Multi-mode transmitter and receiver

A transmitter (300) comprises summers (301-307, 3178-319), and mixers (309-315, 333). During multi-carrier transmission, multiple I and Q components enter the transmitter. I1 is summed with I3, Q3 is subtracted from Q1, Q1 is added to Q3, and I3 is subtracted from I1. The outputs of a first and a second summer (301, 305) enters a first and a second mixer (309, 313) where they are mixed by a cosine function. Similarly, the outputs of a third and a fourth summer (303, 307) enter a third and a fourth mixer (311, 315) where they are mixed by a sine function. The output from first and the second mixer (309, 311) enter a first summer (317) where they are summed along with the I2 component. The output from the third and the fourth mixer (313, 315) enters a second summer (319) where they are summed along with the Q2 component.