A single chip multiband power amplifier using active load modulation techniques

This paper presents a single chip multiband power amplifier (MBPA) using a proposed active load modulation (ALM) technique. Based on Doherty PA´s concept, the single chip MBPA consists of a main amplifier, an auxiliary amplifier, and transmission lines connecting two amplifiers to modulate the main amplifier´s load line over the frequency. The ALM technique achieves the desired load line at specific frequency band by three parameters; RF current ratio of the main amplifier to the auxiliary amplifier (α), a characteristic impedance (ZT) and an electrical length (θ) of a transmission line. The fabricated single chip MBPA operates from 1.6 to 2 GHz with over a 10 dB of gain using the proposed ALM technique. It shows 35.5 % of power added efficiency (PAE), and 25.5 dBc of adjacent channel leakage ratio (ACLR1) at 27 dBm output power with the 10 MHz BW 16QAM LTE signal from 1.6GHz to 2GHz.