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2 unit communication with Multi Gigabit Transceiver via SFP connector

Feantar

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Hello,

I am working with GTY4E_channel and GTY4E_common Xilinx's IP primitives with VHDL via fiber connectors on 2 pcb boards (let's call these boards "ATK" and "SAB"). I am providing communication at 8 Gbps speed over a single lane. I am providing the reference clocks of these boards (MGT_REF_CLK) from an integrated called AD9528. I connected the output of an oscillator that produces 40 mhz to the VCXO input of AD9528 on "ATK" board. In this way, I will not use PLL1 and will only produce the signals with PLL 2. From here, I am producing both a reference clock for GTY and an external clock for "SAB" board (200 mhz reference clock for GTY, 40 Mhz reference clock for "SAB" entering REFA of AD9528). I give this reference clock from MMCX connector and get it from "SAB" side with SMA. I get AD9528 REFA of "SAB" board from "ATK" as External and from here I generate reference clock (200mhz) for GTY_ref_clk in "ATK" board. When I connected them with fiber cable and did their tests, I saw that they did not work. Incoming data comes differently. First, the data I transmit are Special K Characters 28K5(BC) and 28K0(1C). I transmit them until I find 256 in order. First, it needs to find 28k5 256 times, then it needs to wait for 28k0 256 times and then they should enter the link. However, when I look at it with the Chip scope, I see that the incoming data (rx_data_o at the output of GTY) is different. For example, the data which I expected to be BC comes as F7. I decreased the speeds, et pre_cursor and post_cursor to improve signal integrity, changed the polarity etc. none of them worked. The CDRLOCK signal is always 1.

Does anyone have a suggestion on what to do?
 
Make sure that you have the GTY rx equalizer in "LPM" mode, not "DFE".
Use software ADIsimCLK to design/verify the AD9528 PLL loop filter, both the components and the register settings.
Compare the results with the phase noise requirements specified by Xilinx.
Run Xilinx IBERT test on the link.
 


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