Ac Coupled; Table 4-4: Output Swing Versus Pre-Emphasis (Ac Coupled) - Xilinx RocketIO X User Manual

Output Swing and Emphasis

AC Coupled

When the transmit output and receive input of two MGTs are AC coupled and/or the
receiver is differentially terminated, the transmitter sees an AC impedance of
25Ω (50Ω ||50Ω). However, the DC impedance is now 50Ω, thus changing the common
mode voltage from the DC coupled case. The drive/emphasis settings for supported single-
ended output swing (Vos) and pre-emphasis levels (%, dB) when AC coupled are shown in
Table

Table 4-4: Output Swing versus Pre-Emphasis (AC Coupled)

0 1 2
0 120mV
0%
0.0dB
1
2
3
4
5
6
T
X
E
7
M
P
H
L 8
E
V
E
9
L
10
11
12
13
14
15
RocketIO™ X Transceiver User Guide
UG035 (v1.5) November 22, 2004
4-4. The unused (grey) combinations are not supported and should not be used.
3 4 5 6
180mV 240mV 300mV 360mV
0% 0% 0% 0%
0.0dB 0.0dB 0.0dB 0.0dB
150mV 210mV 270mV 330mV
40% 29% 22% 18%
2.9dB 2.2dB 1.7dB 2.9dB
120mV 180mV 240mV 300mV
100% 67% 50% 40%
6.0dB 4.4dB 3.5dB 2.9dB
150mV 210mV 270mV
120% 86% 67%
6.8dB 5.4dB 4.4dB
120mV 180mV 240mV
200% 133% 100%
9.5dB 7.4dB 6.0dB
150mV 210mV
200% 143%
9.5dB 7.7dB
120mV
300%
12.0dB
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7 8 9
420mV 480mV
0% 0%
0.0dB 0.0dB
390mV 450mV
15% 13%
1.2dB 1.1dB
360mV
33%
2.5dB
330mV
55%
3.8dB
10 11 12 13
R
14 15
99