Uplink carrier aggregation architecture. In some embodiments, an uplink (UL) carrier aggregation (CA) architecture may include a first antenna port and a second antenna port. The UL CA architecture may also include a first radio-frequency (RF) circuit configured to route a first transmit (TX) signal and a first receive (RX) signal to and from the first antenna port, respectively, the first RF circuit further configured to route a second RX signal from the first antenna port. The UL CA architecture may further include a second RF circuit configured to route a second TX signal to the second antenna port to provide UL CA capability between the first and second TX signals.