AND8090 Datasheet, PDF (15/20 Pages) ON Semiconductor – AC Characteristics of ECL Devices

AND8090/D
Typical Set and Reset Recovery Times – The typical set
and reset recovery times specified on data sheets are not
guaranteed, and they are only included for failure analysis
calculations. They are measured by moving the
active−to−inactive Set and Reset transitions towards the
active clock edge until the outputs no longer enter the
respective non−Set or non−Reset state.
JITTER
Jitter Definition
Jitter is defined as the deviation of an actual edge location
from its ideal location. The possibility of a data transmission
error increases as jitter increases. Total jitter consists of
“Random Jitter” and “Deterministic Jitter” as described in
the following sections.
Random Clock Jitter
Random jitter (RJ, also referred to as “non−systematic”
jitter) is characterized by an unbounded Gaussian
probability density function as shown in Figure 37. Random
jitter is specified on data sheets as Cycle−to−Cycle Jitter, and
is specified as an RMS value (the one sigma value). The
function is described below, followed by a description of the
Cycle−to−Cycle Jitter specification.
The center of the symmetrical probability distribution is
the mean and represents an ideal edge location. The area
under the distribution represents the probability that an
actual edge location will lie within the range surrounding the
ideal edge location. For instance, note from Figure 37 that
a distribution range of plus/minus one sigma from the mean
includes 68.27% of the total distribution area. This means
that there is a 68.27% probability that the actual edge
location will be within the plus/minus one sigma window.
RJ Confidence Levels
As sigma increases, the confidence that the actual edge
location will lie within the distribution range surrounding
the ideal edge location increases. This is why the sigma level
is commonly referred to as the “Confidence Level.”
Confidence levels per sigma are specified in Table 2 where
“Sigma” represents the distribution range for one side of the
mean, and “Total Sigma” represents the distribution range
for both sides of the mean.
Table 2. Confidence Level per Sigma
Sigma
Total Sigma Confidence Level
plus/minus 1
2
68.27%
plus/minus 2
4
95.45%
plus/minus 3
6
99.73%
plus/minus 4
8
99.99%
y
0.4
0.3
0.2
0.1
−3
−2
−1
0
+1
m $ 1s = 68.27%
m $ 2s = 95.45%
m $ 3s = 99.73%
z
+2
+3
Figure 37. Gaussian Random Clock Jitter Distribution
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