Radio-over-fiber (RoF)-based front haul architecture has attracted considerable attention for fifth-generation (5G) cellular systems because of its cost effectiveness, however, it is susceptible to harmonic frequency distortion and intermodulation products (IMs) arising from the nonlinearity of the laser diode. To overcome this limitation, an asymmetric electrical predistortion method, using a single Schottky diode with nonlinear characteristics similar to those of a laser diode, was previously proposed. However, its asymmetric structure causes a phase mismatch, which limits the system bandwidth. In this study, we propose an enhanced electrical predistortion technique using dual-parallel Schottky diode blocks. The proposed technique was validated by experiments involving an IM3 drop of approximately 27 dB, and by using identical dual Schottky diode blocks, the phase mismatch in the previously proposed method is completely eliminated. Thus, the applicable bandwidth is extended to 1.8 GHz. This technique can be used to improve the linearity and increase the bandwidth of RoF systems. Additionally, the simple structure is attractive for low-power applications.

中文翻译：

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用于低功率 RoF 系统的双并联肖特基二极管宽带预失真技术


基于光纤无线电 (RoF) 的前传架构因其成本效益而引起了第五代 (5G) 蜂窝系统的广泛关注，但它容易受到谐波频率失真和互调产物 (IM) 的影响。激光二极管的非线性。为了克服这一限制，先前提出了一种非对称电预失真方法，该方法使用具有与激光二极管类似的非线性特性的单个肖特基二极管。然而，其不对称结构会导致相位失配，从而限制了系统带宽。在这项研究中，我们提出了一种使用双并联肖特基二极管块的增强型电预失真技术。所提出的技术通过涉及约 27 dB 的 IM3 压降的实验进行了验证，并且通过使用相同的双肖特基二极管块，完全消除了先前提出的方法中的相位失配。因此，适用带宽扩展到1.8 GHz。该技术可用于改善 RoF 系统的线性度并增加带宽。此外，简单的结构对于低功耗应用也很有吸引力。