Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
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Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#2This is a fun reminder that a MOSFET is useful as a transistor, a diode, and a capacitor.
Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#3If 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 trouble appear during the transition of Vin between the two state.
Un the middle of the range both MOSFETs are likely conducting, effectively producing a dead short!
On silicon they will design both MOSFETs to control and reduce this effect as much as possible. If you attempt to reproduce this, you might be in for a magic smoke release moment.
I did manage to somewhat reproduce this without a constant meltdown with tiny discrete MOSFETs by using two tiny ones with the most complementary specifications as possible. The goal was to have them with the least amount of overlap in conduction with regard to their respective inputs.
Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#4I like how I've been able to use MOSFETs as switches for the past 5 years while being almost completley unaware of the other things it can do. To me, it's a component that uses a small (low-voltage, low-current, low-resistance) signal to switch on a much larger path. Anything that makes it not behave like that idea is just problems for me (I spent a better part of a day debugging a circuit that works fine with a 5V arduino but not a 3.3V ESP32. I don't think I've even built a circuit with two transistors (multistage amp, flipflops...)
Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#5I like how I've been able to use MOSFETs as switches for the past 5 years while being almost completley unaware of the other things it can do. To me, it's a component that uses a small (low-voltage, low-current, low-resistance) signal to switch on a much larger path. Anything that makes it not behave like that idea is just problems for me (I spent a better part of a day debugging a circuit that works fine with a 5V a…
Discrete power MOSFETs are only switches. Discrete linear-stable MOSFETs are also usable as linear amplifiers. TFA is about mosfets on ICs. When making your own ICs, you have precise control over a lot of the variables, and the variables you have less precise control over are often going to be very similar for adjacent FETs on the same wafer, so you can do things with them that you can't do with discrete MOSFETs.
Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#6I like how I've been able to use MOSFETs as switches for the past 5 years while being almost completley unaware of the other things it can do. To me, it's a component that uses a small (low-voltage, low-current, low-resistance) signal to switch on a much larger path. Anything that makes it not behave like that idea is just problems for me (I spent a better part of a day debugging a circuit that works fine with a 5V a…
Discrete power MOSFETs are only switches. Discrete linear-stable MOSFETs are also usable as linear amplifiers. TFA is about mosfets on ICs. When making your own ICs, you have precise control over a lot of the variables, and the variables you have less precise control over are often going to be very similar for adjacent FETs on the same wafer, so you can do things with them that you can't do with discrete MOSFETs.
What stinks is that linear use has waned so much that most lateral mosfets are no longer produced. Everything is vertical switching for PWM control.
Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#7What 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).
Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#8What 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).
I'm afraid there really isn't any hobbiest simulators out there. A lot of these arrangements rely on the intrinsic characteristics and geometry of the MOSFETs used.
Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#9If 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…
The same thing would happen on silicon. It's just a question of transition time. I've seen power mosfet inverters on some board designs, but you're probably better off using a discrete logic inverter because it would be cheaper...
Re: Variations of Two-Transistor Circuits: A Tribute to the Versatility of MOSFETs
#10What 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 component (I've never ventured this far): https://ltwiki.org/index.php?title=B_sources_(complete_refer...