Seagate ST450MP0074 Savvio 15K SAS Product Manual - Page 68
Eye masks, 5.2.1.1, Eye masks overview, 5.2.1.2, Receive eye mask, Table 16, General
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Table 16 defines the general interface characteristics. Table 16: General interface characteristics Characteristic Bit rate (nominal) Unit interval (UI)(nominal) Impedance (nominal, differential ) Transmitter transients, maximum Receiver transients, maximum Units Mbaud ps ohm V V 1.5 Gbps 1,500 666.6 100 ± 1.2 ± 1.2 3.0 Gbps 3,000 333.3 100 ± 1.2 ± 1.2 9.5.2.1 Eye masks 9.5.2.1.1 Eye masks overview The eye masks are graphical representations of the voltage and time limits on the signal at the compliance point. The time values between X1 and (1 - X1) cover all but 10-12 of the jitter population. The random content of the total jitter population has a range of ± 7 standard deviations. 9.5.2.1.2 Receive eye mask Figure 16 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). Absolute amplitude (in V) Z2 Z1 0 V -Z1 -Z2 0 X1 X2 1-X1 1 1-X2 Normalized time (in UI) Figure 16. 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. 60 Savvio 15K SAS Product Manual, Rev. B