Differential stripline impedance calculate
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Transcript of Differential stripline impedance calculate
Differential Stripline
Impedance Calculate
Using 3 Simulation Toolkit
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Jay Chang
按照板廠提供的數據, L4 ref L3/L5算出來的impedance = 77.5 Ω
http://www.multek.se/engelska/engineering/pcb-structures-
2/differential-stripline-impedance-calculator-2 2
Use one of the most popular simulation tool Saturn_PCB_Toolkit_V7.02
按照板廠提供的數據, L4 ref L3/L5算出來的impedance = 77.51 Ω
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Use one of the most popular simulation tool Polar Si9000
按照板廠提供的數據, L4 ref L3/L5算出來的impedance = 81.32 Ω
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既然都用Polar惹, 那就算一下 freq dependent behavior
Z0 vs freq
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和total loss vs freq
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Why Polar Si9000跟前兩個算出來的很接近但不太一樣
因為Polar 是EM field solver (field solver condition代對�就是準!!)
field solver分兩大類1. Differential Maxwell equations�電磁場所在的整個域的離散化(網格化)�解稀疏線性
matrix
代表的有FD(有限差分), FEM(有限元素 HFSS為代表)…
2. integral equation methods�對電磁場的源(通常是電荷密度)進行離散化�解Green function
代表的有BEM(邊界元素 Polar為代表)…
結論:
a. QTI算的impedance應該有問題, lossless又是freq independent阻抗應該沒那麼大, initial
value不知道有沒有代對也不知道用甚麼算的(猜是SIWAVE or ADS ?)
b. 那time skew FAIL應該就是differential line不等長的關係
先降~
To be continued…
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Single-ended Microstrip
Impedance Calculate Using
ADS
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• ADS用優化的辦法來求出阻抗• 先用一個簡單的Microstrip來驗證ADS and Polar的結果是否吻合, 再回到我們與QTI的simulation
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Our Qlink Case
Impedance Calculate Using
ADS Optimization
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Our Qlink Case
Impedance Calculate Using
ADS EM Model
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Differential Line Analysis
Using ADS
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v1: excited voltage與反射電壓的疊加v2: output端電壓
v3: near end crosstalk (NEXT)
v4: far end crosstalk (FEXT)
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Diff mode excitation Comm mode excitation
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TDR Analysis Using ADS
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