Month: May 2015

Applied chaos theory

Today I am having fun with a very nerdy circuit – Chua’s circuit. An electronic circuit that exhibits chaotic behaviour. I had a hard time getting this circuit to oscillate, but finally, after some prayers, throwing beans and doing black magic here it is:

Chua's circuit

Chua’s circuit

Heheh, looks terrible, but works. Here are some cool pictures of the Lorenz attractor. I was not able to spread the two twirls further, as my LC tank (in fact gyrator-capacitor tank) would stop oscillating.

Lorenz attractor curves tiral 1

Lorenz attractor curves tiral 1

Lorenz attractor curves tiral 2

Lorenz attractor curves tiral 2

Lorenz attractor curves tiral 3

Lorenz attractor curves tiral 3

Lorenz attractor curves tiral 4

Lorenz attractor curves tiral 4

And in case you also want to see how it sounds like and what my setup was here’s a short video clip:

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How long are your wires?

Lately I have been busy working on my analog to digital converters, I have gotten up to the phase of laying out the transistors and interconnect. A question struck me – how long are my wires? I mean, the total sum of lengths of all my wires? Usually the average bus length does not exceed a few hundred micrometers before the signals are being re-buffered, but we have hundreds, if not thousands of them sometimes. To illustrate what I mean, let’s have a sneak on my chip’s interconnect:

Here are a few of the metal layers shown separately. Sorry, can’t afford to show you the rest of the system and more than the metal layers as it’s still a secret, shhh… : )

A close view of vertical interconnect

A close view of vertical interconnect

Vertical interconnect

Vertical interconnect

Horizontal interconnect

Horizontal interconnect

A close view

A close view

Horizontal interconnect two

Horizontal interconnect two

Considering the fact that some SoCs can have up to 16 metal layers, we can continue our list forever. Notice the ruler showing the scale of the first figure, the unit is in micrometers. I was wondering what is the best way to calculate all sums, however Domenico Pacifici has done this analysis in his PhD thesis before me and I dare to reprint one of his figures.

Total interconnect length in km/cm2 vs year of process development

Total interconnect length in km/cm2 vs year of process development

Wowsh, I had guesses that it may be in the order of hundreds of meters, but 10km? Also notice the log scale, nicely matching with Moore’s law. Remember also that in 2008 the cutting-edge process nodes were at about 90 to 65nm. Some large SoCs may reach areas of about 5 cm^{2}, this means that the computer chips we have in an average town contain enough wire to probably reach the Moon? Impressive! Now keep calm and continue pushing polygons!

VIP pass to a holograpahy lab

Greetings! I am proud to present our brand new labs at the Institute of Optical Materials and Technologies! After a whole year of construction work, repairs and various emotions, the renovated labs are finally ready for action. And for our (many…) readers exclusively, I will present our optical arsenal:

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Overview of the CW lasers lab

Our CW lasers lab is home of Coherent’s mighty Verdi laser – a DPSS at 532 nm wavelength and a maximum output power of 12 W. Right next to it is the Japanese hero from Kimmon – a He-Cd laser at 441,6 nm and 0,18 W output.

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He-Cd laser and a huge mirror

We also got two laser diode systems from BWtek at 780 and 635 nm and a few more systems from Cobolt and Coherent – no need for an extensive description of everything for now, hopefully you’ll meet again with some of these lasers in a future post that will be more specific. The important thing is we got the reds, the greens and the blues covered. So a multicolour hologram, maybe, someday? It will be very exciting!

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Lots of optomechanics as well…

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These tools are never enough… And never organised

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Preparation for a holographic recording setup… You can see how huge the laser spot is and we will make it even bigger in order to “capture” the object

Apart from the CW lab, we also got a separate pulse lab, where our two Nd:YAG lasers rest for now. They are around 1 μm (I always forget the exact value) but they are mainly used for second harmonic generation. Third and fourth harmonics are also possible although weak.

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This guy is from Stuttgart (or so it says on the sticker)

Hmm, this post turned out shorter than I imagined… Sorry! I hope you liked this sneak peek of the labs and I will be glad to show you some *real* work soon. In the meantime, here’s an abstract-spectrum-thing painting I made for our new office rooms at the Institute – if my colleagues like it, we may even hang it on the wall: