Hello Andy

And thank you for the reply. If you're worried about not being in your area of expertise, what can I say? I''' be brave and try to address your notes in the order you posted them.

> Why is the Gain of the first VCCS (G1) so very low?

The upsampler, as it is now, uses a SW controlled by V(0.3), but I also tried removing SW (replaced by the nearby R17) and using a B-source with the expression V(0.3)*V(108). You probably know that they tend to get slower as the processed values are higher so, given that with a unity gain at the input I could have gotten some hundred volts at the resampler (with the current input) and could have gotten even higher depending on the input levels, I decided to use the (M*R)**-N gain at the input knowing that it would, eventually, have had to be used somewhere along the way. The schematic you see is what is left after testing. After changing the upsampler I was left with the small gain at the input which made no difference to the output so I just left it there.

Still, you have a point there with the V <-> nV (MV <-> V in the case of unity gain input), so that may be one of the causes, but I suspect not because I also tried using integrators with 1/M/R gain, each stage, but didn't get any improvement. I haven't fiddled with tolerences, though, I will later today.

> Current source I1 looks odd

Since .AC through a S&H is not possible and since I try not to use voltage sources otherwise than grounded (convergence issues, as by the book), I used Rout=1 for the S&H (unlike its cousins, it defaults to 1k) and used I1 with only "AC 1" for .AC analysis. However, .AC works just fine (it needs a minor change to the current schematic to work).

> V4 and V5 have "zero" fall times

Yes, I know about the default times and that's the reason they are there as such: the clock sources are only needed for their rise times; fall times and pulse width have no influence (other than messing with the time-step). So, forcing only tr and period makes the source give the needed rise time while relaxing tf and ton, thus achieving the same results only a bit faster. In more complicated schematics this can be quite the time saver.

> The time-delay elements in the lower string are curious

They're intended. In order to turn it into an integrator and make it as the simplest approach, I used the tline as inverting output feeding the - input.

> Have you considered using B-elements as the delay lines

Yes, various combinations, with or without custom functions (like comb(x) {v(x)-delay(v(x),tcomb)}) and they seemed to behave worse. Maybe it's because of the nV <> V difference? I'll have to try this one today, too.

> You may need to specify a Maximum Timestep.

I even had patience for usec timesteps :-) , no change, though it's true I, too, would've expected a more "detailed" clock output with no timestep imposed.

> How did you get the "COUNTER" behavioral element to use a gate-type symbol?

You simply rename INV to COUNTER. No, it doesn't matter :-)

> The error log has several "singular matrix" flags

I don't know why, node q is the output of the first integrator, node o is the output of the last one (the output of the filter). If it complains about them, why not complain about the other 6? Is it only because they're named? Apparently not since deleting q (for example) will make LTspice complain about N025 (as I have it) and o. The simulation runs, though, as you can see... No idea what other meaning it has.

At the end, it seems there are two things to try: the nV <> V difference and the reltol, abstol & co. I'll test these later and see what comes out of it.

Thank you for the answers.

Vlad

Yahoo has always retired accounts that go unused for just a few months.
?(At most 6.) ?I know this from personal experience.

Yes? I can appreciate there are various? sources of inaccuracy? Those? I have seen are not even close to a narrow band response.for example 1.5 MHz at 14MHz, similar bandwidth % at 1kHz

If someone can send me the set-up details to show what is possible for a simple square-wave it would be enormously helpful?

开云体育

In last days I faced to a problem to renew my LTspice group's membership. Simply, I am
not a member right now, because Yahoo canceled my account, like inactive (?) and for
renewal is asking for a cell-phone number (for verification ?) What happens, if some one
has no cell-phone, or does not want to by a new one just for that reason.

Honestly, I do not
want to give out my cell-phone number for the public, for future selling it for advertisement
reason, how the companies frequently do it. How to become again a LTspice member? ...
Why do I mention it? So, if I read reactions, "see ... this and this letter/folder on the LTspice
group's website" I doubt I will be able to do it in future or other with same problem.

Is there a different way to enter into this group's website?

Thanks,
Peter

In last days I faced to a problem to renew my LTspice group's membership. Simply, I am
not a member right now,

because Yahoo canceled my account,

like inactive (?) and for
renewal is asking for a cell-phone number (for verification ?) What happens, if some one
has no cell-phone, or does not want to by a new one just for that reason.

?Hello

I need help in making a stable output from a CIC interpolator in .TRAN. It works well for a few periods of the input signal, but then it goes exponentially noisy. The settings seem to be extremely influenced by the clocks' dely and rising time, but the integrator stages also multiply any bit of error, too.

I wanted to make a list of the things I tried but it seems to strech for too long, so I'll just say that I've tried clocks with voltage sources only, A-devices only, combined (to benefit from tripdt), I tried adding a S&H between the 6th and 7th integrator stage (by that stage the samples simply aren't "straight" anymore and it's about there that the spikes get visible), then between other two stages, then between every integrator stage (a pain since the sample clocks need to be delayed for each S&H), I tried an alternative upsampler with B-source [V(upsample)*V(comb8)], w/out S&H, before and after the upsampler, I tried using B-sources as combs and integrators with proper .FUNCS defined, I tried fiddling with td and tr (delay and rise time for clocks), I simply cannot make this any better than its current state.

So I'm asking you: do you know any methods for improving the outcome of this? To be able to run it for 100 (or more) periods of the input signal and not have distortions? Before answering, you should probably try and test your solutions, every new idea I had seemed good before it got put to use. I uploaded CIC.asc in Temp.

Anticipated thanks,

Vlad

开云体育

Actually, I don't know the developers, but my impression has been that WINE tries its best to merge the Windows window manager with the Linux window manager, so that linux and windows apps will cooperate nicely among each other. There are limitations of course, but it's believable to me that WINE may include linux programs in the list of open windows available to Windows programs.

I have never EVER gotten the LTSpice web update to work in Linux, in any distribution. It may have worked a long time ago, but I just download the new .exe when I want to update.

-- 

AC2CL 

I do not think there is any thrill that 
can go through the human heart like that felt by the inventor as 
he sees some creation of the brain unfolding to success... 
Such emotions make a man forget food, sleep, friends, love, everything. 

- Nikola Tesla 

 

Actually, I don't know the developers, but my impression has been that WINE tries its best to merge the Windows window manager with the Linux window manager, so that linux and windows apps will cooperate nicely among each other. There are limitations of course, but it's believable to me that WINE may include linux programs in the list of open windows available to Windows programs.

I have never EVER gotten the LTSpice web update to work in Linux, in any distribution. It may have worked a long time ago, but I just download the new .exe when I want to update.

I am a simple soul? ( BTW maybe we are both Brits )

If one conducts an FFT on a pure sinewave in theory there should be a
single spike of infinite height and zero width.? The more the spike
departs from those unattainable ideals shows the accuracy of the
process.?

What I have seen in LTPSPICE is far off and essentially useless?