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9.5.2.2
Transmitter signal characteristics
Table 16 specifies the signal requirements at the transmitter end of a TxRx connection as measured into the
zero-length test load. All specifications are based on differential measurements.
The OOB sequence is performed at signal voltage levels corresponding to the lowest supported transfer rate.
Table 16 specifies the signal characteristics.
Table 16:
Transmitter signal characteristics
a
Signal characteristic
b
Skew
c
Tx Off Voltage
d
Maximum rise/fall time
d
Minimum rise/fall time
Maximum transmitter output imbalance
f
OOB offset delta
OOB common mode delta
a All tests in this table shall be performed with zero-length test load shown in figure 21.
b The 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 Tx+ and Tx- signals. Skew is
defined as the time difference between the means of the midpoint crossing times of the Tx+ signal and the Tx- signal.
c The transmitter off voltage is the maximum A.C. voltage measured at compliance points when the transmitter is
unpowered or transmitting D.C. idle (e.g., during idle time of an OOB signal).
d Rise/fall times are measured from 20 % to 80 % of the transition with a repeating 0101b pattern on the physical link.
e The maximum difference between the V+ and V- A.C. RMS transmitter amplitudes measured on a CJTPAT test
pattern (see 9.5.2.3.3) into the test load shown in figure 21, as a percentage of the average of the V+ and V- A.C.
RMS amplitudes.
f The maximum difference in the average differential voltage (D.C. offset) component between the burst times and the
idle times of an OOB signal.
g The maximum difference in the average of the common mode voltage between the burst times and the idle times of
an OOB signal.
Cheetah 15K.6 SAS Product Manual, Rev. A
e
g
Units
1.5 Gbps
ps
20
mV(P-P)
< 50
ps
273
ps
67
%
10
± 25
mV
± 50
mV
3.0 Gbps
15
< 50
137
67
10
± 25
± 50
67
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