高效率暨高線性度發射機設計

A High Efficiency and High Linearity Transmitter Design

張豐麟(Feng-Lin Zhang)

指導教授 ： 李健榮

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00114

摘要

傳統線性發射機具有高線性度但效率低的特性，當輸入為具有高峰值對平均功率比(Peak-to-Average Power Ratio, PAPR)的非固定波包調制訊號時，線性發射機需要採用功率倒退的方式以維持訊號品質，但同時也將導致功率轉換效率的下降。有別於線性發射機架構，波包追隨式發射機的功率放大器供應電源電壓與調制訊號波包之間呈現正比關係以降低功率放大器的直流功率消耗，進而提升轉換效率。本論文實現了一個頻率為2.4 GHz之波包追隨式發射機，主要電路包含線性AB類的射頻功率放大器、波包放大器以及基頻數位處理器。在波包路徑上，傳統的波包消除與回復架構是利用波包檢測器取得調變訊號的波包之後，再經由波包放大器將波包放大。本論文的波包產生方式與一般極座標發射機架構相同，使用數位訊號處理的方式將 訊號經由CORDIC轉換來產生波包。波包放大器是由Buck切換式直流對直流轉換器、比較器以及寬頻線性操作放大器所組成的，亦稱為分頻波包放大器，分頻的方法可以減緩傳統架構對直流轉換器切換速度的要求。

關鍵字

波包追隨式發射機 ； AB類功率放大器 ； 分頻波包放大器

並列摘要

The conventional linear transmitter possesses the characteristic of trading the efficiency for linearity. When a non-constant envelope modulated signal with a high peak-to-average power ratio (PARR) goes into the transmitter, the transmitter has to request the power amplifier (PA) of power backing-off to keep the signal quality from degradation. In this scenario, the power back-off is going to decrease the PA efficiency for the linearity. In contrast to the linear transmitter, the envelope following transmitter is supplied by a voltage source that has a regulated output voltage proportional to the amplitude of the input RF signal, and consequently increases the conversion efficiency while reduces the dc power consumption of the PA. This work has implemented a 2.4 GHz envelope following transmitter built by a linear class-AB PA, an envelope amplifier, and a baseband digital processor. The split-band technique of the envelope amplifier was applied in this work to avoid the dc-to-dc converter from high-speed switching, and this makes the envelope following transmitter more attractive to the wide-band applications.

並列關鍵字

Envelope following transmitter ； Class AB power amplifier ； Split band envelope amplifier

參考文獻

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