RF Power Amplifiers for Emerging Wireless Communications: Single Branch Vs. Multi-Branch Architectures

This paper proposes an experimental study of the architectures of the high power amplification stage and their influences on the system´s linearity and power efficiency with application to wireless communication infrastructures. Two architectures are investigated: the single branch power amplification stage using class A/B power amplifiers and the promising multi-branch architecture using dynamic load modulation techniques such as the Doherty amplifier. Two LDMOS based high power amplifiers line-ups operating around 2.14 GHz were designed. In order to improve their efficiency vs. linearity trade-off, a predistortion based linearization technique has been applied to the both studied amplification stages. Measurement results under multi-carriers W-CDMA signals confirm the promising potential of the multi-branch approach. Indeed, the multi-branch architecture greatly improves the power efficiency of the amplification stage while maintaining good linearity performances