- •Introduction
- •Outline
- •PWB Construction
- •PWB/CCA Examples
- •Types of Rigid PWB
- •Types of Flex PWB
- •Footnotes on Flex PWBs
- •PWB Stack-Ups (1 and 2 Layer)
- •Multi-Layer PWBs
- •Exploded View of Multi-Layer PWB
- •Multi-Layer Stack-Up Examples
- •PWB Stack-Up Guidelines
- •PWB Materials
- •PWB Materials
- •PWB Material Examples
- •Dielectric, Common Thickness
- •Copper Options
- •Etch-Back
- •Etch-Back
- •Signal Distribution
- •Single Ended Structure Examples
- •Differential Structure Examples
- •PWB traces as Transmission Lines
- •Characteristic Impedance
- •Trace Impedance
- •Strip-Line & Micro-Strip Impedance
- •Asymmetrical Strip-Line Impedance
- •Impedance Examples
- •Loss
- •Conductor Loss
- •Loss due to Skin Effect & Roughness
- •Time Delay
- •Signal Dispersion
- •Signal Dispersion
- •Signal Dispersion Example
- •Mitigation of Dispersion
- •Coupling
- •Coupling Examples
- •Mitigation of Coupling
- •Differential Pairs
- •Differential Pair Routing Options
- •Differential Impedance Definitions
- •Differential Impedance Examples
- •Field Intensity - 1
- •Field Intensity – 2
- •Field Intensity - 3
- •Field Intensity - 4
- •PWB Pad and Trace Parameters
- •Vias
- •Fine Pitch BGA (FG456) Package
- •Fine Pitch BGA (FG1156) Package
- •Via Parameters
- •Source Terminations
- •Destination Terminations
- •“Intentional” Mismatch Example
- •“Intentional” Mismatch Example
- •Power Distribution Purpose
- •Supply Power Loss Budget
- •DC Loss Model
- •Power Distribution Considerations
- •Plane Capacitance, Inductance, Resistance
- •Capacitor Parameters
- •Capacitor Parameters
- •Capacitor Guidelines
- •Capacitor Mounting Pads
- •Decoupling Examples
- •Trace Width Example
- •References
- •References (continued)
- •Material Suppliers
- •PWB Fabricators
- •Design Tools
Destination Terminations
♦Driving waveform propagates at full intensity over trace
♦Reflections dampened
by terminating resistors(s)
♦Received voltage is equal to transmitting voltage (ignoring losses)
♦Increased peak current demands on driver
Delay = T |
|
Zo=50 Ω |
C |
A B
50 Ω
1 A
0
1 B
0
1 C
0
0 |
T |
2T |
♦More applicable to daisy-chained receivers (first incident switching)
♦Thevenin termination reduces steady-state drive current
Revision 4 |
Copyright Telephonics 2002-2005 |
59 |
|
“Intentional” Mismatch Exampleple
♦
♦
♦
Five selectable sources Four destinations Modeled signal paths
-CCA PWB
-Back Plane PWB
-Connectors
-Driver
♦Took advantage of relatively slow clock (30 MHz)
Revision 4 |
Copyright Telephonics 2002-2005 |
60 |
|
“Intentional” Mismatch Exampleple
♦Allow reflections to dissipate before clocking data (Clocks distributed point-to-point)
Revision 4 |
Copyright Telephonics 2002-2005 |
61 |
|
Power Distribution
&
Grounding