A 400 W 2-way asymmetrical doherty PA with 50% efficiency based on second-generation airfastTM LDMOS technology

This paper reports the first high power LDMOS amplifier solution which breaks the 50% drain efficiency barrier at 8 dB output back-off (OBO) for 2.1 GHz cellular application. Targeted for fourth-generation (4G) LTE communication systems, the work seeks to achieve high average efficiency when used with OFDM or other high peak-to-average ratio (PAR) digitally modulated signals. A power transistor, the A2T21H360, is designed specifically for Doherty architecture using Freescale second-generation Airfast^TM semiconductor technology. Developed concurrently with the transistor to achieve optimal performance, the 2- way asymmetrical minimum-phase Doherty PA is designed for 2110-2170 MHz band delivering 400 W peak and 50% power added efficiency (PAE) @ 8 dB OBO.