Doherty power amplifier with dynamic load modulation for wireless communications

초록

In this article, Doherty power amplifier (DPA) with dynamic load modulation (DLM) is proposed for wireless communications with high peak-to-average ratio (PAR) signals. The proposed DPA with DLM operates as a conventional DPA from peak to 6-dB back-off powers, and DLM starts to operate at lower power than 6-dB back-off. The DPA with DLM was designed using 6-W GaN high mobility transistors (HEMTs) at 1.85 GHz. The fabricated DPA with DLM shows a power-added efficiency (PAE) of 44.7% at 10-dB back-off power of continuous-wave input signal, which is 5% higher than that without DLM. Dynamic measurement was also carried out using 3.84 MHz W-CDMA signal with 7.4 dB PAR. The measurement of the DPA with DLM exhibits an average PAE of 32.1% at output power of 27.1 dBm, and adjacent channel leakage ratio (ACLR) of -45.1 dBc, which corresponds to 6.1% improvement in PAE compared with the DPA without DLM.

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