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LAUNCHXL-CC13-90: CC13-90 matching at 888MHz

Part Number: LAUNCHXL-CC13-90
Other Parts Discussed in Thread: CC1190, CC1310


I have an application where I need to transmit a tone at a frequency anywhere in the range of 886-892 MHz and I have identified that the CC1310 + CC1190 has the specs I need so the CC13-90 Launchpad is the natural choice for testing

I have a US-version of the CC13-90 that I removed the A2 inductor and sorted R158 so that I can use the on-board SMA instead of the antenna. I conducted a frequency sweep from 850-930 MHz @ 26 dBm using the SMARTRF Studio and recorded the data using a keysight SA.

As expected,at the frequency range of interest is far from the nominal 26 dBm and it ranges from -16 dBm to 8dBm. I suspected that this is a matching issue so I went into the schematic of the Launchpad and saw that the EU model (tuned at 868 MHz) has a C24 2.2 pF installed whereas in the US model it is DNP. Aside from the differences in the antenna matching (which I'm not using) I didn't see anything else to be different, see here:

So I installed a 1.8 pF cap to try it out but the frequency response barely budged. Am I missing something here?

How can I tune the CC13-90 launchpad to a frequency range of 880-890 MHz?


  • Ok I found the issue. The CC13-90 US launchpad uses the B39921B3588U410 SAW filter after the CC1310 output. The filter has a response that doesn't include the 880-890 MHz band that I'm interested in. Here is the response for reference:

    Which is basically exactly what I measure with the SA.

    Unfortunately the EU launchpad includes a SAW filter that ihas a passband outside of my band of interest. Do you have any SAW filter recommendationsfor that band ? Would I have an issue if I operate my launchpad without it?


  • Ok after removing the SAW filter and shorting the corresponding pads I get the response that I need see below. I suspect that the 3rd harmonic is gonna be awful but I don't care much for this application.

  • Hi,

    Glad to hear you've had some success with this. To answer the question in your original post about the addition of C24 (and explain the reason for adding it):

    You're correct that the EU BOM is essentially the same apart from the addition of C24 (to give improved performance at the 2nd harmonic); I would recommend including this component if you are operating in this frequency band.

    This LC filter has a narrowband response, however, so you would need to optimise it for operation at your band of interest to see any benefit (aiming for a resonance at 885 MHz) as it is currently optimised for 868 MHz.



  • or "L25/C210 and C24/L27 form two notches to filter the second harmonic" as described in