Differential Structure Examplesles
Edge Coupled |
Broadside Coupled |
Signal
Traces
Ground
Edge-Coupled Micro-Strip 
Plane Edge-Coupled Imbedded Broadside-Coupled Strip-Line
Micro-Strip
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Edge-Coupled Asymmetrical |
Edge-Coupled Symmetrical |
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Offset Broadside-Coupled |
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Strip-Line |
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Strip-Line |
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Strip-Line |
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Revision 4 |
Copyright Telephonics 2002-2005 |
26 |
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PWB traces as Transmission Linesines
♦Signal wavelength approaches component size
♦Dielectric Loss (G)
♦Trace Copper Loss (R)
♦Trace series inductance (L)
♦Trace capacitance (C)
R
L
C G
Revision 4 |
Copyright Telephonics 2002-2005 |
27 |
|
Characteristic Impedance
L R L R L R
C G C G C G
Z0 = |
R + jϖL |
Line impedance in terms of R, L, C and G |
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G + jϖC |
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Z0 = |
L |
Line Impedance for Lossless line (R and G 0) |
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C |
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Revision 4 |
Copyright Telephonics 2002-2005 |
28 |
|
Trace Impedance
♦Impedance Determined By
-Topology
-Dielectric constant of PWB material
-Dielectric height
-Conductor width
-Conductor thickness (small extent)
♦Impedance Critical
-Delivering max power to load
-Maintaining signal integrity
-Prevent excessive driver loading
Revision 4 |
Copyright Telephonics 2002-2005 |
29 |
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