• For ATX PLL, Read-Modify-Write 0x0 to offset address 0x110[2] of the ATX
PLL.
• For fPLL, Read-Modify-Write 0x0 to offset address 0x126[0] of the fPLL.
4. Recalibrate TX PMA of all the bonded channels driven by the ATX PLL or the fPLL.
Note: For this 10-channel example, two ATX PLLs are instantiated. Six channels of the
tx_bonding_clocks on the Native PHY IP core are connected to the first ATX PLL
and the remaining four channels are connected to the second ATX PLL's
tx_bonding_clock outputs.
Related Information
• ATX PLL Recalibration on page 581
• Fractional PLL Recalibration on page 581
• PMA Recalibration on page 582
3.11.3. Implementing PLL Cascading
In PLL cascading, the output of the first PLL feeds the input reference clock to the
second PLL.
For example, if the input reference clock has a fixed frequency, and the desired data
rate was not an integer multiple of the input reference clock, the first PLL can be used
to generate the correct reference clock frequency. This output is fed as the input
reference clock to the second PLL. The second PLL generates the clock frequency
required for the desired data rate.
The transceivers in Arria 10 devices support fPLL to fPLL cascading. For OTN and SDI
applications, there is a dedicated clock path for cascading ATX PLL to fPLL in Arria 10
production silicon. Only maximum two PLLs are allowed in the cascading chain.
Note: When the fPLL is used as a cascaded fPLL (downstream fPLL), a user recalibration on
the fPLL is required. Refer to "User Recalibration" section in "Calibration" chapter for
more information.
Figure 197. PLL Cascading
pll_refclk0 hssi_pll_cascade_clk
pll_powerdown pll_locked
pll_refclk0
pll_powerdown
fPLL (Cascade Source) fPLL (Transceiver PLL)
3. PLLs and Clock Networks
UG-01143 | 2018.06.15
Intel
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Arria
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10 Transceiver PHY User Guide
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