Research On Reconfigurable Outphasing RF Power Amplifiers

At present,peak-to-average power ratio(PAPR)of RF signals in mobile communication systems is getting higher and higher.Complex modulated signals have been difficult to be efficiently amplified by single transistors.To this end,a series of load-modulated power amplifier structures composed of multiple transistors are proposed,among which the Outphasing power amplifier(OPA)is one of the current hotspots of academic research.However,Transmission line structures are often applied in classical OPA structures,and the dispersion effect of the transmission line will lead to the power amplifier to only achieve good performance in a small frequency range(bandwidth),which greatly limits the application range of the OPA.In recent years,there is an increasing shortage of continuously available frequency resources due to the application of various communication systems.In this context,the transmission bandwidth improvement technology represented by carrier aggregation is gradually becoming popular,requiring communication systems to support cross-frequency and wide-band work.At the same time,The researchers began to apply reconfigurable technology to various mobile communication circuits to realize wireless mobile communication systems that can support multi-frequency and multi-standard,operating conditions,and the research related to reconfigurable power amplifier is also increasing year by year.This paper is devoted to studying the bandwidth enhancement technology of OPA,focusing on the reconfigurable and extension of working frequency by applying reconfigurable technology to Outphasing power combiner.The main innovative work of this paper is as follows:The working principle and basic structure of OPA are briefly introduced.The load modulation theory of OPA is derived by mathematical formula.On this basis,different kinds of Outphasing power combiner are studied.In addition,some common reconfigurable technologies are also introduced.The working principle and bandwidth characteristics of non-commensurate transmission line combiner are systematically analyzed.The reason of bandwidth limitation is explained by dispersion analysis of transmission line.In order to improve the dispersion effect of the transmission line,this paper proposes to replace the transmission line with a T-type structure,and deduces the equivalent parameters of the T-type structure innovatively.On this basis,the reconfigurable T-type structure design theory is proposed to replace the non-commensurate transmission line structure.Finally,a wideband reconfigurable OPA operating from 2.4 to 2.8 GHz is designed and implemented based on this theory.MMIC process is introduced comprehensively.A dual-band reconfigurable OPA that can switch between X band and Ku band is designed based on the theory of reconfigurable T-type structure.The reconfigurable T-type structure is implemented with active switches.The capacitance of the access Ttype structure is changed by controlling the gate voltage of the switch,and this design ultimately realizes two frequency switching operations at 10 GHz and 15 GHz.