Seagate Cheetah 15K.5 SAS ST373455SS - Manual (Page 69)

Cheetah 15K.5 SAS Product Manual, Rev. E 63
9.5.2.1.2 Receive eye mask
Figure 20 describes the receive eye mask. This eye mask applies to jitter after the application of a single pole
high-pass frequency-weighting function that progressively attenuates jitter at 20 dB/decade below a frequency
of ((bit rate) / 1.667).
Figure 20. Receive eye mask
Verifying compliance with the limits represented by the receive eye mask should be done with reverse channel
traffic present in order that the effects of crosstalk are taken into account.
9.5.2.1.3 Jitter tolerance masks
Figure 21 describes the receive tolerance eye masks and is constructed using the X2 and Z2 values given in
table 18. X1
OP
is half the value for total jitter intable 18 and X1
TOL
is half the value for total jitter in table 19, for
jitter frequencies above ((bit rate) / 1.667).
Figure 21. Receive tolerance eye mask
Absolute
amplitude
(in V)
Z1
Z2
0 V
-Z1
-Z2
X1 X2
1-X2
1-X1
Normalized time (in UI)
0 1
Absolute
amplitude
(in V)
Z1
TOL
0 V
-Z1
OP
X1
OP
X2
1-X1
TOL
1-X1
OP
Normalized tim e (in UI)
(additional sinusoidal jitter) / 2
-Z1
TOL
Z1
OP
X1
TOL
Outline of eye mask
after adding
sinusoidal jitter
Outline of eye mask
before adding
sinusoidal jitter
0 1
Z2
-Z2