Load Modulated Balanced Amplifier with Reconfigurable Phase Control for Extended Dynamic Range
This paper presents a RF-input load-modulated balanced amplifier (LMBA) with reconfigurable phase shifting circuit at the control path. With an integrated varactor-based phasing shifter, the control signal from RF input can offer concurrent amplitude and phase manipulations. Together with Doherty-like design of the main balanced amplifiers and control amplifier, this hybrid load modulation technique achieves optimal dynamic impedance trajectory, high back-off efficiency, and extended dynamic power range. A demonstration LMBA is designed 2.4 GHz using GaN transistors. The fabricated prototype achieves 69% of efficiency at peak output power of 43 dBm, and it maintains >50% efficiency down to 12-dB power back-off.