CC1100: Inverted layout for RF-N and RF-P and consequences for FCC testing

Lenio Cacula

Part Number: CC1100
Other Parts Discussed in Thread: CC1101

If by mistake the layout has reversed pins 12 and 13 (RF_P and RF_N) of CC1100, what would be the consequences for the performance of the RF circuit? Are there any risks with out of band frequencies? In this particular layout, the balun is the same as the one recommended in our documentation (below). Thank you!

over 7 years ago

0 PM over 7 years ago

TI__Mastermind 27145 points

Hi Lenio,

Theoretically they can reverse it and it should not have any impact on spurious signals.

Thanks,
PM

0 TER over 7 years ago in reply to PM

TI__Guru**** 317180 points

No impact since RF_N is the inverted version of RF_P

0 Lenio Cacula over 7 years ago in reply to TER

TI__Genius 16700 points

Follow up question: if RF_P and RF_N are interchangeable, why is the balun circuit not perfectly symmetrical? Also, what method or simulation did we use to determine that 5% tolerance components are acceptable? Thank you!

0 TER over 7 years ago in reply to Lenio Cacula

TI__Guru**** 317180 points

From a RF point of view the balun is symmetrical. C124 is a DC block. www.ti.com/.../swra168 covers the details of the balun.

Not sure what type of methods that where done to check if 5 % tolerance was OK but based on the sales numbers for the CC1101 family a lot of systems uses this balun and nobody has reported any issues with it as far as I know.

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CC1100: Inverted layout for RF-N and RF-P and consequences for FCC testing