| With the rapid development of wireless communication,more and more communication standards and frequency bands have been proposed.Power amplifier plays an important role in communication systems.And the study of power amplifier compatible with various communication frequency bands has become a hot topic.However,the reconfigurable multiband amplifier based on PIN-diodes can be compatible with different communication frequency bands.In addition,along with the unceasing enhancement of information transmission rate,complex modulated signals with high peak-average-power ratio have been widely used.Therefore,more and more high efficiency power amplifier is required,and the variable load power amplifier based on varactor diode is widely concerned in academic circles for improving the average efficiency of power amplifier.In accordance with the above background,the reconfigurable multiband power amplifier and variable load power amplifier will be studied respectively in this thesis,it includes the following three parts:Firstly,this thesis analyzes the basic characteristics of reconfigurable devices(varactor diode,PIN diode)in detail,and this thesis analyzes and compares the basic characteristics of the traditional fixed matching network and the variable matching network based on reconfigurable devices.According to the above analysis,the variable matching networks are designed: L-type and hybrid dynamic-impedance matching networks operating in 2.5GHz are designed using varactor diodes,and a reconfigurable switch operating in 1.96 GHz is designed using PIN diode.Secondly,this thesis analyzes the reason of low average efficiency of traditional power amplifier and the relationship between efficiency of power amplifier and optimal impedance.In addition,this thesis expounds the basic characteristics of dynamic-impedance matching network of variable load power amplifier by mathematical derivation.Based on the dynamic-impedance matching network,a 3.5GHz variable load power amplifier is designed,which has a saturated output power of 33 dBm and a 4dB back-off efficiency of 40%.Finally,this thesis analyzes and deduces the basic characteristics of dual-band matching network,and a dual-band power amplifier operating in 1.72 GHz and 3.48 GHz is designed based on the dual-band matching network,which has a saturated output greater than 40 dBm and a saturated efficiency over 67%.Besides,this thesis describes how to design the reconfigurable radio frequency switch based on PIN diodes.According to the structure of the dual-band matching network,this thesis proposed a reconfigurable dual-band matching network.Based on the proposed reconfigurable dual-band matching network,a reconfigurable dual-band power amplifier operating in 1.6GHz,2.1GHz,1.8GHz and 2.3GHz is designed,which has a saturation output power greater than 40 dBm and a 60% saturation drain efficiency,and the gaol of compatible with different communication frequency band is achieved. |
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