|
DuckConference posted:I've now reached the stage of madness where one becomes convinced that the termination provided by attaching a scope probe is fixing everything on the bus I watched a talk by an integrated circuit professor where he claimed that the first integrated circuit only worked when you stuck the oscilloscope probe on the output. The professor reverse engineered the circuit, noticed this, and asked the engineer at Texas Instruments who got the Nobel Prize for designing the first IC about it, and the guy quickly changed the subject. silence_kit fucked around with this message at 16:58 on Mar 4, 2016 |
#
¿
Mar 4, 2016 16:51
|
|
|
|
| # ¿ May 3, 2024 11:59 |
|
|
Barnyard Protein posted:i know its not the point silence kit was making, but IC's do need to be biased properly to function. his first IC was just a transistor with some biasing resistors wasn't it? it'd be pretty dopey of someone to claim it didn't work just from not being able to replicate what must be a really finicky circuit. it looks like a peanut-butter and germanium sandwich on rye. I didn't read the patent and check the professor's claims, but he said that the first IC was an oscillator circuit. I don't think that he went through the trouble of trying to reproduce the circuit--it'd be pretty impractical to do that with the exact same circuit technology. He claimed that a high value of shunt capacitance, which could be provided by an oscilloscope probe and was not shown in the patent circuit diagram, was totally necessary for the circuit to work as intended. It's just kind of an amusing story about how something held up as being a great invention was actually a flawed demonstration.
|
|
#
¿
Mar 5, 2016 00:12
|
|
|
BobHoward posted:the thing is, there's this whole spectrum of products out there where it isnt suicide to be on an old node. I have been told that this has been the case for most analog and RF integrated circuits for a pretty long time now. Those types of products don't have the volumes to justify paying the up-front cost of the most modern integrated circuit processes and it also usually isn't compelling performance-wise for them to use the most modern IC technology. The modern IC technologies are developed to make digital chips better and aren't really developed for analog. I have also been told that analog integrated circuits can be really profitable.
|
|
#
¿
Mar 5, 2016 10:53
|
|
|
longview posted:i imagine it's pretty profitable making things like OP07 opamps, they've been production for something like 30 years and I doubt the price has gone down much while the costs must be close to zero compared to when they were new Yeah, those are two good reasons. Also, one reason why I have been told that they resist commoditization is that analog chips (especially at high frequencies) can be kind of finicky to work with and also the system designers rely a lot on "undefined behavior" of the different custom chips and so it is harder to design out one for another. Although IDK if that is really true or if it is a result of there being less money overall in analog and thus less engineering effort put into engineering analog sub-systems. silence_kit fucked around with this message at 17:17 on Mar 5, 2016 |
|
#
¿
Mar 5, 2016 17:12
|
|
|
Sagebrush posted:Was that professor an engineer? Because glossing over the most blatantly important part of the thing (achieving the construction of multiple components on a single piece of silicon) to point out the one irrelevant detail that makes it ~technically wrong~ (it needs one more component to do something useful) is totally an engineer thing to do Uh, to be extremely nerdly, actually the circuit Kilby designed was on germanium, the popular semiconductor of his time. His scheme also wasn't really scalable to high levels of complexity and his circuit today probably wouldn't be called a monolithic circuit, since it relied on wire bonds as interconnects between devices, which have to be serially made. The guy who really invented the IC was Robert Noyce, and his scheme that was developed like a year after Kilby is at its core still pretty much what we do today. Kilby mostly gets the credit because Noyce wasn't alive when they awarded the Nobel Prize for integrated circuits. silence_kit fucked around with this message at 19:13 on Mar 5, 2016 |
|
#
¿
Mar 5, 2016 17:36
|
|
|
Mr Dog posted:ya risc-v is extremely ftw but i asked rjmcall about it in a couple of other threads and he said it's an academic wanking exercise because function call prolog/epilog is comically bloated or something like that I don't really understand why designing an open ISA will ever be anything more than an academic wanking exercise. People have become accustomed to high levels of complexity and sophistication in computer chips and so designing and manufacturing a computer chip that people actually would be interested in that would use this open ISA can only be done at great cost. What's the point of opening the ISA when everything else about making a computer chip is extremely costly and proprietary? I don't get it. To me it's like being a Rolls-Royce dealer and offering free lifetime car washes to prospective buyers as a way to get them in the door. Or maybe it is like being an international standards committee whose goal is to try to get the fins on all of the nuclear missiles in various countries' arsenals to be all the same shape as a way to allow interchangeability in parts. It's kind of trivial in the face of all of the other economic barriers to being able to work on real computer chip technologies. Computer chip designing is not like software, where at least in principle anybody who has free time and owns a laptop could download the Linux source code and read it and start contributing. silence_kit fucked around with this message at 16:21 on May 4, 2016 |
|
#
¿
May 4, 2016 05:56
|
|
|
What is the fastest speed used in on-board signaling in consumer electronics? What causes that speed limit--is it FR-4 attenuation, affordable transceiver speed x power limits, or is it a need to reduce system complexity and avoid obsessing over how to do the wiring?
|
|
#
¿
Jul 19, 2016 20:42
|
|
|
Why weren't the PCI-E and DDRX standards set to be 10x higher in speed? What is the technological limitation? I'm assuming that there is a technological limitation, and people are always wanting for more communication capacity between chips in PCs, etc. Maybe I'm wrong about that. silence_kit fucked around with this message at 17:30 on Jul 20, 2016 |
|
#
¿
Jul 20, 2016 17:28
|
|
|
Oh yeah, I think cosmic rays aren't that uncommon. I know a guy who spent most of his time in graduate school measuring really weak optical signals using a pretty nice silicon camera. It took hours of measurement and integrating out noise to be able to see his signal, and he said that sometimes he could see blips in his spectra, ostensibly from cosmic rays.
|
|
#
¿
Oct 21, 2016 21:35
|
|
|
Sagebrush posted:i assume that's cause of leakage or tunneling or something as it gets closer to the breakdown voltage of the dielectric? I didn't know about this, but I did a little bit of Google-searching, and found that the highest energy density ceramic capacitors with the highest dielectric constants are often made with dielectrics like barium titanate and related materials. A lot of materials in this class exhibit a lot of unusual effects like piezo-electricity (ac electricity <--> vibration conversion--this is probably why longview's circuit worked like a microphone) and ferro-electricity (the electrical analogue of a permanent magnet). The micro-scopic theory of these materials gets some material scientists and condensed matter physicists really excited, and seems really complicated. Kind of like magnetic materials (loving magnets, how do they work?) these materials are probably not very well understood fundamentally and the microscopic theory is a mess and doesn't really make good predictions.
|
|
#
¿
Jun 4, 2017 22:35
|
|
|
spankmeister posted:I have some soviet surplus teflon film capacitors but they are MASSIVE. Yeah, the dielectric constant of Teflon is 2. The dielectric constant of the material in the previously mentioned Y5V capacitors is in the 1000's.
|
|
#
¿
Jun 5, 2017 12:01
|
|
|
|
| # ¿ May 3, 2024 11:59 |
|
|
Oh man that's pretty bad, and misuses terms describing real effects in cables and circuits. However, when you are going at very high speeds, with signals at frequencies much much higher than audio frequencies, you no longer get good functionality from cabling and interconnections for free and the cable and connector construction & design actually matters. Really nice coaxial cabling which is durable, flexible, and has good phase stability for speeds of 10's of GHz can be pretty expensive, and can set you back on the order of a couple grand per cable assembly. High-quality coaxial connectors which work well up to 67 GHz are $50 a connector. silence_kit fucked around with this message at 12:52 on Aug 18, 2017 |
|
#
¿
Aug 18, 2017 00:09
|
|