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Julia receives DARPA award to accelerate electronics simulation
111–120 of 175 posts
Re: Julia receives DARPA award to accelerate electronics simulation
#112This seems very promising to me One big part of circuit simulation is solving differential equations. That's the whole inducer, resistor, capacitor thing. Julia has hands down the best toolkit for differential equation solving. Most circuit simulators today are going to be using old methods invented in the 60's-80's. Neglecting the state of the art developments. Someone made a blog post recently comparing the time to…
As someone that actually uses LTSpice I’ve never considered speed to be an issue. The main draws for it are 1. It’s free unlike Altium addons or orcad p-spice 2. Graphical, I’m happy to code things but code literacy varies widely among EEs. Much easier to share results when it looks like a schematic 3. Good enough component library. The time spent finding and inputting component parameters are gonna be way bigger tha…
1. yeah these are super expensive. Even the cheaper ones are close to a grand a liscense
2. definately got to have a front-end. Writing netlist by hand is suffering.
3. Interestingly (to me) the components are more or less portable between them. With only a little manual writing i have translated components from ORCAd p-spice, to ISpice, to LTSpice. No idea on the liscensing for that. (I suspect the IC manufacturers produce these)
I think speed is very much a question of what kind of thing you are doing. I agree it often doesn't matter. and without your 3 points, it certainly doesn't matter
Re: Julia receives DARPA award to accelerate electronics simulation
#113Earlier quoted context omitted.
Just curious, what's your current works involves?
I'm a math grad student studying numerics and scientific computing actually. But I do not see a future in it as it does not seem to pay well and the relevant jobs are scarce. So it seems risky to get into it as a career when I can pivot to a more profitable SWE role or do something with ML.
1) If you are a US-born citizen and qualify for a security clearance, jobs aren't as scarce as you think.
2) You are right the pay is worse in the public / government side. I will say - you might not believe me now, but it really is true that once you make enough money to pay all your bills, suddenly more money is less motivating than the ability to work on interesting problems.
What I just said above supposes that most lab work is interesting, which is not not the case, but I still think it's better than the average SWE's workload at your average tech company, just based on my personal experience having done both at different times in my career.
Re: Julia receives DARPA award to accelerate electronics simulation
#114This seems very promising to me One big part of circuit simulation is solving differential equations. That's the whole inducer, resistor, capacitor thing. Julia has hands down the best toolkit for differential equation solving. Most circuit simulators today are going to be using old methods invented in the 60's-80's. Neglecting the state of the art developments. Someone made a blog post recently comparing the time to…
As someone that actually uses LTSpice I’ve never considered speed to be an issue. The main draws for it are 1. It’s free unlike Altium addons or orcad p-spice 2. Graphical, I’m happy to code things but code literacy varies widely among EEs. Much easier to share results when it looks like a schematic 3. Good enough component library. The time spent finding and inputting component parameters are gonna be way bigger tha…
LTSpice is my go-to circuit simulator, but I have spent weeks of my waking life waiting on it to run simulations. My current demon is simulating a 1 MW DC power supply to validate current output smoothing solutions in low load scenarios. The topology is a delta-delta and delta-wye transformer, each feeding a summing bridge rectifier, the two rectifiers have their negative legs tied together and the positive legs are the outputs.
I only simulate one pulse (about 3 ms), but the simulation takes minutes to resolve the inrush. Tuning circuit impedances to match measurement is a real pain. At this point I'm just going to take many more direct measurements. If it was quick I would have written a script to scan through unknown parameters to maximize correlation with measurements, but that isn't reasonable when the simulation fails after several minutes of trying for most values.
Re: Julia receives DARPA award to accelerate electronics simulation
#115A modern circuit simulator, that has a fully featured programable API, that can be run from a real modern programming language, would be a dream. Every simulator i have used has been pretty limited in that way, or at least those features were not well advertized. Even the insanely expensive ones. I mean the most expensive ones (like $100K liscense type deals, like Cadence) are if anything even less modern from a user…
A lot of semi companies have built their own simulation environments because the EDA vendor's provided tools are very limited in what they can do and difficult to use. Many users go to Python, Excel or MATLAB because the programming/math capabilities of the EDA tools are inadequate. Over time these home-grown environments become a burden and the developer disowns it and it becomes a headache. The EDA tools have no ec…
It's an absolute nightmare. Cadence added support for Matlab calculations on simulator outputs, but its clunky and inconsistent. Don't even get me started on how long it takes to do basic calculations on numbers that should already be in memory...
Re: Julia receives DARPA award to accelerate electronics simulation
#116Earlier quoted context omitted.
That is an interesting optimization trick, essentially a brute force search over a parameter space in order to minimize silicon area, I am assuming this was for cells that were going to be replicated many times on the same die?
Something like that is the idea. Silicon area is what costs money. Use as little as possible while still being fast enough to beat the clock-rate of your system. PSO's are way better than brute force. but yeah. It was a purely academic work for a masters level CS unit. I had just finished a masters level electrical engineering unit on silicon circuit design. Where the final project was to design an adder that minimiz…
Thank you for writing it up and posting it here, one of the more interesting comment threads.
Re: Julia receives DARPA award to accelerate electronics simulation
#117Earlier quoted context omitted.
> From your other comments, it seems that the general principle is to create a simple model that captures most of the behavior then apply corrections on top of that. It's not applying corrections as in doing a taylor expansion and then adding terms to it, it's basically a projection of the systems. The basic details are in the CTESN paper, though I think there's improvements that haven't been published yet to make it…
> improvements that haven't been published yet to make it work in this domain Are you able to share what some of those are? > You can choose what parameters to fix and which to keep variable over the training process Can you explain more about the parametrization? Do your parameters correspond 1-to-1 with schematic parameters like transistor sizes or resistance/capaciance values? Or internal transistor model paramete…
> Are you able to share what some of those are?
The papers are being written, so should be public in a few months, but I can't go into detail quite yet.
> Can you explain more about the parametrization? Do your parameters correspond 1-to-1 with schematic parameters like transistor sizes or resistance/capaciance values? Or internal transistor model parameters? Or are they more abstract mathematical parameters?
All of the above. We have a fully symbolic representation of the circuit, so any part of it can be replaced by a parameter. Transistor sizes and device values are a natural thing to do, but the system is generic.
> % SPICE Accuracy"
Heh, we've actually found some SPICE implementations to have significant numerical issues when compared to our baseline simulator, which has some fancier integrators - I suppose that would make us worse on this metric ;).
> That might be an interesting thing for you to consider investigating through the course of your research.
Yup, characterizing error trade offs is one of the primary outcomes of this research.
> One last question - why did you choose this particular DARPA project? Was it any specific interest/relationship with the circuit design industry? Or did it just happen to be a very cool application of CTESN?
Circuit design was my first job, and I have a second desk with a soldering iron and test equipment, though it's collecting dust ;). I have a bit of a hypothesis that - between open source tooling becoming more mature, and more people getting into the chip design space for custom accelerators - we're on the cusp of a major overhaul in EDA tooling. I thought we'd be good at it, so I was advocating internally for us to start up a team in the domain. We have a bit of an "if you can get it funded it, you can do it" attitude to those sorts of things, so I was trying to find the money to jumpstart it, and this is that.
Re: Julia receives DARPA award to accelerate electronics simulation
#118Huh, did not expect our press release to end up on HN, but I'm the PI on this project, so AMA, I guess. Will jump into the questions already asked here and provide some context.
I've been doing analog integrated circuit design for a decade and I'm somewhat skeptical that this is practical. I hope you can convince me otherwise because this would be great to avoid multi week simulations. From your other comments, it seems that the general principle is to create a simple model that captures most of the behavior then apply corrections on top of that. Can you elaborate on how the model is trained…
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Re: Julia receives DARPA award to accelerate electronics simulation
#119Huh, did not expect our press release to end up on HN, but I'm the PI on this project, so AMA, I guess. Will jump into the questions already asked here and provide some context.
Is there a good way of doing analytic analysis on circuits with a sensible GUI, if restricted to passive components? I have a few interesting problems that I'd like to analytically explore, but the best I've been able to find is OpenModellica piped into something like Maxima or sympy. Mathematica looks like it has a nice tool -- system builder -- but it costs a lot and I don't have a license.
Julia would of course be ideal for this, and I very much like where you project is going!
Re: Julia receives DARPA award to accelerate electronics simulation
#120Huh, did not expect our press release to end up on HN, but I'm the PI on this project, so AMA, I guess. Will jump into the questions already asked here and provide some context.
Is there a good way of doing analytic analysis on circuits with a sensible GUI, if restricted to passive components? I have a few interesting problems that I'd like to analytically explore, but the best I've been able to find is OpenModellica piped into something like Maxima or sympy. Mathematica looks like it has a nice tool -- system builder -- but it costs a lot and I don't have a license. Julia would of course be…
The underlying representation of the simulator we have is symbolic, so you can have it spit out a https://github.com/JuliaSymbolics/Symbolics.jl representation of the equations that make up the circuit and feed it into a symbolic integrator from there. Not a focus for us, but I don't see why it wouldn't work.