UHF頻段低相位雜訊鎖相頻率合成器之研製

Abstract

本論文研製一個UHF頻段高穩定度,低相位雜訊以作為通訊設備和 電子儀器的訊號源,並且找出一套達成低相位雜訊頻率合成器的製作程序. 按此設計程序,吾人可得到大範圍頻率變化及低相位雜訊的輸出訊號,更可 縮短研發製作的時間. 論文中採用單迴路的設計型態,利用高穩定性 的晶體振盪器(TCXO)當作參考頻率,並且探討兩種不同共振腔的高品質壓 控振盪器之相位雜訊.一種是同軸共振腔壓控振盪器(CoxialResonator VCO),另一種是微帶線共振腔壓控振盪器(Microstrip line resonator VCO).最後所製成的鎖相頻率合成器之相位雜訊為-112dBc/Hz@20kHz.輸出 功率約為7dBm,可調頻寬為748~956MHz.另外本文亦詳細探討迴路頻寬對相 位雜訊的影響,迴路頻寬的量測以及假性諧波訊號(spurious)的抑制. All communication facilities and electronic instruments need a localsignal source with high stability and low phase noise. In this thesis, anUHF-band low phase noise phase-locked frequency synthesizer for electric instruments has been developed. The fabrication procedure of achieving thelow phase noise is figured out. Using this procedure, a synthesizer with widetunning range, low phase noise can be easily fabricated. A single loop frequency synthesizer is employed in this study. The refreence frequency is from a TCXO. Two high quality VCO's with different kind of tank circuit are intensively examined. One is designed with coxial resonator, and the other is designed with microstrip line as inductor. The typical phasenoise among fabricated synthesizers is about -112dBc/Hz at 20kHz offset and output power is about 7dBm. The tunning range of frequency is 748~956MHz which is above quarter octave. The loop parameters are also verified to be good agreement with the theoretical prediction. The technique of reducing the spurious inteference are also presented.