A novel single-RF multiple-input multiple-output
transmitter architecture based on the outphasing principle is presented.
An efficient switching amplifier feeds a tunable analogue
network with the unmodulated carrier. The carrier is modulated
utilising the outphasing principle and distributed to the antennas.
Featuring only a small set of standard RF components -namely
power splitters, phase shifters, and hybrid couplers- the structure
can be readily implemented in a cost-efficient passive integration
fashion. Various modulation schemes for the architecture are
investigated including the particular power efficient phase shift
keying on the hypersphere. Our numerical results show that the
proposed architecture is a power- and cost-efficient solution for
multi-antenna transmitters on energy-limited user devices.