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Hi amaktoom,

Thank you very much for that explanation about the time invariant system. Like you I learn something every time.
By the way I posted a simplified version of the op Amp response, see in the Temp Files 'Re: Inverting Op Amp'
Please note:- the first block in the chain represents the transfer function of the proportional block (unity gain, for convinience); the next block represents the transfer function of a single exponential lag(unity gain for convinience, you can select any gain to suit); the next block represents the R2/R1 of the op amplifier. Vxa represents the overall transfer function of the preceding blocks and Vxb represents the corresponding output signal response after multiplyng the overall transfer function by the input signal, w
[Vo =(Vo/Vin)*Vin].

Best regards,

Michael P Kiwanuka




To: LTspice@...
From: amaktoomamu@...
Date: Thu, 18 Apr 2013 17:21:40 +0000
Subject: [LTspice] Re: inverting opamp simulation: rapid component variation






Dear Michael,
I will be able to see your solution closely after completing some work that I am doing currently. To use your solution, I will have learn many new concepts of control system (and perhaps including that of LTspice! what an irony that I am writing FREE beginners book for LTspice: !).
I am not good in Signals System (or any other subject- still a lot of concepts to learn) but to quote wiki-
"Time invariance means that whether we apply an input to the system now or T seconds from now, the output will be identical except for a time delay of the T seconds. That is, if the output due to input x(t) is y(t), then the output due to input x(t-T) is y(t-T). Hence, the system is time invariant because the output does not depend on the particular time the input is applied".
Using this definition, the system with output Vo=-(R2/R1)Vi will be linear for some R2(t) and Non-linear for other R2(t)- it depends what kind of function R2 is that of time.

I actually avoid those discussion here that don't relate to LTspice specifically. Although I very much like to listen to the views of experienced members that we have here, If you wish we could take this discussion to edaboard. I would love to learn new ideas.

Laplace is not valid for such time varying systems:

--- In LTspice@..., Michael Peter Kiwanuka <michael883575@...> wrote:

Hi amaktoom,

Thank you for your message. The 'w' is supposed to be the same signal as that at the input of the control process. It was not meant to be replaced by any value although that may correct the LTspice error. To correct the LTspice error issued, delete the source V2 and label the subsquently remaining input line to the proportional block. Label it 'w' . The LTspice error will go and things will run as intended.

Could you please explain to me what a time varying signal/circuit is. I thought Laplace is intended for time varying functions and signals. Please enlighten me about the prof, advice.

Best regards,

Michael




To: LTspice@...
From: amaktoomamu@...
Date: Thu, 18 Apr 2013 13:58:42 +0000
Subject: [LTspice] Re: inverting opamp simulation: rapid component variation







--- In LTspice@..., Michael Peter Kiwanuka <michael883575@> wrote:

Hello Michael
Thanks for your file. I saw that file and when it reported error msg for 'w' i assigned it some value and it ran smoothly.
But, I don't have much idea of control theory so i couldn't follow at all what you have tried to do. However, Thank you for taking my attention Helmut's control lib. Its a new thing for me to do control theory using LTspice.
A prof (Phd form UCB in 1960) told me that my circuit is time varying so i cant think of 'transfer function, Laplace etc. That's why I decided to manage things with time-domain plots as suggested by Andy and others.
Thank you,again.

Hi amaktoom,

I posted a solution in the temp files of this group

and I assumed that the source signal approximate a steady voltage over an appropriate period of time. For example, the source frequency could be 1mHz and in modelling this, an AC source would definetely be adequate and correct and would approximate to a steady dc soorce for a relatively short period of time. The resulting response of gain Vs frequency would not be far too wrong. Please take a look at my solution.

Best regards

Michael P Kiwanuka




To: LTspice@...
From: amaktoomamu@
Date: Wed, 17 Apr 2013 10:28:43 +0000
Subject: [LTspice] Re: inverting opamp simulation: rapid component variation





Hi All,
Thanks for your comments. I got it why hypothesis doesn't make sense at high frequency. I will rely on transient, as suggested.

--- In LTspice@..., Andy <Andrew.Ingraham@> wrote:

MOHAMMAD A MAKTOOMI <amaktoomamu@> wrote:

Thank you, Andy for your hints.
But, in '.AC' we need to have an AC voltage or current source. Here, I don't
have any such thing (as I wish to vary the frequency of R2, NOT that of any
source), so how do I proceed?

Yes indeed, and I think that is why you must do this as a .TRAN
analysis. .AC analysis just doesn't work for your case.

Then .STEP the frequency.

With your 741 op-amp model, you do have an interesting situation
because of the severe distortion at higher frequencies (which by the
way only a .TRAN analysis would show, if there was a way to do this as
a .AC analysis). Given that, you need to consider what parameter of
output amplitude you measure: peak-to-peak vs. RMS vs. fundamental
amplitude?

Andy

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

--- In LTspice@..., "lainthales" <miboe24238@...> wrote:

Hello Guys,

im looking for a model of the ltc 1666 / 1667 / 1668
its an ADC and i cant find any ADC models at the standart lib of LTSpice

someone got this model? or got an idea what i should use as equivalent?

thx :)!

Hello,

The LTC1666 is not an ADC. It's a DAC.
That's a very fundamental difference.
Please read the datasheet more carefully. :-)


Best regards,
Helmut

--- In LTspice@..., "elena.ruorui" <elena.ruorui@...> wrote:

HI all,
i'm really new with LTspice...
I want to simulate an LTC2377-18 SAR ADC, but in the library there isnt any LTC2377 model.
I've seen that the LT gives an .ibis file. How can i add or use this with LTspice?
Or maybe there is another library with this component in it?

Thanks in advance for help!

Hello,

May be you misunderstood the target applications/simulations
of SPICE programs.

What do you expect from an ADC model in SPICE?

Best regards,
Helmut

In message <kkp9jt+euqg@...>, dated Thu, 18 Apr 2013, hisotaso <flirm777@...> writes:

In the header of the .lib file from which I posted my example, mu professor states "Models are written in LTSpice syntax." But where is this syntax detailed thoroughly!?

Are you not allowed to ask your professor? OK, some give silly answers, but not all.

Also, go to the list's web site and click on 'Links' in the left column. That leads you to enough documentation to last at least a year.
--
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Dear Michael,
I will be able to see your solution closely after completing some work that I am doing currently. To use your solution, I will have learn many new concepts of control system (and perhaps including that of LTspice! what an irony that I am writing FREE beginners book for LTspice: !).
I am not good in Signals System (or any other subject- still a lot of concepts to learn) but to quote wiki-
"Time invariance means that whether we apply an input to the system now or T seconds from now, the output will be identical except for a time delay of the T seconds. That is, if the output due to input x(t) is y(t), then the output due to input x(t-T) is y(t-T). Hence, the system is time invariant because the output does not depend on the particular time the input is applied".
Using this definition, the system with output Vo=-(R2/R1)Vi will be linear for some R2(t) and Non-linear for other R2(t)- it depends what kind of function R2 is that of time.

I actually avoid those discussion here that don't relate to LTspice specifically. Although I very much like to listen to the views of experienced members that we have here, If you wish we could take this discussion to edaboard. I would love to learn new ideas.

Laplace is not valid for such time varying systems:

Thank you Jim for your prompt reply. I have the B source documentation open in front of me: the LTSpice user manual, LTSpice help file (they appear to be the same thing), and the LT Wiki. I have looked through these documents prior to posting, and I cannot find any of the example parameters I listed in my original post. Surely there must be a complete listing of ALL possible component parameters in LTSpice, or perhaps the parameters are common to all Spice flavors, I don't know.

In the header of the .lib file from which I posted my example, mu professor states "Models are written in LTSpice syntax." But where is this syntax detailed thoroughly!? Am I supposed to know what these parameters mean from experience? Any help is appreciated.

Look in the documentation for B source.


You can also use the search function of LTspice help file to find some of those things.


Jim Wagner
Oregon Research Electronics

Hello, I am looking for a guide or list of all LTSpice/Spice syntax for designing components. Of course I would like to keep this as a reference, but I would also like to be able to read a library file and be able to interpret it. For example one of my professors has created a library with several components in it, including edge detectors, but I don't know what some of the syntax means.

Ex.:

* first_cross_detect
.subckt first_cross_detect in out ref
.params vtrig=0 scale=1meg tholdoff=1u tripdt=10p tripdv=10u td=10n
A1 shi 0 clk 0 0 0 sho 0 SAMPLEHOLD vhigh=10g tripdt={tripdt}
B1 shi 0 V=(time)*{scale}
B2 clk 0 V=if ((time < {tholdoff} | v(gate) > 0), 1k, v(in) - v(ref) - {vtrig} + 0.5) tripdt={tripdt} tripdv={tripdv}
B3 gate 0 V=delay(v(sho), {td})
B4 out 0 v=v(sho)/{scale}
.ends cross_detect

In the above syntax, I do not know what scale=1meg, tholdoff=1u, td=10n etc. mean. Perhaps these are industry or Spice standard terms, but I can't seem to find any information or a guide on creating my own components with all the syntax commands listed. Any help would be appreciated

folks:
any one can give an insight into the application of Dual Active Bridge topology with 2 sided control as a very efficient dc-dc converter?
I need to make the smallest most efficient 48V 5kW stage with efficiency >98% from 320V+ 1 cycle transient response for 0 amp to 200amp.
Appreciate your philosophical position on this subject....all I see is battery charging or supercap charging yet they call it dc-dc converter...
-robin
?
?
MARKETPLACE

________________________________


________________________________


Switch to: Text-Only, Daily Digest ? Unsubscribe ? Terms of Use ? Send us Feedback
.


[Non-text portions of this message have been removed]

John( or any one)
In certain simulations of switched mode converters,I see switch current CONTINUE to flow even after the switch has been given TURN-OFF signal.
Happens so in other simulation tools as well.
any idea why & how to fix? this absurd situation.
-robin
?


________________________________
From: John Woodgate <jmw@...>
To: LTspice@...
Sent: Thursday, April 18, 2013 7:40 AM
Subject: Re: [LTspice] TPA2005 or TDA7053A model available

?
In message <mailto:kkoonc%2B8ncd%40eGroups.com>, dated Thu, 18 Apr 2013, martin
<mailto:martin.junker%40online.de> writes:

Does anybody know a spice model for either the TPA2005 or the TDA7053A

I'd be interested in a model for the TDA7053A, as it's probably two
TDA7052A devices in one package.

? For the TPA2005 I found a zip file on the TI web page. Unfortunately
I can not read the subcircuit. It seems to be a problem with the coding
of the text.

It's probably only suited to TI's TINA simulator, which is available in
a free version.
--
OOO - Own Opinions Only. See
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK



[Non-text portions of this message have been removed]

Hi amaktoom,

Thank you for your message. The 'w' is supposed to be the same signal as that at the input of the control process. It was not meant to be replaced by any value although that may correct the LTspice error. To correct the LTspice error issued, delete the source V2 and label the subsquently remaining input line to the proportional block. Label it 'w' . The LTspice error will go and things will run as intended.

Could you please explain to me what a time varying signal/circuit is. I thought Laplace is intended for time varying functions and signals. Please enlighten me about the prof, advice.

Best regards,

Michael




To: LTspice@...
From: amaktoomamu@...
Date: Thu, 18 Apr 2013 13:58:42 +0000
Subject: [LTspice] Re: inverting opamp simulation: rapid component variation







--- In LTspice@..., Michael Peter Kiwanuka <michael883575@...> wrote:

Hello Michael
Thanks for your file. I saw that file and when it reported error msg for 'w' i assigned it some value and it ran smoothly.
But, I don't have much idea of control theory so i couldn't follow at all what you have tried to do. However, Thank you for taking my attention Helmut's control lib. Its a new thing for me to do control theory using LTspice.
A prof (Phd form UCB in 1960) told me that my circuit is time varying so i cant think of 'transfer function, Laplace etc. That's why I decided to manage things with time-domain plots as suggested by Andy and others.
Thank you,again.

Hi amaktoom,

I posted a solution in the temp files of this group

and I assumed that the source signal approximate a steady voltage over an appropriate period of time. For example, the source frequency could be 1mHz and in modelling this, an AC source would definetely be adequate and correct and would approximate to a steady dc soorce for a relatively short period of time. The resulting response of gain Vs frequency would not be far too wrong. Please take a look at my solution.

Best regards

Michael P Kiwanuka




To: LTspice@...
From: amaktoomamu@...
Date: Wed, 17 Apr 2013 10:28:43 +0000
Subject: [LTspice] Re: inverting opamp simulation: rapid component variation





Hi All,
Thanks for your comments. I got it why hypothesis doesn't make sense at high frequency. I will rely on transient, as suggested.

--- In LTspice@..., Andy <Andrew.Ingraham@> wrote:

MOHAMMAD A MAKTOOMI <amaktoomamu@> wrote:

Thank you, Andy for your hints.
But, in '.AC' we need to have an AC voltage or current source. Here, I don't
have any such thing (as I wish to vary the frequency of R2, NOT that of any
source), so how do I proceed?

Yes indeed, and I think that is why you must do this as a .TRAN
analysis. .AC analysis just doesn't work for your case.

Then .STEP the frequency.

With your 741 op-amp model, you do have an interesting situation
because of the severe distortion at higher frequencies (which by the
way only a .TRAN analysis would show, if there was a way to do this as
a .AC analysis). Given that, you need to consider what parameter of
output amplitude you measure: peak-to-peak vs. RMS vs. fundamental
amplitude?

Andy

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]

In message <kkoonc+8ncd@...>, dated Thu, 18 Apr 2013, martin <martin.junker@...> writes:

Does anybody know a spice model for either the TPA2005 or the TDA7053A

I'd be interested in a model for the TDA7053A, as it's probably two TDA7052A devices in one package.

? For the TPA2005 I found a zip file on the TI web page. Unfortunately I can not read the subcircuit. It seems to be a problem with the coding of the text.

It's probably only suited to TI's TINA simulator, which is available in a free version.
--
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

--- In LTspice@..., John Woodgate <jmw@...> wrote:

In message <kkn52h+e41n@...>, dated Wed, 17 Apr 2013, jtanalog
<ltlist@...> writes:

Aha! Thanks! (I scoured all the helps and tutorials and NOTHING shows
about that automatic rotation.)

The earth moves for you automatically and you're *complaining*?!(;-)
--
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK

Thanks, John, You made me break out laughing!!

-Jim Thompson

--- In LTspice@..., Michael Peter Kiwanuka <michael883575@...> wrote:

Hello Michael
Thanks for your file. I saw that file and when it reported error msg for 'w' i assigned it some value and it ran smoothly.
But, I don't have much idea of control theory so i couldn't follow at all what you have tried to do. However, Thank you for taking my attention Helmut's control lib. Its a new thing for me to do control theory using LTspice.
A prof (Phd form UCB in 1960) told me that my circuit is time varying so i cant think of 'transfer function, Laplace etc. That's why I decided to manage things with time-domain plots as suggested by Andy and others.
Thank you,again.

Hi amaktoom,

I posted a solution in the temp files of this group

and I assumed that the source signal approximate a steady voltage over an appropriate period of time. For example, the source frequency could be 1mHz and in modelling this, an AC source would definetely be adequate and correct and would approximate to a steady dc soorce for a relatively short period of time. The resulting response of gain Vs frequency would not be far too wrong. Please take a look at my solution.

Best regards

Michael P Kiwanuka




To: LTspice@...
From: amaktoomamu@...
Date: Wed, 17 Apr 2013 10:28:43 +0000
Subject: [LTspice] Re: inverting opamp simulation: rapid component variation





Hi All,
Thanks for your comments. I got it why hypothesis doesn't make sense at high frequency. I will rely on transient, as suggested.

--- In LTspice@..., Andy <Andrew.Ingraham@> wrote:

MOHAMMAD A MAKTOOMI <amaktoomamu@> wrote:

Thank you, Andy for your hints.
But, in '.AC' we need to have an AC voltage or current source. Here, I don't
have any such thing (as I wish to vary the frequency of R2, NOT that of any
source), so how do I proceed?

Yes indeed, and I think that is why you must do this as a .TRAN
analysis. .AC analysis just doesn't work for your case.

Then .STEP the frequency.

With your 741 op-amp model, you do have an interesting situation
because of the severe distortion at higher frequencies (which by the
way only a .TRAN analysis would show, if there was a way to do this as
a .AC analysis). Given that, you need to consider what parameter of
output amplitude you measure: peak-to-peak vs. RMS vs. fundamental
amplitude?

Andy

[Non-text portions of this message have been removed]

Does anybody know a spice model for either the TPA2005 or the TDA7053A ?
For the TPA2005 I found a zip file on the TI web page. Unfortunately I can not read the subcircuit. It seems to be a problem with the coding of the text.

--- In LTspice@..., "reinhold_pieper" <reinhold.pieper@...> wrote:

Hello,
I want to simulate a wheatstone brige-sensor with a very high amplifikation.
In my lab i see a high 1/f noise on the output. It is en effect of current noise of the thick film resistors.
Background:


SPICE has no resistor modells with 1/f parameter option. So I can not simulate this effects of current noise.
Has someone a subcircuit solution for me?

Best regards
Reinhold

Hello Reinhold,

Please take a look to these subcircuits.

Files > Tut > noisegen_with_subcircuits


Files > Tut > noisegen


Best regards,
Helmut

Hello,
I want to simulate a wheatstone brige-sensor with a very high amplifikation.
In my lab i see a high 1/f noise on the output. It is en effect of current noise of the thick film resistors.
Background:


SPICE has no resistor modells with 1/f parameter option. So I can not simulate this effects of current noise.
Has someone a subcircuit solution for me?

Best regards
Reinhold

HI all,
i'm really new with LTspice...
I want to simulate an LTC2377-18 SAR ADC, but in the library there isnt any LTC2377 model.
I've seen that the LT gives an .ibis file. How can i add or use this with LTspice?
Or maybe there is another library with this component in it?

Thanks in advance for help!

Hello Guys,

im looking for a model of the ltc 1666 / 1667 / 1668
its an ADC and i cant find any ADC models at the standart lib of LTSpice

someone got this model? or got an idea what i should use as equivalent?

thx :)!

In message <kkn52h+e41n@...>, dated Wed, 17 Apr 2013, jtanalog <ltlist@...> writes:

Aha! Thanks! (I scoured all the helps and tutorials and NOTHING shows about that automatic rotation.)

The earth moves for you automatically and you're *complaining*?!(;-)
--
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK