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CC1200 Receive Only and Transmit Only designs (916 MHz)

Michael Burns
Intellectual 440 points
Other Parts Discussed in Thread: CC1200

I will be using multiple CC1200's in Receive Only mode and Transmit Only mode. One PCB will use four CC1200s in Receive Only mode and one CC1200 in Transmit Only mode; the other PCB will use eight CC1200s in Receive Only mode and two Cc1200s in Transmit Only mode. Obviously, it would be desirable to remove unnecessary components. There is a reason for this configuration - trust me.

Referring to the CC1200EM_866_915 Reference Design Schematic (SWRR121), for Transmit Only operation, I assume that I can remove all six passive components connected to the LNA_P and LNA_N pins (L191, L192, L193, L201, C191, C201) as well as C161. Is that correct? Can the LNA pins be left open, or do they require a DC connection to the TRX_SW pin? For receive only operation, it's not so clear. Can the PA "pull up to VDD" be removed (L171, R171, C173, C171, C172)? Can C174, C176, and L172 also be removed?

I realize that a similar question was asked a few months, but the answer wasn't clear.

Thanks.

  • 0
    TI__Guru**** 317180 points
    For Tx only:
    Remove L191, L192, L201, L193, C191, C201. Ground RF_P/N. Ground C181 and leave TRX_SW unconnected. The size of C181 may be adjusted one value or two up or down to give the most optimal impedance. Grounding this will give a different impedance than connecting it to the TRX_SW line and the Rx network.

    For Rx only:
    If I'm not mistaken the point where C191 and L201 is connected together is a 50 ohm point and an antenna could be connected directly here. Keep place holder for L193 and C181 in case. The connection to TRX_SW is not needed. C/L17x are not needed for Rx only.