新手入門
SI/PI部落格
生活隨筆
財經電子
明心見性
國內大專院校SI/PI/EMC的課程與師資相對較少,除了台大 吳瑞北、吳宗霖老師,中原 薛光華老師,逢甲 林漢年老師,中山 洪子聖老師,高雄大學 吳松茂老師,大部分是做天線設計、電力電子、微波材料或微波電路/濾波器的相關研究。有感於一位夠水準的SI/PI/EMC工程師養成不易,筆者野人獻曝,參考一些大師著作加上個人理解,將相關領域的基本觀念整理,希望更多人能一窺堂奧。唯個人能力有限,雖然字字斟酌力求精確,但如有未盡完善之處,還請各界專家不吝指正。
電感
特性阻抗
Crosstalk
S參數 -- 基礎篇, 範例
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S參數 -- 進階篇, 範例
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Smith Chart 史密斯圖 怎麼用-高頻電路的好幫手 -- 引用
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終端匹配 (差模終端與共模終端)
-- 引用
Termination Techniques for high-speed digital circuit p.40 -- 引用
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法拉第電磁感應定律與馬克斯威爾方程式
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IBIS and AMI Model -- 引用
Q & A
(點擊以下項目,展開內容)
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SI、PI領域常探討的問題是?
-- Reflections/Distortion、Time Delay and Crosstalk.
-- Power supply system input impedance, simultaneous switching noise (SSN), printed circuit board (PCB) resonance, decoupling capacitor placement, and edge radiations
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何謂有限元素法、邊界元素法、矩量法
-- 有限元素法(Finite Element Method, FEM) -- 一種電磁場數值分析方法,把物體切成很小的單元分析其電磁場(以馬克斯威爾方程式計算),以Ansoft的HFSS為例,是切成四面體單元,計算其四個點與四個邊的值,其餘用內差取得。
-- 邊界元素法(Boundary Element Method, BEM) --
一種電磁場的數值分析方法,網格計算時只
考慮邊界/表面,不像FEM會內部也切。
-- 矩量法(Moment Method, Method of Moment, MOM) -- 一種電磁場數值分析的(近似)方法,適合於第三維度上均勻變化的結構。SIwave v4.0~5.0與PlanarEM即屬此
如何以自學的方式,跨入SI、PI與EMC領域
有心學習的人,以下幾個topic都最少要找兩本原文書,一本中文書,兩份網路上的文件讀過
-- HSPICE, IBIS, IBIS-AMI model有何差異?
-- 駐波為什麼叫"駐"波? Resonance的成因是什麼?
-- 什麼是無源性(passivity),什麼是因果性(causality)?
-- 什麼是特性阻抗? 電阻、阻抗與特性阻抗有何不同?
-- S-parameter怎麼看? S11、S21是指什麼? 更進一步的還有S31、S41又是指什麼?
-- 天線定理是什麼? 傳導干擾與輻射干擾為何法規分開規範,並且後者從30MHz開始看?
-- 近場與遠場差在哪裡? 電場、磁場、電磁波的基本差異?電場探棒與磁場探棒差在哪裡?
-- 什麼是Common mode、differential mode? 成因是什麼,影響是什麼?分別的防治方法是什麼?
-- 什麼是傳輸線模型? 進入傳輸線模型的條件? why訊號反射(reflection)? 各種阻抗匹配方式與差異?
-- SI領域中,考慮訊號的頻寬0.35/tr、0.5/tr,這公式是怎麼來? 在PI領域中Target Impedance是指什麼?
-- 什麼是ISI (Inter Symbol Interference)? It is from Crosstalk induced jitter and Data-Dependent Jitter (DDJ)
-- 不同的PCB堆疊方式對特性阻抗、訊號傳輸速度、雜訊抑制效果、地迴路阻抗、內層寄生電容、EMI防治效果的影響
-- 理想的RLC元件與實際的元件差在哪裡?為何我們需要注意元件的操作頻寬?電感與磁珠(bead)的差異在哪裡? 哪一種會引起高頻諧振?
-- PCB設計的常見rule,像3W rule、20H rule,是什麼意思?物理意義上的原因是什麼? 繞蛇線有什麼要注意的? 貫孔效應的影響是什麼?
-- 什麼是loop inductance? De-coupling capacitor的performance與什麼有關? SI、PI為何與loop inductance都有關? 當換層走線時,為何我們說return path會不連續? 為何割地不良所引起的訊號跨地,會造成SI, EMI issue?為何高頻訊號的return path是尋最小loop inductance路徑而不是最短路徑,兩者有何差別?
有哪幾種signal loss,其特性又如何? loss tangent又是什麼?
-- Skin effect loss and Dielectric loss
-- The loss tangent is the ratio at any particular frequency between the real and imaginary parts of the impedance of the capacitor.
A large loss tangent means you have a lot of dielectric absorption.
If you construct a capacitor C from a lossy dielectric, the dielectric absorption causes the value of C to change with frequency.
-- For a crummy dielectric with higher dielectric loss, the decay in capacitance with frequency will be more pronounced.
The rate of deterioration in capacitance is directly linked to the loss tangent. -- by Dr. Howard Johnson
-- Loss tangent跟介電係數一樣都是隨頻率而變的,一般模擬我們取loss tangent=0.016~0.02是worse case. (about 0.01@K~MHz)
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何謂Full-wave analysis (HFSS, SIwave),其與Quasi-static analysis (Q3D, TPA)的主要差異是?
-- A simple explanation that facilitates the understanding is: full-wave analysis is to solve the complete set of Maxwell's equations without any simplifying assumptions.
Usually the fields described by the equations are time-variant/frequency-dependent.
Compared to full-wave analysis are some methods such as Quasi-static analysis, where the Maxwell's equations are simplified first (the fields are assumed time-invariant/frequency-independent).
Full-wave analysis is often used to analyze electrically-large structures (physical size is much much larger compared to wavelength), in other words, doing high frequency analysis. Some famous full-wave solvers are:
Ansoft HFSS, CST Microwave Studio.Quasi-static analysis is suitable for electrically small structures (usually physical size is assumed to be less than 1/10 wavelength or 1/6 wavelength or... depends on applications as can be seen from a lot of text books). One of the most famous solver is: Ansoft Q2D/Q3D.
-- smithchart
-- Full-wave: considering all field components: Ex,Ey,Ez,Hx,Hy,Hz Quasi-static (as example of non-full-wave one): only one component is considered to be dominant. Imagine you have micro-strip line in XY plane --> then Ez component is dominant in substrate region. You omit Ex and Ey and speed up the calculation.
-- eirp
參考資料:
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Intel(Altera) SI中心、AMD(Xilinx) 資料中心
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"Signal Integrity", 台大吳瑞北教授2019課程講義 (推薦)
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"Power Integrity in SiP", 台大吳瑞北教授2017課程講義 (推薦)
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"Signal Integrity - Simplified", Eric Bogatin, Prentice Hall PTR, 2003
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"Signal and Power Integrity - Simplified", Eric Bogatin, Prentice Hall PTR, 2010.(推薦)
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"Digital Systems Engineering", 史丹佛大學W.J. Dally, J.W. Poulton教授寫的書,投影片講義
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"High-speed Links Circuits and Systems", 德州農工大學Sam Palermo教授2012課程講義(持續有更新, 推薦)