損耗基板模型建立與高頻雜訊模擬射頻場效電晶體與探針墊結構之研究

Abstract

在本論文中，首先對金氧半場效電晶體的雜訊理論與原理、各種不同雜訊模型的介紹與雜訊量測的原理及架構做基本的介紹其中包括熱雜訊(高頻)與閃爍雜訊(低頻)。接下來進入本論文的核心部分，利用130nm製程研製之射頻互補式金氧半場效電晶體來建立並驗證一個寬頻且可調性的矽基板損耗模型。在第三章，利用開路探針墊的量測結果建立一個可以適用於包括：損耗(lossy)、標準(normal)、小型(small)等三種不同探針墊架構的改良型損耗矽基板模型。在第四章，藉由量測電晶體的電流-電壓特性、轉導與導納參數來校正電晶體的本質特性模型，其中包跨電流-電壓、電容-電壓模型。在第五章，探討不同的探針墊架構其矽基板損耗效應所貢獻的額外雜訊的影響。藉由將探針墊的等效電路搭配經過準確校正的本質元件模型構成的完整電路來進一步驗證改良型矽基板損耗模型。已完成的可調性矽基板模型可以準確的預測損耗型探針墊 (lossy pad)在雜訊參數上所表現的異常閘極指叉數(gate finger number)相關性與對頻率的非線性關係。更進一步的，可以有效分析探針墊架構，如金屬堆疉層次與形狀大小，以及連線佈局之影響，得以準確模擬矽基板損耗經由傳輸線與探針墊所貢獻的額外雜訊。最後，改良型損耗矽基板模型提供了一個適當且能有效降低由傳輸線與探針墊所貢獻的額外雜訊的佈局方法。本論文中，小型(small) 探針墊可以很明顯的降低由探針墊所貢獻的外在雜訊，使直接量測到的雜訊特性幾乎接近元件的本質雜訊特性。

In this thesis, the basic noise theory, noise models, noise measurement principles and the equipment configuration will be introduced at the first place. Both thermal noises at high frequency and flicker noise dominant at low frequency will be covered. Then a broadband and scalable lossy substrate model is developed and validated for nanoscale RF MOSFET, which were fabricated by 130nm 1.2V CMOS technology. In chapter 3, an enhanced lossy substrate model adopting various pad structures, such as lossy, normal, and small pads was developed based on open pad S-parameters at high frequency up to 40 GHz. In chapter 4, the intrinsic MOSFET model through extensive calibration on I-V and C-V models will be presented. The model calibration was done based on the measured I-V, transconductance, and admittance from Y-parameters. In chapter 5, a detailed discussion on the pad structures effect on RF noise will be provided. The enhanced lossy substrate model is verified by integration with the intrinsic devices model for full circuit model. The scalable lossy substrate model can consistently predict the abnormally strong finger number dependence and nonlinear frequency dependence of noise figure (NFmin) revealed by the devices with lossy pads. Furthermore, the scalable model can precisely distribute the substrate loss between the transmission line (TML) and pad with various metal topologies and the resulted excess noises. Finally, the enhanced model provides useful guideline for appropriate layout of pads and TML to effectively reduce the excess noises. The remarkably suppressed noise figure to ideally intrinsic performance can be approached by the small pad in this thesis.