Investigating the linearity versus efficiency trade-off of different power amplifier modes in an envelope tracking architecture
Investigating the linearity versus efficiency trade-off of different power amplifier modes in an envelope tracking architecture
复制标题
研究包络跟踪架构中不同功率放大器模式的线性与效率权衡
DOI：
10.1109/eumic.2015.7345143
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
C. Cassan
中科院分区：
文献类型：
--
作者：
Z. Mokhti;J. Lees;P. Tasker;C. Cassan
包络跟踪（ET）功率放大器通过响应于输入包络信号幅度调制电源电压来实现动态范围内的宽带效率。整形函数将输入包络幅度与动态电源电压相关联，并且可以被定义为不仅在效率和功率方面而且在线性度方面实现最佳性能。使用有源谐波负载牵引测量系统，本文探讨了线性度和效率之间的权衡方面的固有电流和电压的行为在仿真ET环境中，并确定由不同的包络整形函数。分析比较了传统的AB类和高效率的F类模式在ET架构中的行为，使用50 V的LDMOS器件。在900MHz的实验结果表明，只有二阶项的简单成形函数能够产生的基本输出电流和输入电压包络之间的线性关系。在F类的情况下，这是在保持高效率的同时实现的，并且因此提高了使用ET架构来降低所需线性化器复杂性的有吸引力的前景，所述线性化器复杂性是小小区基站功率放大器（PA）设计中的重要因素。
Envelope tracking (ET) power amplifiers achieve wideband efficiency over dynamic range by modulating supply voltage in response to the input envelope signal magnitude. Shaping functions relate input envelope magnitude to dynamic supply voltage and can be defined to achieve optimum performance in terms of not only efficiency and power, but also linearity. Using an active harmonic load-pull measurement system, this paper explores the trade-off between linearity and efficiency in terms of the intrinsic current and voltage behavior within an emulated ET environment, and as determined by different envelope shaping functions. The analysis compares the behavior of conventional class-AB and high-efficiency class-F modes in an ET architecture, using a 50V LDMOS device. Experimental results at 900MHz show that simple shaping functions with only second order terms are able to generate linear relationships between the fundamental output current and input voltage envelopes. In the case of class-F, this is achieved while maintaining high-efficiency, and thus raises the attractive prospect of using an ET architecture to reduce required linearizer complexity - an important factor in small-cell base station power amplifier (PA) design.