An electronic device for supporting carrier aggregation (CA) is provided. The electronic device includes a radio frequency integrated circuit (RFIC) including a plurality of mixers and a feedback circuit, at least one antenna, a coupler disposed between the RFIC and the at least one antenna to transfer a reflected signal of a transmission signal to the feedback circuit, and at least one processor operatively connected to the RFIC, wherein the at least one processor may identify whether there is a mixer which is not in use among the plurality of mixers, when the first mixer which is not in use among the plurality of mixers is identified, perform antenna impedance tuning through a first mixer and the feedback circuit, and when the plurality of mixers are all in use, perform the antenna impedance tuning through a second mixer assigned to a secondary cell (Scell) among the plurality of mixers and the feedback circuit.