DS250DF810: Approx. Post de-emphasis question

AJ Cheng

Genius 3615 points

Part Number: DS250DF810

Hello.

We have questions on the SigCon GUI and would like to ask you.

What does it mean to show "NaN" dB on Approx. Post de-emphasis? Thanks for help~

over 7 years ago

0 Lee Sledjeski over 7 years ago

TI__Mastermind 43795 points

The main cursor should be a positive value.

Regards,

Lee

0 AJ Cheng over 7 years ago in reply to Lee Sledjeski

Genius 3615 points

Dear Lee.
If only has a set of settings that can pass the test, can it be used?
What does "NaN"dB mean? Thanks for help~

0 Rodrigo Natal over 7 years ago in reply to AJ Cheng

TI__Mastermind 19235 points

HI,

I agree with Lee's input. Please implement positive polarity for the FIR main cursor to simplify your signaling convention. With positive FIR main cursor setting, based on validation TI has found that only negative pre-cursor values (i.e. pre-cursor boost) are useful for link optimization. For the FIR post-cursor both positive (i.e. post-cursor attenuation) and negative (i.e. post-cursor boost) values may be evaluated.

Cordially,

Rodrigo Natal

HSSC Applications Engineer

0 AJ Cheng over 6 years ago in reply to Rodrigo Natal

Genius 3615 points

Dear Rodrigo.

Thank you for your reply. The following pattern example. What does "NaN" dB mean? Thanks for kindly help~

0 Lee Sledjeski over 6 years ago in reply to AJ Cheng

TI__Mastermind 43795 points

AJ,

It means that it the coefficients are not really valid and the waveform is not practical.

If you increase your Post Cursor Tap to -10 you will notice that the de-emphasis is over 15dB with these other settings

Regards,

Lee

0 AJ Cheng over 6 years ago in reply to Lee Sledjeski

Genius 3615 points

Dear Lee.
I got it. Thanks for kindly help~

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DS250DF810: Approx. Post de-emphasis question