Controlled impedance printed circuit boards (PCBs) often include a measurement “coupon”, which typically includes sample traces, 6 inches long and constructed as part of the printed circuit board panel. They are measured to assure the PCB stack-up and the accuracy of the PCB transmission lines. These coupons, as well as the actual PCB signal traces, interconnects and cables are typically measured using a Time Domain Reflectometer (TDR). A TDR is generally a large, expensive instrument that includes a high-speed edge pulse and a sampling oscilloscope.
“The computer was born to solve problems that did not exist before.”— Bill Gates. You must be thinking this is such an odd statement to start today’s article, which is about high-end technology. Well though it’s because of this technology that we are standing here today, it’s also kind of confusing. Well, high-end technologies are bringing along some high-end confusion among high-end technical people. So let alone the state of mind of a common man. There was a time when a computer took up an entire room to perform just basic stuff like calculations.
From signal integrity to roughness of the copper and stack-up design, here are a few PCB design tips you could use:
- Insertion loss and attenuation
- Signal integrity for automotive electronics and IoT
- Fine lines
- Copper for ground and power planes
- Roughness of the copper
- Stack-up design
- Work with your fabricator
Once upon a time, there was an age, an age of simple pleasure and little things. They formed our base of happiness. Then came the industrial revolution and technological advancements. And it changed our world. Our world got engulfed by extravagant gadgets and extraordinary technology. As for now what makes us happy are mobile phones and never-ending data pack; everything wireless. The more wireless we go, the more happiness we show.
The topic of clock jitter performance seems to be a current focus of clock, ADC, and power supply manufacturers. The reasoning is clear; clock jitter interferes with the performance of digital circuits including high speed ADCs. High speed clocks can be quite sensitive to the “cleanliness” of the power they receive, though quantifying the relationship takes some effort.
After reviewing the differential impedance as well as the even or common mode, let’s now dive into the physical parameters of a differential pair.