9 ms·

But how transistors work is very sketchy to me

WalterBright 6y ago
You really need a course in Quantum Mechanics to understand it. But a workable description is a couple pages in most electronic textbooks. MIT covers it in their first course in electronics on Youtube.
- agumonkey 6y ago
  QM would be ultimate foundational understanding. A transistor is a valve. Here, problem solved :D
- cinntaile 6y ago
  A generic course in QM won't really help you understand electronics any better. Perhaps if you have a background in electronics or if the course makes attempts to link QM with electronics but otherwise it's just relatively abstract physics.
  - selecsosi 6y ago
    I don't know any program of study that would get sufficiently deep enough to get to semi-conductor quantum tunneling (year 2/3 class) without having some foundational E&M to motivate the QM to begin with (pure math here being a more exceptional but rare case). I think the beauty of QM at that point is that it looks and feels a lot like differential field work of EM and Lagrangian mechanics but maps to quantized numerical spaces, where jumps and little shoots like that happen all the time (spontaneous crystal domain alignment in magnets for example). If you were able to get sufficiently skilled in intro QM, it would absolutely help study in E&M. If you E&M questions are just node solving, linear algebra and difeq is all you need for E&M to solve "most" work. You do a lot of specialized versions of that in QM and as mentioned above the people doing the actual semiconductor design are so highly specialized that they are often not transferable to other problem domains and require fundamentally different approaches. Not sure any non-PHD study will really help one advance the field in a meaningful way. Study of QM i would say sufficiently enriches all physics verticals that if you are capable, it's worthy of individual pursuit, but also makes total sense to study as part of a curriculum taking place after intro E&M. Quantum Tunneling in everyday life: https://www.discovermagazine.com/the-sciences/how-quantum-mechanics-lets-us-see-smell-and-touch https://www.discovermagazine.com/the-sciences/how-quantum-me...
    - cinntaile 6y ago
      Now that you mention it. After the QM course there was a solid state physics course where quantum effects show up and where it's applied to electronics/semiconductors.
  - WalterBright 6y ago
    > A generic course in QM won't really help you understand electronics any better. Caltech had an elective course for freshman about how semiconductors worked up through flip-flops and registers. I took it. It involved QM and yes, tunnelling. So it's doable for mortals.
    - cinntaile 6y ago
      Yes, I can see how it would help there. I was more thinking of the situation where you take a QM course and don't apply it to an electronics problem. I agree that it's doable for mere mortals, but it might take a fair bit of time!
    - wuschel 6y ago
      Very interesting discussion thread re how much knowledge you need or can aquire on complex technology platforms. The goal is key here, I presume. I read Charles Perzhold's Code, worked through parts of SICP, developed a bit of high level code software, have a very good knowledge of chemistry, lithographic processes (and QM, half forgotten by now). And yet it is not enough to get a good understanding of the modern computer - EE, compilers, OS de, networks, ... wiring the while thing together, et cetera. I see the point in historical approaches, but it is quite time consuming. At the end, you will most likely attack problems at one to three levels in the "stack". What would you consider to be an above average conceptual tool and skill set for the modern hacker?
- SomeoneFromCA 6y ago
  Do FETs really require QM to understand them?
  - WalterBright 6y ago
    The handwavy explanations you'll find in electronics textbooks are sufficient to enable you to effectively design electronic circuits around them. But personally, I found those explanations inadequate.
- amelius 6y ago
  You need QM to even explain why electrons don't fall into the nucleus. So I'd say if you want to understand anything then you need QM. There's this quote which I think applies here: if you want to bake an apple pie from scratch, you first need to invent the universe.
  - WalterBright 6y ago
    True, but transistors do not behave in a newtonian physics manner, whereas we do just fine understanding most physics using conventional newtonian mechanics.
    - amelius 6y ago
      This makes me wonder what Newtonian physics we actually use in computing?
      - WalterBright 6y ago
        Non-transistor electronics relies on Maxwell's Equations. While not Newtonian mechanics, it is part of classical (pre-Einstein) physics.
TheOtherHobbes 6y ago
You can get a hand-wavey understanding quite easily. Digital circuits use a fairly simple model, and that's not difficult to pick up. Analog circuits can use a number of more complex models, and they're more of a challenge, depending on what you're trying to do. Actually designing transistors - defining dopant levels, topology, and process steps - is a very specialised skill that very few people have. And modern PC motherboards are marvels of electromagnetic engineering as well as electronic engineering. You have GHz signals running reliably on circuit boards with multiple layers. Getting those to work is another very specialised skill. So it would quite something to find someone who had a professional-level understanding of all the levels: from silicon chemistry and quantum physics at one extreme, to electromagnetic design, to all the different levels of electronic design, to binary machine language and processor architectures, to OS design and application software, to all the various data structures and encodings that make all of the above useful.
bserge 6y ago
Kind of blew my mind when I learned they are analog... I previously thought of them as one of the most basic digital components, because they're used in every digital circuit.
- dekhn 6y ago
  I don't know that there is anything truly digital in the universe, except perhaps quantized components like spin. Digital computers are an abstraction implemented using error control and a number of other things, but they ultimately fail like analog objects.
- tasty_freeze 6y ago
  My job for the past 30 years has been designing ASICs, so all the analog stuff is not my concern. Prior to that I designed at the TTL level. I'd spend months working on some project, thinking in terms of logic an timing, and eventually we'd have boards made. We'd stuff a few prototypes and set them up on the lab bench to commence debugging. Every time at this phase I'd suffer the existential horror the first time put an oscilloscope to the circuit -- the clock wasn't square! Signals would ring, and other signals which hadn't transitioned would sometimes bounce a bit. Setup and hold times could be pretty well estimated, but it was still an estimate. Then there were phantoms that might appear on the scope or real issues that would not show up on the scope because the probe lead was enough to make what was measured not the same as what was actually going on.
  - WalterBright 6y ago
    That reminds me of working on the stabilizer trim system on the 757. I got used to thinking of the parts as rubber, bending and twisting on the high loads an airplane has in flight. So much so that when the hardware was finally available, I was surprised at how rigid and immovable it felt under my hands with my puny human strength.
  - bserge 6y ago
    Way over my head, but damn it sounds interesting :D
  - 6y ago

You really need a course in Quantum Mechanics to understand it. But a workable description is a couple pages in most electronic textbooks. MIT covers it in their first course in electronics on Youtube.

agumonkey 6y ago
QM would be ultimate foundational understanding. A transistor is a valve. Here, problem solved :D
cinntaile 6y ago
A generic course in QM won't really help you understand electronics any better. Perhaps if you have a background in electronics or if the course makes attempts to link QM with electronics but otherwise it's just relatively abstract physics.
- selecsosi 6y ago
  I don't know any program of study that would get sufficiently deep enough to get to semi-conductor quantum tunneling (year 2/3 class) without having some foundational E&M to motivate the QM to begin with (pure math here being a more exceptional but rare case). I think the beauty of QM at that point is that it looks and feels a lot like differential field work of EM and Lagrangian mechanics but maps to quantized numerical spaces, where jumps and little shoots like that happen all the time (spontaneous crystal domain alignment in magnets for example). If you were able to get sufficiently skilled in intro QM, it would absolutely help study in E&M. If you E&M questions are just node solving, linear algebra and difeq is all you need for E&M to solve "most" work. You do a lot of specialized versions of that in QM and as mentioned above the people doing the actual semiconductor design are so highly specialized that they are often not transferable to other problem domains and require fundamentally different approaches. Not sure any non-PHD study will really help one advance the field in a meaningful way. Study of QM i would say sufficiently enriches all physics verticals that if you are capable, it's worthy of individual pursuit, but also makes total sense to study as part of a curriculum taking place after intro E&M. Quantum Tunneling in everyday life: https://www.discovermagazine.com/the-sciences/how-quantum-mechanics-lets-us-see-smell-and-touch https://www.discovermagazine.com/the-sciences/how-quantum-me...
  - cinntaile 6y ago
    Now that you mention it. After the QM course there was a solid state physics course where quantum effects show up and where it's applied to electronics/semiconductors.
- WalterBright 6y ago
  > A generic course in QM won't really help you understand electronics any better. Caltech had an elective course for freshman about how semiconductors worked up through flip-flops and registers. I took it. It involved QM and yes, tunnelling. So it's doable for mortals.
  - cinntaile 6y ago
    Yes, I can see how it would help there. I was more thinking of the situation where you take a QM course and don't apply it to an electronics problem. I agree that it's doable for mere mortals, but it might take a fair bit of time!
  - wuschel 6y ago
    Very interesting discussion thread re how much knowledge you need or can aquire on complex technology platforms. The goal is key here, I presume. I read Charles Perzhold's Code, worked through parts of SICP, developed a bit of high level code software, have a very good knowledge of chemistry, lithographic processes (and QM, half forgotten by now). And yet it is not enough to get a good understanding of the modern computer - EE, compilers, OS de, networks, ... wiring the while thing together, et cetera. I see the point in historical approaches, but it is quite time consuming. At the end, you will most likely attack problems at one to three levels in the "stack". What would you consider to be an above average conceptual tool and skill set for the modern hacker?
SomeoneFromCA 6y ago
Do FETs really require QM to understand them?
- WalterBright 6y ago
  The handwavy explanations you'll find in electronics textbooks are sufficient to enable you to effectively design electronic circuits around them. But personally, I found those explanations inadequate.
amelius 6y ago
You need QM to even explain why electrons don't fall into the nucleus. So I'd say if you want to understand anything then you need QM. There's this quote which I think applies here: if you want to bake an apple pie from scratch, you first need to invent the universe.
- WalterBright 6y ago
  True, but transistors do not behave in a newtonian physics manner, whereas we do just fine understanding most physics using conventional newtonian mechanics.
  - amelius 6y ago
    This makes me wonder what Newtonian physics we actually use in computing?
    - WalterBright 6y ago
      Non-transistor electronics relies on Maxwell's Equations. While not Newtonian mechanics, it is part of classical (pre-Einstein) physics.

TheOtherHobbes 6y ago

You can get a hand-wavey understanding quite easily. Digital circuits use a fairly simple model, and that's not difficult to pick up. Analog circuits can use a number of more complex models, and they're more of a challenge, depending on what you're trying to do. Actually designing transistors - defining dopant levels, topology, and process steps - is a very specialised skill that very few people have. And modern PC motherboards are marvels of electromagnetic engineering as well as electronic engineering. You have GHz signals running reliably on circuit boards with multiple layers. Getting those to work is another very specialised skill. So it would quite something to find someone who had a professional-level understanding of all the levels: from silicon chemistry and quantum physics at one extreme, to electromagnetic design, to all the different levels of electronic design, to binary machine language and processor architectures, to OS design and application software, to all the various data structures and encodings that make all of the above useful.

bserge 6y ago

Kind of blew my mind when I learned they are analog... I previously thought of them as one of the most basic digital components, because they're used in every digital circuit.

dekhn 6y ago
I don't know that there is anything truly digital in the universe, except perhaps quantized components like spin. Digital computers are an abstraction implemented using error control and a number of other things, but they ultimately fail like analog objects.
tasty_freeze 6y ago
My job for the past 30 years has been designing ASICs, so all the analog stuff is not my concern. Prior to that I designed at the TTL level. I'd spend months working on some project, thinking in terms of logic an timing, and eventually we'd have boards made. We'd stuff a few prototypes and set them up on the lab bench to commence debugging. Every time at this phase I'd suffer the existential horror the first time put an oscilloscope to the circuit -- the clock wasn't square! Signals would ring, and other signals which hadn't transitioned would sometimes bounce a bit. Setup and hold times could be pretty well estimated, but it was still an estimate. Then there were phantoms that might appear on the scope or real issues that would not show up on the scope because the probe lead was enough to make what was measured not the same as what was actually going on.
- WalterBright 6y ago
  That reminds me of working on the stabilizer trim system on the 757. I got used to thinking of the parts as rubber, bending and twisting on the high loads an airplane has in flight. So much so that when the hardware was finally available, I was surprised at how rigid and immovable it felt under my hands with my puny human strength.
- bserge 6y ago
  Way over my head, but damn it sounds interesting :D
- 6y ago