RF Front-End Circuit Employing LC-Tank for Carrier Aggregation

This paper proposes an RF front-end circuit for mobile terminals supporting carrier aggregation using two frequency bands. This RF front-end circuit employs two LC-tank circuits with reactive elements between an antenna switch and duplexers. The LC-tank circuits followed by one duplexer makes the input impedance high at the passband of the other duplexer, which achieves the low insertion loss at the passband of the duplexers. The reactive elements help to match the impedances between LC-tank circuits and the following duplexers. Measured results of the proposed RF front-end circuit without duplexers verify its fundamental functionality. The proposed circuit shows the insertion loss of 0.5 dB at 0.87 GHz and 0.8 dB at 1.92 GHz.