| Power amplifiers(PAs)play an essential role in advanced mobile communication systems.For example,5G requires efficient processing of wideband signals and high peak-to-average power ratio(PAPR)signals which are characterized by high data rates,low latency and large capacity.Therefore,the development of high-efficiency ultrawideband PAs is important,as it allows for system simplification and complexity reduction.Besides,the dual-band or multi-band PAs can be utilized to optimize the performance for working bands.PAs with a larger output back-off(OBO)range can handle high PAPR signals.These technical demands have created an urgent requirement for PAs.In this thesis,two novel design methods are proposed for PAs.Firstly,the input nonlinearity factor is introduced to alleviate the limitation caused by the overlap of the fundamental and the harmonic bands in ultra-wideband PAs.Secondly,based on the noninfinite peaking impedance and complex load impedance,a design method is proposed for dual-band OBO-extended Doherty PAs with arbitrary frequency ratio.The main contents and innovations of this thesis are as follows:1.A design method is proposed for ultra-wideband PAs based on the extended continuous class-GF(E-CCGF)mode.The limited bandwidth in the design of ultrawideband PAs is caused by the overlap between the fundamental and harmonic bands.To alleviate this limitation,a detailed analysis of the input nonlinearity effect of transistors is conducted.As the analysis shows,the input nonlinearity factor γ plays a crucial role in the second harmonic impedance design space of the extended continuous class-F mode,which allows for the overlap between the fundamental and the second harmonic impedance design space.Based on this finding,the E-CCGF mode is proposed,and an ultra-wideband PA design method based on it is presented.To validate the effectiveness of this method,an ultra-wideband PA example working at 0.4～4.3 GHz was designed and fabricated.Both the simulation and measurement results show that this example achieves good efficiency and gain simultaneously.2.A design method is proposed for dual-band OBO-extended Doherty PAs with arbitrary frequency ratio.Traditionally,dual-band Doherty PAs utilize dual-band λ/4impedance transformation lines limited to fixed frequency ratios with OBO of only 6 d B.In this thesis,the load condition is derived for the carrier PA operating in the continuous B/J mode at any OBO level,and then a design method is proposed for dual-band OBOextended Doherty PA based on noninfinite peaking impedance.A 9-d B-OBO Doherty PA example working at 0.7 GHz and 2.6 GHz was designed for verification.However,this method is limited to dual-band Doherty PAs with fixed frequency ratios.To realize arbitrary frequency ratios,a complex load impedance is introduced,and an improved design method is proposed for dual-band OBO-extended Doherty PA with arbitrary frequency ratios.A 9-d B-OBO Doherty PA example operating at 0.7 GHz and 3.6 GHz was designed and fabricated for verification.Both dual-band Doherty PA examples exhibit a large frequency ratio while maintaining high efficiency within the 9-d B-OBO range. |
