A power amplifier, PA, system (152; 156; 162) comprising: a first PA module including a plurality of first PAs configured to operate in a 2G or 3G mode, each of the plurality of first PAs being configured to amplify a radio-frequency, RF, signal for transmission; a second PA module separate from the first PA module including a plurality of second PAs configured to operate selectively in both, a 3G or 2G mode, each of the plurality of second PAs being configured to amplify an RF signal for transmission; an interface implemented as routing circuit within the first PA module, the interface configured to be capable of routing a frequency-separated RF signal received from a transceiver at a first input port of the first PA module to the one of the plurality of first PAs, the interface further configured to be capable of routing the frequency-separated RF signal to one of the plurality of second PAs and the interface including at least one single-pole double-throw switch (S1; S2; S3), the at least one single-pole double-throw switch (S1; S2; S3) having its pole connected to the first input port of the first PA module and its first throw selectively connected to the plurality of first PAs; and a signal path implemented between the interface within the first PA module and the second PA module for routing a frequency-separated RF signal received from the transceiver at a first input port of the first PA module through the routing circuit within the first PA module to the second PA module, the second throw of the the at least one single-pole double-throw switch (S1; S2; S3) connected to an interface port (114a; 114b) of the first PA module to selectively allow the routing of the RF signal through the signal path to the plurality of second PAs. a first PA module including a plurality of first PAs configured to operate in a 2G or 3G mode, each of the plurality of first PAs being configured to amplify a radio-frequency, RF, signal for transmission; a second PA module separate from the first PA module including a plurality of second PAs configured to operate selectively in both, a 3G or 2G mode, each of the plurality of second PAs being configured to amplify an RF signal for transmission; an interface implemented as routing circuit within the first PA module, the interface configured to be capable of routing a frequency-separated RF signal received from a transceiver at a first input port of the first PA module to the one of the plurality of first PAs, the interface further configured to be capable of routing the frequency-separated RF signal to one of the plurality of second PAs and the interface including at least one single-pole double-throw switch (S1; S2; S3), the at least one single-pole double-throw switch (S1; S2; S3) having its pole connected to the first input port of the first PA module and its first throw selectively connected to the plurality of first PAs; and a signal path implemented between the interface within the first PA module and the second PA module for routing a frequency-separated RF signal received from the transceiver at a first input port of the first PA module through the routing circuit within the first PA module to the second PA module, the second throw of the the at least one single-pole double-throw switch (S1; S2; S3) connected to an interface port (114a; 114b) of the first PA module to selectively allow the routing of the RF signal through the signal path to the plurality of second PAs.