應用於毫米波接收機之寬中頻CMOS混頻器研究

Abstract

本論文的目標在於設計適用於毫米波接收機的混頻器元件，其中RF模組所使用的混頻器是用來將78.3-113.1GHz的訊號降頻到DC-34.8GHz；而IF模組中另外三個混頻器的功能，則是分別將8.7-17.4、17.4-26.1、26.1-34.8GHz的訊號降頻到DC-8.7GHz。所有混頻器其RF、LO、IF端的輸入反射係數均低於-10dB，並且擁有至少5dB正的轉換增益，各埠間隔絕度在30dB以上，而線性度(IIP3)則至少大於0dBm。除此之外，電路中使用來產生相差180度平衡訊號的重要元件─莫氏巴倫，也需要小心的設計。經過我們多方的努力，一個訊號振幅誤差小於0.2dB，並且相位誤差小於2度的莫氏巴倫將會被提出。 在本論文中我們將首先設計IF模組所使用的三個混頻器；並且對最高頻段26.1-34.8GHz的混頻器，我們提出了它次諧波混頻的兩個改良版本，目的是為了降低所需之LO頻率與功率，以減少LO模組設計者的負擔。並且我們打算利用轉換矩陣理論來對我們所使用之寬中頻混頻結構的原理提出解釋。最後，我們將運用前面設計電路所得到的經驗來完成用於RF模組之W波段混頻器。

This thesis aims to design the mixing components used in a millimeter-wave receiver, where the mixer of the RF module will down-convert the 78.3-113.1GHz signal to DC-34.8GHz while the three mixers used in the IF module transform the 8.7-17.4, 17.4-26.1 and 26.1-34.8GHz signals to their DC-8.7GHz counterparts, respectively. All these mixers have their RF, IF, and LO input return loss below -10dB; conversion gain larger than 5dB; port-to-port isolation more than 30dB; and the linearity (IIP3) expected to be better than 0dBm. Besides, performance of the critical elements, such as Marchand balun for producing balanced signals, has each been optimized. In our design, the balun has less than 0.2dB magnitude error and 2-degree phase error which outperforms any existing one, and will be presented in detail. In this thesis, the three IF mixers have all been design and measure. As for the 26.1-34.8GHz frequency range, two types of sub-harmonic mixers have been proposed for allowing lower LO frequency (and power), thus, alleviate the difficulty in the design of LO module. Furthermore, we intend to explore the theoretical aspect of the wide-IF-band mixer using conversion matrix. Finally, with the experience from the IF mixers, we will start working on the design of the W-band mixer.