採用CMOS製程之THz影像系統信號源設計

Abstract

依據MIT 2004 年技術評鑑報告，太赫茲電磁波(300 GHz~3 THz)為非離子化輻射波，相較於X-射線對人體風險較低，是公認理想醫學影像信號源。除此之外，太赫茲電磁波對於分子檢測、金屬探測、安檢系統、短距離雷達及超高速無線資料安全傳輸等應用，亦深具潛力，為近年來科學及工程上之重點研究領域。 過去太赫茲信號源多採用高功率雷射結合光學模組及化合物半導體實現，其體積及成本耗費甚巨，普及化有其困難。隨著互補式金屬氧化物半導體製程技術之演進，電晶體之功率單位增益頻率已提升近300 GHz左右。此一重大技術進展開啟了矽製程在太赫茲系統應用之序幕，同時對於降低太赫茲系統成本及面積之可行度大為增加。本論文開發互補式金屬氧化物半導體製程積體電路之設計技術，以基頻振盪模式之鎖相迴路完成130 GHz信號源電路設計，結合倍頻技術將頻率提升至260 GHz，且提出鎖鍊式注入式振盪器天線陣列技術，利用注入式振盪器和天線陣列技術，實現功率合成技術提升輸出功率，開啟太赫茲訊號應用機會。 在傳統空間功率合成是利用多個相同頻率訊號源藉由天線發射在空氣中做合成，可使輸出功率增加。傳統上多個訊號源的天線陣列是做在同一個晶片上面，由於天線面積大，因此若多個天線陣列在同一晶片上，晶片面積將會很大，使得製作成本增加。 為解決此一難題，本論文提出將天線陣列做在不同晶片上，利用打線方式和注入式鎖定振盪器，使用一個鎖相迴路輸出一個固定頻率訊號，再經由打線將訊號注入下個晶片的振盪器，使得振盪器振盪出一個頻率的訊號，再繼續注入下個晶片的振盪器，以此類推。這些不同晶片的振盪器訊號再藉由天線發射，在空氣中做功率合成，這些不同晶片可利用其他較便宜的載具做整合以降低晶片成本。 本論文一開始先概述THz影像系統背景，且介紹一些常用的THz影像系統相關設計。再來介紹毫米波和太赫茲功率合成的基本技術，提高訊號輸出功率。因為功率合成需有相位考量，再介紹先前文獻所使用高速鎖相迴路。而後介紹260 GHz鎖鏈式注入鎖定振盪器設計，先展示以接收機型式架構實現的130 GHz鎖相迴路晶片設計，詳細介紹其子電路架構及設計考量，再說明注入鎖定振盪器設計原理，並且展示量測架設與結果，之後與現有論文做比較。最後總結本論文主要成果，對於未來之建議也於此章節闡述。

In contrast to X-ray, THz wave (300 GHz-3 THz,T-ray) is a non-ionized light source for non-invasive detection of biological tissues without the concern of much radiation exposure. Thus it is believed as an emerging technology for next generation medical imaging system. Additionally, T-ray is capable to penetrate clothing and many (non-metallic) packaging materials. It opens up unique screening possibilities for detection of concealed weapons, chemicals and biological agents, tumors, cavities, and also opportunities for short range radars and secured high data rate wireless communications. Until recently, THz range signal sources are mostly addressed by silicon-germanium process or bulky and expensive optics. As the fmax of CMOS reach over 300 GHz, it opens up an opportunity to provide a small size and low cost platform in CMOS technology. In this paper, we used a CMOS technique to realize a 130 GHz signal source, which boosted into 260 GHz range with the aid of phase combination or push-push techniques, and proposed chain array injection locked voltage controlled oscillator antenna array, which used injection locked oscillator and antenna array to realize power combine technology to promote output power, to open up opportunities of THz applications. To implement power combine in free space, it usually promoted output power to use several signal source which was in the same frequency emitted into free space with antenna array to do power combine. In conventional architecture, antenna array was implemented on single chip. Because antenna area was larger, total chip area was larger so that the cost was more expensive. To circumvent this critical issue, we propose a multi-chip antenna array that uses a phase-loop locked circuit to generate a fixed frequency output signal, and then inject into injection locked oscillator with bonding-wire. The injection locked oscillator output signal inject into the next injection locked oscillator again and so on. The multi-chip of injection locked oscillator signal is used antenna emitting to do power combine in the free space. The multi-chip can use cheaper carriers to reduce chip cost. In this thesis, the background of THz system will be introduced first, and several architectures for THz system design will be discussed. Then we introduce mm-wave and THz wave power combine technology to increase output power. Because we need in-phase signal, several architectures for high speed PLL will be discussed. After that, we propose chain array injection locked voltage controlled oscillator. At first, we accomplish a 130 GHz RX-PLL and introduce the detail schematics, and then discuss injection locked voltage controlled oscillator. Finally, I will summarize the main results of this thesis. The recommendations for future works are also addressed.