DS90UB954-Q1: Compliance DS90UB954-Q1 PCB lines

Carlos Rodriguez1

Part Number: DS90UB954-Q1

Dear,

Based on TI recomendation regarding PCB Tracks impedance of FPDLink, we have this table:

Since you have to measure the S parameters working in PoC mode, I mean single ended, could you confirm, which is the proper way to do this measurements?, with VNA. As far as I understand:

Measurement of S11 parameters, 954 IC has been removed from the PCB, and two termination resistor has been soldered

In this case, to measure S21 Paremeter.

Thanks and BR

over 6 years ago

0 Hamzeh Jaradat over 6 years ago

TI__Guru** 107810 points

Hello,

yes the demonstrated is the correct way to measure S11 and S21. But it would be more correct if you add a load at the end of the PoC filter to draw the current as in normal application. This is useful because some inductors and Ferrite beads have less inductance once the current is high enough.

0 Carlos Rodriguez1 over 6 years ago in reply to Hamzeh Jaradat

Intellectual 345 points

Thanks Hamyeh,

Then, If I am not wrong, place Resistor in Vpoc PIN (See the pictures), like for exam 100Ohms?

0 Hamzeh Jaradat over 6 years ago in reply to Carlos Rodriguez1

TI__Guru** 107810 points

Yes, to act as a load. but you need to make sure that you are using the correct resistor value to simulate the real power consumption, not more and not less.
Also on the connector where you connect the VNA you will need to use a Bias-tee to provide the power and protect your VNA. To my knowledge not all VNA can tolerate DC Voltage.

0 Carlos Rodriguez1 over 6 years ago in reply to Hamzeh Jaradat

Intellectual 345 points

Thanks again Hamzeh,

Our VNA tolerate 30V DC input, so in this case we have no problems.

Final connection then:

Thanks!

0 Hamzeh Jaradat over 6 years ago in reply to Carlos Rodriguez1

TI__Guru** 107810 points

You can't place the Load at this position. It will affect your RF measurements and introduce additional Insertion Loss.
It will be better if you place the load at the Pin Vpoc, and feed your voltage from Port1 using an RF Bias-Tee.

0 Carlos Rodriguez1 over 6 years ago in reply to Hamzeh Jaradat

Intellectual 345 points

Perfect Hamzeh, thanks for your support.

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DS90UB954-Q1: Compliance DS90UB954-Q1 PCB lines