RF-Input Doherty-Like Load-Modulated Balanced Amplifier With Decade Bandwidth Enabled by Novel Broadband 180° Power Divider

Abstract

This letter presents the first demonstration of a decade-bandwidth Doherty-like load-modulated balanced amplifier (DL-LMBA). Leveraging the recently developed signal-flow-based broadband LMBA theory, a frequency-agnostic phase-alignment condition is identified that is critical for ensuring intrinsically broadband load modulation (LM) behavior for DL-LMBA, thereby overcoming longstanding bandwidth limitations in DL-LMBA design. In addition, a reflective-type-phase-shifter-based 180° power divider is proposed for the wideband operation of DL-LMBA. To prove the proposed concept, an ultrawideband RF-input DL-LMBA is developed using GaN technology covering the frequency range from 0.2 to 2 GHz. Experimental results demonstrate an efficiency of 44%–67% for peak output power and 43%–75% for 6 dB output back-off (OBO), respectively.