Radio frequency front end, terminal device, and carrier aggregation method

A carrier aggregation method, applied to a terminal device, wherein the terminal device comprises:

• an antenna, the antenna configured to radiate a modulation signal to space and receive an electromagnetic wave in the space;
• a radio frequency front end, the radio frequency front end comprising:
• P transmit branches, wherein each transmit branch is used to transmit a carrier modulation signal on at least one of M different frequency bands, wherein each transmit branch comprises at least one transmit filter, wherein the transmit filter is a band-pass filter, wherein a frequency band on which a carrier is allowed by the transmit filter to pass is consistent with the at least one frequency band on which transmitting is performed on each transmit branch, wherein P is an integer greater than or equal to 1 and less than or equal to M, and wherein M is an integer greater than or equal to 2;
• N receive branches, wherein each receive branch is used to receive a carrier modulation signal on at least one of the M different frequency bands, wherein each receive branch comprises at least one receive filter, wherein the receive filter is a band-pass filter, wherein a frequency band on which a carrier is allowed by the receive filter to pass is consistent with the at least one frequency band on which receiving is performed on each receive branch, and wherein N is an integer greater than or equal to 1 and less than or equal to M;
• and
• a switch circuit having L input ports and at least one output port, wherein the at least one output port is connected to an antenna or a back end circuit of an antenna, wherein the L input ports are used to simultaneously connect a transmit branch of the P transmit branches and a receive branch of the N receive branches, wherein the transmit branch and the receive branch are corresponding to a same frequency band, and wherein L is an integer greater than or equal to 2, wherein the output port is connected to the antenna;
• and
• a controller, the controller configured to control a connectivity status between the L input ports and the transmit branch and between the L input ports and the receive branch;
• wherein the method comprises:
• determining at least two frequency bands for carrier aggregation;
• in downlink carrier aggregation, controlling L input ports to simultaneously connect receive branches corresponding to the at least two frequency bands and a transmit branch corresponding to one of the at least two frequency bands;
• and
• in uplink carrier aggregation, controlling the L input ports to simultaneously connect transmit branches corresponding to the at least two frequency bands and a receive branch corresponding to one of the at least two frequency bands.