具基體雜訊考量之射頻電壓控制振盪器電路設計

Abstract

本論文主旨在探討不同結構的變容器對於基體雜訊的隔絕能力。就標準互補式金氧半導體製程而言，有四種金氧半導體結構可以作為變容器，而且這四種變容器都具有可以隔絕基體雜訊的特定結構。本論文的第二章將探討與比較這四種變容器的高頻特性。 這四種變容器中，其中兩種生成於n型井上且利用介於n型井與基體的p-n接面隔絕基體雜訊；另外兩種生成於p型井上且被深層n型井與n型井所包圍以隔絕基體雜訊。本論文的第三章將比較這兩種結構對於基體雜訊的隔絕能力。 在本論文的第五章中，我們利用0.25微米互補式金氧半導體製程設計且實現了三個操作在2.4GHz頻段的電感電容共振型電壓控制振盪器電路。VCO1與VCO2唯一不同的地方在於所使用的變容器，這兩種變容器以不同的結構來隔絕基體雜訊。將訊號產生器提供的一個射頻訊號注入基體中作為基體雜訊，我們將探討耦合至變容器的基體雜訊對於VCO1與VCO2輸出頻譜的影響。VCO1與VCO3採用相同結構的電感與變容器但是不同的電路架構，我們將利用VCO1與VCO3來比較不同電路架構的相位雜訊。

The isolation capabilities of varactors with different structures against substrate noise are investigated in this thesis. In chapter 2, four types of MOS structure varactor available in standard CMOS processes are investigated. They all have specific structures able to isolate substrate noise. High-frequency characteristics of them are compared. Among these four varactors, two of them are fabricated on n-well and use the p-n junction between n-well and substrate to isolate substrate noise. The other two are fabricated on p-well and surrounded by deep n-well and n-well in order to isolated substrate noise. Isolation capabilities of different isolation structures are compared in chapter 3. In chapter 5, three 2.4GHz LC VCO circuits are designed and realized in a 0.25-um CMOS process. VCO1 and VCO2 differ only in the type of varactor. An RF signal provided by signal generator is injected into the substrate as substrate noise. The influences of substrate noise coupling to the varactors on the output spectrums of VCO1 and VCO2 are investigated. VCO1 and VCO3 use the same type of inductor and varactor, but they differ in the type of circuit topology. The phase noise of them is compared.