rom t he me an.
A standa rd devia tion is r equired when calculat ing peak -to-peak jitter.
Since true peak- to-pe ak ji tter is rando m and unbo unded , it is
importan t to always associate a bit erro r ratio ( BER) when sp ecifyin g
a peak-to-peak jitter lim it. Withou t it, the sp ecifica tion is
meaningless. Given that a BER is applica tion specifi c, many
frequency timi ng devices specify ji tter as an RMS. T his allows the
peak-to-peak jitter to be calculat ed for the sp ecific appli cation an d
BER requ iremen t. B ecause a sta ndard dev iatio n is the variat ion
from the m ean of t he da ta se t, i t i s imp ort an t to al way s c al cul ate the
peak-to-peak jitter using the typical RMS value.
The table s hows the B ER wi th it s ap propr iate RMS Mu ltipli er. O nce
the BER is chosen, t he peak to pea k jitter ca n be calcula ted by
simply multiplying the RMS multiplier with the typical RMS datasheet
specification. For example, if a 10-12 BER is required, multi ply
14.260 time s the typ ical jitt er s pecif ication .
Jitter (pea k-to- peak) = R MS Mul tipli er x RMS ( typic al)
This calculati on is not spe cific to on e type of Jit ter classi ficati on. It
can be used to calcu late BE R on vario us t ypes of RMS j itte r. I t is
important that the user understands their jitter requirement to ensure
they are ca lcula ting the corr ect B ER fo r their jit ter requi remen t.
BER RMS Multiplier
10-3 6.582
10-4 7.782
10-5 8.834
10-6 9.784
10-7 10.654
10-8 11.462
10-9 12.218
10-10 12.934
10-11 13.614
10-12 14.260
10-13 14.882
10-14 15.478
10-15 16.028