Manual CTLE vs ADAPTIVE CTLE PMA settings

[SK_VA]

Hi,

I am new to transceivers.I would like to know which scenarios Manual CTLE and Adaptive CTLE is used for RX PMA settings?

Does Adaptive CTLE has advantages over Manual CTLE?

[CheePin_C_Intel]

Hi,

As I understand it, you have some inquiries related to CTLE. For your information, generally I would use adaptive CTLE first during PMA tuning because it is automated and adapts itself based on a specific setup and environment. However, sometimes, adaptive CTLE might not be enough to give you the required BER. In these cases, we will need to perform further fine tuning through manual CTLE by using the adapted values as baseline to start with.

Please let me know if there is any concern. Thank you.

Best regards,

Chee Pin

[SK_VA]

Hi,

I am running my transceiver at 5 Gbps data rate. I use transceiver training toolkit for transceiver tuning. I got the best values for TX PMA after running autosweep. I set these values in qsf and tested again. Even though initially BER is zero,when I run transceiver link BER is toggling very frequently without settling to a value.I ran autosweep again I got different values for Premphasis taps that are close to previous values.

I expect once the best values from autosweep is kept in qsf settings, BER will settle to 0 consistently.But this is not happening!!

In my experiment I have kept VOD constant at 31 as Stratix 10 user guide suggests VOD to be between 17-31.But when I run autosweep with complete range of VOD,I get the best value as 12.

For lower values of VOD in the range of 17-20 Fitter throws follwing error :

Error(15744): The settings must match one or more of these conditions:  

Error(15744): ( tx_powerdown == POWER_DOWN_TX ) OR ( compensation_en == DISABLE ) OR ( vod_output_swing_ctrl inside {[0:16],[18:31]} ) OR ( powermode_ac_tx_vod_w_jitcomp == TX_VOD_W_JITCOMP_AC_L17 ) 

[CheePin_C_Intel]

Hi,

As I understand it, you observe that the PMA value that you obtain from the autosweep seems still get into intermittent bit error. 

In this case, you would need to perform further fine tuning to select the optimal value. After your autosweep, you can try to export the autosweep report which should show the BER for all the combination tested. From there, you can try to find the passing range for each of the PMA parameters and then select the middle value for each parameters to ensure you have sufficient margin for PVT variation. You may refer to the "AN871 - Quick Guide for Intel Arria 10 and Intel Cyclone 10 GX Transceiver High-Speed Link Tuning" for further details on finding the optimal range.

https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/an/an871.pdf

Regarding the VOD values, it is recommended for you to keep within the recommended range of the user guide. 

Please let me know if there is any concern. Thank you.

Best regards,

Chee Pin