本文選題：寬頻帶 + 并發(fā)雙波段�。� 參考：《寧波大學》2015年碩士論文

【摘要】：隨著2013年中國移動率先實現(xiàn)TD-LTE(Time Division Long Term Evolution)的商用,我國正式進入了4G時代。語音、視頻等多媒體業(yè)務將呈現(xiàn)噴井式的增長。同時,我國的通信系統(tǒng)將呈現(xiàn)出2G、2.5G、3G以及4G多種通信標準共存的局面。多標準、多波段共存的通信模式不可避免的成為未來無線通信系統(tǒng)發(fā)展的趨勢。Doherty結(jié)構(gòu)功放電路以其針對高峰均比(PAPR)信號具有高效線性放大的特點,已經(jīng)大量的在基站中商用。然而傳統(tǒng)的Doherty結(jié)構(gòu)的工作帶寬相對較窄,無法適應現(xiàn)代多模多波段的通信需求,因此拓展傳統(tǒng)Doherty功放的工作帶寬成為亟待解決的問題。針對上述問題,本文對傳統(tǒng)Doherty功放的合路結(jié)構(gòu)進行了改進,從而拓展了其工作帶寬。本文的主要工作分為以下4個部分:第一部分對傳統(tǒng)Doherty合路結(jié)構(gòu)的頻率響應進行了研究,發(fā)現(xiàn)λ/4阻抗變換線的窄帶特性影響了其工作帶寬,提出減小λ/4阻抗變換線的阻抗變換比來拓展帶寬。第二部分首先研究了寬帶匹配結(jié)構(gòu),按照寬頻帶阻抗匹配特點仿真設計了1.7-2.7GHz寬帶功率放大器。然后采用兩段70.7歐姆λ/4阻抗變換線代替?zhèn)鹘y(tǒng)Doherty合路結(jié)構(gòu),設計了一款工作帶寬為1.85-2.65GHz的平衡式寬帶Doherty功放,實現(xiàn)整個頻帶內(nèi)在輸出功率回退5-6dB時漏極效率大于38%。第三部分首先介紹了幾種并發(fā)多波段阻抗變換網(wǎng)絡,并分析了Doherty結(jié)構(gòu)中相位補償對不同頻點實現(xiàn)最佳回退效率的影響。在上述分析的基礎上,采用并發(fā)方式對傳統(tǒng)合路結(jié)構(gòu)和補償線進行改進。設計完成了工作在2.1GHz和2.5GHz兩個頻段上的并發(fā)雙波段Doherty功放,實現(xiàn)在并發(fā)頻帶內(nèi)回退6dB時漏極效率大于33%,輸出功率大于41.5dBm。第四部分首先對可調(diào)器件和可調(diào)電路進行了研究,對PIN開關和變?nèi)荻䴓O管等可調(diào)器件進行了實際測試。在分析了補償線對寬帶Doherty結(jié)構(gòu)的影響后,結(jié)合平衡式Doherty寬帶合路特性和并發(fā)匹配特性的基礎上,對補償線進一步優(yōu)化。按照串聯(lián)接入和并聯(lián)接入兩種方式,通過PIN開關的調(diào)節(jié),設計了兩款工作在1.85-2.65GHz寬帶可調(diào)Doherty功放。通過ADS仿真驗證了上述兩種可調(diào)方式有力的提升了整個頻段內(nèi)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.
【學位授予單位】：寧波大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN722.75

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