【作者】 陈新民；

【导师】 宋开宏；

【作者基本信息】 安徽大学 ， 电磁场与微波技术， 2011， 硕士

【摘要】 随着现代无线通信技术的发展,通信产品已经广泛的融入了人们的生活中,对人们的影响也越来越大。射频功率放大器作为无线通信系统中主要能耗器件之一,其性能对系统终端的影响越来越受到重视。无线通信系统的标准由传统的GSM标准向第三代通信标准WCDMA.TD-SCDMA.CDMA2000转变,以及今后的第四代通信标准LTE(Long Term Evaluation),信号的调制方式也随之发生改变,由恒包络调制向包络变换调制方式转变。例如,在WCDMA中采用的OFDM包络变换调制方式,其传输功率有着较高的均峰比,来满足最大限度的增加系统的容量,因此在保证线性度的前提下则需要功率放大器能够在一定的功率回退中实现。但是传统的功率放大器在功率回退范围内的效率很低,因此,提高基站中功率放大器在功率回退中的效率变得尤为重要。提高效率的方法有很多,Doherty功率放大器技术结构简单,性价比高等优势,成为基站功率放大器研究的热点。本文详细介绍了功率放大器的基本理论知识,重点介绍了Doherty功率放大器技术的基本原理和Doherty功率放大器工作状态分析以及非对称结构和多路结构Doherty功率放大器的原理。并且详细介绍了Doherty功率放大器的设计过程,分析了补偿线和辅助功率放大器偏置电压对Doherty功率放大器的性能的影响。设计利用ADS仿真软件平台以及Freescale公司的MRF6S21140H的LDMOS器件模型设计仿真了WCDMA频段的Doherty功率放大器。通过与平衡式AB类功率放大器比较,得出Doherty功放在功率附加效率上的提高。为了弥补传统Doherty功率放大器存在的缺陷,设计了采用不等分输入功率结构的非对称Doherty功率放大器,使得Doherty功放的线性度和输出功率得到改善.更多还原

【Abstract】 With the development of current wireless communication technology, the products of wireless communication have been widely appeared and the effects are getting more and more important in people’s life. As a main of energy consumption device in wireless communication system, the performance of RF power amplifier is getting more and more attention impacted on the terminal system. The standard of wireless communication system has been changed form the traditional standard of GSM to 3G standard of WCDMA、TD-SCDMA. CDMA2000,as well as to the future 4G standard of LTE(Long Term Evaluation).The mode of signal modulation also has been changed form constant-envelope signals to envelope-varying signals. For instance, the transmit powers of wireless communication system which using OFDM on WCDMA carried high peak-to-average power ratio signals, so that signals can be strength to maximize system capacity. Owing to such a system requirement, it is common for power amplifiers operating at output power back-off from peak power under keeping linearity. Unfortunately, the consequence of this requirement is that the traditional power amplifier which operating in regions of back-off from peak power has low efficiency. So it is very important for power amplifier in base station that to enhance higher efficiencies at back-off power in these applications. The way to enhance efficiency is not just a few. Owing to such advantage as simply structure and high performance-to-price ratio, the Doherty power amplifier technology becomes hotspot at base station.This dissertation describes the basic theoretical knowledge of power amplifier and focused on the basic principle and working condition analysis of Doherty power amplifier as well as the principle of asymmetric Doherty amplifier and N series Doherty amplifier. Also the design progress of Doherty power amplifier is described and the offset lines & the bias voltage of peak power amplifier impacted on the performance of Doherty power amplifier are analyzed. This design uses the RF simulation software ADS and combined with the LDMOS, model MRF6S21140H from Freescale Company, the Doherty power amplifier in WCDMA band was designed. The simulation results are presented to demonstrate the Doherty power amplifier advantage in power added efficiency by comparing with the balanced class AB amplifier. In order to remedy the drawback of traditional Doherty amplifier, I design asymmetric Doherty amplifier with inequality input power structure which making the linearity and output power of Doherty amplifier improved.更多还原