LC tuning circuit for RF 868Mhz Antenna circuit.

Discussion in 'Wireless & RF Design' started by abc14, Apr 30, 2019.

  1. abc14

    Thread Starter Member

    Oct 15, 2017
    105
    0
    Hi Guys,

    I am doing a custom PCB for an RF transceiver IC operating at 868Mhz. I understand most of the concepts laid out in the data sheet, But I need some clarity on the LC tuning circuit, how the resonant frequency is calculated. LC tuning part of my schematic is attached as screenshot.

    upload_2019-4-30_12-34-38.png


    I think frequency is calculated as 2*pi*F= 1/sqrt(L*C). I have attached the datasheet as well.


    https://www.semtech.com/uploads/documents/sx1231.pdf
     
  2. cariban

    Member

    Aug 14, 2018
    66
    11
    They are not used as resonance purpose. Except L2 is RF choke, the rest are used for impedance matching or filtering purpose. Different working band needs different values. That is reflected in the datasheet.
     
  3. abc14

    Thread Starter Member

    Oct 15, 2017
    105
    0
    Thanks for reply, Ok they acting as filters. I made a mistake in the schematic L2 wasn't connected properly.

    upload_2019-4-30_13-35-59.png
     
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