Figure 9, gives the total probability of an edge being greater than t (or less than -t). The
contribution to the system BER by jitter is given by the probability that an edge occurs at a time
greater than t as we mentioned earlier. In order to guarantee a BER contribution from jitter below
a certain value, the positive and negative values of t are chosen so that the probability of an edge
at a time greater and less than these times is equal to the desired bit error rate. These jitter
values can be measured by finding the intersection between a horizontal line at the bit error rate
and the total jitter curve. The horizontal spacing between these two points is the total jitter.
Figure 9. Total jitter curve. The vertical values of this curve represent the probability of a data
transition occurring at a time represented by the horizontal axis. The horizontal center of the plot is
0 ps. The two markers are placed at the vertical level corresponding to a bit error rate of 10 e-12 and
the horizontal distance between these two points is the total jitter at this bit error rate.
376 SDA-OM-E Rev H
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