Dual-Band Doherty Power Amplifier with Extended Back-Off Range Using Input Phase Control

This paper presents a dual-band Doherty power amplifier (DPA) with extended back-off (OBO) range based on dual-band symmetrical out-phased current load modulation and input phase control. To satisfy the phase requirements at both center frequencies and to enhance the operating bandwidth, a dual-band differential phase shifter is implemented in the proposed DPA. To validate the proposed architecture, a dual-band DPA operating around 2.6 GHz and 3.5 GHz is designed, fabricated and measured. Under continuous-wave signal excitation, the DPA achieves drain efficiencies of 40%-47.5% at 8-dB OBO across 2.4-2.7 GHz and 41.5%-48% at 8-dB OBO across 3.3-3.7 GHz, with drain efficiencies of 65.4%-76.9% and 67.5%-74% at saturation, respectively. When driven by 20-MHz long-term evolution (LTE) signal with 8-dB peak-to-average power ratio (PAPR), the proposed dual-band DPA obtains average drain efficiencies of 42.8%-48% and 46.4%-52.8% in the two operating frequency bands, and adjacent channel leakage ratio (ACLR) both below −53 dBc after digital predistortion (DPD).