DS90UB953-Q1: Eye-diagram measurement result failed

chentsu chung

Hi,

Due to the eye-diagram measurement result failed, besides trying different value of inductor and bead, could you help to review the schematic and the layout and see if anything could be improved.

Thank you.

Schematic:

37BMIPITBDA2.pdf

Layout Files Link:

over 8 years ago

0 Palaniappan Manickam over 8 years ago

TI__Genius 10475 points

Hello,
Please do not share confidential schematics here since E2E is a public forum.
You can review the layout guidelines in the 953 datasheet for additional information.
Can you provide more information about the eye diagram measurement results?

0 chentsu chung over 8 years ago in reply to Palaniappan Manickam

Mastermind 6180 points

Hi,
Customer have already followed the layout guide in datasheet (like the guidelines of PoC and the AC-Coupling Capacitor)and other application note, due to customer will re-layout recantly, could you please help to check that if there anything could be improved.

For the eye diagram measurement results, the Ew is less than 0.45UI (customer have tried many kind of cable), and screen flash sometimes(it happens once for few hours)

Thank you very much.

0 Steven(Shenzhen) Shi over 8 years ago

TI__Mastermind 30515 points

Hi,

The R14 can be removed for better layout.

also, as mentioned, layout is very important, please be careful for it. You can refer to d/s, TiDeisgn document or UB953 EVM board design, which provide some examples for layout.

btw, it seems only 1 CSI2 data lane is used. what is the video resolution? If possible, you can also use UB933 in this case.

best regards,

Steven

0 chentsu chung over 8 years ago in reply to Steven(Shenzhen) Shi

Mastermind 6180 points

Hi,

Thanks for your suggestion, customer "have followed" d/s and EVM design, but due to the board size is very small, that means layout could not be same as EVM. We have review d/s and EVM layout many times, just need your help to check that if any point that we missed or any point could be improved.

Thank you very much.

0 Steven(Shenzhen) Shi over 8 years ago in reply to chentsu chung

TI__Mastermind 30515 points

Chentsu,
Please check above replyss. The board design includes two aspects: sch. and layout, regarding sch. in the attached, please refer to below d/s link in page66, it has PoC circuit design reference, your attached does NOT follow up it, e.g, the R14 can be removed as this socket would introduce more stub/via in the high speed link but no helpful for PoC circuit design.
www.ti.com/.../ds90ub953-q1.pdf
also, below link is UB953 EVM board, you can refer to it as well.
www.ti.com/.../snlu224.pdf
for the layout, please make sure you can follow up the design guide in page73-76 of UB953 d/s. thanks.

best regards,
Steven

0 chentsu chung over 8 years ago in reply to Steven(Shenzhen) Shi

Mastermind 6180 points

Hi Steven,

This board is a test version. The eye-diagram measurement tested before this version, this version is for debuging only.
We usually use 0603 bead for test requirement.
Finally we will delete R14, R18...co-lay parts.

Resolution : 1920*1080p30
So we use 1 lane now.
But we will use 2 lane for 1920*1080p60 on next step.

Those two document we HAVE read many times already, and seems it doesn't mention too much about GND, is there any special request about it? Or there is anything could be improved in our Layout?

Thank you.

0 chentsu chung over 8 years ago in reply to chentsu chung

Mastermind 6180 points

Hi Steven,

Customer also try different kind of GND layout, and it does affect the eye-diagram measurement result, is there any suggestion for this part?

Thank you very much.

0 Steven(Shenzhen) Shi over 8 years ago in reply to chentsu chung

TI__Mastermind 30515 points

Chentsu,
Sure, the layout would impact the highn speed signal quality. please follow up d/s design guide on high speed signal design rules.

best regards,
Steven

0 chentsu chung over 8 years ago in reply to Steven(Shenzhen) Shi

Mastermind 6180 points

Hi Steven,

I didn't see any rule about GND layout in d/s, please indicate that what rule in d/s I should follow?

0 Steven(Shenzhen) Shi over 8 years ago in reply to chentsu chung

TI__Mastermind 30515 points

Chentsu,
you are careful of GND layout??
regarding the layout recommendation, in ub953 d/s, you can refer to page73/74/75, we also have some layout example in d/s.
If you need know high speed signal GND layout knowledge, you can refer to below app. note, the rules are common for high speed design, thanks.
www.ti.com/.../spraar7g.pdf

best regards,
Steven

0 chentsu chung over 8 years ago in reply to Steven(Shenzhen) Shi

Mastermind 6180 points

Hi Steven,

Customer have checked layout make sure that follow the rule in d/s.

Now they need TI officily response to let the gerber out.

They need any commend from TI for the layout to process. anyone is okey.

Please indicate that YES or NO for this layout file to colse the thread.

Or just let us know that TI won't review layout file, thank you very much.

0 Steven(Shenzhen) Shi over 8 years ago in reply to chentsu chung

TI__Mastermind 30515 points

updated.

0 Steven(Shenzhen) Shi over 8 years ago in reply to Steven(Shenzhen) Shi

TI__Mastermind 30515 points

The sch. in the attached doesn't follow up TI's EVM board design, such as PoC filter, power supply filter, PDB pin, etc, please follow up it strictly based on UB953EVM board (www.ti.com/.../DS90UB953-Q1 and includes some notes in d/s.

also, sorry we can't review the layout in this forum as your attached message is filtering by system due to confidential. if you need more help, you can work with TI local team for this.

Steven

0 chentsu chung over 8 years ago in reply to Steven(Shenzhen) Shi

Mastermind 6180 points

Got it, thank you very much, this is the answer that customer wants.

0 Steven(Shenzhen) Shi over 8 years ago in reply to chentsu chung

TI__Mastermind 30515 points

what EE is your customer working? more comments: the sch. is quite different with TI's EVM refer design, it is false that "Customer have checked layout make sure that follow the rule in d/s". please share with your customer with TI more technical resources, and this is the first step for your customer to design and review internally. thanks.

regards,
Steven

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DS90UB953-Q1: Eye-diagram measurement result failed