Signal Integrity and EMC Design

54  Signal and Power Integrity: Advanced High-Speed Design and Characterization
Power distribution is becoming an increasing challenge in today’s electronic designs, small and big alike.  Properly designed power distribution is a key requirement to achieve good signal integrity and to avoid electro-magnetic interference problems.
In recent years, parallel signalling rates exceeded 1000Mbps and main-stream serial signalling is in the 5-10 Gbps range; signal rise and fall times shrink to below 100 ps. 
As a result, interconnect losses, frequency-dependent trace and component parameters, inter-symbol interference (ISI), jitter and finite bit-error-rate (BER) all need to be considered. With the increasing utilization of equalization and pre-emphasis, validations even with eye diagrams may not be sufficient. 
Today, equally challenging is the proper design of power distribution. A multitude of supply voltages and signalling levels come with reduced timing and noise margins. The allowed noise on signals and on supply rails decreases and the increasing density and bandwidth of interconnects inter-link the previously independent power-integrity, signal-integrity and EMC design domains. 
55  Signal Integrity: Advanced High-Speed Design and Characterization
High-speed designs continue to undergo major technology changes. In recent years, parallel signalling rates exceed 1000 Mbps and main-stream serial signalling is in the 5-10 Gbps range; signal rise and fall times shrink to way below 100 ps. As a result, interconnect losses, frequency-dependent trace and component parameters, inter-symbol interference (ISI), jitter and finite bit-error-rate (BER) all need to be understood and taken into account during the design process. With the increasing utilization of transmit and receive equalizations, validation even with eye diagrams measured at package pins may not be sufficient in itself. Today, equally challenging is the proper design of power distribution. A multitude of supply voltages and signalling levels come with reduced timing and noise margins. The allowed noise on signals and on supply rails decreases and the increasing density and bandwidth of interconnects eventually link the previously independent power-integrity, signal-integrity and EMC design domains.

 
56  Power Integrity: Advanced Design and Characterization
One of the biggest design challenges today is to properly design, manufacture, simulate and validate a Power Distribution Network (PDN) in systems with increasing speed, power dissipation and density. A multitude of supply voltages and signalling levels come with reduced timing and noise margins. The allowed noise on signals and on supply rails decreases and the increasing density and bandwidth of interconnects link the previously independent power-integrity, signal-integrity and Electro-Magnetic Compatibility (EMC) design domains. Eventually, the power distribution design and characterization becomes a corner stone and enabler for good signal integrity and electromagnetic compatibility.

60  Grounding and Shielding: The Essence of EMC Design
The discipline of Electromagnetic Compatibility (EMC) is concerned with the design of Electronic Systems, while minimizing electromagnetic coupling and interference from within the system and between systems to their environment. 
Meeting the strict EMC standards, as well as ensuring the satisfactory performance of the equipment in its intended electromagnetic environment, requires the implementation of technical measures into the system’s design. 
Grounding forms an inseparable part of all electronic and electrical designs, from circuit through system up to installation design. Grounding is implemented for EMC and ESD protection, for safety purposes, for lightning and surge protection. 
Shielding, on the other hand, is a necessity for avoiding electromagnetic field coupling from and into equipment enclosure. Adequate shielding is necessary to enhance immunity of equipment, and reduce emissions from the equipment enclosure. 

Grounding and shielding are two of the essential concepts in EMC design. No design will be acceptable without them being properly implemented. 

70  High-Speed PCB Design for EMC and Signal Integrity
All EMI problems begin and end on the Printed Circuit Board. In recent years, PCBs have become increasingly complex. The use of high density VLSI on the one hand, combined with the increased processing speed and data rates on the other hand, have led to the increased density of the circuits. The use of high speed/high edge rate digital circuits, along with the need for low power consumption, have contributed to higher electromagnetic emissions from circuits, on the one hand, and increased sensitivity of the circuits on the other, leading to Electromagnetic Interference (EMI) problems. 
A special problem is that of Signal Integrity (SI). For the adequate control of EMI, strict international standards and regulations have been developed worldwide. These standards require the suppression of electromagnetic emissions from circuits and systems, and their increased immunity to externally induced interference. The proper design of PCBs is a cost effective approach for the control of EMI in high-speed circuits. 
Upcoming Course Weeks

News
