Class20_CrosstalkII_calculations

# Class20_CrosstalkII_calculations - C rosstalk C alculation...

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Crosstalk Calculation and SLEM

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Crosstalk Calculation 2 Topics Crosstalk and Impedance Superposition Examples SLEM
Crosstalk Calculation 3 Cross Talk and Impedance Impedance is an electromagnetic parameter and is therefore effected by the electromagnetic environment as shown in the preceding slides. In the this second half, we will focus on looking at cross talk as a function of impedance and some of the benefits of viewing cross talk from this perspective.

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Crosstalk Calculation 4 Using Modal Impedance’s for Calculating Cross Talk Any state can be described as a superposition of the system modes. Points to Remember: Each mode has an impedance and velocity associated with it. In homogeneous medium, all the modal velocities will be equal.
Crosstalk Calculation 5 Super Positioning of Modes Odd Mode Switching Even Mode Switching Even States Single Bit States Rising Edge Odd Falling Edge 0 No Change (Line stays high or low, no transition occurs) Odd States , 0 , 0 , Don’t Care State 0 0 Digital States that can occur in a 2 conductor system Total of 9 states = Single bit state V Time V Time 1.0 Line 1 Line 2 ½ Even Mode ½ Odd Mode 0.5 V Time 0.5 V Time 0.5 V Time -0.5 V Time For a two line case, there are two modes +

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Crosstalk Calculation 6 Two Coupled Line Example Calculate the waveforms for two coupled lines when one is driven from the low state to the high and the other is held low. H=4.5 mils t=1.5 mils W=7mils Er=4.5 S=10mils 30[Ohms] 50[inches] Input V Time V Time 1.0 Line A Line B Output? V Time ? V Time ? Line A Line B At Driver At Receiver V Time ? V Time ?
Crosstalk Calculation 7 Two Coupled Line Example (Cont. .) First one needs the [L] and [C] matrices and then I need the modal impedances and velocities. The following [L] and [C] matrices were created in HSPICE. Lo = 3.02222e-007 3.34847e-008 3.02222e-007 Co = 1.67493e-010 -1.85657e-011 1.67493e-010 Zodd 38.0 [Ohms] Vodd 1.41E+08 [m/s] Zeven 47.5 [Ohms] Veven 1.41E+08 [m/s] H=4.5 mils t=1.5 mils W=7mils Er=4.5 S=10mils Sanity Check: The odd and even velocities are the same 30[Ohms] 50[inches]

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Crosstalk Calculation 8 Two Coupled Line Example (Cont. .) Now I deconvolve the the input voltage into the even and odd modes: = Single bit state V Time V Time 1.0 Line A Line B ½ Even Mode ½ Odd Mode 0.5 V Time 0.5 V Time 0.5 V Time -0.5 V Time Line A Line B This allows one to solve four easy problems and simply add the solutions together! Case i Case ii Case iii Case iv
Crosstalk Calculation 9 Two Coupled Line Example (Cont. .) Zodd 38.0 [Ohms] Vodd 1.41E+08 [m/s] Zeven 47.5 [Ohms] Veven 1.41E+08 [m/s] 30[Ohms] 50[inches] Case i and Case ii are really the same: A 0.5[V] step into a Zeven=47.5[ ] line: Line A Line B 0.5 V Time 0.5 V Time Case i Case ii Td=len*Veven=8.98[ns] Vinit=0.5[V]*Zeven/(Zeven+30[Ohms]) Vinit=.306[V] Vrcvr=2*Vinit=.612[V] 0.000[V] Driver (even) 0.0[ns] 9.0[ns] 0.306[V] 0.612[V] 0.000[V] Receiver (even) 0.0[ns] 9.0[ns] 0.306[V] 0.612[V]

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## This note was uploaded on 08/23/2009 for the course ECLT 762 taught by Professor Yinchaochen during the Spring '03 term at South Carolina.

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Class20_CrosstalkII_calculations - C rosstalk C alculation...

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