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Re: SPICE Error

Tony Casey
 

<Snip>
--- In LTspice@..., Tan Micheline Tambayong <micheline.tambayong@...> wrote:

Hi,
thanks so much for helping me solving the problem.. But both solution
(adding Roff and changing the ground position) are giving different results.
So I wonder which one should I use.

Also Tony, can you please explain to me what's actually Roff do in the
diode?

Thanks so much everyone..

Kind regards,
Micheline
</snip>
Hello Micheline,

All of the parameters of the diode model are explained in the LTspice>Circuit Elements>Diode section of the Help.

Regards,
Tony
Re: Hi.. Where could I find "tsmc90.lib" file??

Tony Casey
 

--- In LTspice@..., "dinesh" <dinsul1986@...> wrote:

Can anyone tell me where can I find the file "tsmc90.lib"

Thank you.
Where did you last leave it? :-)
Re: SPICE Error

Tony Casey
 

--- In LTspice@..., "Ian"<iw1904@...> wrote:

Hi,



The GND is in the wrong place.

Please see corrected circuit in TEMP folder



Regards


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Ian,

With respect, we don't know for sure where the circuit should be grounded, as we don't know what the application is. Perhaps the rectified bit should be floating?

Regards,
Tony
Regardinfd Delay Element simulation

 

Hi,

I had tried the "Diff-amp-based delay element" simulation on ltspice but i couldn't get the results.Can anyone guide me what I did wrong while circuit design.

Please find the files - I have uploaded the original circuit and .asc file in the folder Files > Temp

Schematic file Name - Diff-amp-based delay element.asc
Original Circuit Name - Diff-amp-based delay element.jpg


Please help me on this and do the needful.



Thanks and Regards,
Dinesh
Re: Hi.. Where could I find "tsmc90.lib" file??

§¢§à§â§Õ§à§Õ§í§ß§à§Ó §¡§Ý§Ö§Ü§ã§Ñ§ß§Õ§â
 

Hi dinesh.
May help link:

There is this:
IBM 0.50 micron (5HP, 5AM, 5DM, 5PA)
IBM 0.35 micron (5HPE, 5PAe)
IBM 0.25 micron (6HP, 6DM, 6RF)
IBM 0.18 micron (7RF, 7RFSOI, 7WL, 7SF, 7HP)
IBM 0.13 micron (8RF-LM, 8RF-DM, 8HP, 8WL)
IBM 90 nanometer (9SF, 9LP, 9RF)
IBM 65 nanometer (10SF, lOLPe/lORFe)
IBM 45 nanometer (12SOI)
IBM 32 nanometer (32SOI)
TSMC 0.18 micron
TSMC 0.25 micron
TSMC 0.35 micron
Bordoynov

20.09.2011, 13:00, "dinesh" <dinsul1986@...>:

Can anyone tell me where can I find the file "tsmc90.lib"

Thank you.
Re: SPICE Error

 

--- In LTspice@..., Tan Micheline Tambayong <micheline.tambayong@...> wrote:

Hi,
thanks so much for helping me solving the problem.. But both
solution (adding Roff and changing the ground position)
are giving different results.
So I wonder which one should I use.

Also Tony, can you please explain to me what's actually
Roff do in the diode?

Thanks so much everyone..

Kind regards,
Micheline

Hello Micheline,

The result of both solutions is the same.
Please take a look to the enhanced version.

Files > Temp > Pefficiency_analysis-1_abc.asc

You have to plot the voltage difference V(a,b) at the output
and not the single signal V(a).

Best regards,
Helmut
Hi.. Where could I find "tsmc90.lib" file??

 

Can anyone tell me where can I find the file "tsmc90.lib"

Thank you.
Re: New Member and Updated Help File

 

--- In LTspice@..., "Joe Walsh" <smknjoe@...> wrote:

Hi all,

Just joined this group a few days ago and I'm quite surprised at the level of traffic on this list.

I've been a VLSI design engineer for 21 years and am currently using Cadence tools (Virtuoso, etc), but have used Mentor Graphics in times past as well as Daisy systems in the very beginning. I now need to get a lot of BSIM3V3 models brought in so I can "play" on LTSpice.

I have used the Field Update Tool recently to make sure my LTSpice has the latest and greatest, but, the help seems very outdated. Case in point: Special Functions. The help says that the standard logic gates are available plus a VARISTOR and a MODULATE. However, when I go to place a symbol in the schematic, it shows that there are SRFLOP, PHIDET, BUF, and BUF1 available too.

Does anybody know (or can check their version of the tool) to see if the help has been updated to at least mention these newer components? I'm imagining that they have been there for awhile now and didn't recently appear after I ran the FUT.

Regards,
Joe

Hello Joe,

You always have the latest Help-file when you update LTspice
or when you install the latest version, but simply not
everything is in the help pages.

analogspiceman has started a wiki with info especially about
these non-documented features.



Best regards,
Helmut
Re: Frequency

 

--- In LTspice@..., "Apparajan" <dg1@...> wrote:

How do you measure frequency of an oscillator accurately in
LTspice..( I probably need this for .disto to work well)
cheers
AG

Hello AG,

You could make an FFT of the signal or you use .MEASURE commands.

Please take a look to the examples.

Files > Tut > MEASURE > TRAN

Best regards,
Helmut
Re: How to make AC voltage source symbol with a sine wave shape

 

--- In LTspice@..., "desmond00036" <desmond00036@...> wrote:




Hi, I am confused how do I get the AC voltage source with
the sine symbol as shown on the left side.

I tried plotting myself on the right side but no matter
how I try I was not able to make out the same thing.

I see that it is done in transient mode, and even if I
change to AC analysis under simulation command I am
still unable to get the same pattern.


Would be glad to have some enlightement here.

Regards,

Desmond

Hello Desmond,

This SINE-symbol is available in the LTspice component's
selection.

F2
[Misc]
signal

Best regards,
Helmut
Re: How to make AC voltage source symbol with a sine wave shape

 

Nope im referring to the "symbol" of the voltage source located in the left diagram not the results...
*note that there is a sine wave in the symbol itself..
The symbol is just a symbol ... an icon. You can draw it any way you
want. It makes no difference whatsoever to the simulation.

You could go into the symbol editor and change it to anything you like.

That is apparently what someone else did, for the picture you saw.

Andy
Re: How to make AC voltage source symbol with a sine wave shape

 

It looks like some body modified the symbol for a voltage source. If you control + right click on the voltage symbol you get the "Component Attribute Editor" dialog. In the upper left corner Click on the "Open Symbol" dialog. You can then modify the symbol. The drawing tools are pretty crude. But it looks like some body found a way to insert a symbol for a sine wave. After modifying a symbol click on "Save" in the "File" menu and you will then see your changes in the schematic.

Howard

On 9/19/2011 10:45 PM, desmond00036 wrote:
Nope im referring to the "symbol" of the voltage source located in the left diagram not the results...
*note that there is a sine wave in the symbol itself..


I found the left side diagram somewhere, and tried to plot my own in the right diagram, but the symbol of the voltage source is different.

That makes me wonder if I am getting the same results as the diagram on the left.


Regards,

Desmond



------------------------------------

Yahoo! Groups Links
Re: Ho do I Measure RMS AC riding on DC signal?

 

Thanks Tony. I learned a lot. Landrum

--- In LTspice@..., "Tony Casey" <tony@...> wrote:



--- In LTspice@..., Landrum Haddix <lhaddix@> wrote:

Hi,
I may be missing something obvious. I've been measuring lots of ripple voltages on DC power supply votages.
Is there a way to get a waveform showing RMS AC volts regardless of offest.

I did a crude work around and temporatily place a 15pf cap in series with a 10meg resistor hanging off the node I want to measure.
I'm calling this an AC coupled 'Scope probe'. What is the regualr way to do this.

Landrum Haddix
lhaddix@

Hello Landrum,

You questions are somewhat ambiguous, since there is no such thing in this context as an RMS AC waveform.

If you just want to look at the AC portion of the waveform in the viewer, you have several choices:
- Change the Y-axis plot range to only show the portion of the waveform, you're interested in. This method has the disadvantage that every time the viewer re-plots, it will autoscale so you will have to repeat the scaling exercise. An alternative is to save a .plt file with your preferred axis settings, and reload it each time the waveform is re-plotted. Hint: assign a Hotkey to do this. I use [spacebar] like others have mentioned recently
- Plot the quantity V(ACnodename)-DCOffset (where DCOffset is the numerical value for the estimated offset.

Of necessity, this will be a manual process, as the waveform viewer has no way of knowing what you mean it to plot. Alternatively, you can carry on doing it your way, but with the same advantages and disadvantages as AC-coupling with a real scope.

If you actually want to measure the rms value, as suggested by the title of your post, you can use post-processing scripts to calculate that from the simulation data.

Add the following lines in a SPICE directive:
.meas TRAN Vavg avg V(out); calculates the DC offset
.meas TRAN Vrms rms (Vavg-V(out)); calculates rms after substracting the average

You will find the results of these calculations in the logfile after each simulation. Of course having found the average value by this means, you can then substitute its value into your viewer plot expression. This is helpful since if you are also performing a .stepped simulation, the Waveform Viewer won't calculate the average and rms values of a waveform.

One more tip: if the AC voltage is small compared to the DC offset, you will also need to add the directive:
.option plotwinsize=0

...too, or the waveform compression will distort the ripple voltage and the rms calculation will be wrong.

There's also a really nerdy way to display exactly what you want to see in the waveform viewer, but it requires some subterfuge, and can only show the ripple voltage right at the end of your tran time, since it calculates the DC offset on the fly. This will only work if your DC offset is stable over time. You can find this example as RMS_Value.zip in Files>Temp

Hope this helps.

Regards,
Tony
New Member and Updated Help File

Joe Walsh
 

Hi all,

Just joined this group a few days ago and I'm quite surprised at the level of traffic on this list.

I've been a VLSI design engineer for 21 years and am currently using Cadence tools (Virtuoso, etc), but have used Mentor Graphics in times past as well as Daisy systems in the very beginning. I now need to get a lot of BSIM3V3 models brought in so I can "play" on LTSpice.

I have used the Field Update Tool recently to make sure my LTSpice has the latest and greatest, but, the help seems very outdated. Case in point: Special Functions. The help says that the standard logic gates are available plus a VARISTOR and a MODULATE. However, when I go to place a symbol in the schematic, it shows that there are SRFLOP, PHIDET, BUF, and BUF1 available too.

Does anybody know (or can check their version of the tool) to see if the help has been updated to at least mention these newer components? I'm imagining that they have been there for awhile now and didn't recently appear after I ran the FUT.

Regards,
Joe
Re: How to make AC voltage source symbol with a sine wave shape

 

Nope im referring to the "symbol" of the voltage source located in the left diagram not the results...
*note that there is a sine wave in the symbol itself..


I found the left side diagram somewhere, and tried to plot my own in the right diagram, but the symbol of the voltage source is different.

That makes me wonder if I am getting the same results as the diagram on the left.


Regards,

Desmond
Re: How to make AC voltage source symbol with a sine wave shape

 

Hi, I am confused how do I get the AC voltage source with the sine symbol as shown on the left side.

I tried plotting myself on the right side but no matter how I try I was not able to make out the same thing.
It works for me!

What do you get? We can't fix something if you don't tell us what
seems to be wrong.

I get a nice sine wave with +/-230V amplitude and 20ms period.

You can improve the accuracy of the waveform slightly by using a
smaller maximum timestep (the fourth parameter of the .tran statement)
and by adding ".options plotwinsize=0" to disable LTspice's waveform
compression of saved/plotted waveforms. But that doesn't change the
waveform much in this case.

Using AC analysis is completely different, and you don't get waveforms
at all from it.

Regards,
Andy
How to make AC voltage source symbol with a sine wave shape

 




Hi, I am confused how do I get the AC voltage source with the sine symbol as shown on the left side.

I tried plotting myself on the right side but no matter how I try I was not able to make out the same thing.

I see that it is done in transient mode, and even if I change to AC analysis under simulation command I am still unable to get the same pattern.


Would be glad to have some enlightement here.

Regards,

Desmond
Frequency

Apparajan
 

How do you measure frequency of an oscillator accurately in LTspice..( I probably need this for .disto to work well)
cheers
AG
Re: What changes would make LTspice better? - an improved diode type filter

 

Hiya Heinz

I am sorry but I have to disagree.

My approach is to have the databases loaded with all the possible parts that
I may use. The only time that I hand draw a circuit diagrams now, is on a
bus, train or aeroplane, when I do not have my lap top with me. If I need to
copy an existing circuit diagrams, I am as likely to photograph it with my
mobile phone and transfer it to my computer net.

I find that Ltspice is an excellent tool creating circuits and then refining
them.

I have just done a proper check and my diodes database has grown to 279
entries including some 150 Zener diodes selecting the right one is quite a
drag. The power rating is not immediately visible and very little clues when
using one from the 1nxxxx ranges

The same can be said for varactors. I have some 50 of them in the database.
Do you keep the specs in your head? I most certainly don't.

It's just a different way of working that's all.

I also do MYSQL, PHP, C and C++ programming so I am very well aware of how
dialogue boxes work in windows, both plain vanilla and MFC. I did clone
dbaseII in C so that C programs could access and manipulate dbase files. (I
have a pathological hatred of proprietary data formats. Q what happens if
the company goes bust. A. The data becomes useless.)

I was not asking for a parametric search. A much more simple approach

Presumably the dialogue box reads the database on creation, extracts the
data that it can display and shrinks the whitespaces of the text based
model, into an array of structures. Then displays it.

Adding a select box for type would not add that much complexity. Plus it
would allow the space where type was displayed to be replaced with say power
rating or varactor capacitance or whatever.

Adding a simple filter using partial entry name is not that major either.
It's just a matter of creating a secondary array that matches the filter
term then displaying that. Thankfully C and C++ both have case less
comparison functions.

So selecting Zener in the select box and 1n in the filter would display all
the 1n series zener diodes plus a bit more of their spec


Best regards

Suusi Malcolm-Brown

PP Mike please don't think that I am trying to teach you how to suck eggs.

-----Original Message-----
From: LTspice@... [mailto:LTspice@...] On Behalf Of
Heinz-W. Schockenbaum
Sent: 19 September 2011 16:40
To: LTspice@...
Subject: [LTspice] Re: What changes would make LTspice better? - an improved
diode type filter



--- In LTspice@..., "Suusi M-B" <smalcolmbrown@...> wrote:

Now that I have well over 100 different diode types in Ltspice I think
that something that I would find useful would be a selector box for diode
type "All, Germanium, Silicon, ZENER, SCHOTTKY, VARACTOR, LED" above the
select window.


LTspice is not intended as a parametric search for all possible diodes. You
setup your schematic, choose the approriate parts and put them into LTspice.
LTspice is only for simulating an existent schematic.

BTW: when you open "pick new diode" click on e.g. "type" in the header. The
colum will be sortet alphabetically: first all germanium, following LED,
then ... up to type Zener .. :-)

hws



------------------------------------

Yahoo! Groups Links
Re: SPICE Error

Tan Micheline Tambayong
 

Hi,
thanks so much for helping me solving the problem.. But both solution
(adding Roff and changing the ground position) are giving different results.
So I wonder which one should I use.

Also Tony, can you please explain to me what's actually Roff do in the
diode?

Thanks so much everyone..

Kind regards,
Micheline

On Tue, Sep 20, 2011 at 9:46 AM, Ian <iw1904@...> wrote:

**


Hi,

The GND is in the wrong place.

Please see corrected circuit in TEMP folder

Regards

_____

I am using the Free version of SPAMfighter <
.
SPAMfighter has removed 3438 of my spam emails to date.

Do you have a slow PC? <
>
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