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LTspice Install problem under linux

Business Kid
 

I can't install the latest update in linux. It certainly doesn't go in painlessly like the last one did, and may need shoehorning in. That's a pity, because I uninstalled the older version.

Is this a 'known issue?' (m$ speak for A BUG)? Where should I report it?
Re: Perl Optimizer initiation problems

 

thanks a lot, i will try it and hope it will work


Jad
Re: FFT Resolution

John Woodgate
 

In message <ENcQOfEjUjrSFwah@...>, dated Sun, 15 Dec 2013, John Woodgate <jmw@...> writes:


Working backwards through that last bit in the Help, to get 100 Hz resolution, the window width is 1/100 s = 10 milliseconds. You need to consider at least harmonics up to the ninth, 90 MHz, so the number of samples has to be at least 90 MHz/100 Hz = 90000. LTspice supports much larger numbers. But the necessary simulation time may be archaeological.
I'm sorry: I got a bit confused myself in trying to explain this and I inadvertently sent it before I'd fixed the text. Please disregard.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
Re: UC 3825 Ltspice Model

 

Hi Andrew.
Look
File is LTspiceIV.zip. It contains a files Valvol.lib and UC3825.asy.
Bordodynov.
Re: My collection of models and examples for LTspice.

 

Hi.
My file 100MEG LTspiceDoc contained different files with instructions on using LTspice. These files I found on the internet. Files including in Russian. Links to some of them are in this group. These files can be useful for beginners. To reboot I have technical difficulties (very slow internet).
Bordodynov.
Re: Questions about phase in .AC LTspice Analysis

hoa van nguyen
 

Hello Andy,
Thank for sharing your thoughts with me. I discover something that I do not
understand. Maybe you or other people can answer my questions.

All 2stages_2CascodeDiff_ACsim_test1_orig.asc,
Readme,Cmosedu_models.txt,
2stages_2CascodeDiff_ACsim_test1_orig.jpg (graph)
are under Files > temp > GainPhase_inAC (folder).

1) from the graph 2stages_2CascodeDiff_ACsim_test1_orig.jpg:
the difference of first stage outputs (Vodp - Vodm) = 2dB, but the
Difference of second stage outputs (Vod - Vom) = 0.6dB.

Q: Why the Vod & Vom are nearly equal now? (Improved)

2) At f=30MHz the Vodp-phase goes up to positive, but the
the gain is below 0dB.

Q: How does the diff. Amplifier behave in real life at this frequency?

Best Regards

Hnguyen


On Tuesday, December 10, 2013 4:01 PM, Andy wrote:
?
Hnguyen wrote: "
Q1: Why |Vop| and |Vom| are nearly equal??why not equal?"

A1: ?Ideally they are equal. ?Real circuits are not ideal. ?If there is any common-mode component present in the output signal, the two output pins would not be precisely complementary and then their amplitudes might not be equal.

"
Q2: How do you know that V(vop,vom) would be larger than either one."

A2: ?When exactly complementary, if you look at their AC components (and ignore the DC offset), V(vom) = -V(vop).

V(vop,vom) = V(vop)-V(vom) = V(vop)-(-V(vop)) = 2*V(vop).

So, in an AC simulation, the amplitudes of vop and vom should be equal, and the amplitude of V(vop,vom) should be 6 dB higher.

Andy
Re: FFT Resolution

 

Hello Ron,

If you want 100Hz resolution, you have to simulate at least 1/100s=10ms.

I have uploaded an example "fft10meg.asc" to the Temp-folder folder. I simulated 20ms.

http://groups.yahoo.com/neo/groups/LTspice/files/%20Temp/

Run the simulation. Then in the FFT dialog window choose 4194304 samples.

Please be aware that the FFT/DFT only looks so perfect because my second source has 100Hz offset which exactly fits to the FFT's frequency resolution. If this is not the case, one would try with a window function to get a good resolution.

Best regards,
Helmut
Re: A Noisy Question

 

I guess my question with respect to noise and LTspice is how the time step between noise samples is established? And, how is it then interpreted - as a PWL source, for example??All I see is .noise - I don't see how to create a time-domaine noise signal is LTspice. To do an FFT on the noise, doesn't it have to be in the time domain? I see rand() but that appears to be uniform, not gaussian.?

The time between noise samples must set the upper frequency of the noise spectrum (maybe at 1/2T, where T is the sample interval ??). Where and how is T set in LTspice??

And, if the noise samples are taken as points in a PWL, then that says how the system treats that source between the sample points. Or, is there no "between the sample points"? I see random() which says it is smoothed between samples, but still nothing about the time interval between samples.

I hope these questions make sense, because I am not totally certain what I am asking about :) [If I were certain, I probably would not have to ask!!]

Thanks
Jim Wagner

On Dec 15, 2013, at 1:40 PM, David Hawkins wrote:

?

Hi Jim,

> I have a question about modeling noise in a real system.
>
> Lets say I start with a uniform distributed sequence of random values
> with a span of +1 to -1. I know that I can average over N of these
> values and get a Gaussian sequence with a mean of zero and a standard
> deviation of 0.5. This much is pretty easy.
>
> Now, these values represent discrete time samples. How do I turn them
> into real signal that has a defined bandwidth? Yes, I can put the
> sequence through a low-pass filter, but I have to define a time
> interval between samples. Do I need to set this time at 1/10X the
> filter bandwidth? 1/100X? And, does it matter whether I take the
> values as though the output of a first-order sample/hold, or do
> linear interpolation between them? Or something else? And, what sort
> of filtering is normally assumed? Single pole? Two or three poles?
>
> Yes, this is for an LTspice project. And, the reason I am being a
> bit coy about specific values is that I would like to apply this in a
> variety of communication systems with varying operating frequencies
> and bandwidths. In some cases, the system bandwidth will be very
> broad (maybe 100 MHz) encompassing HF frequencies with lots of
> ambient noise as well as VHF that is much quieter.

I typically use an LFSR and then average the uniform distribution
as you mention above.



If I'm using this noise to "simulate" an analog noise signal, and
I want to "sample" that signal with a jittery clock signal, or
I want to alias the signal to baseband, I will filter the noise
to say 4x the bandwidth I really want, generate my
clock sample times, and then interpolate (using MATLAB here,
not LTSpice).

For example, see the spectra in this doc



it contains simulated noise power ratio, clock jitter, etc.

I use PRBS generated noise so that I can reproduce the simulations
in hardware in FPGA-based DSP.



Cheers,
Dave
Re: FFT Resolution

John Woodgate
 

In message <l8l5j2+4h2m77@...>, dated Sun, 15 Dec 2013,
ronw6wo@... writes:


? RC and John Thanks? for the response,but I am blinded by science now
as

this is my first attempt to model FT behaviour


I would like to be clear on at least one matter? " 'the value of the
window"
It isn't very clear.

Is this the same as the number of cycles AKA Span ?
No. It's the 'width' in frequency of one window.


Is it possible to display the harmonics of say a 10MHz square wave to
100Hz resolution ? My 30 year-old HP spectrum analyzer can
Working backwards through that last bit in the Help, to get 100 Hz
resolution, the window width is 1/100 s = 10 milliseconds. You need to
consider at least harmonics up to the ninth, 90 MHz, so the number of
samples has to be at least 90 MHz/100 Hz = 90000. LTspice supports much
larger numbers. But the necessary simulation time may be archaeological.

Your spectrum analyser works in the analogue domain, so the only time
constraint is the settling time of the 100 Hz filter, which might be as
long as 100 ms. So you do need to sweep the frequency slowly enough.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
Re: A Noisy Question

 

Hi Jim,

I have a question about modeling noise in a real system.

Lets say I start with a uniform distributed sequence of random values
with a span of +1 to -1. I know that I can average over N of these
values and get a Gaussian sequence with a mean of zero and a standard
deviation of 0.5. This much is pretty easy.

Now, these values represent discrete time samples. How do I turn them
into real signal that has a defined bandwidth? Yes, I can put the
sequence through a low-pass filter, but I have to define a time
interval between samples. Do I need to set this time at 1/10X the
filter bandwidth? 1/100X? And, does it matter whether I take the
values as though the output of a first-order sample/hold, or do
linear interpolation between them? Or something else? And, what sort
of filtering is normally assumed? Single pole? Two or three poles?

Yes, this is for an LTspice project. And, the reason I am being a
bit coy about specific values is that I would like to apply this in a
variety of communication systems with varying operating frequencies
and bandwidths. In some cases, the system bandwidth will be very
broad (maybe 100 MHz) encompassing HF frequencies with lots of
ambient noise as well as VHF that is much quieter.
I typically use an LFSR and then average the uniform distribution
as you mention above.



If I'm using this noise to "simulate" an analog noise signal, and
I want to "sample" that signal with a jittery clock signal, or
I want to alias the signal to baseband, I will filter the noise
to say 4x the bandwidth I really want, generate my
clock sample times, and then interpolate (using MATLAB here,
not LTSpice).

For example, see the spectra in this doc



it contains simulated noise power ratio, clock jitter, etc.

I use PRBS generated noise so that I can reproduce the simulations
in hardware in FPGA-based DSP.



Cheers,
Dave
Re: FFT Resolution

 

? RC and John Thanks? for the response,but I am blinded by science now as

this is my first attempt to model FT behaviour


I would like to be clear on at least one matter? " 'the value of the window"


Is this the same as the number of cycles AKA Span ?


Is it possible to display the harmonics of say a 10MHz square wave to 100Hz resolution ? My 30 year-old HP spectrum analyzer can


Can anyone illustrate? with the pulse and Tran statements using a square wave at any freqency



---In LTspice@..., <ron_liff@...> wrote:

In any event the resultant "spectral accuracy", even if optimized for some set of conditions, resolution, and bandwidth of spectrum, will be directly dependent on the accuracy of represented distortion (read non-linear) effects.
?
- In general large scale spectra will tend to more accurate representation, whereas the smaller the spectral component the more the sensitivity, and deviation, from the actual results in a real world circuit. This effect is exploited in so-called "Harmonic balance" type solvers to great success.
?
- Cordially - RC


On Tuesday, December 10, 2013 2:58 PM, John Woodgate <jmw@...> wrote:
?
In message <l87u7c+ebvu@...>, dated Tue, 10 Dec 2013,
"skleiser@..." <skleiser@...> writes:

> Given (in this case) a square wave of fixed frequency, fast but
>non-zero rising & falling edges, 50% duty cycle, and an exact integer
>number of cycles (etc.), what's the narrowest possible harmonic
>bandwidth that ought to be expected? In other words, when is the
>simulation as optimized as it can be?

harmonic bandwidth doesn't depend on those things. Embedded in the Help
on the B source is:

"In LTspice, the impulse response is found from the FFT of a discrete
set points in frequency domain response. This process is prone to the
usual artifacts of FFT's such as spectral leakage and picket fencing
that is common to discrete FFT's. LTspice uses a proprietary algorithm
that exploits that it has an exact analytical expression for the
frequency domain response and chooses points and windows to cause such
artifacts to diffract precisely to zero. However, LTspice must guess an
appropriate frequency range and resolution. It is recommended that the
LTspice first be allowed to make a guess at this. The length of the
window and number of FFT data points used will be reported in the .log
file. You can then adjust the algorithm's choices by explicitly setting
nfft and window length. The reciprocal of the value of the window is the
frequency resolution. The value of nfft times this resolution is the
highest frequency considered."

The significant words are:

"The reciprocal of the value of the window is the frequency resolution."

Frequency resolution is the same as the observed 'harmonic bandwidth'.

>
> On a more general note, assuming artifacts of a non-ideal simulation
>have been minimized, does the harmonic bandwidth provide useful
>information, or do only the peak values matter?

The harmonic energy is averaged over the bandwidth, so widening the
bandwidth tends to reduce the observed amplitude.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
Re: A Noisy Question

monettsys
 

--- In LTspice@..., Jim Wagner <wagnejam99@...> wrote:
Greetings folks -
I have a question about modeling noise in a real system.
Lets say I start with a uniform distributed sequence of random values with a span of +1 to -1. I know that I can average over N of these values and get a Gaussian sequence with a mean of zero and a standard deviation of 0.5. This much is pretty easy.
I don't think that will give a very good approximation to Gaussian noise. You might want to try the Box-Mueller method.

Now, these values represent discrete time samples. How do I turn them into real signal that has a defined bandwidth? Yes, I can put the sequence through a low-pass filter, but I have to define a time interval between samples. Do I need to set this time at 1/10X the filter bandwidth? 1/100X? And, does it matter whether I take the values as though the output of a first-order sample/hold, or do linear interpolation between them? Or something else? And, what sort of filtering is normally assumed? Single pole? Two or three poles?
For the Box-Mueller, just take the output signal. You don't need S/H, interpolation, or any other tricks. You may need to adjust tripdV and tripdt. There are several Box-Mueller files available. Try

"

and

"

In a hardware noise generator, you normally want the noise spectrum to remain flat well past the frequencies of interest. But if you need to define the bandwidth, how about doing a FFT on the resulting noise signal? That should give answers to your questions.

Thanks
Jim Wagner
Oregon Research Electronics
Mike
Re: Cmos 4026

John Woodgate
 

In message <CAFL0OtQZcJSRTgEKrDT3ObSrjGatJzBfoLanqGr7Y2uN6vZOOQ@...>, dated Sun, 15 Dec 2013, Business Kid <business.kid@...> writes:

And I have stopped thinking in 4xxx logic, because they are not recommended for new designs, to put it mildly.
No doubt, but the fact that they are very slow by modern standards means that they produce much less EMI. If you don't need the speed, don't buy it.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Nondum ex silvis sumus
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
Re: Cmos 4026

Business Kid
 

I thought I was the only one with any 4000 chips left. I never saw or met the 4026. There are a few on ebay if you want to prototype :-)

I am guessing that you are simulating an idea which you are going to program. Use a separate 74xx counter and 74xx bcd decoder chip if you must, but I also fail to see the point. And I have stopped thinking in 4xxx logic, because they are not recommended for new designs, to put it mildly.


On 14 December 2013 10:55, <xcheta1@...> wrote:
?

HI there,

I Would like to build a speeometer.
My plan was that i use the CMOS 4026 because i need the Carry Out for my 7-Single-Digit-Nummeric Display but in LTSpice i can?t find the 4026 to Simulate my circiut.
Please help my i search a alternate component for the CMOS 4026 with the same application and where i can use at LTSpice.

Thank you for Help

Xcheta1
A Noisy Question

 

Greetings folks -

I have a question about modeling noise in a real system.

Lets say I start with a uniform distributed sequence of random values with a span of +1 to -1. I know that I can average over N of these values and get a Gaussian sequence with a mean of zero and a standard deviation of 0.5. This much is pretty easy.

Now, these values represent discrete time samples. How do I turn them into real signal that has a defined bandwidth? Yes, I can put the sequence through a low-pass filter, but I have to define a time interval between samples. Do I need to set this time at 1/10X the filter bandwidth? 1/100X? And, does it matter whether I take the values as though the output of a first-order sample/hold, or do linear interpolation between them? Or something else? And, what sort of filtering is normally assumed? Single pole? Two or three poles?

Yes, this is for an LTspice project. And, the reason I am being a bit coy about specific values is that I would like to apply this in a variety of communication systems with varying operating frequencies and bandwidths. In some cases, the system bandwidth will be very broad (maybe 100 MHz) encompassing HF frequencies with lots of ambient noise as well as VHF that is much quieter.

Thanks
Jim Wagner
Oregon Research Electronics
Convert ADS and/or AWR (MWO) RF FET Models to SPICE

 

Does anybody know how to convert RF FET models that were made for ADS or AWR (MWO) to SPICE models.? Seems some RF device manufacturers (NXP, Freescale, ...) do not make SPICE models for their parts.? Not good if you can't afford one of these expensive simulators.
Re: i need help

 

Then ask in the Hspice list?

Jim Wagner
Oregon Research Electronics

On Dec 14, 2013, at 5:01 PM, Á¢ Çf wrote:

?

?I really need ?the hspice netlist of Dflipflop with reset

please help me><~~

i already have dflipflop without reset

.SUBCKT DFF gnd vcc d clk q q_bar
X1 gnd vcc 1 2 3 nand2
X2 gnd vcc 3 clk 2 nand2
X3 gnd vcc 2 clk 1 5 nand3
X4 gnd vcc 5 d 1 nand2
X5 gnd vcc 2 q_bar q nand2
X6 gnd vcc q 5 q_bar nand2
.ends

.SUBCKT nand2 gnd vcc a b vout ??

Mx1 vout b vcc vcc ?p w=1.5u l=0.18u
Mx2 vout a vcc vcc ?p w=1.5u l=0.18u
Mx3 vout a 2 gnd ?n w=1u l=0.18u
Mx4 2 b gnd gnd ?n w=1u l=0.18u

.ENDS
i need help

 

?I really need ?the hspice netlist of Dflipflop with reset

please help me><~~

i already have dflipflop without reset

.SUBCKT DFF gnd vcc d clk q q_bar
X1 gnd vcc 1 2 3 nand2
X2 gnd vcc 3 clk 2 nand2
X3 gnd vcc 2 clk 1 5 nand3
X4 gnd vcc 5 d 1 nand2
X5 gnd vcc 2 q_bar q nand2
X6 gnd vcc q 5 q_bar nand2
.ends

.SUBCKT nand2 gnd vcc a b vout ??

Mx1 vout b vcc vcc ?p w=1.5u l=0.18u
Mx2 vout a vcc vcc ?p w=1.5u l=0.18u
Mx3 vout a 2 gnd ?n w=1u l=0.18u
Mx4 2 b gnd gnd ?n w=1u l=0.18u

.ENDS
hspice netlst

 

I really want the hspice netlist about d flip flop with reset!!

someone know it?? please told me~~


ex:d flip flop without reset

.SUBCKT DFF gnd vcc d clk q q_bar
X1 gnd vcc 1 2 3 nand2
X2 gnd vcc 3 clk 2 nand2
X3 gnd vcc 2 clk 1 5 nand3
X4 gnd vcc 5 d 1 nand2
X5 gnd vcc 2 q_bar q nand2
X6 gnd vcc q 5 q_bar nand2
.ends

.SUBCKT nand2 gnd vcc a b vout ??

Mx1 vout b vcc vcc ?p w=1.5u l=0.18u
Mx2 vout a vcc vcc ?p w=1.5u l=0.18u
Mx3 vout a 2 gnd ?n w=1u l=0.18u
Mx4 2 b gnd gnd ?n w=1u l=0.18u

.ENDS
Re: LTSpice 4026

 

Xcheta1 wrote, "...?
i need the Carry Out for my 7-Single-Digit-Nummeric Display but in LTSpice i can?t find the 4026 to Simulate my circiut."

This is one of those situations that makes me ask, Why do you want to simulate that?

I don't mean that there isn't a good reason. ?I just don't see one.

The CD4026 is a digital counter, with digital inputs and outputs. ?SPICE is used when you need to know whether some voltage is 8.47 volts or 9.75 volts; or if you need to know the risetime, or to look for overshoot ... things of an analog nature. ?Those things MIGHT be concerns, but often they are not. ?When the wires or PCB traces are short, often you can just hook up the ICs, and it works, without having to know the voltages with millivolt precision.

Just wondering.

Regards,
Andy
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