A Novel Analog Broadband RF Predistortion Circuit to Linearize Electro-Absorption Modulators in Multiband OFDM Radio-Over-Fiber Systems
A Novel Analog Broadband RF Predistortion Circuit to Linearize Electro-Absorption Modulators in Multiband OFDM Radio-Over-Fiber Systems
复制标题
DOI：
10.1109/tmtt.2010.2074530
复制
发表时间：
2010-09
影响因子：
4.3
通讯作者：
Yiming Shen;B. Hraimel;Xiupu Zhang;G. Cowan;K. Wu;Taijun Liu
中科院分区：
文献类型：
--
作者：
Yiming Shen;B. Hraimel;Xiupu Zhang;G. Cowan;K. Wu;Taijun Liu
我们提出并演示了一种新颖而简单的预失真电路，该电路使用反射反平行二极管，用于多频段正交频分复用（MB-OFDM）超宽带（UWB）光纤无线电系统中3.1至4.8 GHz超宽带信号的电吸收调制器（eam）的线性化。在这种新型预失真电路中，既不使用放大器，也不使用移相器，只使用两个反平行连接的二极管，通过调节二极管的直流偏置电流来调节预失真信号。该电路结构简单，性价比高，适用于超宽带系统。通过在EAM前增加预失真电路，在3.1-4.8 GHz频率范围内，即MB-OFDM UWB的频带组1，实现了对三阶互调失真的抑制7db以上，对无杂散动态范围的改善11db。实验结果表明，采用所设计的预失真电路，误差矢量幅度提高了1 db。
We propose and demonstrate a novel and simple predistortion circuit using reflective antiparallel diodes for linearization of electro-absorption modulators (EAMs) in multiband orthogonal frequency-division multiplexing (MB-OFDM) ultra-wideband (UWB) radio-over-fiber systems for UWB signals from 3.1 to 4.8 GHz. In this novel predistortion circuit, neither amplifiers, nor phase shifters are used, while only two antiparallel connected diodes are used, and the predistortion signal is adjusted by tuning the diodes' dc-bias current. The simple architecture makes the circuit cost effective and suitable for UWB system applications. By adding the predistortion circuit before the EAM, more than 7-dB suppression in third-order intermodulation distortion and 11-dB improvement in spurious-free dynamic range are achieved over the frequency range of 3.1-4.8 GHz, i.e., bandgroup 1 of MB-OFDM UWB. Correspondingly, 1-dB improvement in error vector magnitude is obtained experimentally when the designed predistortion circuit is used.