本論文第一個設計是應用於5.8GHz頻段之低電壓,高線性度CMOS降頻混頻器。改善傳統吉柏特混頻器有三顆電晶體操作在飽和區的缺點，將低電壓的目標納入研究，我們採取折疊式的架構使汲極偏壓在1V仍可提供增益1.6dB。同時為了增加輸出功率和減輕下一級放大器的操作，線性度的特性亦是混頻器發展的重點之一。在RF端我們利用4顆pMOS做交錯相接的連接方式來取代傳統nMOS的連接方式並減少noise使雜訊指數為7.861dB線性度為9.149dBm。同時我們將「LC Tank」和「AC路徑的電容」合成濾波器，使輸入/輸出端的隔離度非常理想LO-RF, LO-IF, IF-RF皆大於100dB。
第二個設計是應用於Ka頻段之對稱式次諧波混頻器，對衡式次諧波架構具有LO Leakage效應很小，LO輸入功率不需要很大等特色，我們的LO輸入功率為10 dBm，比一般設計的15dBm要來的小，且Conversion loss可達-7.5dBm。在LO和RF端採用藍吉耦合器使Return loss的特性變好。採單平衡架構在模擬時具有 LO/輸出端不錯的隔離度，使輸入/輸出端的隔離度非常理想LO-RF, LO-IF, IF-RF皆大於15dB。

This thesis consists of two mixers for 802.11a and Ka-band applications. The first design is a low-voltage, high-linearity CMOS down-conversion mixer for 5.8GHz applications. Folded structure is used for low operation voltage to improve the drawbacks of Gilbert mixer where three transistors are operated in the saturation region. Then, high-linearity is considered so as to increase the output power. In RF stage, a cross-connect configuration with four pMOSs to replace the traditional nMOS connection is proposed to reduce noise and enhance linearity. Furthermore, the integration of the LC tank with coupled capacitor for a filter can further enhance the isolations lager than 100 dB between LO- RF, LO- IF, and IF- RF ports.
The second design is a balanced sub-harmonic mixer with the advantages of low LO Leakage effect and low LO input power, implemented by PHEMTs for Ka-band application. Lange Couple in RF and LO ports is used to improve the return loss. The designed mixer with the input LO power as low as 10 dBm and conversion loss of 7.5dB can be achieved. The use of single balanced framework can improve the isolations lager than 15 dB for LO-RF, LO-IF, IF-RF ports.

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