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On Mon, Mar 17, 2025 at 02:19 AM, <ericsson.sunshine@...> wrote:

Sorry, forgot, I have used 1e-9 today in Matlab, I didn't wait it ran all
200us, Just 23% to see the most shape of the leading, the scale is the same,
peak approx 40mV.

You only need the first 40us, and even 1us should already be enough...

-marcel

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It's common for the TUNE input to be voltage driven through a low value resistor. It may be that the YIG already has that resistor built-in, but it's usually external because the tuning current can be a few hundred mA, and the dissipation could be considerable.

Thanks Tony and John,

LTspice v24.1.0 was installed automatically yesterday with the internal update. Today tried to update again and now installed new version 24.1.5

I've loaded the test simulation of LF356 and make sure to reset all settings, modified again the "Component attribute editor" to original setting for U2, applied the suggestions (rise/fall times and the option directive), now works perfectly... Thank you Tony!

Best regards, Stephano

I think I found it. When the time-domain waveform is plotted from t=0 to t=50us, it
shows a *negative-going* exponential pulse reaching -5.037kV at 960ns. (The shape is
approximately waht your picture shows, the scale is not.) At 41us it is about -20V. I am
sure that when Simulink is told to use a sample-rate of 10ns and an accuracy of 10e-9
or better, it will show the same thing. As should LTspice.

-marcel

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On 17/03/2025 11:40, Stephano via groups.io wrote:

using the TI model of LF356 on LTspice v24.1.0 result in strange behaviour, DC output from OpAmp is over 18V when the supply voltages are ± 15V.

In the "Component attribute editor" I've changed parameters for this version of LTspice, the original from the file area "LF356_test.zip" result in errors at simulation start.

I want to simulate a input circuit of an test equipment (Boonton 4200) that is oscillating at 93Hz square wave with amplitude near the supply coltages. I'm curious to see the Phase Margin of this differential stage with three LF356.

Clearly this pspice model is incompatible with this LTspice version, or there is a workaround possible to apply ?

I don't have version 24.1.0 installed, but with 24.1.5, the (Helmut's) original circuit stalled at 40% completion, but was correct up to that point. When I changed the rise and fall times of the source to 100n from 10n, it simulated perfectly. With version 25.0.12, the original unedited circuit had no problems. I also ran an input voltage sweep and saw the output clipped well inside the supply voltages.

The version 24.1.0 was quite short-lived because there were a number of problems with it. There have been many internal changes in the 24.1.x release. some of these have since been fixed, but others remain.

It may be that nobody can duplicate the problem you are having, but if you have changed anything in the schematic, you should upload it to Files > Temp, so more people can try. Did you change any of the Control Panel > SPICE settings from default? The Trtol parameter in 24.1 is different from 24.0 in the default state.

Adding ".options gshunt=1e-12 cshunt=1e-14" fixed the stalling at 40% issue with 24.1.5.

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using the TI model of LF356 on LTspice v24.1.0 result in strange behaviour, DC output from OpAmp is over 18V when the supply voltages are ± 15V.

In the "Component attribute editor" I've changed parameters for this version of LTspice, the original from the file area "LF356_test.zip" result in errors at simulation start.

I want to simulate a input circuit of an test equipment (Boonton 4200) that is oscillating at 93Hz square wave with amplitude near the supply coltages. I'm curious to see the Phase Margin of this differential stage with three LF356.

Clearly this pspice model is incompatible with this LTspice version, or there is a workaround possible to apply ?

I don't have version 24.1.0 installed, but with 24.1.5, the (Helmut's) original circuit stalled at 40% completion, but was correct up to that point. When I changed the rise and fall times of the source to 100n from 10n, it simulated perfectly. With version 25.0.12, the original unedited circuit had no problems. I also ran an input voltage sweep and saw the output clipped well inside the supply voltages.

The version 24.1.0 was quite short-lived because there were a number of problems with it. There have been many internal changes in the 24.1.x release. some of these have since been fixed, but others remain.

It may be that nobody can duplicate the problem you are having, but if you have changed anything in the schematic, you should upload it to Files > Temp, so more people can try. Did you change any of the Control Panel > SPICE settings from default? The Trtol parameter in 24.1 is different from 24.0 in the default state.

--
Regards,
Tony

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We can't help much unless you let us see more of what you are doing. Upload your .ASC file AND all the other files required to run the simulation, but not .RAW? and .LOG files or pictures,? in a ZIP archive to Files => Temp.

Go to the web page: /g/LTspice/topics. Click on Files in the list on the left. Then click on Temp. Then click on New Upload in the blue box at top left. Click on Upload File in the drop-down menu. Then send a message to tell us that you did that.

Hi,

using the TI model of LF356 on LTspice v24.1.0 result in strange behaviour, DC output from OpAmp is over 18V when the supply voltages are +/- 15V.

In the "Component attribute editor" I've changed parameters for this version of LTspice, the original from the file area "LF356_test.zip" result in errors at simulation start.

I want to simulate a input circuit of an test equipment (Boonton 4200) that is oscillating at 93Hz square wave with amplitude near the supply coltages. I'm curious to see the Phase Margin of this differential stage with three LF356.

Clearly this pspice model is incompatible with this LTspice version, or there is a workaround possible to apply ?

Thanks, Stephano

Hi,

using the TI model of LF356 on LTspice v24.1.0 result in strange behaviour, DC output from OpAmp is over 18V when the supply voltages are +/- 15V.

In the "Component attribute editor" I've changed parameters for this version of LTspice, the original from the file area "LF356_test.zip" result in errors at simulation start.

I want to simulate a input circuit of an test equipment (Boonton 4200) that is oscillating at 93Hz square wave with amplitude near the supply coltages. I'm curious to see the Phase Margin of this differential stage with three LF356.

Clearly this pspice model is incompatible with this LTspice version, or there is a workaround possible to apply ?

Thanks, Stephano

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That's a bit too much freedom. LTspice will not warn you of duplicate designators until you run an analysis, which will obviously fail. If you leave it entirely to LTspice you will never get duplicates. Caution! This does not apply to net names.

The transfer function and time domain expressions look OK to me but the scope plot is obviously "wrong".
This could be caused by the sample-based Simulink implementation. What is the sample-rate / solver
algorithm? If there is aliasing all three representations could be correct.

-marcel