雙頻帶鏡像抑制混頻器與小型低功率低相位雜訊壓控振盪器設計

Abstract

本論文分為混頻器與壓控振盪器兩個部份。利用TSMC 0.18μm RF CMOS製程完成可應用於WiFi系統之雙頻帶鏡像抑制混頻器與小型低功率低相位雜訊壓控振盪器設計。 混頻器提出一個操作於2.5GHz、5.2GHz雙頻帶（中頻為500MHz）並帶有高鏡像抑制的混頻器。將分別從射頻輸入端利用LC的雙頻帶匹配、介於其中的LC雙頻帶鏡像抑制方法、提高鏡像抑制的手段來討論。鏡像抑制效果，在2.5GHz頻帶的鏡像抑制率為36.3dB，在5.2GHz頻帶的鏡像抑制率為47.3dB。 壓控振盪器是以電流再利用為主要架構，結合共振腔的調整與逆向基板偏壓，來解決電流再利用架構先天的波形對稱性與輸出振幅大小的取捨的難題。同時也能降低功率消耗與相位雜訊。此外，在修改過的LC共振腔部份同時具備了消除共模態二階諧波項的功能。頻帶操作於5.12GHz~5.36GHz，相位雜訊在5.14GHz時有-118.9 dBc/Hz 在 1MHz 位移，此時輸出功率為 -3.1dBm，功率消耗為1.9mW。在二倍頻有著約11dB的抑制效果。FOM可達-190.3dBc/Hz，核心面積僅有0.33mm x 0.45mm。

This thesis is mainly divided in two parts: dual-band image rejection mixer and a compact low power low phase noise VCO, fabricated in TSMC 0.18μm RF CMOS process. Both of two circuits can be applied in WiFi communication system. The proposed mixer operates in 2.5GHz and 5.2GHz bands, with 500MHz IF. High image rejection ratio at 2.5Ghz, 5.2GHz bands are 36.3dB, 47.3dB, respectively. We will discuss the dual-band input matching and improved dual-band inter-stage image rejection method. The compact VCO is mainly constructed by current-reuse architecture. It combines with tuned LC tank and reverse-substrate-bias (RSB), to break current-reuse architecture inherent trade-off between waveform symmetric and output swing. In addition, RSB can lower the power consumption. The tuned LC tank is, moreover, added a 2nd harmonic suppression function. The phase noise at 5.14GHz is -118.9 dBc/Hz at 1MHz offset, with output power -3.1dBm, 1.9mW power consumption. The 2nd harmonic suppression is about 11dB. FOM can achieve -190.3dBc/Hz within compact core die size 0.33mm x 0.45mm.