一般傳統無線通訊射頻前端電路所採用的是外差(heterodyne)的架構，然而此架構需要兩個以上用來升頻的本地震盪器，以及需要濾波器去除不必要的旁波帶訊號，因此並不利於高度的RFIC整合。然而避免這個問題的最佳方式是採用直接升頻的架構，乃是將射頻載波直接施於正交調制器，便可以消除中頻的電路部分，以節省面積、成本、功率消耗以及設計時間，大幅簡化射頻電路的複雜度。

本論文主要以TSMC 0.18um 1P6M CMOS製程成功研製將低頻1MHz訊號直接升頻至2.4GHz ISM頻帶的雙閘極混頻器與低電壓混頻器。其中低電壓混頻器是延續雙閘極混頻器的基本設計概念，結合主動雙閘極與被動場效電晶體的混頻機制，設計出新式直接升頻混頻器；因為採用折疊式(Folded)的架構，所以在1V的低電壓便能提供轉換增益，模擬結果也顯示此新式的混波架構具有非常理想的輸入/輸出端隔離度和低雜訊等特性。同時，現今通訊系統產品漸以平衡式或差動式的電路為設計，因此在論文中也將討論平衡式元件的量測方法以及實作電路。

The traditional communication RF front-end circuit applies the heterodyne structure generally. Because this structure needs more than two up-conversion local oscillators and some filters to eliminate spurious signal, it is not advantaged to the high integration of RFIC. The Best method to avoid such a problem is to use direct up-conversion structure which adds RF carrier to quadrature modulator, so it can remove IF circuits to save the area, cost, power consumption and time-to-design.

This thesis uses TSMC 0.18um 1P6M CMOS process to implement the “Dual-Gate Mixer” and “Low-voltage Mixer” which transforms 1MHz signal up to 2.4GHz ISM band directly. The low-voltage mixer based on the basic design concept of Dual-Gate mixer is a novel structure which combines the mixing machines of “Active Dual-Gate Mixer” and “Passive FET Transistor”. Because of “Folded Structure”, the mixer can provide conversion gain at low voltage (1V). From the results of measurement, very good input/output isolation and low noise can be achieved. As the trends of the communication system are according to “Balanced and Differential structure”, the measurement of the balanced devices and circuits design will be also discussed.

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