Seagate ST31000640SSIM manual Receiver signal characteristics, Maximum allowable jitter

9.5.2.3Receiver signal characteristics

Table 17 defines the compliance point requirements of the signal at the receiver end of a TxRx connection as measured into the test loads specified in figure 19 and figure 20.

Table 17: Receiver signal characteristics

Signal characteristic	Units	1.5 Gbps	3.0 Gbps
Jitter (see figure 16)b	N/A	See table 18	See table 18
2 x Z2	mV(P-P)	1,200	1,600
2 x Z1	mV(P-P)	325	275
X1a	UI	0.275	0.275
X2	UI	0.50	0.50
Skewd	ps	80	75
Max voltage (non-op)	mV(P-P)	2.000	2.000
Minimum OOB ALIGN burst amplitudec	mV(P-P)	240	240
Maximum noise during OOB idle timec	mV(P-P)	120	120
Max near-end crosstalke	mV(P-P)	100	100

aThe value for X1 shall be half the value given for total jitter in table 18. The test or analysis shall include the effects 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).

bThe value for X1 applies at a total jitter probability of 10-12. At this level of probability direct visual comparison between the mask and actual signals is not a valid method for determining compliance with the jitter output requirements.

cWith a measurement bandwidth of 1.5 times the baud rate (i.e. 4.5 GHz for 3.0 Gbps).

dThe skew measurement shall be made at the midpoint of the transition with a repeating 0101b pattern on the physical link. The same stable trigger, coherent to the data stream, shall be used for both the Rx+ and Rx- signals. Skew is defined as the time difference between the means of the midpoint crossing times of the Rx+ signal and the Rx- signal.

eNear-end crosstalk is the unwanted signal amplitude at receiver terminals DR, CR, and XR coupled from signals and noise sources other than the desired signal. Refer to SFF-8410.

9.5.2.3.1Jitter

Table 18 defines the maximum allowable jitter.

Table 18: Maximum allowable jitter

1.5 Gbps m, n		3.0 Gbps m, n
Deterministic jitterq	Total jitter c,d,e,f	Deterministic jitter e	Total jitter c,d,e,f
0.35	0.55	0.35	0.55

aUnits are in UI.

bThe values for jitter in this section are measured at the average amplitude point.

cTotal jitter is the sum of deterministic jitter and random jitter. If the actual deterministic jitter is less than the maximum specified, then the random jitter may increase as long as the total jitter does not exceed the specified maximum total jitter.

dTotal jitter is specified at a probability of 10-12.

eThe deterministic and total values in this table apply to jitter after 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).

fIf total jitter received at any point is less than the maximum allowed, then the jitter distribution of the signals is allowed to be asymmetric. The total jitter plus the magnitude of the asymmetry shall not exceed the allowed maximum total jitter. The numerical difference between the average of the peaks with a BER < 10-12and the average of the individual events is the measure of the asymmetry. Jitter peak-to-peak measured < (maximum total jitter - Asymmetry).

64 Barracuda ES.2 SAS Product Manual, Rev. G