A device combines filter circuits to be connected to an antenna, enabling carrier aggregation for wireless communications over multiple RF frequency bands in different operational environments. The device includes first, second and third filter circuits having first, second and third matching networks and one or more first, second and third band pass filters with corresponding passbands, respectively. The device further includes multiple individual matching networks not dedicated to any of the first, second or third filter circuits, and a multi-state switch configured to provide different filter circuit combinations by selectively connecting at least two of the first, second and third filter circuits, respectively, and at least one individual matching network of the multiple matching networks. Each filter circuit combination includes a combined matching network having at least two of the first, second and third matching networks and the at least one individual matching network.