DS90UB953-Q1: PoC Design Guidelines

Vincent Tsao

Part Number: DS90UB953-Q1

According to the document "snla272(Power-over-Coax Design Guidelines for DS90UB953-Q1)" table1 and figure3, the PoC return loss need "< –25 dB at 20 MHz" and "< –12 dB at 2 GHz".

We followed the design guidelines to design schematic and impedance matching, but it can't meet spec of return loss, so how to tune the return loss and let it to meet spec.

over 7 years ago

0 Steven(Shenzhen) Shi over 7 years ago

TI__Mastermind 30515 points

Hi,
the return loss is on the high speed signal channel parameter, it is NOT dependent on the design only. please check the layout, PoC component electrical spec., connector spec., etc.

regards,
Steven

0 Vincent Tsao over 7 years ago in reply to Steven(Shenzhen) Shi

Prodigy 30 points

I have a questioning in return loss of PoC system.
In the ds90ub953 spec(SNLS552A) table 174, there shows "Return Loss, S11: 1 GHz < f < fFC -12 dB(MAX)" and "Insertion Loss, S12: f =2.1 GHz -1.2 dB(MIN)".
In the Power-over-Coax Design Guidelines for DS90UB953-Q1(SNLA272) Figure 3., there shows Return Loss Specification Graph.

So, which spec should I follow?

0 Steven(Shenzhen) Shi over 7 years ago in reply to Vincent Tsao

TI__Mastermind 30515 points

Hi,
Both are compatible.

regards,
Steven

0 Vincent Tsao over 7 years ago in reply to Steven(Shenzhen) Shi

Prodigy 30 points

Hi Steven
But it writes 'Single-Ended PCB "Traces" With Attached PoC Networks' in SNLS552A.
Other one is 'Return Loss for the DS90UB953-Q1 "PoC Network" Running at 4Gbps' in SNLA272.
So Return Loss of Traces+PoC Network should meet the Figure 3 of SNLA272 ?

0 Steven(Shenzhen) Shi over 7 years ago in reply to Vincent Tsao

TI__Mastermind 30515 points

As PoC network is designed in single-end, both have same return loss spec..

this is used for reference. the lower S11 spec., the better high speed link SI performance.

regards,
Steven

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DS90UB953-Q1: PoC Design Guidelines