GS2984 Datasheet, PDF (14/20 Pages) Gennum Corporation – GS2984 Adaptive Cable Equalizer

4.8 Output Rise/Fall Times
200
0
0
100
200
300
400
Cable Length (m)
Figure 4-3: Typical Rise/Fall time for 270Mb/s data rate (VCC=3.3V, room
temperature, 800mV launch swing)
The GS2984 was designed to limit bandwidth as cable length is increased. During
normal 3G (2.97Gb/s), HD (1.485Gb/s), and SD (270Mb/s) operation, the impact of this is
minimal on rise and fall time over the operating range from 0-200m. Above 200m, this
bandwidth limitation becomes more significant, and reduction in rise and fall time is
observed. This means that for SD (270Mb/s) operation at cable lengths greater than
200m, rise and fall times slow as shown in Figure 4-3 above. This is beneficial because at
270Mb/s, one unit interval is equal to 3.7ns, therefore rise and fall times less than 100ps
are not required, and slower rise and fall times actually help to reduce EMI.
GS2984 Adaptive Cable Equalizer
Data Sheet
50985 - 3
March 2010
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