XAUI v12.3 Product Guide
98
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 GTX/GTH Transceiver User Guide
(UG476)
X-Ref Target - Figure 6-8
Figure 6
‐
8:
Clock Scheme for Internal Client-Side Interface 7 Series FPGA GTH Transceiver
Shared Logic in Core
GTHE2_CHANNEL
GTREFCLK
txusrclk
txusrclk2
rxusrclk
rxusrclk2
txoutclk
dclk
refclk_p
refclk_n
refclk
dclk
BUFG
XAUI Encrypted HDL
Shareable logic
CORE
clk156
usrclk
Clock Logic
Virtex7
x13729
BUFG
IBUFDS_GTE2
0+]
GHIDXOW
clk156_out