Reliable Systems Design using Current Boundaries

Many years ago, I started my career as an electromagnetic compatibility (EMC) educator. The reason to teach EMC were some irregularities at the company where a fresh crew of young engineers had been assigned to design and build modern 4-layer double-euro sized printed circuit boards (PCBs) using fast digital logic, to save cost and time over the expensive complicated 20+ layer, much smaller company specific PCB versions that were built before. Unfortunately, the logic devices had become much faster than their predecessors and the boards did not work! It turned out that many other companies were facing the same problems: cross-talk and transmission line effects on PCBs made the, originally independent, hardware modules interfere with each other. It was difficult to build the increasingly complex hardware. A true Hardware Crisis. A similar thing had happened to software engineering (SE) two decades earlier: the Software Crisis [1]. It had become increasingly difficult to produce software as the programs became larger. One programmer could no longer solve the problem on his own and many programmers had to work together on the task.