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CC1352P: Feedback to PLL scheme available in CC1352p or not?

Part Number: CC1352P
Other Parts Discussed in Thread: CC1200

Hi Sir,

We just trying to extend the RX filter bandwidth for improving the sensitivity of 50kbps and 100kbps rate by feedback to PLL.

If available, may we know how to proceed it?

It seems there is a upper limit like for 50kbps, 100KHz RX bandwidth cannot be increased up to close to 200KHz since the selectivity test defined 200KHz as the inteferer frequency step

Thanks,

Wilson Chen 

  • Have to check some more what we can provide here.

    But could you elaborate a bit on what you mean by the following: "It seems there is a upper limit like for 50kbps, 100KHz RX bandwidth cannot be increased up to close to 200KHz since the selectivity test defined 200KHz as the inteferer frequency step" Is this the main reason for wanting to use feedback to PLL?

  • Hi Sir,

    What I mean is for 50kbps (25Khz dev.) data rate its RX filter bandwidth is around 100KHz, and via CC1200 document it says the increasing amount is likely to be +-(RX-BW)/N, N=2,4.

    Therefore I think the bandwidth after FB2PLL will be 150KHz, less than 200KHz so as selectivity test defining 200KHz as the step of interfere.

    So, may we know FB2PLL available?

    Thanks,

    Wilson Chen

  • We can provide some overrides to enable FB2PLL but it will require some tuning from your part. 

    But it's not clear for me why this feature is wanted. It's also not clear where measure selectivity @200kHz comes from. Before I give you more information I need to understand more about what you wanting to solve using this feature since I suspect that this could be solved differently. 

  • Hi TER,

    Sorry for late reply. The +-200 KHz offset selectivity test is coming from TI CC1352 datasheet that you can check further

    I am trying to understand the side effect or effort of FB2PLL. For now the picture to me is something that I think inteference or adjacent 915 MHz TI chip built-in device is more important than the sensitivity enhancement consideration

    Thanks you

    Wilson Chen

  • I assume that https://e2e.ti.com/support/wireless-connectivity/sub-1-ghz/f/156/t/891962 is the same case? If so, I will only cover the post I linked to to avoid supporting the same case in two different posts.