GTS Transceiver PHY User Guide: Agilex™ 3 FPGAs and SoCs

ID 848344
Date 8/04/2025
Public
Document Table of Contents

3.5.2. TX and RX Reference Clock and Clock Output Interface Signals

Table 36.  TX and RX Reference Clock and Clock Output Interface Signals
Signal Name Clocks Domain/Resets Direction Description

o_rx_clkout[(N-1):0]

o_rx_clkout2[(N-1):0)]

o_tx_clkout[(N-1):0]

o_tx_clkout2[(N-1):0]

N/A output Refer to Clock Ports
i_tx_coreclkin[N-1:0] N/A input The FPGA core clock. Drives the write side of the TX FIFO.
i_rx_coreclkin[N-1:0] N/A input The FPGA core clock. Drives the read side of the RX FIFO.
i_tx_pll_refclk_p[N-1:0] N/A input Reference clock for each of the TX PLLs. The local reference clock or the regional reference clock pins must be assigned here.

You must ensure that the input reference clock is present, stable and at the configured frequency before you release i_tx_reset.

There is no configurable termination setting for the input reference clock. It is always on by default, with a typical differential value of 100 Ω. I/O standard support includes CML and HCSL.

i_rx_cdr_refclk_p[N-1:0] N/A input Every transceiver bank provides a reference clock input for the RX CDR clock block. The local reference clock or the regional reference clock pins must be assigned here.

You must ensure that the input reference clock is present, stable and at the configured frequency before you release i_rx_reset.

i_system_pll_clk N/A input To be connected to the GTS System PLL Clock IP PLL output.
o_tx_pll_locked[N-1:0] asynchronous output This signal is to indicate the initial lock to reference clock status of the TXPLL. Once asserted, this signal does not deassert regardless of the lock state of the TX PLL unless the TX channel is reset.
This signal goes high under two conditions:
  1. TX PLL achieves lock to the reference clock when the reference clock is within the PPM threshold.
  2. In the presence of a reference clock, after approximately 150 μs (microsecond).
  • 1’b1: The TX PLL has achieved lock at least once or, in the presence of a reference clock, after approximately 150 μs.
  • 1’b0: The TX PLL has never achieved lock and, in the presence of a reference clock, approximately 150 μs have not been reached.
To check the real time TX PLL lock state, refer to the Guidelines for Obtaining the Real-Time GTS TX PLL Lock Status section.
o_rx_cdr_divclk N/A output This is the clock used to bring the recovered clock to an output pin to be used as reference clock.
o_refclk2core[N-1:0] N/A output Transceiver PLL reference clock that you can route to the FPGA fabric, for example for the HDMI use case.
i_system_pll_lock asynchronous input System PLL locked signal