μblog: engineering from the trenches

First of all, a big thank you goes out to all of the readers for making this possible. I added a Google advertisement to the right frame of this website last December to settle if I could show that advertisements can be used to generate some revenue without filling up most of the site, and it looks like you can. Some may argue that 100USD (the threshold for Google to actually pay you) in a year is not all that much, however, I never intended to make much money off this site so I am right on the mark. As for the advertisement box, I think it will stick around to see how long it takes to make the next 100. To return the favor, below are logs of earnings and traffic that other website operators judge the effectiveness of a single Google Ad unit on their site.

google_adsense-reports-daily.pdf

jan2007.pdf - feb2007.pdf - mar2007.pdf - apr2007.pdf

may2007.pdf - jun2007.pdf - jul2007.pdf - aug2007.pdf

sep2007.pdf - oct2007.pdf - nov2007.pdf

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Looking over my posts, I noticed that I often simply include links to papers without much discussion of their contents or merit. To change this, I am proposing a sort of journal club. Every week or two, I will post a freely available, scholarly paper and write up a summary of key points and a bit of analysis to motivate understanding and discussion. The range of topics will include all things related to electrical and computer engineering, physics, mathematics and neuroscience. Suggestions for papers to be “presented” are also very welcome provided the papers are freely accessible to anyone with an internet connection. I am looking at a few papers on solid-state physics/quantum mechanics so it is likely that I will pick one of those unless someone feels strongly otherwise.

The image above is from the Ancient Library of Alexandria.

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Here is a short application note (AN-404) from Analog Devices that deals with high performance analog and digital layout on the same printed circuit board.  The specific example deals with AD1845 and CS4231 codecs and demonstrates some ideas for clean power and ground plane separation, among others. The application note provides some handy numbers, such as a “ballpark” estimate inductance of a PCB trace of 1nH/mm. Another helpful hint is that the note helps prioritize the various pins of the codec on page six to optimize noise management.

While on the subject of PCB design, here is a nice tutorial covering various dielectric materials used in printed circuit board fabrication. Its main goal is to give an overview of the various properties of the materials so the designer has a better judgement of which to use for higher performance RF boards and which is most economic for medium-speed digital designs.

( an-404.pdf )

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The PP5020E is a dual-core ARM processor used in some of the mid-generation Apple iPods. It can be seen that there is layout mirroring across the horizontal axis of the chip with differentiated analog circuits on the right half of the chip. This can also be observed when looking at the ARM trademark left on the die that is clearly readable in the top part but inverted in the bottom (top bottom).

pp5020e-4x-stitched.jpg

( pp5020e.pdf )

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