Altera Corporation
2–19
October 2007
Stratix II GX Device Handbook, Volume 2
Stratix II GX Transceiver Architecture Overview
is greater than the internal noise of the VCO, the PLL filters out the noise
above the –3dB frequency of the closed-loop gain of the PLL. The medium
bandwidth setting is a compromise between the high and low settings.
The –3dB frequencies for these settings can vary because of the non-linear
nature and frequency dependencies of the circuit.
Inter-Transceiver Line Routing
The inter-transceiver lines allow the
REFCLK
of one transceiver block to
drive other transceiver blocks. There are a maximum of five
inter-transceiver clock routing lines available in each device in the
Stratix II GX family. Each transceiver block can drive one
inter-transceiver line from either one of its associated
REFCLK
pins. The
inter-transceiver lines can drive any or all of the transmitter PLLs and
receiver PLLs in the device. The inter-transceiver lines offer flexibility
when multiple channels in separate transceiver blocks share a common
reference clock frequency. The inter-transceiver lines only distribute the
reference clock and cannot be used to bond channels because each PLL
and clock dividers operate independently. If you select an input reference
clock frequency such that it requires the use of the
REFCLK
pre-divider,
you cannot use the clock on
REFCLK
pins to drive PLD logic.
The inter-transceiver lines also drive the reference clock from the
REFCLK
pins into the PLD, which reduces the need to drive multiple clocks of the
same frequency into the device.
The Quartus II software automatically uses the appropriate
inter-transceiver line if the transceiver block is being clocked by the
dedicated reference clock (
REFCLK
) pin of another transceiver block.
Figure 2–8
shows the inter-transceiver line interface to the transceivers in
the gigabit transceiver blocks and to the PLD. The connections of
transceiver block 0 are shown. The other connections are the same, with
the exception of the inter-transceiver line number that the transceiver
block drives.
Содержание Stratix II GX
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