- 學位論文
2.45 GHz 被動與主動混頻器之設計
Design of 2.45 GHz Passive and Active Mixers
摘要
本論文主要討論混頻器的分析與設計，首先介紹兩種平衡式混頻器，分別 為偏壓二極體平衡式混頻器和零偏壓二極體平衡式混頻器，將二極體偏壓主要 目的是為了增加轉換效率，而最佳的偏壓點也在文中一併討論，將二極體偏壓 於IV 特性曲線最非線性的區域可以得到最大的轉換增益。 第二部分主要討論主動混頻器的分析與設計，轉換增益是主動混頻器最大 的優點，偏壓電的選擇和二極體電路相同，也是將HBT 偏壓於特性曲線最非線 性的區域得到最大的轉換效率，另外穩定度也是主動混頻器討論的重點之ㄧ， 較大的本地振盪器功率位準會使得電路不穩定，因此主動混頻器必須使用於較 低的功率位準系統之中。 第三部份主要介紹SAW 振盪器的分析與設計，SAW 諧振器利用高Q 值的 特性幫助振盪器改善相位雜訊並且穩定振盪頻率，文中也萃取SAW 諧振器的非 線性等效模型，模擬時更能掌握其諧振器特性，文中證明考畢子振盪器在SAWR 的幫助之下振盪頻率更為穩定。 最後一個部份主要介紹三倍頻器的設計，文中證明倍頻器的偏壓區域和混 頻器相同，負載效應也是探討的重點之ㄧ，最後一個部份是利用振盪器和混頻 器組成的穩定振盪源驗證混頻器的特性。
並列摘要
This thesis is to investigate into design of mixer. At first, two types of balanced mixer were design. One is a balanced mixer using biased diode and another is a zero-bias diode balanced mixer. Conversion Gain was raised by biased Schottky diode and the optimum bias point was also discussed. Maximum conversion efficiency can be obtain by biased the most nonlinear region of the IV characteristic curve of diode. Second, Active mixer with SGA-8343 HBT were designed. Active Mixer was also biased the most nonlinear region of HBT, and it can arrive the maximum conversion gain with minimum LO power. One of discussion was stable. The circuit was unstable which input larger LO power level. The conversion gain and IMD were trade-off by adjusting bias point. The third section was discussed the design of SAW oscillator. SAW resonator can improve the phase noise and frequency of oscillator. The nonlinear model of SAW resonator was extract. It is that Colpitts oscillator at first oscillates near the series resonant of SAWR can get the optimum performance was proved. The last part was discussed the design of tripler. It was proved that the bias point of diode mixer and diode tripler were the same. The final circuit improves load effect that is the frequency of oscillator didn’t change. Oscillator and tripler were combined to test the performance of mixer.