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CC1101 Frequency Shift using Johanson Balun

Other Parts Discussed in Thread: CC1101, MSP430F2350

Hi Community,

I have a projekt where I use an MSP430F2350 together with an CC1101 Transceiver.

I am using the reference design. In order to save some components I used the Johanson Balun Filter for CC11xx chips for 868 MHz.

I programmed the CC1101 according to the register values of SmartRF Studio for 868 MHz.

Now when I only turn on the carrier (STX Strobe) and connect my board to an spectrum analyzer I see the carrier frequency at 830 MHz.

Its the same case on both of my boards that I built.

Does anybody have ideas where to look for the mistake?





  • What XTAL are you using? Have you checked that you have the correct load capacitors mounted on the board?



  • Hi,

    thanks for your answer. I am using a 26 MHz Crystal with confirmed 18 pF load capacitance. Digikey number of the crystal is: 887-1284-1-ND

    Just to make sure I changed the load capacitance to 12 pF and then to 22pF. I was able to see a slight movement of the carrier frequency, but still around 830 MHz.

    I am using the design suggestions in swra250 (Desing Note DN025), there is an additional LC filter and DC-block after the johanson balun. I also tried to bridge the LC filter and DC-Block, but the frequency still remained at 830 MHz.


    I heared there are some bugs in the SmartRF Studio. Is it possible that it presented me wrong values and I therefore programmed the frequency synthesizer wrong?




  • Hi,

    What are your TEST0 and FSCAL2 register settings? For operation at 868 MHz these should be TEST0 0x09 and FSCAL2 0x2A.


  • Hi Charlie,

    you made my day!!! It is working now!!!

    My registers where TEST2=0x88, TEST1=0x31, TEST0=0x00

    Thanks a lot!