Design and Experimental Validation of a High-Efficiency Sequential Load Modulated Balanced Amplifier

The purpose of this paper is to present a detailed design procedure for a highly efficient sequential load-modulated balanced amplifier (SLMBA) to provide an in-depth analysis of this complex power amplifier (PA) architecture. SLMBA’s basic theory is presented and discussed. An SLMBA with a frequency range from 2.45 GHz to 2.65 GHz was implemented and then measured in order to validate the proposed design methodology. In both saturation and back-off states, the fabricated SLMBA exhibits extremely high efficiency and output power. It delivers a maximum output power of 43~44.4 dBm and a drain efficiency (DE) of 71.6~75% at saturation, a DE of 63.5~66% at 6 dB output back-off (OBO) state, a DE of 61.8~66% at 10 dB OBO state, and a DE of more than 51% at 12 dB OBO state in the targeted frequency band. The achieved results demonstrate the effectiveness of the proposed design procedure.