Research On Efficiency Improvement And Miniaturization Of Microwave Power Amplifier

With the rapid development of wireless communication technology,the performances of key components determine that of a wireless transmission system.As one of the key components,power amplifier is located at the end of wireless transmission system,and plays the role of amplifying the input power to a certain level and then feeding it into antenna.Its performance and size have an important impact on the whole system performance.In this thesis,an in-depth research on the miniaturization and multi-component fusion design of power amplifiers was made.The main work of this thesis includes the following several aspects.1.A new type of Filtering Power Amplifier(FPA)is proposed.Conventional conception that power amplifier and filter are regarded as two separate components and designed separately.In order to further optimize the overall performance and reduce the size of the component,this thesis proposes a new kind of the FPA.The output matching network of the FPA adopts a specific topology structure and its physical mechanism is revealed through the lumped parameter equivalent circuit.In the design process,multiple harmonic iterative pull methods are used to determine its optimal source and load impedance values.With high efficiency being obtained,the proposed FPA is also featured by the excellent performance such as good frequency selectivity and suppression of up to the 4th harmonic.Both the simulation and measurement results show that the FPA is superior to those similar components in other literatures at home and abroad in terms of efficiency,bandwidth and harmonic suppression capabilities.2.A new Filtering Doherty Power Amplifier(FDPA)is proposed.Conventional Doherty power amplifier uses a Wilkinson power divider to distribute the input signal.In order to effectively purify the frequency spectrum of the input signal,this thesis proposes a new type of filtering power divider with harmonic suppression capability and applies it to the conventional Doherty power amplifier.The physical mechanism of the filtering power divider is revealed through the lumped parameter equivalent circuit,and this method is effectively applied to the design process.According to the above design method,a FDPA operating at 2 GHz was fabricated and tested.Compared with similar components reported in the literature at home and abroad,the proposed FDPA maintains high back-off efficiency and back-off power,and also has the advantages of the wideband bandwidth of 300 MHz and the good out-of-band suppression up to 4th harmonic.