CC1125 Change Freq and low dBm

Emrah MERCAN

Other Parts Discussed in Thread: CC1125, CC1190

Hi,

I have CC1125 development kit. Everthing is normal when set to freq 869.224854MHz ( Default Settings). If i change another freq like 868.2MHz receving dBm dropped from -40dBm to -70dBm. Why this is happen?

Thanks

over 10 years ago

0 TER over 10 years ago

TI__Guru**** 317180 points

Do you have a CC1125 Cat 1 EM? If that is the case you havea SAW filter in the receive path. Ensure that you are within the bandwidth of this filter or remove it.

0 Emrah MERCAN over 10 years ago in reply to TER

Prodigy 50 points

Yes, I have Cat1 EM. How can i remove? What is the purpose of that ?

0 TER over 10 years ago in reply to Emrah MERCAN

TI__Guru**** 317180 points

YOu can remove it with a soldering iron or similar. Not sure if I understand you second question. Either you want to be cat 1 compliant and for that the SAW filter is required and if you don't need to be cat 1 you are free to remove the SAW filter (place a 0 ohm resistor there)

0 Emrah MERCAN over 10 years ago in reply to TER

Prodigy 50 points

Thank you for reply. I understand of SAW role. Can I get any gain of overall receving performance? Because SAW has loss.

0 Sverre over 10 years ago in reply to Emrah MERCAN

TI__Mastermind 39860 points

A SAW filter will improve blocking performance in RX and attenuation of spurs (both above and below the carrier) in TX. The SAW filter has a certain insertion loss so you will lose sensitivity, but if the SAW filter is placed between the CC1125 and the CC190 the insertion loss will to some extent be "masked" by the CC1190 gain.

Assuming a SAW filter with 3 dB insertion loss and CC1190 with 12 dB gain and 1.9 dB noise figure the SAW will give a degradation in sensitivity of roughly1.1 dB

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CC1125 Change Freq and low dBm