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Original question:

LAUNCHXL-CC1352R1: Matching network: Balun

CC1352P: PA and SubGHz path Impedance matching to 50ohm? 100ohm?

Adnan Hussain
Intellectual 270 points
Part Number: CC1352P

Hello, we are currently planning to use the CC1352P solution in our new company project. I would like to know the required impedance values for the Sub GHz PA traces and the regular SubGHz traces as shown in the attached screenshot. I looked for an IPC that could take both the PA part and SubGHZ part but only found ones that take the SubGHz path and not the PA path. Anyways, a feedback on the above question and a material regarding the layout guidelines would be greatly appreciated.

  • +1
    TI__Guru**** 317180 points

    Please note that these traces will be too short to act like transmission lines and we typically don't treat them at traces that should have a given impedance. We have a guide that also include some on layout here: www.ti.com/.../swra640

    For 1 and 3 the most important is they are symmetrical and as short as possible. 2 and 5 are 50 ohm traces.

  • 0 in reply to TER
    Intellectual 270 points

    Thank you for the feedback TER. I would like to know more thing. In the TI LaunchPad schematic design for CC1352P, the inductors used for the RF paths have dots at one end. Does this mean that I can only use similar inductors and follow the dot convention?

    Thank you

  • +1 in reply to Adnan Hussain
    TI__Guru**** 317180 points

    Sorry, pressed something I should have. 

    Anyway, the reference design has been verified with the inductor type specified in the BOM list. Some inductors are not fully symmetrical and hence they have a marking to indicate direction. I haven't seen any effect of the orientation of the inductor on the designs I have measured on but I haven't done specific tests related to this. 

    Other inductors can be used but if you don't want to use any time tuning the design they should be as equal as possible to those in the BOM.