Phase control for carrier aggregation. In some embodiments, a carrier aggregation circuit can include a first filter configured to allow operation in a first frequency band, and a second filter configured to allow operation in a second frequency band. The circuit can further include a first path implemented between the first filter and a common node, with the first path being configured to provide a substantially matched impedance for the first frequency band and a substantially open-circuit impedance for the second frequency band. The circuit can further include a second path implemented between the second filter and the common node, with the second path being configured to provide a substantially matched impedance for the second frequency band and a substantially open-circuit impedance for the first frequency band.