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DS110DF410: Adaptive CTLE algorithm, CTLE gain at insertion loss exceeding the gain table

Kawai
Guru 19785 points
Part Number: DS110DF410

Hi Team,

Please allow me to clarify the adaptive CTLE algorithm.

I am understanding that the device will choose the CTLE setting which has the largest HEO/VEO. However, it also checks the CTLE settings with "look beyond counts".

If the trace insertion loss is too large for the device to equalize, let's say something like -50dB, would the device always choose the highest CTLE boost setting of REG 0x5F = 0xA5 ?

I wanted to make sure the device operation in this case, because the device cannot find the point where eye starts closing.

Best Regards,
Kawai

  • 0
    TI__Mastermind 43795 points

    Hi Kawai,

    If the insertion loss is very large (- 50 dB), then the CTLE will not open the eye even at the maximum setting.  In this case I believe the CTLE adapt will fail, but will likely increment until it achieves the maximum value.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Guru 19785 points

    Hi Lee-san,

    Q1). If that is the case would the device always choose the maximum value ?

    Q2). Does the device need to find the gain setting where the eye starts closing to decide the CTLE boost value to be used ? I am asking this because if the maximum gain setting is equal to the insertion loss, there is no way for the device to see the eye opening to get smaller.

    Best Regards,

    Kawai

  • 0 in reply to Kawai
    TI__Mastermind 43795 points

    Hi Kawai-san,

    Q1 - It is almost certain that the device will go to the highest equalization value (A5'h) in the lookup table and stop if no eye is present.  This would likely be the case in a -50dB application.

    Q2 - If the eye opening is just starting to open for the last couple settings in the CTLE table, then the maximum setting will be used.

    Regards,

    Lee 

  • 0 in reply to Lee Sledjeski
    Guru 19785 points
    Hi Lee-san,

    I understood!!
    Thank you so much for the great support.

    Best Regards,
    Kawai