In his afternoon presentation on illustrations and demonstrations of signal returns, grounds, and ground problems in product design, Mr. Hill asked: "What picture comes to your mind when someone says the word "ground" to you within the context of electrical design?" Most electronic and EMC design personnel describe surprisingly different electrical circuit concepts when asked to define exactly what "ground" means to them. This presentation discusses in detail the three different functions of signal ground. Ground loops within PCBs and systems were formally defined, with a detailed discussion of their characteristic magnetic and common impedance immunity problems.

Dr. Bruce Archambeault first presented "The "Ground" Myth." The term "ground" is probably the most misused and misunderstood term in EMC engineering, and in fact, in all of circuit design. Ground is considered to be a zero potential region with zero resistance and zero impedance at all frequencies. This is just not the case in practical high-speed designs. The term "ground" is a fine concept at DC voltages, but it does not exist at the frequencies running on today's typical boards. This presentation discussed the origin of the word "ground", what we really mean when we use the term "ground" and how to optimize our designs to achieve the over all goals for our reference strategy.

In the afternoon, Dr. Archambeault presented decoupling of PCB's for EMC and functionality in the real world. Decoupling of power and ground-reference planes is an important issue for both EMI emissions control and for circuit functionality. This topic has generated a lot of technical papers, and controversy. This talk focused on the sources of noise that the decoupling capacitors are intended to control, the physics involved in the noise propagation, and how to properly analyze the decoupling capacitor performance. The analysis must be performed in BOTH the time domain and the frequency domain. The frequency domain analysis is a steady state analysis, and will determine resonances, which are most useful for EMI emissions analysis. The time-domain analysis is a transient analysis and will help determine how well the current is delivered to the IC, and ultimately, how large (or small) the generated noise pulse will become. Real-world examples of measurements, as well as computer simulations, were used to demonstrate the optimal decoupling strategy.