RF power transmission, modulation, and amplification, including direct cartesian 2-branch embodiments

An apparatus for at least one of power transmission, modulation, and power amplification, comprising:

• first circuitry configured to receive information, and configured to generate in-phase and quadrature phase amplitude control signals from said received information;
• second circuitry configured to receive said amplitude control signals and a frequency reference signal, and configured to generate first and second substantially constant envelope signals using said frequency reference signal and said amplitude control signals;
• and
• third circuitry configured to determine (a) a bias control signal from said received information, and (b) a phase difference between said first and second substantially constant envelope signals;
• power amplification circuitry comprising two or more circuit branches each comprising one or more transistors, and configured to amplify and combine said first and second substantially constant envelope signals to create an output signal, and that varies instantaneous signal output power using said bias control signal and said phase difference.