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Below are some self-written articles. I update them once every month, so please check back often.

February 10 - Slots on boards:Tame them with vias

I have added an excerpt of the article below:

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 creates reference discontinuities for signals that travel across the length of the PCB making them run over many of these split planes. The straight forward result of this being the increase in return path length and loop area. And as we know, increase in loop area directly translates to increase in EMC issues. So how do we tackle this age old problem of discontinuities in return paths (referred to as “Slots”) in PCB designs without causing any major impact to cost?

Liked the excerpt? Do have a read through the article here:.

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January 10 - The amazing mobile phone

I have added an excerpt of the article below:

Almost everyone carries a mobile phone ‐ from farmers in poor countries to Hollywood stars. It is amazing to see how this humble mobile phone has moulded itself to suit the needs of different classes and is still considered by many as a status symbol. They are no more a luxury but have become a necessity in our day to day lives. Today’s mobile phones are alarm clocks, calculators, personal music systems, Television sets, digital cameras, navigational devices, gaming consoles, computers, credit cards, status symbols and of course mobile phones ‐ just to list a few. So what are the components that help the mobile phone achieve such versatile functions? Keep reading…

Liked the excerpt? Do have a read through the article here:.

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December 09 - Emission pattern in Series Terminations

I have added an excerpt of the article below:

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 series terminations are and how they work, before going on to explain their emission pattern.

Liked the excerpt? Do have a read through the article here:.

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November 09 - Via Stubs:How long is long?

I have added the excerpt from the article below:

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 length to create problems at reasonably high frequencies. But on PCBs with higher layers which can have a total PCB thickness of about 5mm and above, any vias present, will have a definite impact on signal integrity. So how do we tackle this problem? Welcome to the concept of back drilling!

Liked the excerpt? Do have a read through the article here:.

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October 09 - Picket Fences: A poor mans’ faraday cage? I have added the excerpt from the article below:

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 using it on PCB designs. But some engineers go to an extreme of using picket fences (ground vias on PCB edges) and believe that they act as a faraday cage while being cost effective. Can this be true? I set out to investigate.

Liked the excerpt? Do have a read through the article here:.

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September 09 - Crosstalk: Optimum trace spacing I have added the excerpt from the article below:

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 show how crosstalk varies with trace spacing.

Liked the excerpt? Do have a read through the article here:.

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August 09-TRACE BENDS: Their impact on Near Fields (and EMC) I have added the excerpt from the article below:

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 near fields and I have considered bends with various angles and have formed a relationship between the variations of the associated near fields with respect to the variation of the bends.

Liked the excerpt? Do have a read through the article here:.

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July 09-Stripline or Microstrip: Which is better for EMC?

My very first article! I have tried to capture a basic doubt that is on almost every electronics engineers mind – what is the actual benefit of using a stripline over a microstrip. I have tried to explain this question in simple terms and also using 3D simulations. I have added just the excerpt from the article below:

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.

Liked the excerpt? Do have a read through the article here:.

Liked the articles? Then feel free to pass it on to your friends and colleagues. If you have any questions or comments on what is presented in the articles, then feel free to drop in an email to karthik@basebandhub.com and i would be more than happy to reply to you. Not in the mood to email? – don’t worry- the comments form is now up and running. Just type in your comments and post it on the website.