Class-G Supply Modulation for MIMO and Radar with Phased Array Antennas

Class-G supply modulation, i.e., discrete level supply modulation, is a powerful efficiency enhancement technique. It allows wideband modulated operation of RF power amplifiers and high output power. For massive multiple-input multiple-output functionality in 5G systems, phased array antennas can be used to implement dynamic beamforming, similar to radar systems. Different configurations for driving the phased array antennas are possible. The configuration under investigation consists of a single baseband source that is distributed to antennas driven by dedicated power amplifiers with controllable input delay lines. This complexity-reduced topology where the power amplifiers are discretely supply modulated with the same supply waveform has only minor impact on the efficiency improvement. Instead the linearity is limited by a trade-off that depends on the relative modulation bandwidth, the electrical antenna size and the beam angle. It is shown that planar phased array antennas with 2×2 or 4×4 elements can be efficiently driven with this topology and an efficiency improvement of 10%-points can be achieved. Even 8×8 phased arrays are supported by this topology at reduced bandwidth and beam angles.