A thorough investigation of major contributors to out-of-band emission (OOBE) in transmitters (TXs) utilizing digital modulation schemes is provided. Specifically, the paper delves into the detrimental effects of phase noise of the local oscillator (LO), typically realized using a phase-locked loop (PLL), on the OOBE phenomenon. Furthermore, the effects of the circuit nonlinearity in a TX, widely recognized as a primary contributor to spectral regrowth and elevated levels of OOBE, are investigated. Additionally, the impact of filtering and bandwidth (BW) limitation on OOBE is taken into account. Comprehensive simulations verify the accuracy of the analytical study. The results provided throughout this paper can be used to determine the linearity and phase noise requirements of different blocks, such as PLL and power amplifier (PA) within a TX chain to design a system complying with a specific mask emission dictated by a particular standard.

中文翻译：

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PLL 相位噪声、电路非线性和带宽限制导致的数字发射机带外发射的研究

对利用数字调制方案的发射机 (TX) 中带外发射 (OOBE) 的主要影响因素进行了全面调查。具体来说，本文深入研究了通常使用锁相环 (PLL) 实现的本地振荡器 (LO) 相位噪声对 OOBE 现象的不利影响。此外，还研究了 TX 中电路非线性的影响，该影响被广泛认为是频谱再生和 OOBE 水平升高的主要因素。此外，还考虑了过滤和带宽 (BW) 限制对 OOBE 的影响。综合模拟验证了分析研究的准确性。本文提供的结果可用于确定不同模块（例如 TX 链内的 PLL 和功率放大器 (PA)）的线性度和相位噪声要求，以设计符合特定标准规定的特定掩模发射的系统。