XAUI v12.3 Product Guide
102
PG053 April 6, 2016
Chapter 6:
Design Considerations
A 156.25 MHz clock is derived from the transceiver TXOUTCLK port inside the core, and
used as the clock for the datapath logic of the XAUI core. This clock should be used for user
logic connecting to the core, using the clk156_out port; however, it cannot be used as a
clock source for the user logic of a different XAUI core, due to problems of phase alignment.
For more information about 7 series FPGA transceiver clock distribution, see the section on
clocking in the
7 Series FPGAs GTP Transceiver User Guide
X-Ref Target - Figure 6-12
Figure 6
‐
12:
Clock Scheme for Internal Client-Side Interface 7 Series FPGA GTP Transceiver
Shared Logic in Core
GTPE2_COMMON
GTREFCLK0
PLL0OUTCLK
PLL1OUTCLK
PLL0OUTREFCLK
PLL1OUTREFCLK
GTPE2_CHANNEL
PLL0REFCLK
PLL1REFCLK
PLL0CLK
PLL1CLK
TXUSRCLK
TXUSRCLK2
RXUSRCLK
RXUSRCLK2
TXOUTCLK
DCLK
refclk_p
refclk_n
refclk
dclk
BUFG
XAUI Encrypted HDL
Shareable logic
CORE
clk156
usrclk
Clock Logic
Artix7
x13736
IBUFDS_GTE2
BUFG
0+]
GHIDXOW
clk156_out