Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs

researchgate.net

Post reply on HN
Print view View original

31–35 of 35 posts

Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs

#31

Post by guenthert »

amelius wrote: post #28
bombela wrote: post #3

If you happen to play with electronics, most circuits in the paper cannot be built at home realistically. Those circuits work best with MOSFETs built in silicon, with very precise tolerances. For example the first circuit; the inverter; when Vin is low, the bottom NMOS is off, the top PMOS is on. And vice versa when Vin is at the high voltage suitable for the devices. Statically this works pretty well. But the troubl…

You can buy push-pull configured transistor pairs in a package.

CD4007 comes to my mind, but that one is ancient (still available though in a breadboard friendly package).

Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs

#32

Post by madengr »

nomel wrote: post #10
foobarian wrote: post #7

What layperson-friendly tools are out there to simulate simple analog circuits? For years now I've been going to the ancient app at https://www.falstad.com/circuit/ but wondering that surely there must be something that Real Electronics Builders use. (I intentionally did not say Engineers because I assume that would be covered by the pricy and/or UI-challenged tools like spice and company).

For simple circuits, LTspice: https://www.analog.com/en/design-center/design-tools-and-cal... And it's definitely used by real engineers. It's for making switching power supplies, so it can handle fairly complex circuits. I wouldn't venture into RF/high speed circuits with it though, since the included parasitics aren't sufficient. And, custom functions are supported, so, I believe, you can put whatever maths in a co…

The parasitics all depend on the model, as I used LTSpice recently for an RFIC class for a 5 GHz LNA. The .net directive allows two-port analysis and even a Smith chart. Though Microwave Office is my go-to tool.

Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs

#33

Post by amelius »

kayson wrote: post #29
amelius wrote: post #27

Earlier quoted context omitted.

> a few are genuinely clever Another perspective is that it would take a computer only a few minutes to generate all these circuits and test them for usefulness in a simulator.

That's harder than you might think. How would you test for all possible uses? Even if you looked at something fundamental like an N-port, you'd still have to define metrics for usefulness and many of the topologies in the paper would evade most obvious circuit metrics.

Well, you are right to some extent, but in practice you don't need "all possible uses" and instead you are looking for a specific behavior, which you can easily encode in a test that uses a simulator.

Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs

#34

Post by ajnin »

amelius wrote: post #33
kayson wrote: post #29

Earlier quoted context omitted.

That's harder than you might think. How would you test for all possible uses? Even if you looked at something fundamental like an N-port, you'd still have to define metrics for usefulness and many of the topologies in the paper would evade most obvious circuit metrics.

Well, you are right to some extent, but in practice you don't need "all possible uses" and instead you are looking for a specific behavior, which you can easily encode in a test that uses a simulator.

The article mentions that circuit 23 was found using an "exhaustive search", so presumably using an automated means.

But I don't think that works in the general case to find all "useful" circuits. For example figure 27 is a pA source and requires 2 precise control voltages and a clock source. 39 is a peak detector. Does not seem that easily encoded.

Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs

#35

Post by SAI_Peregrinus »

nomel wrote: post #10
foobarian wrote: post #7

What layperson-friendly tools are out there to simulate simple analog circuits? For years now I've been going to the ancient app at https://www.falstad.com/circuit/ but wondering that surely there must be something that Real Electronics Builders use. (I intentionally did not say Engineers because I assume that would be covered by the pricy and/or UI-challenged tools like spice and company).

For simple circuits, LTspice: https://www.analog.com/en/design-center/design-tools-and-cal... And it's definitely used by real engineers. It's for making switching power supplies, so it can handle fairly complex circuits. I wouldn't venture into RF/high speed circuits with it though, since the included parasitics aren't sufficient. And, custom functions are supported, so, I believe, you can put whatever maths in a co…

One can also use KiCAD to generate netlists for other SPICE tools like ngspice.

Most EDA packages will include some sort of simulator, often SPICE-based. The fancier ones for RF work include or integrate with field solvers.

Post reply on HN