四埠射頻金氧半電晶體與共用源汲極主動區之新型串疊結構的小訊號等效電路模型

Abstract

本論文中，建立了小訊號等效電路模型，其中包括新型基板網路模型及其參數萃取方法，以應用於含有深N型槽(deep n-well)的射頻互補式金氧半場效電晶體電路模擬上。本研究設計四端點的射頻金氧半電晶體於四埠測試結構，並利用UMC 65奈米互補式金氧半場效電晶體製程(UN65)研製出來探討元件高頻特性及模型的發展。本論文提出之新型基板網路模型，具備完整之參數萃取流程並且解決了傳統模型與BSIM-4內建模型之問題。此基板網路模型乃是四埠元件小訊號等效電路模型之核心，直接影響四埠散射參數模擬之準確性，並且能夠簡易地取代BSIM-4內建模型以改進其四埠元件模擬之嚴重誤差。所建立的小訊號等效電路模型在不同偏壓進行模擬以作廣泛的驗證，其準確性已證明可應用於高達40GHz 的寬頻範圍，以及不同的偏壓條件如截止區、線性區與飽和區。此外，本論文涵蓋BSIM-4模型之參數校正以及探討基板效應與電容模型中內部電荷計算方法。 論文的第二部份為新型串疊結構之設計與小訊號等效電路模型研發，其構成元件為共用源汲極主動區之雙閘極金氧半場效電晶體。此小訊號等效電路模型亦在不同偏壓下透過模擬做廣泛的驗證。再者，為了能夠同時模擬雙閘極金氧半場效電晶體大訊號特性與小訊號特性，我們利用BSIM-4建立傳統的串疊結構，即二個串疊之電晶體，並外掛寄生元件和調整BSIM-4參數以近似雙閘極金氧半場效電晶體模型，並透過模擬做廣泛的驗證，以應用於40GHz 的寬頻範圍。

In this thesis, small signal equivalent circuit models have been established for 4-port RF MOSFET and new cascade structure. For the first time, a new body network model is developed for RF MOSFET fabricated with UN65 process in which the 4-port test structure was arranged with p-well body and deep n-well tied together to one port for body terminal. The proposed body network model is supported with a comprehensive model parameters extraction method and can be easily integrated with intrinsic MOSFET to build a small signal equivalent circuit model. The simulation accuracy has been proven by good match with measured 4-port S-parameters up to 40GHz and under different operation conditions, such as off-state, linear region, and saturation. On the other hand, the simulation using BSIM-4 with default body network fails to predict 4-port S-parameters with particularly large deviation in the parameters related to body node. The problem with BSIM-4 can be solved by replacing the default model with our new body network model. In the second part, a small signal equivalent circuit is developed for new cascode structure, which is a kind of dual gate MOSFET with merged source/drain diffusion region. A modified body network model is adopted to match different configurations in deep n-well and p-well body. 4-port S-parameters can facilitate the extraction of complicated model parameters in dual gate MOSFET, such as in-stage capacitances, inter-stage capacitances, and cross-stage capacitances. The small signal equivalent circuit model built with core model for dual gate MOSFET and modified body network model demonstrates acceptable simulation accuracy at off state and saturation region. BSIM-4 is utilized to approach new cascode structure by incorporating parasitic elements such as inter-stage resistance and capacitances into conventional cascode with two single MOSFETs and enable both small signal and large signal simulations.