Compiler/DS90UB954-Q1: ds90ub953-q1 and ds90ub954-q1 RF noise effect GPS

user6353047

Part Number: DS90UB954-Q1

Tool/software: TI C/C++ Compiler

When 953 and 954 works, the signal transmission line has strong noise at 1500-1700mhz, which affects GPS signal reception. Is there any way to reduce or eliminate the noise?

over 5 years ago

0 Jiashow Ho over 5 years ago

TI__Genius 11340 points

Hello,

The 953-954 runs at 2GHz forward channel and 50MHz back channel in sync mode. I would suggest using a near field probe to isolate where on the board is the 1500-1700MHz signal transmitting. You can use copper tape to provide shielding near the source of noise.

Best,

Jiashow

0 user6353047 over 5 years ago in reply to Jiashow Ho

Prodigy 70 points

Hello,

In addition to the above methods, can filter component be added to the signal transmission line?

0 Vijaya Ceekala over 5 years ago in reply to user6353047

TI__Intellectual 2930 points

Hello

Yes, you can use CMC chokes on the PCB. You can also use spred-spectrum clocking

Thanks

Vijay

0 user6353047 over 5 years ago in reply to Vijaya Ceekala

Prodigy 70 points

1.Can common mode inductance be used instead of CMC chokes? Should it be placed close to AC coupling caps ? We use FPD link III signal traces and POC filter.
2.How to use the spread spectrum clock ? Is it modified by software?

0 Jiashow Ho over 5 years ago in reply to user6353047

TI__Genius 11340 points

Hello,

We've only done testing with CMC chokes.

Spread spectrum oscillator can be used instead of the traditional oscillator. The spread spectrum limit is defined in the 954 datasheet. You could also try to run the system in AON clock mode.

I would suggest first isolating the source of noise.

0 user6353047 over 5 years ago in reply to Jiashow Ho

Prodigy 70 points

The location of the noise source is shown in the picture. It's hard to shield

0 Vijaya Ceekala over 5 years ago in reply to user6353047

TI__Intellectual 2930 points

Hello

Can you run the overall system in AON clock mode and see the results?

Thanks

Vijay

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Compiler/DS90UB954-Q1: ds90ub953-q1 and ds90ub954-q1 RF noise effect GPS