2–14
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Transmitter Modules
The PLL contains two multiplier blocks in the PLL feedback loop to
multiply the reference clock to support the required data rate. The
Quartus II software automatically selects the values for all the dividers.
You must input a data rate and select the input clock frequency.
The PLL output feeds the central clock divider block through the
high-speed transmitter PLL clock multiplexer or feeds the transmitter
local clock divider block in each transmitter channel through the
high-speed transmitter PLL clocks.
Central Clock Divider Block
The central clock divider block is located in the central block of the
transceiver block (refer to
Figure 2–2
). This block provides the high-speed
clock for the serializer and the low-speed clock for the transceiver’s PCS
logic within the transceiver block in a four-lane mode. In Physical
Interface for PCI Express (PIPE) ×8 mode, the central clock divider block
also provides the high-speed clock and low-speed clock for the adjacent
upper transceiver block and provides the high- and low-speed clocks to
the associated transceiver block. The PLLs, central clock divider block,
and the transmitter local clock dividers are powered down in the adjacent
upper transceiver block in an eight-lane configuration.
Figure 2–5
shows the central clock divider block. The
/
4, /5, /8, and /10
block generates the slow-speed clock based on the serialization factor. In
an eight-lane configuration in PIPE mode, the slow-speed clock is
multiplexed from the lower transceiver block. The high-speed clock goes
directly into each channel’s serializer through a clock multiplexer.
Содержание Stratix II GX
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