| Switching RF power amplifier is an essential part in current mobile communications systems and the basis of low energy consumption,green operation and broadband highspeed operation,for its higher efficiency and better broadband potential.In terms of design methods,for the same technical indicators,there are several methods can be choosed in design.However,the circuit and the performance will be different with different design methods applied,therefore the optimal method cannot be determinated.Take all these factors mentioned into account,a new method by constructing ideal output voltage and current waveforms is proposed in this thesis to enhance efficiency for switching RF power amplifier.Firstly,the design methods of switching RF power amplifier,such as class-E,classF and class-J,are compared and discussed in respect of output waveforms,then the characteristics of high efficiency waveforms are studied.Secondly,the factors affecting the output waveforms are analysed and the optimal waveforms are deduced based on waveforms without any match circuits,consequently,the method to construct the optimal waveforms is proposed.Finally,comparison between this new proposed method with other methods is carried out to verify the effectiveness of the optimal waveforms.As examples of application of this new proposed method,simulations with related experimental verifications of single-band are completed in this thesis.The specific contents of this thesis are as follows: 1.Different design methods of switching RF power amplifiers such as class-E,class-F and class-J are studied in terms of waveforms.Various output waveforms of switching power amplifiers are analysed in frequency domain.The relationship between impedance control conditions and waveforms is studied.The differences,advantages and disadvantages of waveforms are compared and analysed,and the basic points of high efficiency power amplifier design are summarized.2.The factors affecting the output waveform are studied from three aspects: static operating point of power amplifier,parasitic effect of transistor and matching network.The shortcomings of current waveform design of switching RF power amplifier are analysed,and a new design idea based on high efficiency waveform is proposed.3.The characteristics of output waveforms of power amplifier without any match circuits are analysed,and the optimal solution of high efficiency waveforms is deduced.Then the design method of reducing DC component of current waveform and flattening voltage waveform is proposed to realize high efficiency waveforms.Based on this method,a high efficiency power amplifier working at 2.4 GHz is designed,which is compared with the one designed by other methods under the same working conditions.Finally,the construction process of the optimal waveforms is summarised in detail.4.The waveform-based design method is applied to broadband applications.A broadband power amplifier working at 1.5GHz-2.5GHz is designed,the measured results show that the powered-added efficiency in the frequency band is 65-73% and the gain varies between 9.9d B-11 d B with the input signal of 30 d Bm.The work conducted in this thesis has reference values for switching RF power amplifier research and engineering design. |
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