CPRI Intel® FPGA IP User Guide

ID 683595
Date 5/19/2023
Public

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3.2. CPRI Intel® FPGA IP Core Clocking Structure

Figure 12.  CPRI Intel® FPGA IP Core Clocking StructureIllustrates the clocks and clock domains in the CPRI IP. Clock domains shown are cpri_clkout, clk_ex_delay, cpu_clk, and mii_{rx,tx}clk. The external clean-up PLL is only required in slave clocking mode. The tx_clkout is only available in external clocking mode, and the xcvr_recovered_clk is only available in slave clocking mode.


The main CPRI IP core clock is cpri_clkout.

Table 20.   CPRI Intel® FPGA IP Core Input Clocks
CPRI Input Clock Information
xcvr_ext_pll_clk or xcvr_ext_pll_clk[1:0]

Clocks the transmitter PMA.

You should drive this input clock with the output of the external TX PLL. The frequency of this clock must be one half of the CPRI line bit rate, multiplied by the local clock division factor. You must configure a PLL IP core that is capable of driving the required frequency.

xcvr_cdr_refclk or xcvr_cdr_refclk[1:0] Receiver CDR reference clock. You must drive this clock at the frequency you specified for the Receiver CDR reference clock frequency (MHz) parameter in the CPRI parameter editor. This signal must come from a dedicated transceiver reference clock pin.

If you set the Number of receiver CDR reference clock(s) parameter in the CPRI parameter editor to the value of 2, this clock is two bits wide.

In the case of a two-bit xcvr_cdr_refclk port, drive xcvr_cdr_refclk[0] with the reference clock for the initial CPRI line bit rate, because by default, this is the clock signal that drives the CDR.

The IP core supports all CDR reference clock frequencies available in the drop-down menu for the Receiver CDR reference clock frequency (MHz) parameter.

pll_refclk0 or pll_refclk TX PLL reference clock input. You must connect this port to dedicated transceiver reference clock pin. This input clock is not present in the CPRI IP top-level. However, it is present on a PLL instantiated outside of the CPRI IP. In Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile devices, this clock is a reference clock for channel PLL.

pll_refclk0 is an input to TX PLL for Intel® Arria® 10/ Intel® Stratix® 10 devices.

pll_refclk is an input to TX PLL for V-series devices.

reconfig_clk

In Arria V, Arria V GZ, Cyclone V, and Stratix V variations, clock for the CPRI IP core transceiver start-up and reconfiguration.

In Intel® Arria® 10 and Intel® Stratix® 10 variations, clocks the signals on the CPRI transceiver reconfiguration interface. In these variations, this clock is not present if you turn off all of Enable start-up sequence state machine, Enable Native PHY Debug Master Endpoint(NPDME), transceiver capability, control and status registers access, and parameters only available in Intel® Arria® 10 variations, Enable line bit rate auto-negotiation, Enable single-trip delay calibration.
Note: You cannot calibrate your PHY, if you disable the Enable Native PHY Debug Master Endpoint(NPDME), transceiver capability, control and status registers access parameter.

In variations that target any other supported device family, this clock is not present if you turn off both Enable line bit rate auto-negotiation, Enable start-up sequence state machine.

The supported frequency range of this clock is 100–150 MHz.

ex_delay_clk Clock for extended delay measurement.
latency_sclk Clock for delay measurement through the Intel® Stratix® 10 hard FIFO buffers in the PCS and the core. You can (but need not) drive this clock at the same frequency as ex_delay_clk. This clock is present only in IP cores that target an Intel® Stratix® 10 device.
cpri_coreclk

In hybrid clocking mode, this drives the CPRI IP core clock cpri_clkout when the IP core is running at the CPRI line bit rate of 8.11008, 10.1376, 12.16512 or 24.33024 Gbps and a clock from the transceiver PHY drives the cpri_clkout at all other rates. In external clocking mode, cpri_coreclk drives cpri_clkout at all CPRI line rates. In internal clocking mode, the clock from transceiver PHY drives cpri_clkout.

The frequency at which you must drive cpri_coreclk depends on the CPRI line bit rate:
CPRI Line Bit Rate cpri_coreclk Frequency
0.6144 Gbps 15.36 MHz
1.2288 Gbps 30.72 MHz
2.4576 Gbps 61.44 MHz
3.0720 Gbps 76.80 MHz
4.9152 Gbps 122.88 MHz
6.1440 Gbps 153.60 MHz
8.11008 Gbps 245.76 MHz
9.8304 Gbps 245.76 MHz
10.1376 Gbps

153.60 MHz (For Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device variations)

307.20 MHz (For all other device variations)

12.16512 Gbps 184.32 MHz
24.33024 Gbps 368.64 MHz

You must drive this clock from the same clock source as the xcvr_ext_pll_clk input signal to the IP core.

cpu_clk Clocks the signals on the CPRI CPU interface. Supports any frequency that the device fabric supports.
mii_txclk mii_txclk clocks the MII transmitter interface and mii_rxclk clocks the MII receiver interface. You must drive these clocks at the frequency of 25 MHz/2.5 MHz to achieve the 100 Mbps/10 Mbps bandwidth required for this interface.

These clocks are present only if you set the value of Ethernet PCS interface to the value of MII in the CPRI parameter editor.

mii_rxclk
gmii_txclk gmii_txclk clocks the GMII transmitter interface and gmii_rxclk clocks the GMII receiver interface. You must drive these clocks at the frequency of 125 MHz to achieve the 1000 Mbps bandwidth required for this interface.

These clocks are present only if you set the value of Ethernet PCS interface to the value of GMII in the CPRI parameter editor.

gmii_rxclk
ehip_clk_403 Single lane TX/RX data path clock. This clock drives the internal TX/RX data path for the CPRI PHY. Embedded Multi-die Interconnect Bridge (EMIB) uses this clock. You need to generate the required frequency 402.83203125 MHz for this port externally by using an E-tile Native PHY IP channel PLL. Refer to Figure: Required External Block for the Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile Device Variations for more information on connecting a PLL to CPRI IP core.

This clock is present only in the IP cores that target an Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device.

ehip_clk_806 The EMIB uses this clock. You need to generate the required frequency of 805.6640625 MHz for this port externally by using an E-tile Native PHY IP channel PLL.

This clock is present only in the IP cores that target an Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device.

ehip_ref_clk[4:0] Reference clock used to generate high speed serial clocks and data path parallel clocks.

For rates using 8b/10b encoding, supply 153.6 MHz to this port. For rates using 64b/66b encoding supply 184.32 MHz to this port. When you perform rate switching, you can use both bits and select the clock that the reconfiguration interface uses.

This clock is present only in the IP cores that target an Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device.

ehip_system_pll_clk_link System PLL clock link port.

Only available in the Intel Agilex® 7 F-tile device variant.

ehip_tx_pll_refclk_link TX PLL reference clock link port.

Only available in the Intel Agilex® 7 F-tile device variant.

ehip_tx_pll_refclk_hs_link TX PLL reference clock link port for high speed rates (rates using the 64B/66B encoding).

Only available in the Intel Agilex® 7 F-tile device variant.

ehip_tx_pll_refclk_ls_link TX PLL reference clock link port for low speed rates (rates using the 8B/10B encoding).

Only available in the Intel Agilex® 7 F-tile device variant.

ehip_rx_cdr_refclk_link RX CDR reference clock link port.

Only available in the Intel Agilex® 7 F-tile device variant.

ehip_rx_cdr_refclk_hs_link RX CDR reference clock link port for high speed rates (rates using the 64B/66B encoding).

Only available in the Intel Agilex® 7 F-tile device variant.

ehip_rx_cdr_refclk_ls_link RX CDR reference clock link port for low speed rates (rates using the 8B/10B encoding).

Only available in the Intel Agilex® 7 F-tile device variant.

Table 21.   CPRI Intel® FPGA IP Core Output Clocks
CPRI Output Clock Information
cpri_clkout

Master clock for the CPRI IP core. In hybrid clocking mode, when the IP core is running at the CPRI line bit rate of 8.11008, 10.1376, 12.16512 or 24.33024 Gbps, the cpri_coreclk input clock drives cpri_clkout. At all other CPRI line bit rates, the Tx PCS drives cpri_clkout.

In internal clocking mode, the TX PCS drives the cpri_clkout at all CPRI line bit rates.

In external clocking mode, the cpri_coreclk input clock drives cpri_clkout at all CPRI line bit rates.

The frequency of cpri_clkout depends on the CPRI line bit rate:

CPRI Line Bit Rate cpri_clkout Frequency
0.6144 Gbps 15.36 MHz
1.2288 Gbps 30.72 MHz
2.4576 Gbps 61.44 MHz
3.0720 Gbps 76.80 MHz
4.9152 Gbps 122.88 MHz
6.1440 Gbps 153.60 MHz
8.11008 Gbps 245.76 MHz
9.8304 Gbps 245.76 MHz
10.1376 Gbps

153.60 MHz (For Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device variations)

307.20 MHz (For all other device variations)

12.16512 Gbps 184.32 MHz
24.33024 Gbps 368.64 MHz
xcvr_recovered_clk Direct recovered clock from the receiver CDR. Use this output clock to drive the external clean-up PLL when your IP core is in slave mode.

The IP core drives this clock from the PCS or the PMA block of the transceiver, depending on the value you set for the Recovered clock source parameter in the CPRI parameter editor.

This clock is present only in CPRI IP cores in slave clocking mode that support RX traffic. This clock is not present in CPRI IP cores with Operation mode set to the value of TX simplex.

The frequency of recovered clock speed (xcvr_recovered_clk) depends on the CPRI line bit rate.

CPRI Line Bit Rate xcvr_recovered_clk Frequency
0.6144 Gbps 15.36 MHz
1.2288 Gbps 30.72 MHz
2.4576 Gbps
  • 122.88 MHz (For Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device variations)
  • 61.44 MHz (For all other device variations)
3.0720 Gbps 76.80 MHz
4.9152 Gbps
  • 245.76 MHz (For Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device variations)
  • 122.88 MHz (For all other device variations)
6.1440 Gbps 153.60 MHz
8.11008 Gbps 220.75 MHz
9.8304 Gbps
  • 491.52 MHz (For Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device variations)
  • 245.76 MHz (For all other device variations)
10.1376 Gbps
  • 158.4 MHz (For Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device variations)
  • 253.44 MHz (For all other device variations)
12.16512 Gbps 304.12 MHz
24.33024 Gbps
  • 380.16 MHz
tx_clkout TX PCS clock. In external clocking mode, you can use this clock to drive the cpri_coreclk input clock. If your IP core is configured with the single-trip delay calibration feature, you can use this clock to drive the IOPLL block.
ehip_cdr_lock This signal indicates the data locks the recovered clocks. This signal is only present in the Intel® Stratix® 10 E-tile and Intel Agilex® 7 E- tile device variations.