2.45 GHz 被動與主動混頻器之設計

Abstract

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.