GSM Antenna coupling and matching implementation

3 thoughts on “GSM Antenna coupling and matching implementation

  1. Good afternoon,

    I hope that you could help me to understand the following issue:

    I am implementing an external antenna interface for both xE910 module (2G GE910 QUAD V3 and 3G HE910-D options). 

    The antenna detection circuit is also present according to Telit’s guideline.

    As suggested I placed an AC coupling capacitor (33pF) isolating the xE910’s RF input from the DC source path sinking into the the external antenna path for its detection.

    The question is:

    There is some advantage in keeping the AC coupling in case a simple direct connection from ext antenna to RF pad is required? (e.g. when the antenna detection circuit is not populated).

    Do I have to insert other passive network on RF track in between for ext antenna tuning for device certifications?

    Basically I would like to find the righ compromise using the minimum number of parts for RF antenna connection in order to optimize RF performance (PCB layout).

    Thanks

    1. Do I gain some advantage in keeping the AC coupling in case of simple direct connection from ext antenna to RF pad? (e.g. when the antenna detection circuit is not populated).

      No, there aren’t advantage; the 33pF capacitor can be substituted by a zero Ohm resistor.

      Do I have to add some passive network on RF track in between for ext antenna tuning for getting device certifications?

      No, you haven’t; in similar cases it isn’t suggested an antenna network matching circuit.