Figure 4-3: Effect Of 3-Tap Pre-Emphasis On A Pulse Signal - Xilinx Virtex-4 RocketIO User Manual

R
and also to preserve the subsequent pulse of the next bit being transmitted in an actual
system.
Transmitted Pulses
Cursor
Composite
Pre-
cursor
Post-cursor
Time

Figure 4-3: Effect of 3-Tap Pre-Emphasis on a Pulse Signal

Table 4-2
for a range of differential swing settings and line loss conditions. 3.5 dB of line loss
approximates the signal attenuation for a 10 Gb/s signal across 5 inches of FR4. For lower
data rates, traces longer than 5 inches of FR4 can be traversed before the signal experiences
3.5 dB of attenuation.
Table 4-2: TXDAT_TAP_DAC and TXPOST_TAP_DAC Settings
Virtex-4 RocketIO MGT User Guide
UG076 (v4.1) November 2, 2008
shows the recommended TXDAT_TAP_DAC and TXPOST_TAP_DAC settings
Line Loss Differential Swing
(dB) (mV)
3.5
7
10
www.xilinx.com
Pre-
cursor
TXDAT_TAP_DAC
600
10011
800
11011
400
01001
600
10001
800
11000
400
01000
600
01111
800
10110
Output Swing and Emphasis
Received Pulses
Degraded
Pulse
Improved
Pulse
Post-
cursor
Time
ug076_ch4_15_062405
TXPOST_TAP_DAC
00000
00010
00001
00101
01001
00100
01001
01111
141