頻率合成器是通訊系統之發射機與接收機的重要核心，而為了提高LTE OFDMA/SCFDMA之傳輸效益，本論文分別針對頻率合成器之相位雜訊貢獻進行分析與討論，但可以發現為了滿足頻率解析度以及鎖定時間之需求，使得除頻器除值必須變大，可是這樣會造成除頻器的相位雜訊也跟著被放大，所以為了抑制除頻器的相位雜訊，所以必須將迴路濾波器的頻寬縮小，但是這樣又會使得抑制電壓控制振盪器的相位雜訊能力變差，且系統鎖定時間變慢，為了改善這情況，是本論文之研究重點，最後再將頻率合成器之相位雜訊透過MTALAB與LTE OFDMA/SCFDMA訊號結合，並且進行模擬觀察頻率合成器之相位雜訊對於LTE OFDMA/SCFDMA訊號品質的影響性。;The frequency synthesizer is critical to the functions of transmitter and receiver in the communication system. Present study investigated the contribution of frequency synthesizer phase noise to improve the transporting performance efficiency of LTE OFDMA/SCFDMA. Optimization of the frequency resolution and locked time conditions leads to the frequency divider value and phase noise of frequency divider increased. To suppress the phase noise of frequency divider, bandwidth of the loop filter must be reduced. However, reduced bandwidth increased phase noise of voltage controlled oscillator and slowed the locked time of the system. To improve the performance, we combine phase noise of the frequency synthesizer with LTE OFDMA/SCFDMA signal using MATLAB. The effects of frequency synthesizer phase noise to LTE OFDMA/SCFDMA signal quality were simulated and analyzed.
