| With the rapid development of wireless communication technology,the new generation of wireless communication systems needs to be compatible with different wireless communication standards such as 2G,3G,4G,etc.,resulting in numerous and sparse operating frequency passbands.Therefore,dual-band power amplifiers that support multi-band operation have become the domestic and international research hotspot.At the same time,as the highest energy consumption in transmitters,improving the efficiency of power amplifiers is significant for energy conservation and emission reduction.This paper focuses on controllable bandwidth and efficiency improvement methods for dual band power amplifiers.The main content and innovative work are as follows:(1)The structure and design method of asymmetric dual-band impedance matching network are presented.The bandwidth of two working frequency bands can be controlled through the parameter to realize the "one wide and one narrow" bandwidth.And the design equations are deduced in detail.Based on this structure,a dual-band power amplifier with asymmetric bandwidth is designed.The measurement results show that drain efficiency is greater than 60%at 2.35-2.75 GHz and 3.1-3.35 GHz and the bandwidth is 15.7%(400MHz)and 7.7%(250MHz)at low band and high band respectively.The relative bandwidth ratio of two passbands is 2.03.(2)The structure of a dual-band impedance matching network with controllable bandwidth ratio is proposed.By combining algorithm and analysis,the bandwidth of the wide passband is controlled through increasing the number of matching points to achieving controllable bandwidth ratio of two passbands.Based on this structure,a dual-band power amplifier with controllable bandwidth ratio is designed.The measurement results show that the saturated output power is 40.7-42.1 dBm and 40.7-41.8dBm,drain efficiency is 58-66%and 61-73%,relative bandwidth is 26.9%and 5.8%in 2.25-2.95GHz and 3.35-3.55GHz,respectively.The relative bandwidth ratio of two passbands is up to 4.64.(3)Based on the impedance design space of hybrid continuous amplifiers,a high efficiency and large back-off dual-band Doherty power amplifier is designed.The measurement results show that the saturated output power is 45.6-45.9dBm and 44.7-45.3dBm,drain efficiency is 6469%and 59-66%,drain efficiency of 8 dB output power back-off is 46.660%and 43-48%in 2.5-2.7GHz and 3.3-3.5GHz,respectively.The proposed Doherty power amplifier achieves high efficiency in the 8 dB back-off range with bandwidth of 200 MHz in each of the two passbands.In this paper,three dual-band power amplifiers achieve high efficiency and controllable bandwidth ratio.which can effectively meet the multi-frequency requirements of wireless communication systems. |
