Articles
Picket Fences: A poor mans’ faraday cage?
Faraday cage is an enclosure that shields electromagnetic fields from penetrating into or radiate out of the enclosure. Faraday cages have been around for a long time and are generally used to isolate test equipments or to measure radiated emissions and immunity from a DUT. The concept of Faraday cage works so well that engineers have been [...]
Via antipads: How much care do they need?
When dealing with high speed designs, electronics engineers tend to match trace impedances to the utmost level possible. They take care of ground returns and crosstalk and try to minimise EMC while maximising Signal Integrity. Though with the increase in PCB complexity, this happens to be a challenge, they try and sacrifice many other parameters [...]
Emission pattern in Series Terminations
Ever wondered how the emission pattern from an impedance controlled trace using series terminations looked like? Ever asked what are the major factors that have an effect on emissions? Well, a while back i had the same questions and went on to investigate further. In this article, i have presented a brief about why terminations are used, what [...]
Slots on boards:Tame them with vias
Most PCBs designed today have planes for power supplies and ground returns. While most designs try and designate separate layers in the PCB stack-up for power and ground, some high density PCBs go with the idea of a split planes and sharing one physical copper layer across many different power supplies and ground returns. This idea invariably [...]
Via length:How long is long?
Most PCBs made today are cost sensitive and use traditionally drilled vias. In a multilayer PCB, these vias are mechanically drilled after the layers are bonded together to form a complete PCB. On PCBs that are 1.6mm thick and have less number of layers, the vias that travel across the top and bottom layers of the PCB do not have enough stub [...]
Optimum trace spacing for Crosstalk
When frequencies are higher the effect of having a trace next to another becomes more pronounced and the associated losses increase. In this article I have discussed about this particular effect of having traces next to each other. I have presented some background on this phenomenon called Crosstalk and also tried to present some numerical data to [...]
TRACE BENDS: Their impact on Near Fields (and EMC)
This article is about trace bends on PCBs and its potential impact on near fields and EMC. Considering the complexity of the PCBs of today, it is impossible to have a trace without a bend on it and continuing with this trend we will have to use bends more often than before. Hence in this article, I have tried explaining the effect of a bend on [...]
Stripline or Microstrip: Which is better for EMC?
This article talks about the two most commonly used routing configurations on PCBs – Microstrip and Stripline configurations. The article covers the basic structural differences, impedance calculation formulas and analysis of emission performance in a 3D simulation environment for both the configurations. In simple terms, the Microstrip is [...]