Issue link: https://iconnect007.uberflip.com/i/1163814
60 DESIGN007 MAGAZINE I SEPTEMBER 2019 So, what about crosstalk in the return path of the reference planes as the current weaves its way back through the expansive wasteland of copper? This column followed my previous column "Return-Path Discontinuities" [3] and elaborated on crosstalk in the unseen "dark side" of the signal. 3. Next-gen PCBs: Substrate-integrated Waveguides As PCB transmission frequencies head toward 100 GHz and beyond, the current main- stream PCB technology—the copper intercon- nect—is reaching its performance threshold. Ultimately, it is dielectric loss, copper rough- ness, and data transfer capacity that are the culprits. However, the biggest performance restriction for PCB interconnects is the size of the conductor. Metallic waveguides are a bet- ter option compared to traditional transmis- sion lines, but they are bulky, expensive, and non-planar in nature. Recently, substrate integrated waveguides (SIW) structures have emerged as a viable alter- native and are ideally suited to the high-speed transmission of electromagnetic waves. SIW are planar structures fabricated using two periodic rows of PTH vias or slots connecting the top and bottom copper ground planes of a dielectric substrate. In this column, I reviewed the sub - strate integrated waveguide and its incorpora- tion with the microstrip transmission line. 2. Stackup Planning, Parts 1–5 Design methodologies change over time, particularly in the ways to simulate electro- magnetic fields and return current paths. In my first four columns on stackup planning, I described the traditional stackup structures that use a combination of signal and power/ ground planes. But to achieve the next level in stackup design, one needs to not only consider the placement of signal and plane layers in the stackup but also visualize the electromagnetic fields that propagate the signals through the substrate. Part 5 covers all of the latest con- cepts in stackup design (Figure 3). 1. The 10 Fundamental Rules of High-speed PCB Design, Parts 1–5 Over the years, in a plethora of published technical articles, I have focused on high- speed design, signal and power integrity, and EMC design techniques. All of these have key points to consider and present a tremendous amount of information to absorb. In this five- part series, I reflected on the 10 most impor- tant considerations to embrace to achieve a successful high-speed PCB design that per- forms reliably to expectations. These 10 golden rules should be the prime checklist for all high- speed PCB designers (Figure 4). Moving forward, does anyone have a sugges- tion for the theme of my 101 st column? How about "Signal Integrity 101"? Feel free suggest Figure 3: Digital signals travel as a wave of electromagnetic energy in a multilayer PCB.