Switching Characteristics
Page 23
Table 22 lists the simulation data on the transmitter pre-emphasis levels in dB for the
first post tap under the following conditions:
■
Low-frequency data pattern—five 1s and five 0s
Data rate—2.5 Gbps
■
The levels listed are a representation of possible pre-emphasis levels under the
specified conditions only and the pre-emphasis levels may change with data pattern
and data rate.
Cyclone V devices only support 1st post tap pre-emphasis with the following
conditions:
■
The 1st post tap pre-emphasis settings must satisfy |B| + |C| ≤ 60 where
|B| = VOD setting with termination value, RTERM = 100 Ω and |C| = 1st post tap
pre-emphasis setting
■
■
|B| – |C| > 5 for data rates < 5 Gbps and |B| – |C| > 8.25 for data rates
> 5 Gbps.
(VMAX/VMIN – 1)% < 600%, where VMAX = |B| + |C| and VMIN = |B| – |C|.
Exception for PCIe Gen2 design:
■
VOD setting = 50 and pre-emphasis setting = 22 are allowed for PCIe Gen2 design
with transmit de-emphasis –6dB setting (pipe_txdeemp = 1’b0) using Altera PCIe
Hard IP and PIPE IP cores.
■
VOD setting = 50 and pre-emphasis setting = 12 are allowed for PCIe Gen2 design
with transmit de-emphasis –3.5dB setting (pipe_txdeemp = 1’b1) using Altera PCIe
Hard IP and PIPE IP cores.
For example, when VOD = 800 mV, the corresponding VOD value setting is 40. The
following conditions show that the 1st post tap pre-emphasis setting = 2 is valid:
■
■
■
|B| + |C| ≤ 60 → 40 + 2 = 42
|B| – |C| > 5 → 40 – 2 = 38
(VMAX/VMIN – 1)% < 600% → (42/38 – 1)% = 10.52%
1
To predict the pre-emphasis level for your specific data rate and pattern, run
simulations using the Cyclone V HSSI HSPICE models.
Table 22. Transmitter Pre-Emphasis Levels for Cyclone V Devices (Part 1 of 2)
Quartus II VOD Setting
Quartus II 1st Post Tap
Unit
10
20
30
35
40
45
50
Pre-Emphasis Setting
(200 mV) (400 mV) (600 mV) (700 mV) (800 mV) (900 mV) (1000 mV)
0
1
2
3
4
5
0
0
0
0
0
0
0
dB
dB
dB
dB
dB
dB
1.97
3.58
5.35
7.27
—
0.88
1.67
2.48
3.31
4.19
0.43
0.95
1.49
2
0.32
0.76
1.2
0.24
0.61
1
0.19
0.5
0.13
0.41
0.69
0.96
1.26
0.83
1.14
1.49
1.63
2.1
1.36
1.76
2.55
July 2014 Altera Corporation
Cyclone V Device Datasheet
INTEL [ INTEL ]
