Dynamic Supply Modulation of a 6-12 GHz Transmit Array

This paper presents dynamic supply modulation results of a broadband 6-12 GHz 4x1 transmit antenna array. The four 2-W GaN MMIC PAs share a 4-level GaN MMIC dynamic power supply. A single GaN MMIC PA is first characterized at 6.5 and 11.5 GHz, and its efficiency while tracking a 10-MHz signal is compared to static drain supply performance, showing 10 percentage point (pp) average efficiency improvement. Four such PAs are then assembled in a modular array of broadband double-ridge dielectrically-loaded horn antennas and characterized under supply modulation. The measured average efficiency when each of the four PAs are terminated with 50 Omega is compared to when the PAs are loaded with the antenna array. An average PAE improvement of 3.4 pp is achieved over the static case with the supply modulated array at 6.5 GHz when amplifying a 10-MHz 10.7-dB peak-to-average power ratio (PAPR) signal, not taking the >80% efficient modulator into account. Linearity is characterized in terms noise power ratio (NPR) of the individual PAs, and at 6.5 GHz the improvement ranges from 2 to 6 dB, depending on the PA. To the best of the authors' knowledge, this is the first demonstration of dynamic supply modulation for broadband array efficiency and linearity enhancement.