Design of Mixers for Microwave and Millimeter-wave Applications

本論文主要是在討論被動的平衡式次諧波混波器、利用改良的平衡不平衡器以實現在高頻的寬二極體頻混波器以及架構上較為簡單的閘極驅動單端次諧波混波器。主要研究方向在於如何以較低的本地振盪訊號即可驅勳混波器達成混波效果。 此論文共分三個部份皆為被動式的混波器，在第一部份中先討論並設計一於pHEMT 製程上的71-76 GHz平衝式閘極驅動次諧波混頻器並利用相同架構的混波器作為基本元件實現一60 GHz 的解調變器；第二部份則是介紹一用於天文觀測所需的高頻混波器，矽基材料所製作的電晶體之最大振盪頻率不夠高，在高頻時已無法提供應有的增益，所以這類高頻電路常會以砷化鎵作為實現的材料但是由於基板厚度較厚，以微帶線在高頻實現馬遜平衡轉非平衡器時會受到接地不良的影響而導致其特性不佳，所以在這一部份藉由增強耦合強度來改進此一問題，進而使整體電路更加對稱增加設計上的方便性；第三部份是設計並實現一CMOS單端的閘極驅動次諧波混波器，由於沒有使用平衡轉非平衡器，其面積可以較為縮減。雖然沒有平衡轉非平衡器，但是在利用耦合線當作共振腔來作為濾波器之後隔離度也有相當的改善。將汲極和基座相接可以抑制在中頻輸入信號強度增加時所造成的直流位準漂移，因為只用到一個電晶體，所以只需要約0 dBm即可推動此混波器波減少系統中其他電路的負擔。This thesis discusses an gate-pumped resistive sub-harmonic mixer, high frequency broadband diode mixer with improved balun in high frequency and a single-ended gate-pumped sub-harmonic mixer. The main purpose is to reduce the level of LO power needed to drive a mixer. This thesis consists of three parts and they are all passive mixer in common. The first part introduced a 71-76 GHz balanced resistive gate-pumped mixer using in pHEMT process. Based on this topology, a 60 GHz demodulator is also presented. In the second part, a high frequency diode mixer for space observation is realized. Because the MOSFET fabricated by Si-based material has no gain in such high frequency, the circuits in high frequency usually are implemented in GaAs process. However the thickness of the substrate in these processes is large and may corrupt the ideal ground needed in Marchand balun. A modified Marchand balun which has better coupling factor and resists non-ideal ground effect is introduced in this part to enhance the symmetry of the circuit and relieve the design difficulty. A single-ended gate-pumped sub-harmonic mixer is designed and presented in part three. Without the baluns, the size of the mixer can be more compact than balanced mixers. Although there is no balun, the isolation can still be achieved by filter using coupled-line resonator which is more compact than a balun. Connecting drain to body can help the problem that dc voltage of drain changes. Due to its simple topology, this mixer can be driven with LO power of about only 0 dBm, and eases the requirement of other components in the system