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SPICE on entered schamatic(s)
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Jim Thompson
electronics forum Guru


Joined: 06 May 2005
Posts: 5440

PostPosted: Fri May 13, 2005 12:59 pm    Post subject: Re: Synchronizing T-flops? John/Chris Reply with quote

On Thu, 28 Apr 2005 19:49:28 -0700, Jim Thompson
<thegreatone@example.com> wrote:

Quote:
The problem...

Running from a 2.2 GHz clock and squeezing power, I'm using T-flops
(toggle-flops).

I DIV2 on positive edge to get 1.1GHz
I also DIV2 on negative edge to get 1.1GHz but shifted +/- 90

Continuing with the dividing I get down also to...

137.5MHz
and 137.5MHz, angle +/- 90

I want to mix the 1.1GHz and 137.5MHz signals to get either 1.2375GHz
or 962.5MHz in a image-reject mixer

The snag...

The sum/difference depends on phasing of each component, but, since
each of the final components started out from toggle flops the final
sign of the 90 is unknown.

Anyone have clever ideas to determine whether each component is + or -
90 ??

If I can determine phase I can flip to the correct phase thru a PECL
inverter.

If I can solve this then the system can simply call for high or low
sideband and be assured its the right one.

Right now it's random :-(

This is on an ASIC, so I must DESIGN the circuit, NOT buy something
off-the-shelf which consumes more power than this whole WiFi chip.

...Jim Thompson

See...

Newsgroups: alt.binaries.schematics.electronic
Subject: Problem Solution for S.E.C Posting - SidebandFix.pdf
Message-ID: <rhf9815826rvrfsbvm98mk0rf1j155u1kj@4ax.com>

Two D-flops, "WHOSFIRST", plus logic, "FLIPPER", convert commanded
"SIDEBAND" to "SBINT", providing correct sideband selection
irrespective of incoming phasing of quadrature signals 1056MHZ and
132MHz.

Thanks John and Chris!

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
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Andrew Tweddle
electronics forum beginner


Joined: 13 May 2005
Posts: 35

PostPosted: Fri May 20, 2005 1:08 pm    Post subject: Re: Can you help me to discover manufacturer of 4431 1503 Reply with quote

Etantonio wrote:

Quote:
Good Morning,
I've a Gericom Webshox laptop, it is of 2001, I changed the battery
but it is still not working, the problem seems to be that the 15 volts
coming from power supply don't reach the battery, they seems stopped
from an 8-pin dual in line IC named 4431 1503 that I don't know who is
the manufacturer, I search for it on internet but with no results.
To solve the problem I need the following information :

1) Who is the producer of this IC 4431 1503 or equivalent, it have
4431 in the first line, a little delta on the second line and
following 1503
2) where I can find the schematic of the motherboard N241S1 ver:0.1
possible for free

Many thanks for your help

Antonio D'Ottavio
etantonio@etantonio.it
Could be an SO-8 FET like FDS4431 from fairchild or IRF4431 from

International Rectifier.

regards Andrew
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Chris Jones
electronics forum Guru Wannabe


Joined: 06 May 2005
Posts: 278

PostPosted: Fri May 20, 2005 8:34 pm    Post subject: Re: 0.18um cmos model file Reply with quote

Jason,

At 2.4GHz, the inductors and capacitors are actually easier to use on-chip
than off-chip, since the parasitics are less of a problem. You'll need a
good model for your inductor, I suggest the free programs FastHenry and
FastCap from MIT as a starting point, though they simulate inductance and
capacitance separately so you'll have to do some work to make a good
distributed model. Also for decent inductors you'll want a metal layer at
least 2um thick, preferable 5um or more. You could also strap several thin
metal layers together, but the USPTO was silly enough to let someone patent
that.(5446311)

If you have access to the IEEE Journal of Solid State Circuits, you'll find
that since 1995 or so it has printed many VCO papers. This should be of
interest to you.

Chris Jones

jason wrote:

Quote:
Thanks Jim
Then I will wait for Mike then
By the way Jim, is it true that nowadays capacitor and inductor still
cannot be fabricated together with digital and analog circuit in the
same chip?
So the layout for an oscillator circuit is better to use pcb layout or
chip level layout?
I am not sure if I express what I am in doubt
Kindly enligthen
Thanks a lot


Jason
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Kevin Aylward
electronics forum Guru


Joined: 03 May 2005
Posts: 329

PostPosted: Mon May 30, 2005 4:52 am    Post subject: Re: PSpice Model for SST201 Reply with quote

beagle197@hotmail.com wrote:
Quote:
I've been searching for a spice device model for SST201, VISHAY
SILICONIX, an N-Channel JFETs. Any such model or substitute exist?
thanks
bea

I think this is a j201. I think the sst is refering to the sot-23
package.

..MODEL J201 NJF(Beta=1.621m Betatce=-500m Rd=1 Rs=1 Lambda=2.236m
Vto=-600m Vtotc=-2.5m Is=114.5f
+ Isr=1.091p N=1 Nr=2 Xti=3 Alpha=506.8u Vk=251.7 Cgd=4.667p M=227.1m
+ Pb=500m Fc=500m Cgs=2.992p Kf=0.6042f Af=1)


I did a quick check on the data sheet and Vto appears to be consistant
with this.

Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
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Guest






PostPosted: Mon May 30, 2005 1:16 pm    Post subject: Re: PSpice Model for SST201 Reply with quote

How do I associate this model with the part? If I right click for
properties, "Edit Spice Model" option is grayed out/non-selectable. Is
there another way to add the model?
Thanks
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Kevin Aylward
electronics forum Guru


Joined: 03 May 2005
Posts: 329

PostPosted: Mon May 30, 2005 1:47 pm    Post subject: Re: PSpice Model for SST201 Reply with quote

beagle197@hotmail.com wrote:
Quote:
How do I associate this model with the part? If I right click for
properties, "Edit Spice Model" option is grayed out/non-selectable.

This is only greyed out if you open the model browser from the symbol
properties dialog. You can use the blue "Md" button, or main menu
"Components\Model Library" to open the model editor directly, this will
ungrey tie button, or see below.

Quote:
Is
there another way to add the model?

Yes.

Quote:
Thanks

In SS you don't really have to do anything as the model is already there
under the alternate name j201.

If are adding a new model to SS, you can do one of two things:

1 put the model in a single file with an extension of .lib or .mod, and
then drag drop the file from Windows Explorer to the SS main window.
Your done. It will show up in the file browser. SS automatically
attaches symbols to those types of models.

or

2 In the model file browser (left main window), right click on a model
in a model file folder, and go "edit model file". This pops up the txt
file within the SS main frame. Paste in the model text and go save. Your
done.

Its best to put all your new models in your own file so that SS don't
overwrite them in a updated install.

Kevin Aylward
informationEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
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Genome
electronics forum Guru


Joined: 30 Apr 2005
Posts: 789

PostPosted: Sun Jun 12, 2005 2:58 pm    Post subject: Re: looking for simulator Reply with quote

"Tim Hubberstey" <bogus@bogusname.com> wrote in message
news:RhZqe.46502$on1.35864@clgrps13...
Quote:
colin wrote:
Hi,
Im looking for a simulator - mixed mode with schematic capture, ive
been
trying to evaluate several freeware/trial ones but when it takes half a
day
trying to put a simple sinewave generator and r/c circuit and look at
the
output and frequency plot etc i tend to give up with it. ive looked at
the
simulation in protel before although its quite good i cant say i was
happy
enough with it to pay the very high price for the whole package

Ive just looked at simetrix but although it seems quite powerfull i
dont
have any more time to waste trying to figure out how to even do
something
trivial. I tried to download ltspice but all i ended up with was some
library files, couldnt seem to find the main program.

To start with I wish to look at the spectrum of a phase modulated
carrier
that gets divided with a counter then filtered then multiplied with a
frequency multiplier etc.

Can anyone sugest something that I can just get up and runing in a
short
space of time ? ... thanks

I use LT Spice (aka SwitcherCAD III) when I need analog simulation. I
think you just picked the wrong thing to download. What you want is:

http://www.linear.com/designtools/softwareRegistration.jsp

If you don't end up with 'swcadiii.exe', you've done something wrong.


Or try....

http://ltspice.linear.com/software/swcadiii.exe

Which is the 'No Thanks, just download the software'.

Mike Englehart, the author, pops up every so often.

?For Mike, is there an advantage to registering?

Quote:
The basic library includes only minimal logic components so you'll need
to build your counter from FFs and gates, create a model from scratch,
or find a more complete digital library.


You can get logic models from the LTspice user group at

http://groups.yahoo.com/group/LTspice/

In the files/lib section.

You have to join.

Helmut Sennewald, the moderator, pops up every so often.

Try posting questions in sci.electronics.cad

I've cross posted your query there.

Mike and Helmut are really helpful people. (Sorry if I pisspelt the names)

Quote:
Tim Hubberstey, P.Eng

DNA
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colin
electronics forum Guru Wannabe


Joined: 30 Apr 2005
Posts: 247

PostPosted: Sun Jun 12, 2005 3:54 pm    Post subject: Re: looking for simulator Reply with quote

"Genome" <ilike_spam@yahoo.co.uk> wrote in message
news:jRZqe.21622$cN2.20382@newsfe4-gui.ntli.net...
Quote:

"Tim Hubberstey" <bogus@bogusname.com> wrote in message
news:RhZqe.46502$on1.35864@clgrps13...
colin wrote:
Hi,
Im looking for a simulator - mixed mode with schematic capture, ive
been
trying to evaluate several freeware/trial ones but when it takes half
a
day
trying to put a simple sinewave generator and r/c circuit and look at
the
output and frequency plot etc i tend to give up with it. ive looked at
the
simulation in protel before although its quite good i cant say i was
happy
enough with it to pay the very high price for the whole package

Ive just looked at simetrix but although it seems quite powerfull i
dont
have any more time to waste trying to figure out how to even do
something
trivial. I tried to download ltspice but all i ended up with was some
library files, couldnt seem to find the main program.

To start with I wish to look at the spectrum of a phase modulated
carrier
that gets divided with a counter then filtered then multiplied with a
frequency multiplier etc.

Can anyone sugest something that I can just get up and runing in a
short
space of time ? ... thanks

I use LT Spice (aka SwitcherCAD III) when I need analog simulation. I
think you just picked the wrong thing to download. What you want is:

http://www.linear.com/designtools/softwareRegistration.jsp

If you don't end up with 'swcadiii.exe', you've done something wrong.


Or try....

http://ltspice.linear.com/software/swcadiii.exe

Which is the 'No Thanks, just download the software'.

Mike Englehart, the author, pops up every so often.

?For Mike, is there an advantage to registering?

The basic library includes only minimal logic components so you'll need
to build your counter from FFs and gates, create a model from scratch,
or find a more complete digital library.


You can get logic models from the LTspice user group at

http://groups.yahoo.com/group/LTspice/

In the files/lib section.

You have to join.

Helmut Sennewald, the moderator, pops up every so often.

Try posting questions in sci.electronics.cad

I've cross posted your query there.

Mike and Helmut are really helpful people. (Sorry if I pisspelt the names)

Tim Hubberstey, P.Eng

DNA



Thanks i got the real ltspice now, just looking at the FFT output now and
trying to figure out all the peaks, with a 1.6khz carrier and 10hz
modulation, the peaks at 10hz from the carrier are preserved but smaller
when divided as i expected, but theres a lot more small peaks close to the
carrier after several stages they get similar size to the expected
sidebands, wich i assume is due to digitisation. not sure if i can redcuce
this yet ...

Colin =^.^=
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Genome
electronics forum Guru


Joined: 30 Apr 2005
Posts: 789

PostPosted: Sun Jun 12, 2005 4:16 pm    Post subject: Re: looking for simulator Reply with quote

"colin" <no.spam.for.me@ntlworld.com> wrote in message
news:wF_qe.13532$jS3.10587@newsfe2-win.ntli.net...
Quote:

"Genome" <ilike_spam@yahoo.co.uk> wrote in message
news:jRZqe.21622$cN2.20382@newsfe4-gui.ntli.net...

"Tim Hubberstey" <bogus@bogusname.com> wrote in message
news:RhZqe.46502$on1.35864@clgrps13...
colin wrote:
Hi,
Im looking for a simulator - mixed mode with schematic capture,
ive
been
trying to evaluate several freeware/trial ones but when it takes
half
a
day
trying to put a simple sinewave generator and r/c circuit and look
at
the
output and frequency plot etc i tend to give up with it. ive looked
at
the
simulation in protel before although its quite good i cant say i was
happy
enough with it to pay the very high price for the whole package

Ive just looked at simetrix but although it seems quite powerfull
i
dont
have any more time to waste trying to figure out how to even do
something
trivial. I tried to download ltspice but all i ended up with was
some
library files, couldnt seem to find the main program.

To start with I wish to look at the spectrum of a phase modulated
carrier
that gets divided with a counter then filtered then multiplied with
a
frequency multiplier etc.

Can anyone sugest something that I can just get up and runing in a
short
space of time ? ... thanks

I use LT Spice (aka SwitcherCAD III) when I need analog simulation. I
think you just picked the wrong thing to download. What you want is:

http://www.linear.com/designtools/softwareRegistration.jsp

If you don't end up with 'swcadiii.exe', you've done something wrong.


Or try....

http://ltspice.linear.com/software/swcadiii.exe

Which is the 'No Thanks, just download the software'.

Mike Englehart, the author, pops up every so often.

?For Mike, is there an advantage to registering?

The basic library includes only minimal logic components so you'll
need
to build your counter from FFs and gates, create a model from scratch,
or find a more complete digital library.


You can get logic models from the LTspice user group at

http://groups.yahoo.com/group/LTspice/

In the files/lib section.

You have to join.

Helmut Sennewald, the moderator, pops up every so often.

Try posting questions in sci.electronics.cad

I've cross posted your query there.

Mike and Helmut are really helpful people. (Sorry if I pisspelt the
names)

Tim Hubberstey, P.Eng

DNA



Thanks i got the real ltspice now, just looking at the FFT output now and
trying to figure out all the peaks, with a 1.6khz carrier and 10hz
modulation, the peaks at 10hz from the carrier are preserved but smaller
when divided as i expected, but theres a lot more small peaks close to the
carrier after several stages they get similar size to the expected
sidebands, wich i assume is due to digitisation. not sure if i can redcuce
this yet ...

Colin =^.^=



I..... am personally clueless.

The best I can do with an FFT plot is realise that I have to sample between
two points that start and end with the same level and are going in opposite
directions(?)

That's got something to do with FFT's or something. Otherwise I'd have to
figure out the other bits and pieces you can stick in the thing.....

Seee, I am THICK.


However..... in case you didn't know.....

LTspice saves your circuit diagrams as .asc files which are really .txt
files.

If you open up notepad (if you doze) then you can open up the .asc file and
copy then paste it in your newsgroup message so those who know something can
have a look and give better advice.

In reverse, if you select the text in a newsgroup message and paste into
notepad and save it with a .asc extension then you can load it into LTspice
and see what someone else is trying to do.

DNA
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Helmut Sennewald
electronics forum Guru Wannabe


Joined: 25 Mar 2005
Posts: 153

PostPosted: Sun Jun 12, 2005 6:21 pm    Post subject: Re: looking for simulator Reply with quote

"colin" <no.spam.for.me@ntlworld.com> schrieb im Newsbeitrag
news:fo%qe.13547$jS3.6823@newsfe2-win.ntli.net...
Quote:

"Genome" <ilike_spam@yahoo.co.uk> wrote in message
news:NZ_qe.21652$cN2.15320@newsfe4-gui.ntli.net...

"colin" <no.spam.for.me@ntlworld.com> wrote in message
news:wF_qe.13532$jS3.10587@newsfe2-win.ntli.net...

"Genome" <ilike_spam@yahoo.co.uk> wrote in message
news:jRZqe.21622$cN2.20382@newsfe4-gui.ntli.net...

"Tim Hubberstey" <bogus@bogusname.com> wrote in message
news:RhZqe.46502$on1.35864@clgrps13...
colin wrote:
Hi,
Im looking for a simulator - mixed mode with schematic capture,
ive
been
trying to evaluate several freeware/trial ones but when it takes
half
a
day
trying to put a simple sinewave generator and r/c circuit and
look
at
the
output and frequency plot etc i tend to give up with it. ive
looked
at
the
simulation in protel before although its quite good i cant say i
was
happy
enough with it to pay the very high price for the whole package

Ive just looked at simetrix but although it seems quite
powerfull
i
dont
have any more time to waste trying to figure out how to even do
something
trivial. I tried to download ltspice but all i ended up with was
some
library files, couldnt seem to find the main program.

To start with I wish to look at the spectrum of a phase
modulated
carrier
that gets divided with a counter then filtered then multiplied
with
a
frequency multiplier etc.

Can anyone sugest something that I can just get up and runing
in
a
short
space of time ? ... thanks

I use LT Spice (aka SwitcherCAD III) when I need analog simulation.
I
think you just picked the wrong thing to download. What you want
is:

http://www.linear.com/designtools/softwareRegistration.jsp

If you don't end up with 'swcadiii.exe', you've done something
wrong.


Or try....

http://ltspice.linear.com/software/swcadiii.exe

Which is the 'No Thanks, just download the software'.

Mike Englehart, the author, pops up every so often.

?For Mike, is there an advantage to registering?

The basic library includes only minimal logic components so you'll
need
to build your counter from FFs and gates, create a model from
scratch,
or find a more complete digital library.


You can get logic models from the LTspice user group at

http://groups.yahoo.com/group/LTspice/

In the files/lib section.

You have to join.

Helmut Sennewald, the moderator, pops up every so often.

Try posting questions in sci.electronics.cad

I've cross posted your query there.

Mike and Helmut are really helpful people. (Sorry if I pisspelt the
names)

Tim Hubberstey, P.Eng

DNA



Thanks i got the real ltspice now, just looking at the FFT output now
and
trying to figure out all the peaks, with a 1.6khz carrier and 10hz
modulation, the peaks at 10hz from the carrier are preserved but
smaller
when divided as i expected, but theres a lot more small peaks close to
the
carrier after several stages they get similar size to the expected
sidebands, wich i assume is due to digitisation. not sure if i can
redcuce
this yet ...

Colin =^.^=



I..... am personally clueless.

The best I can do with an FFT plot is realise that I have to sample
between
two points that start and end with the same level and are going in
opposite
directions(?)

That's got something to do with FFT's or something. Otherwise I'd have to
figure out the other bits and pieces you can stick in the thing.....

Seee, I am THICK.


However..... in case you didn't know.....

LTspice saves your circuit diagrams as .asc files which are really .txt
files.

If you open up notepad (if you doze) then you can open up the .asc file
and
copy then paste it in your newsgroup message so those who know something
can
have a look and give better advice.

In reverse, if you select the text in a newsgroup message and paste into
notepad and save it with a .asc extension then you can load it into
LTspice
and see what someone else is trying to do.

DNA

Without much thinking I just ran the simulation in time domain mode, and
if
u click on the graph u get an FFT option, i found u can select the
'alternate' simulator and the millions of spikes in the fft droped by
about
40db.

I tend to run out of brain power these days so thats usefull after a cat
nap, although i just open up the software and select open last file used.

Just need to decide if its worth modeling a frequency multiplier.

Colin =^.^=


Hello Colin,

Maybe choosing the "Alternate"-solver has simply changed
the automatic timestep control. I recommend to force a useful
timestep and to switch off any data compression. Data compression
is useful for SMPS simulations but not for low distortion application.
Watch how the spurious signals drop from -80dBc to -130dBc just
by reducing the timestep from 1u to 0.1u.

I have attached an example schematic file. Copy the whole following
text in a file "myfm1.asc" . Only the ".asc" counts. Let's hope
that no longer line will be split by any mail server.

Best regards,
Helmut





Version 4
SHEET 1 1244 680
WIRE -48 224 -48 160
WIRE -48 368 -48 304
WIRE 32 160 -48 160
FLAG -48 368 0
FLAG 32 160 fm
IOPIN 32 160 Out
SYMBOL voltage -48 208 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value SFFM(0 1 10k 10 200)
TEXT -104 72 Left 0 !.tran 0 0.1 0 1u
TEXT -104 104 Left 0 !.options plotwinsize=0
TEXT 160 64 Left 0 ;.options reltol=1e-4
TEXT 384 64 Left 0 ;.options trtol=1e-4
TEXT -104 -32 Left 0 ;between 0.1u and 1u.
TEXT -104 0 Left 0 ;Watch the difference in the FFT.
TEXT -104 -64 Left 0 ;Try different timesteps in .tran
TEXT -104 -264 Left 0 ;F0=10kHZ Fm=0.2KHz dF=2kHz
TEXT -104 -304 Left 0 ;FM-Source
TEXT -104 -224 Left 0 ;Modulation Index = dF/Fm = 10
TEXT -104 -184 Left 0 ;Voltage Source: SFFM(0 1 10k 10 200)
TEXT -104 -144 Left 0 ;Checked with FFT of size 131072 points.
TEXT 392 -264 Left 0 ;Other FM and AM sources
TEXT 392 -224 Left 0 ;Components: Special Functions -> Modulate
TEXT 160 104 Left 0 ;Always use ".options plotwinsize=0"
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colin
electronics forum Guru Wannabe


Joined: 30 Apr 2005
Posts: 247

PostPosted: Sun Jun 12, 2005 7:06 pm    Post subject: Re: looking for simulator Reply with quote

"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d8i5gh$r7h$03$1@news.t-online.com...
Quote:
Hello Colin,

Maybe choosing the "Alternate"-solver has simply changed
the automatic timestep control. I recommend to force a useful
timestep and to switch off any data compression. Data compression
is useful for SMPS simulations but not for low distortion application.
Watch how the spurious signals drop from -80dBc to -130dBc just
by reducing the timestep from 1u to 0.1u.

I have attached an example schematic file. Copy the whole following
text in a file "myfm1.asc" . Only the ".asc" counts. Let's hope
that no longer line will be split by any mail server.

Best regards,
Helmut

thanks il try that, i reduced the max time step to 1ns, its crucnhing away
the numvbers as i write this, i increased the carier frequency to 32khz but
can no longer see the 10hz sidebands so trying to increase the data points
for the fft etc but i think i just reached the limit as it said it cldnt get
a contigous block of 131000000, although realisticaly id be surprised if it
can cope.

Colin =^.^=
Back to top
Helmut Sennewald
electronics forum Guru Wannabe


Joined: 25 Mar 2005
Posts: 153

PostPosted: Sun Jun 12, 2005 7:50 pm    Post subject: Re: looking for simulator Reply with quote

"colin" <no.spam.for.me@ntlworld.com> schrieb im Newsbeitrag
news:6t1re.13753$jS3.5938@newsfe2-win.ntli.net...
Quote:

"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d8i5gh$r7h$03$1@news.t-online.com...
Hello Colin,

Maybe choosing the "Alternate"-solver has simply changed
the automatic timestep control. I recommend to force a useful
timestep and to switch off any data compression. Data compression
is useful for SMPS simulations but not for low distortion application.
Watch how the spurious signals drop from -80dBc to -130dBc just
by reducing the timestep from 1u to 0.1u.

I have attached an example schematic file. Copy the whole following
text in a file "myfm1.asc" . Only the ".asc" counts. Let's hope
that no longer line will be split by any mail server.

Best regards,
Helmut

thanks il try that, i reduced the max time step to 1ns, its crucnhing away
the numvbers as i write this, i increased the carier frequency to 32khz
but
can no longer see the 10hz sidebands so trying to increase the data points
for the fft etc but i think i just reached the limit as it said it cldnt
get
a contigous block of 131000000, although realisticaly id be surprised if
it
can cope.

Colin =^.^=


Hello Colin,

The resolution of a DFT or FFT is always 1/Time_span.
If you want see something at 10Hz, then you need a simulation
time which is a multiple of 1/10Hz, e.g. 0.1s, 0.2s, ...

Maybe you see now the drawback of such simulations in Spice if
you have a high carrier frequency. The simulation can take endless.

Best regards,
Helmut
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Jim Thompson
electronics forum Guru


Joined: 06 May 2005
Posts: 5440

PostPosted: Sun Jun 12, 2005 8:24 pm    Post subject: Re: looking for simulator Reply with quote

On Sun, 12 Jun 2005 23:50:58 +0200, "Helmut Sennewald"
<helmutsennewald@t-online.de> wrote:

Quote:
"colin" <no.spam.for.me@ntlworld.com> schrieb im Newsbeitrag
news:6t1re.13753$jS3.5938@newsfe2-win.ntli.net...

"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d8i5gh$r7h$03$1@news.t-online.com...
Hello Colin,

Maybe choosing the "Alternate"-solver has simply changed
the automatic timestep control. I recommend to force a useful
timestep and to switch off any data compression. Data compression
is useful for SMPS simulations but not for low distortion application.
Watch how the spurious signals drop from -80dBc to -130dBc just
by reducing the timestep from 1u to 0.1u.

I have attached an example schematic file. Copy the whole following
text in a file "myfm1.asc" . Only the ".asc" counts. Let's hope
that no longer line will be split by any mail server.

Best regards,
Helmut

thanks il try that, i reduced the max time step to 1ns, its crucnhing away
the numvbers as i write this, i increased the carier frequency to 32khz
but
can no longer see the 10hz sidebands so trying to increase the data points
for the fft etc but i think i just reached the limit as it said it cldnt
get
a contigous block of 131000000, although realisticaly id be surprised if
it
can cope.

Colin =^.^=


Hello Colin,

The resolution of a DFT or FFT is always 1/Time_span.
If you want see something at 10Hz, then you need a simulation
time which is a multiple of 1/10Hz, e.g. 0.1s, 0.2s, ...

Maybe you see now the drawback of such simulations in Spice if
you have a high carrier frequency. The simulation can take endless.

Best regards,
Helmut



AND you need a small timestep, otherwise the "nose" sharpness is
meaningless.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
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colin
electronics forum Guru Wannabe


Joined: 30 Apr 2005
Posts: 247

PostPosted: Sat Jun 18, 2005 4:30 pm    Post subject: Re: [LTSPICE] mixer needed Reply with quote

"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d91kc4$h2p$03$1@news.t-online.com...
Quote:
"colin" <no.spam.for.me@ntlworld.com> schrieb im Newsbeitrag
news:sUXse.23584$m4.2633@newsfe3-gui.ntli.net...

"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d91fki$1pa$00$1@news.t-online.com...
"colin" <no.spam.for.me@ntlworld.com> schrieb im Newsbeitrag
news:i4Xse.23556$m4.16585@newsfe3-gui.ntli.net...
"colin" <no.spam.for.me@ntlworld.com> wrote in message
news:XxTse.22599$m4.9316@newsfe3-gui.ntli.net...
Hi,
is there a mixer availble in LTSPICE?

just a simple idealised (double balanced) one would do ..

ive used the modulator before but this can only modulate a fixed
singal
frequency
i need to mix 2 multi frequency signals.


ok my next problem is i need to introduce a sinusoidaly varying time
delay
into a signal, i cant think what i can use to do this, in the real
world
it
is the result of varying transmision distance wich is what i wish to
examine
the effects of .. any ideas ? i cant use the sffm as it is not a
single
frequency.

Colin =^.^=

Hello Colin,

No problem. The B-source can do it. The variable "time" is available
in the behavioral sources(B).

V=sin(2*pi*f0*(time+deltaTime*sin(2*pi*fdelta*time)))

With numbers:

V=sin(2*pi*1k*(time+0.1m*sin(2*pi*10*time)))

This is a 1kHz sine waveform with a varying delay of +/- 0.1ms and
a frequency of 10Hz.

Increase your time window for the FFT to multiples of 0.1 seconds
in this case. You should also rise the number of samples in
the FFT to 131072. The spectrum looks like PM.

Best regards,
Helmut

Hi Helmut,
thanks again, this would be fine if my signal was a single frequency,
but then i cld use the sffm FM modulator, but unfortunatly i cant reduce
it
to a sinewave,
i need something that effectivly adds PM to an existing voltage node
within
the simulator and i cant see any functions in b-Source that i could do
that
with.

maybe i need to do something like make a model for a transmision line
and
vary the length ?

I gues as a last resort I could make a lumped transmision line with
varactors etc.

Colin =^.^=

Hello Colin,

Sorry for misunderstanding your desire.

There is a delay function in LTspice, but it's only ok to
use it with a constant delay. This means you could only
change the delay in a stepped simulation(.step).
It is not intended for varying delays.


V=delay(V(x1), 0.1m)

or

.step param DELAY1 0 0.1m 0.02m
V=delay(V(x1),{DELAY1})

Best regards,
Helmut


Hi,
thanks again, this is interesting as there is no mention of the delay
function in the help section, it pays to ask :)

I tried to put a variable in the delay, it would not accept the sine
function eg V=delay(v(a),sine(time)) but it would accept
V=delay(v(a),0.001+time/1000) wich gives the result expected it also
accepted a voltage as the second term eg V=delay(v(a),v(b)) wich is
interesting as i can use a sine voltage, however it does give rather jumpy
results but i expect i can improve this with tstep etc.

I gues i could also add sinousoudaly varying amounts of the delayed and non
delayed voltage.

Colin =^.^=
Back to top
colin
electronics forum Guru Wannabe


Joined: 30 Apr 2005
Posts: 247

PostPosted: Sat Jun 18, 2005 4:30 pm    Post subject: Re: [LTSPICE] mixer needed Reply with quote

"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d91kc4$h2p$03$1@news.t-online.com...
Quote:
"colin" <no.spam.for.me@ntlworld.com> schrieb im Newsbeitrag
news:sUXse.23584$m4.2633@newsfe3-gui.ntli.net...

"Helmut Sennewald" <helmutsennewald@t-online.de> wrote in message
news:d91fki$1pa$00$1@news.t-online.com...
"colin" <no.spam.for.me@ntlworld.com> schrieb im Newsbeitrag
news:i4Xse.23556$m4.16585@newsfe3-gui.ntli.net...
"colin" <no.spam.for.me@ntlworld.com> wrote in message
news:XxTse.22599$m4.9316@newsfe3-gui.ntli.net...
Hi,
is there a mixer availble in LTSPICE?

just a simple idealised (double balanced) one would do ..

ive used the modulator before but this can only modulate a fixed
singal
frequency
i need to mix 2 multi frequency signals.


ok my next problem is i need to introduce a sinusoidaly varying time
delay
into a signal, i cant think what i can use to do this, in the real
world
it
is the result of varying transmision distance wich is what i wish to
examine
the effects of .. any ideas ? i cant use the sffm as it is not a
single
frequency.

Colin =^.^=

Hello Colin,

No problem. The B-source can do it. The variable "time" is available
in the behavioral sources(B).

V=sin(2*pi*f0*(time+deltaTime*sin(2*pi*fdelta*time)))

With numbers:

V=sin(2*pi*1k*(time+0.1m*sin(2*pi*10*time)))

This is a 1kHz sine waveform with a varying delay of +/- 0.1ms and
a frequency of 10Hz.

Increase your time window for the FFT to multiples of 0.1 seconds
in this case. You should also rise the number of samples in
the FFT to 131072. The spectrum looks like PM.

Best regards,
Helmut

Hi Helmut,
thanks again, this would be fine if my signal was a single frequency,
but then i cld use the sffm FM modulator, but unfortunatly i cant reduce
it
to a sinewave,
i need something that effectivly adds PM to an existing voltage node
within
the simulator and i cant see any functions in b-Source that i could do
that
with.

maybe i need to do something like make a model for a transmision line
and
vary the length ?

I gues as a last resort I could make a lumped transmision line with
varactors etc.

Colin =^.^=

Hello Colin,

Sorry for misunderstanding your desire.

There is a delay function in LTspice, but it's only ok to
use it with a constant delay. This means you could only
change the delay in a stepped simulation(.step).
It is not intended for varying delays.


V=delay(V(x1), 0.1m)

or

.step param DELAY1 0 0.1m 0.02m
V=delay(V(x1),{DELAY1})

Best regards,
Helmut


Hi,
thanks again, this is interesting as there is no mention of the delay
function in the help section, it pays to ask :)

I tried to put a variable in the delay, it would not accept the sine
function eg V=delay(v(a),sine(time)) but it would accept
V=delay(v(a),0.001+time/1000) wich gives the result expected it also
accepted a voltage as the second term eg V=delay(v(a),v(b)) wich is
interesting as i can use a sine voltage, however it does give rather jumpy
results but i expect i can improve this with tstep etc.

I gues i could also add sinousoudaly varying amounts of the delayed and non
delayed voltage.

Colin =^.^=
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