Efficient Doherty Feed-forward Linear Power Amplifier for CDMA 2000 Base-Station Applications

This paper presents a design of high RF power amplifier using Doherty technique. The objective of this design is to improve the efficiency of a 40-W feed-forward linear power amplifier typically used in code division multiple access (CDMA) base-station applications. The proposed design uses two identical LDMOS FETs, one of which is biased in class AB mode for carrier amplifier and the other is biased in class B mode for peak amplifier. Simulation results with single carrier CDMA signal show S.47 % improvement in efficiency for the proposed design in comparison to a conventional class AB configuration. Both, the proposed design as well as the conventional design use feed-forward technique to meet the ACPR requirement at 40-W output power.