An asymmetric multilevel outphasing, AMO, transmitter architecture comprising: an RF circuit (100, 701) comprising a plurality of RF amplifiers (120, 720), each of the plurality of RF amplifiers having an RF input and RF output and a power supply input; and a control system (150, 750), coupled to said plurality of RF amplifiers, said control system configured to receive a baseband signal, provided as an amplitude and a phase signal (Φ), and in response thereto to select power supply levels of a plurality of voltages (115, 715) to be provided to the power supply inputs of said plurality of RF amplifiers and to provide phase adjusted signals to the RF inputs of said plurality of RF amplifiers; wherein the AMO transmitter architecture further comprises: a power supply configured to provide the plurality of voltages (115, 715); and a switch network (130, 730A, 730B) configured to receive a plurality of control signals (125, V C1, V C2, V CM) from said control system (150, 750) and to couple selected ones of the plurality of voltages (115, 715) provided by said power supply to respective ones of the power supply inputs of the plurality of RF amplifiers, at least two of the selected ones of the plurality of voltages being different ones of the plurality of voltages, an RF power combiner (140, 740) having a plurality of input ports with each of the plurality of input ports coupled to a respective different one of the output ports of said plurality of RF amplifiers. an RF circuit (100, 701) comprising a plurality of RF amplifiers (120, 720), each of the plurality of RF amplifiers having an RF input and RF output and a power supply input; and a control system (150, 750), coupled to said plurality of RF amplifiers, said control system configured to receive a baseband signal, provided as an amplitude and a phase signal (Φ), and in response thereto to select power supply levels of a plurality of voltages (115, 715) to be provided to the power supply inputs of said plurality of RF amplifiers and to provide phase adjusted signals to the RF inputs of said plurality of RF amplifiers; wherein the AMO transmitter architecture further comprises: a power supply configured to provide the plurality of voltages (115, 715); and a switch network (130, 730A, 730B) configured to receive a plurality of control signals (125, V C1, V C2, V CM) from said control system (150, 750) and to couple selected ones of the plurality of voltages (115, 715) provided by said power supply to respective ones of the power supply inputs of the plurality of RF amplifiers, at least two of the selected ones of the plurality of voltages being different ones of the plurality of voltages, an RF power combiner (140, 740) having a plurality of input ports with each of the plurality of input ports coupled to a respective different one of the output ports of said plurality of RF amplifiers. a power supply configured to provide the plurality of voltages (115, 715); and a switch network (130, 730A, 730B) configured to receive a plurality of control signals (125, V C1, V C2, V CM) from said control system (150, 750) and to couple selected ones of the plurality of voltages (115, 715) provided by said power supply to respective ones of the power supply inputs of the plurality of RF amplifiers, at least two of the selected ones of the plurality of voltages being different ones of the plurality of voltages, an RF power combiner (140, 740) having a plurality of input ports with each of the plurality of input ports coupled to a respective different one of the output ports of said plurality of RF amplifiers.