Circuits and methods related to radio-frequency (RF) architectures having carrier aggregation. In some implementations, a carrier aggregation (CA) architecture can include a duplexer configured to provide duplexing functionality for a first frequency band and a second frequency band with a common antenna. The CA architecture can further include a first amplification path and a second amplification path coupled to respective ports of the duplexer, each of the first amplification path and the second amplification path configured to amplify a signal in its respective frequency band, each amplification path including a transmit/receive (TX/RX) switch configured to provide time-division duplexing (TDD) functionality for the amplified signal and a received signal. In some implementations, the first frequency band includes a B39 band, and the second frequency band includes a B41 band.