Transceivers
Figure 2–9. Differential Signaling
Single-Ended Waveform
V
high
True
+V
OD
-
Complement
V
low
Differential Waveform
+400
+V
OD
0-V Differential
−400
2 * V
OD
-V
OD
(Differential)
V
OD
−
= V
V
low
high
Programmable Pre-Emphasis
The programmable pre-emphasis module controls the output driver to
boost high frequency components and compensate for losses in the
transmission medium, as shown in Figure 2–10. Pre-emphasis is set
statically using the ALTGXB megafunction.
Figure 2–10. Pre-Emphasis Signaling
V
V
MIN
MAX
V
MAX
Pre-Emphasis % = (
− 1) × 100
V
MIN
Pre-emphasis percentage is defined as (VMAX/VMIN – 1) × 100, where
VMAX is the differential emphasized voltage (peak-to-peak) and VMIN is
the differential steady-state voltage (peak-to-peak).
2–12
Arria GX Device Handbook, Volume 1
Altera Corporation
May 2008
ALTERA [ ALTERA CORPORATION ]
