Unequal-Cells-Based GaN HEMT Doherty Amplifier With an Extended Efficiency Range

• Published in: IEEE microwave and wireless components letters 2008-08, Vol.18 (8), p.536-538
• Main Authors: LEE, Yong-Sub, LEE, Mun-Woo, JEONG, Yoon-Ha
• Format: Article
• Language: English
• Subjects: Adjacent channel leakage ratio (ACLR); Amplifiers; Applied sciences; Broadband amplifiers; Carriers; Channels; Circuit properties; Code Division Multiple Access; Doherty power amplifier (DPA); efficiency; Electric, optical and optoelectronic circuits; Electronic circuits; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Gallium nitride; gallium nitride (GaN); Gallium nitrides; HEMTs; High electron mobility transistors; III-V semiconductor materials; Microwaves; Multiaccess communication; Noise levels; Peak to average power ratio; Power amplifiers; Power generation; Saturation; Semiconductor devices; Voltage; wide-band code division multiple access (WCDMA); Wideband
• ISSN: 1531-1309; 2771-957X; 1558-1764; 2771-9588
• DOI: 10.1109/LMWC.2008.2001015

This letter reports an extended GaN HEMT Doherty power amplifier (DPA). For high efficiency over a wide output power range, the DPA is designed using two cells with unequal saturation power (P sat ). A cell with lower P sat is used as the carrier cell. For experimental validations, the carrier and peaking cells are designed and implemented with 25 W GaN HEMTs at wide-band code division multiple access (WCDMA) of 2.14 GHz, and then show the P sat of 41.3 dBm and 43.6 dBm, respectively. For the proposed DPA, the single-tone results show the power-added efficiency (PAE) of 50% at an output power of 37.3 dBm (9 dB back-off power from P sat ). For a one-carrier WCDMA signal, the PAE of 47.9% with an adjacent channel leakage ratio of -35.8 dBc is obtained at 37.3 dBm, which is 7.9% improvement compared to the conventional DPA. The PAE of 40% is maintained over an 11.4 dB back-off power.