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cc1110 lattice balun design

Tony Siu
Intellectual 610 points

Dear All,

I am figuring out how the CC1110 balun is calculated based on the suggestion of the IEEE paper to verify the values of the lumped element suggested in CC1110 433 Reference design:
Lumped and Distributed Lattice-type LC-Baluns in microwave symposium digest 2002 Volume1

Please find the picture below for LC value calculation 

Here is the calculation based on the suggested equation by IEEE paper. However It seems that the IEEE paper does not explain how to deal with complex R1 so I just put 116 ohm in the calculation instead of the 116-j*41 suggested by TI.

R1 116
RL 50
Zc 76.15773106
f 4.33E+08
omega 2.72E+09
L 2.80E-08=28nH
C 4.83E-12=4.8pF

Does any one know how to calculate the values of lattice balun if the R1 is a complex value?
Also it seems that TI has chosen C = 3.9 instead of 4.8pF. In what basis do they make such calculations?

Regards,

Tony

  • 0
    TI__Mastermind 36385 points

    Tony, 

    Looks very interesting, you could likely add the complex part of the match with a small cap or coil as a separate section of your match,  please note that there is DC on two RF ports of the CC1110 and you therefore need a decoupling cap for this type of configuration anyway. 

    Overall I would recommend a circuit simulator.

    Regards
    /TA