5-Design tecniques-PCB Layout.pdf

PCB DESIGN TECHNIQUES FOR LOWEST-COST PL... /archive/Old_Archive/
Design Techniques for EMC & Signal Integrity – Part 5
PCB Design and Layout
By Eur Ing Keith Armstrong CEng MIEE MIEEE
Partner, Cherry Clough Consultants, Associate of EMC-UK

This is the fifth in a series of six articles on best-practice EMC and signal integr
electrical/electronic/mechanical hardware design. The series is intended for designers of electronic
products, from building-block units such as power supplies, single-puters, and ‘industrial
components’ such as PLCs and motor drives, through to stand-alone worked products such as
computers, audio/video/TV, appliances, instrumentation and control, etc.
The techniques covered in these six articles are:
1) Circuit design (digital, analogue, switch-mode, communications), and ponents
2) Cables and connectors
3) Filters and transient suppressors
4) Shielding
5) PCB layout (including transmission lines)
6) ESD, electromechanical devices, and power factor correction
A textbook could be written about any one of the above topics (and many have), and this magazine
article format merely introduces the various issues and points to the most important best-practice
techniques. Signal integrity is treated as ‘internal EMC’. Employing these well-proven techniques from the
start of a new design generally reduces the number of iterations of hardware and software during
development, and often reduces unit manufacturing costs too. pliance is generally quicker,
easier, with less risk of serious delays in time-to-market.
Table of contents for this part
5. PCB layout
Circuit segregation
The boundary between outside- and inside-worlds
Boundaries within an inside-world
Segregation
placement and routing of tracks
Interface Suppression
Suppressing outside/inside-world interfaces
Interfaces between dirty/high speed/noisy and clean/sensitive/quiet are