For circuit simulation, we have always been enthralled with the Falstad simulator which is a simple, Spice-like simulator that runs in the browser. [Brandon] has a simulator, too, but it simulates semiconductor devices. With help from [Paul Falstad], that simulator also runs in the browser.
This simulator takes a little thinking and lets you build devices as you might on an IC die. The key is to use the drop-down that initially says “Interact” to select a tool. Then, the drop-down below lets you select what you are drawing, which can be a voltage source, metal, or various materials you find in semiconductor devices, like n-type or a dielectric.
It is a bit tricky, but if you check out the examples first (like this diode), it gets easier. The main page has many examples. You can even build up entire subsystems like a ring oscillator or a DRAM cell.
Designing at this level has its own quirks. For example, in the real world, you think of resistors as something you can use with great precision, and capacitors are often “sloppy.” On an IC substrate, resistors are often the sloppy component. While capacitor values might not be exact, it is very easy to get an extremely precise ratio of two capacitors because the plate size is tightly controlled. This leads to a different mindset than you are used to when designing with discrete components.
Of course, this is just a simulation, so everything can be perfect. If, for some reason, you don’t know about the Falstad simulator, check it out now.
So that’s why the DAC in Successive-Approximation-Register ADCs is a C2C instead of R2R ladder.
I am very curious of as Ken Shirriff’s opinion of this, as he’s discovered so many variations of integrated logic circuits from the chips he’s examined. Does this allow you to simulate the sophisticated Intel designs, or only simplest ones?
You really think you’re going to simulate billions of transistors in your browser?
These are exactly the kinds of software/simulators and games that truly support learning in a simple and interactive way. It may look like ‘just’ a simulator, but in the right hands — with the right drive to learn — it can be the foundation for a future integrated circuit designer. Really great work.
Reminds of Hard Chip.
https://store.steampowered.com/app/3033160/Hard_Chip_Demo/
I’m dubious about that. All chip design today is done with AI and CAD software so complex that it litarary runs on supercomputer-grade PCs.
Early 1970s era of drawing chips on paper is well and truly gone.
While I agree that it is unlikely for it to be commercially viable to hand draw chips, I don’t think that learning about how they are designed is a waste of time. After all, a designer who has strong fundamentals in designing for their chosen field will find CAD a multiplier not a replacement.
And lets not disregard the hobbyists. I don’t see woodworking with hand tools going out of style any time soon, even though it is not commercially viable for most. I can see some retro computing nerds LARPing as a 1970’s chip designer and making a ‘new’ computer.
He’s mine