2–48
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Transmitter Modules
In the individual channel mode, the serializer block supplies the PLD and
transceiver parallel clock. The serializer takes the
÷
8 or
÷
10 parallel clock
from the clock divider block and distributes it to the transmitter’s PCS
logic in the associated transmitter channel. In single-width mode, the
clock is unaltered. In double-width mode, the serializer block creates a
÷
16 or
÷
20 clock from the clock provided by the clock divider block,
depending on the serialization factor.
1
In Quartus II software version 7.1 and later, basic single width
allows 8-bit serialization (disable 8B/10B).
Transmitter Buffer
The Stratix II GX transmitter buffers support 1.2-V and 1.5-V pseudo
current mode logic (PCML) up to 6.375 Gbps and can drive 40 inches of
FR4 trace across two connectors. The transmitter buffer (refer to
Figure 2–42
) has additional circuitry to improve signal integrity—
programmable output voltage, programmable three-tap pre-emphasis
circuit, and internal termination circuitry—and the capability to detect
the presence of a downstream receiver.
Figure 2–42. Transmitter Buffer
Programmable Voltage Output Differential (V
OD
)
Stratix II GX device’s allow you to customize the differential output
voltage (V
OD
) to handle different trace lengths, various backplanes, and
receiver requirements (refer to
Figure 2–43
). You select the V
OD
from a
range between 200 and 1,400 mV, as shown in
Table 2–8
.
50
Ω
Ω
Ω
, 60 , 75
50
Ω
Ω
Ω
, 60 , 75
Transmitter Output Pins
Programmable
Pre-emphasis
and V
OD
+VTT-
Receiver
Detect