Hybrid Load-Modulated Balanced Amplifier With High Linearity and Extended Dynamic Range

• Published in: IEEE microwave and wireless components letters Vol. 31; no. 9; pp. 1067 - 1070
• Main Authors: Lyu, Haifeng, Chen, Kenle
• Format: Journal Article
• Language: English
• Published: IEEE 01.09.2021
• Subjects: Balanced amplifier; Doherty power amplifier (DPA); efficiency; Hybrid power systems; Linearity; load modulation (LM); Loading; Microwave circuits; Modulation; Prototypes; Wireless communication
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2021.3083235

A novel hybrid load modulation (LM) architecture of power amplifier (PA) is presented in this letter, in which three amplifiers are combined through a quadrature coupler in properly defined phase offsets. Together with the well-aligned turning-on sequence, the PA can operate as a Doherty PA (DPA) and load modulated balanced amplifier (LMBA) at different power levels, whose overall behavior is similar to a three-way DPA. This unique hybrid LM mode effectively extends the dynamic power range of efficiency enhancement, which is further compatible with the high-linearity design. This concept is experimentally validated using a GaN-based prototype at 3.56 GHz. The CW measurement shows an efficient PA performance with 49%-63% of efficiency from <inline-formula> <tex-math notation="LaTeX">P_{\mathrm {Max}} </tex-math></inline-formula> to 9-dB back off. Under the modulated evaluation using a 20-MHz LTE signal, an adjacent channel leakage ratio of −37.5 dB is measured together with 45% average efficiency.