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CC2592: Input Impedance of CC2592

venugopal kapre
Intellectual 825 points

Part Number: CC2592
Other Parts Discussed in Thread: CC2510, , CC2530, CC2538

Hello,

I am using chip 2450BM15B0003 for my design with CC2510 (recommended by TI).

In Balun datasheet, they have mentioned that its differential impedance is conjugate of the impedance of CC2510 i.e. 80 - j*74.

I want to add the range extended to this design. I would like to keep it modular so that I will use it if required.

Can I use the same balun for CC2592? If not,

What is the input impedance of CC2592?

Most of the CC2592 reference designs are with CC2530. Should I take it a conjugate of the differential impedance of CC2530 i.e. 69 - j*29.

Please help.

-Venu

  • 0
    TI__Guru**** 317180 points
    For the network from the ANT pin, follow the existing ref designs.

    CC2592 has a differential input and hence the PA outputs of CC2510 should be connected directly to the inputs of CC2592, see e2e.ti.com/.../380754

    The conjugate match is not that important, what you have to do is to provide the CC2510 PA with the optimal load.

    Since 2450BM15B0003 has single ended output you cant' use this with CC2592.
  • 0 in reply to TER
    Intellectual 825 points

    Balun will be connected to CC2592 to it's RF_P & RF_N pins. There will be two baluns one for CC2510 and one for CC2592. Both single ended outputs will be connected to each other through a CoAx cable

    Balun in case of CC2510 converting balanced signal to unbalanced signal during transmission.

    And during reception the conversion is from unbalanced received signal (single ended output) to balanced signal (double ended output)

    So why we can't use it with CC2592?

    And congujate match will be the optimal load for maximum power transfer.

    Please clarify if I am wrong.

    -Venu

  • 0 in reply to venugopal kapre
    TI__Guru**** 317180 points
    Since CC2510 has a differential output and CC2592 a differential input you don't need or want to go via single ended, see what is done in the CC2538 - CC2592 ref design, it's the exact the same principle you want to use.

    "congujate match will be the optimal load for maximum power transfer": Yes, according to the text books. And for a LNA that is fairly correct but PAs are not linear or small signal so conjugate match does not apply for PAs. See also chapter 8 in www.ti.com/.../swra640a.pdf
  • 0 in reply to TER
    Intellectual 825 points
    A RF SP8T switch is connect to CC2510 and has a single ended output 50 ohm. Therefore I have to use balun to connect single ended output to CC2592.
    I am already using balun at CC2510 side.
    Can I use a same balun on CC2592 side?
    If no, why ?
  • 0 in reply to venugopal kapre
    TI__Guru**** 317180 points

    I don't see a good solution on how to combine CC2592 with a bypass option. The traces between CC2510 and CC2592 should be differential and as short as possible. The balun is designed as a match for CC2510, connecting this to CC2592 will give a impedance mismatch and you will not get any good performance.