Hello LV

You need study HDL (VHDL or Verilog) and use appropriate tools like Modelsim
or Active HDL

The gates have a truth table that can be easily implemented in LTspice
with A devices or .MACH. The only things to take care of are the
transition times, since LTspice is a SPICE and, thus, an analog
simulator: it will consider everything, not just the before/after
states, which means there may be occasional spikes, that's all.

--
Vlad
______________________
ltspicegoodies.ltwiki.org v2:
quite universal analog/digital filter,
power electronics, signal processing,
easy to work with math functions,
digital models, and rants.

Hello
You need study HDL (VHDL or Verilog) and use appropriate tools like Modelsim or Active HDL
--
Best Regards
Victor

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A web search indicates that reversible gates can be made from logic that has 3 inputs and 3 outputs. These can be built in LTspice, using the special A-devices or perhaps even with real parts. But LTspice is an analog simulator, with somewhat limited application to pure digital circuits.

Aditya wrote, "I wanted to know if it is possible to implement reversible logic gates like "Toffoli" and "Feynman" in LTSpice."

LTspice (note the spelling, the 's' is not capitalized) is an electronic circuit simulator.

If you have a circuit that can be built using transistors, diodes, resistors, capacitors, inductors, and if you have SPICE models for the semiconductor parts, it can be simulated in LTspice.? It can even simulate circuits that have some other components (valves or vacuum or thermionic tubes) or some imagined devices described mathematically (controlled sources, or math functions).

Do you have a real electronic circuit for the kind of logic gates you want to simulate?? Then it can probably be simulated in LTspice.? If there is no real functional equivalent for the thing you want, then maybe, or maybe not.

Now it's your job to see if there are SPICE models for these devices.

Andy

Aditya wrote, "I wanted to know if it is possible to implement reversible logic gates like "Toffoli" and "Feynman" in LTSpice."

LTspice (note the spelling, the 's' is not capitalized) is an electronic circuit simulator.

If you have a circuit that can be built using transistors, diodes, resistors, capacitors, inductors, and if you have SPICE models for the semiconductor parts, it can be simulated in LTspice.? It can even simulate circuits that have some other components (valves or vacuum or thermionic tubes) or some imagined devices described mathematically (controlled sources, or math functions).

Do you have a real electronic circuit for the kind of logic gates you want to simulate?? Then it can probably be simulated in LTspice.? If there is no real functional equivalent for the thing you want, then maybe, or maybe not.

Now it's your job to see if there are SPICE models for these devices.

Andy

I am new to reversible computing and reversible logic in general. I wanted to know if it is possible to implement reversible logic gates like "Toffoli" and "Feynman" in LTSpice. Any help would be really appreciated.
Thank you.
Aditya

The ADHV4702 is a small signal op amp with operation to 220V and 10MHz GBW. Add an HV current buffer, schematic same as LH0002 and you are set. You'll have to chase down some HV NON and PNP devices as the LTspice library only goes to 150V. And you will likely need a heat sink if there is more than 1mA or so load current.

Will do. Just thought I'd check to see if it's a known bug before assembling the stuff.

dcorner1953 wrote, "LT refuses to bring up the current meter or thermometer icons for just two components in the entire circuit"

Just to be clear, transistors have 3+ terminals, so the currents you're talking about are their pin currents.? You can't measure (plot) the current on a transistor, but you can plot the current into each pin.? Make sure to position the pointer on the wire going to that pin, otherwise the current meter won't appear.

If the transistor model is a .SUBCKT model, you should enable saving subcircuit currents.? That setting is in the Control Panel, Save Defaults tab.? Also, if you used a .SAVE or .PLOT or .PRINT command anywhere on your schematic, those commands limit what voltages and currents are saved, so don't use them unless you really need them.

It is not a known bug.? Certainly nothing that affects transistors in the upper left quadrant of your schematic -- or the upper left I/V quadrant -- or the upper left quadrant of the bridge -- or whatever else you meant.

? ? "What other surprises might LT have in store for this circuit?"

Well, for one thing, the values you used for R34 and L2 are ridiculous, so don't use those!? Also, your 2N3055 might need to be reconsidered.? And don't use a 1N34 as the power rectifiers!? You knew that, right?

? ? "Seems LT glitched something in the original file, but how did copying do a partial fix?"

Isn't it obvious?? When you did that copy, the moon eclipsed Mercury and that rearranged all the charm quarks in the copied version.? I could tell by looking at your schematic, it was as plain as day.

:-)

Now where did you put that schematic?? Oh, wait, you didn't!? I guess my mind-reading skills need a little work.

Stop trying to make us guess what's in your schematic.? Upload it.

Andy

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We can't help much unless you let us see more of what you are doing. Upload your .ASC file AND all the other files required to run the simulation, but not .RAW? and .LOG files,? in a ZIP archive to Files => Temp, and then tell us you did that.

Update: I've f6 copied the entire schematic into a new blank document. This copy shows current and temp for one of the two affected transistors. Tried copying the copy into yet another blank document, with no improvement. Seems LT glitched something in the original file, but how did copying do a partial fix?

Update: I've f6 copied the entire schematic into a new blank document. This copy shows current and temp for one of the two affected transistors. Tried copying the copy into yet another blank document, with no improvement. Seems LT glitched something in the original file, but how did copying do a partial fix?

I meant to add, I've completely isolated the quadrant from the rest of the circuit and tested it on its own load. It is identical to the upper right quadrant, which has no problem.

I'm designing an H bridge driver in LTSpice 17.0.19.0. The bridge is working very well, but LT refuses to bring up the current meter or thermometer icons for just two components in the entire circuit, the transistors in the upper left quadrant. The quadrant must be delivering current, since the load current and waveform are as expected.
I've tried deleting and reinstalling the components, which didn't help. I don't understand LT internals well enough to even hypothesize problems and solutions.

Hoping this is a known bug. It's not holding me up just now, and if needed I can put in 1 milliohm resistors to check branch current. But it is a worry. What other surprises might LT have in store for this circuit? This must be my twentieth design at least, and this is the first time I've seen this.

? ? "I have seen advice not to use the internal R in the inductor for reasons that are not clear to me ..."

I am not aware of a reason not to use the internal R in the inductor.? I may be forgetting something, but I think it is always better to use the built-in resistance.? The Help page even says this:? "It is better to include the device parasitics Rpar, Rser, and Cpar in the inductor than to explicitly draft them. LTspice uses proprietary circuit simulation technology to simulate this physical inductor without any internal nodes. This makes the simulation matrix smaller, faster to compute and less likely to be singular over all time-step sizes."

? ? "... I like having the R shown on the schematic as a reminder."

You can make the internal resistance value visible, by doing this:

Add a value for Series Resistance.? The value can also be a parameter with curly braces, such as {RR}.? Then Ctrl-right-click on the inductor symbol, find the line that has Rser=... (it's probably on the SpiceLine), and double-click in the "Vis." column until there is an 'X' there.? Then click OK.

It is not quite as obvious as the separate resistor.? But it also makes your schematic a little more compact.

Andy

Our replies have gotten out of sync, and occasionally not 100% correct.? But indeed, as John (more or less) noted, David's 'D' unmodified schematic:
-- runs without errors, but
-- it shows little evidence of .STEPping (the .STEP command is not missing, but the K command controlled by it is missing), and
-- it shows no resonance splitting because the inductors are not coupled to one another.

When the K command is added back, then the splitting is evident when K = 0.01, but not for K = 0.0001.

Ignore the comments about the error with that schematic.? That was a mistake.? It was caused by a typo, when adding the K command back to the 'D' schematic.? The last uploaded iteration of the schematic ("DesplitterDJMW.asc") has no errors, and it shows resonance splitting at both V(A) and V(B).

Here are a few other points to note, though they have nothing to do with your objectives with this simulation:

-- You can specify more than 65535 frequency steps with the .AC command, but LTspice reduces the number to 65535.? Therefore, if you need the frequency steps to be closer together, or if you thought you would get more than 65535, you ought to be aware that it ultimately limits you to that number. and quietly tells you in the .log file.
-- The "SINE(0 1 1000000)" attached to V1 has no effect on the .AC simulation.? That is for .TRAN simulations only.? (Well, the DC value of the SINE function does affect it; but the frequency and amplitude have no effect.)
-- I strongly urge you to use multipliers, rather than numbers like 1000000 or 0.000001.? You can write them as 1MEG or 1e6, and 1u or 1e-6, so you don't have to count the digits, and eventually get it wrong.? We are only human.
-- Inductors in LTspice can have a built-in series resistance.? Right-click on the inductor symbol and add a number for "Series Resistance".? By default it doesn't show on the schematic, but you can change that.? The simulation runs a little faster if you do it that way instead of adding a separate resistor, but you might not notice the difference in this case.? And you might prefer the separate resistor anyway.

Andy

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Your D upload runs but without stepping K because the .STEP command is missing.

I am now seeing the splitting.? No idea why my d upload was giving you guys problems though, i downloaded that file and it ran here without errors.

Anyway thanks, issue closed

On Fri, Feb 26, 2021, 3:00 PM Andy I <AI.egrps+io@...> wrote:

John asked, "How can it give identical runs with .step param K list 0.0001 0.01?"

Because the parameter K was not used anywhere.? It's just a dummy parameter, where the entire circuit is unaffected by it.? (That is, in David's version-D uploaded circuit.)

Andy

David, I don't know if this helps with the original question.

Long ago I knew of the effect where the resonance splits depending on coupling, but in a different context: using LC filters in RF tuned circuits such as a front-end or IF strip of a radio receiver.? In that case, signal enters at one end and comes out the other.? As far as signal flow goes, it is inherently unbalanced between the two halves.

In the newer case, I guess it's for power transfer, with two inductors receiving power from a third.? The two that are co-located are probably at right angles to receive power regardless of orientation.? The fact that there are two means they can interact, despite being at right angles which greatly reduces their magnetic coupling with each other.

The first circuit you uploaded had perfect symmetry between the two LC filters.? That's the same as having two electrical circuits in parallel.? When the signals in each one match the other, you can reduce?the two circuits?into one, with all resistors halved, capacitors doubled, etc.? So, with identical voltages and currents in the two LC filters, the two LCs reduce to one LC filter, so there is no double-bump in the response.? They have to be unequal in some way, to?get the double-bump in the response.

I think it means even the real circuit does not have a double-bump response if you manage to position it JUST RIGHT with precisely the same signal amplitude and phase in both pickup coils.? In the vast majority of circuits and orientations, you're left with two unequal coupled tuned circuits, thus giving the double-bump.? The only way to see it in simulation is to avoid the case with equal coupling to both coils.

Andy

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I hope my upload has sorted this and we can close the thread.

John wrote, "...?without stepping because you deleted K L1 L1 K. When you add that back in, to get the steps, it doesn't run. I don't know why, or why the error log has those weird expressions."

Presumably you meant K L1 L2 {K}.

No problem adding it back in on my end.? I am pretty sure you have something else on your end, which is not in the schematic David uploaded.? Where did k1_A0, k1_A1, and k1_A2 come from?? They must have gotten added somehow to your copy of the schematic.? ?I guess you pasted more than you thought.

Andy

John asked, "How can it give identical runs with .step param K list 0.0001 0.01?"

Because the parameter K was not used anywhere.? It's just a dummy parameter, where the entire circuit is unaffected by it.? (That is, in David's version-D uploaded circuit.)

Andy