3–90
Altera Corporation
Stratix II GX Device Handbook, Volume 2
October 2007
Channel and Clock Multiplier Unit (CMU) PLL Reconfiguration
Clocking Enhancements and Requirements
To configure the TX PLLs and RX PLLs for multiple data rates, it is
important to understand the input reference clock requirements. This
helps you to efficiently create the clocking scheme for reconfiguration and
to reuse the MIFs across all channels in the device. The new clocking
enhancements and the implications of using input clocks from various
clock sources are reviewed in this section.
When you enable the
Channel and CMU PLL Reconfiguration
option in
the ALT2GXB MegaWizard (by selecting the
Enable Channel and
Transmitter PLL Reconfiguration
option in the
Reconfig
tab), the
Quartus II software version 7.1 allows a maximum of five possible
sources available for input reference clocks.
Figure 3–39
shows the
different clock sources that connect to the transceiver block.
Figure 3–39. Transceiver Block with Global Clock Line Connections
These five clock inputs appear as a
pll_inclk_rx_cruclk[]
port and
can be provided from the inter transceiver block lines, also referred as
Inter Quad (IQ) lines, or from the global clock networks that are driven by
an input pin.
Figure 3–40
shows the reference clock connections to
TX PLLs and RX PLLs in a transceiver channel.
2
÷
Transmitter
PLL 0
Global clk line
IQ[4..0]
Transceiver Block 0
REFCLK0
Transmitter
PLL 1
To IQ0
IQ[4..0]
IQ[4..0]
Global clk line
4
Receiver
PLLs
REFCLK1
From Global Clock Line
(3)
2
÷
2
÷