宽带可调高效射频功放技术研究

发布时间：2018-05-01 01:02

本文选题：宽频带 + 并发双波段　；参考：《宁波大学》2015年硕士论文

【摘要】：随着2013年中国移动率先实现TD-LTE(Time Division Long Term Evolution)的商用,我国正式进入了4G时代。语音、视频等多媒体业务将呈现喷井式的增长。同时,我国的通信系统将呈现出2G、2.5G、3G以及4G多种通信标准共存的局面。多标准、多波段共存的通信模式不可避免的成为未来无线通信系统发展的趋势。Doherty结构功放电路以其针对高峰均比(PAPR)信号具有高效线性放大的特点,已经大量的在基站中商用。然而传统的Doherty结构的工作带宽相对较窄,无法适应现代多模多波段的通信需求,因此拓展传统Doherty功放的工作带宽成为亟待解决的问题。针对上述问题,本文对传统Doherty功放的合路结构进行了改进,从而拓展了其工作带宽。本文的主要工作分为以下4个部分:第一部分对传统Doherty合路结构的频率响应进行了研究,发现λ/4阻抗变换线的窄带特性影响了其工作带宽,提出减小λ/4阻抗变换线的阻抗变换比来拓展带宽。第二部分首先研究了宽带匹配结构,按照宽频带阻抗匹配特点仿真设计了1.7-2.7GHz宽带功率放大器。然后采用两段70.7欧姆λ/4阻抗变换线代替传统Doherty合路结构,设计了一款工作带宽为1.85-2.65GHz的平衡式宽带Doherty功放,实现整个频带内在输出功率回退5-6dB时漏极效率大于38%。第三部分首先介绍了几种并发多波段阻抗变换网络,并分析了Doherty结构中相位补偿对不同频点实现最佳回退效率的影响。在上述分析的基础上,采用并发方式对传统合路结构和补偿线进行改进。设计完成了工作在2.1GHz和2.5GHz两个频段上的并发双波段Doherty功放,实现在并发频带内回退6dB时漏极效率大于33%,输出功率大于41.5dBm。第四部分首先对可调器件和可调电路进行了研究,对PIN开关和变容二极管等可调器件进行了实际测试。在分析了补偿线对宽带Doherty结构的影响后,结合平衡式Doherty宽带合路特性和并发匹配特性的基础上,对补偿线进一步优化。按照串联接入和并联接入两种方式,通过PIN开关的调节,设计了两款工作在1.85-2.65GHz宽带可调Doherty功放。通过ADS仿真验证了上述两种可调方式有力的提升了整个频段内的回退效率。
[Abstract]:China Mobile entered the 4G era with the first commercial implementation of TD-LTE(Time Division Long Term Evolution in 2013. Voice, video and other multimedia services will present a spurt-like growth. At the same time, the communication system of our country will present the coexistence of 3G and 4G communication standards. Multi-standard, multi-band coexisting communication mode will inevitably become the trend of wireless communication system in the future. Doherty structure power amplifier circuit has been widely used in base stations because of its high efficiency linear amplification for peak-to-average ratio (PAPR) signals. However, the traditional Doherty structure has relatively narrow bandwidth, which can not meet the needs of modern multi-mode and multi-band communication. Therefore, expanding the working bandwidth of traditional Doherty power amplifier becomes an urgent problem to be solved. In view of the above problems, this paper improves the combined circuit structure of traditional Doherty power amplifier, thus expanding its working bandwidth. The main work of this paper is as follows: in the first part, the frequency response of the traditional Doherty structure is studied. It is found that the narrow band characteristic of the 位 / 4 impedance transform line affects its bandwidth. In order to expand the bandwidth, the impedance conversion ratio of 位 / 4 impedance transformation line is reduced. In the second part, the broadband matching structure is studied, and the 1.7-2.7GHz wideband power amplifier is designed according to the characteristics of broadband impedance matching. Then, two sections of 70.7 ohm 位 / 4 impedance transformation line are used to replace the traditional Doherty circuit structure, and a balanced broadband Doherty power amplifier with working bandwidth of 1.85-2.65GHz is designed. The drain efficiency is greater than 38 when the output power of the whole band is retreated from 5-6dB. In the third part, several kinds of concurrent multi-band impedance transform networks are introduced, and the effect of phase compensation on the optimal fallback efficiency at different frequency points in Doherty structure is analyzed. Based on the above analysis, the concurrency method is used to improve the traditional circuit structure and compensation line. The concurrent dual-band Doherty power amplifier working in the 2.1GHz and 2.5GHz bands is designed and completed. The drain efficiency is greater than 33dBm and the output power is more than 41.5 dBm. when the 6dB is retreated in the concurrent band. In the fourth part, tunable devices and tunable circuits are studied, and the tunable devices such as PIN switches and varactor diodes are tested. After analyzing the influence of compensation line on broadband Doherty structure and combining the characteristics of balanced Doherty broadband path and concurrent matching, the compensation line is further optimized. According to the two ways of series access and parallel access, two kinds of adjustable Doherty power amplifier working in 1.85-2.65GHz broadband are designed by adjusting the PIN switch. The results of ADS simulation show that the two adjustable methods can improve the recoil efficiency in the whole frequency band.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN722.75

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