ADS error message: Internal timestep 1.91586e-10 too small at time 5.00000e-10

There might be few reasons.
-Model is not 100% compatible with ADS simulator engine
-Model has some errors or missing points
-If you're using s-parameters, sampling points are out of min. and max. freq.
-The circuit itself has some floating nodes or extremely high or low valued components
-There are short circuits or open circuits
-You're using very short time step in simulator control
-Loads or terminations are non-realistic

There may some others but those are the first ones that came into my mind.
Transient analysis does not like discrete sampling such as s-parameters and discontinuities. If it's possible use time continues models for s-parameter defined components. in order to do this, use ADSs "SPICE Model Creator" and replace with.

BigBoss said:

There might be few reasons.
-Model is not 100% compatible with ADS simulator engine
-Model has some errors or missing points
-If you're using s-parameters, sampling points are out of min. and max. freq.
-The circuit itself has some floating nodes or extremely high or low valued components
-There are short circuits or open circuits
-You're using very short time step in simulator control
-Loads or terminations are non-realistic

There may some others but those are the first ones that came into my mind.
Transient analysis does not like discrete sampling such as s-parameters and discontinuities. If it's possible use time continues models for s-parameter defined components. in order to do this, use ADSs "SPICE Model Creator" and replace with.

Click to expand...

Hi @BigBoss
I am using a model from NXP product. I answer your probabilities respectively,

-Model is not 100% compatible with ADS simulator engine
answer: maybe, but I have performed s-parameter simulation previously and I have got an expected result. so I do not think there is an incompatibility in ADS. BUT, despite of what I said, when I open my project, I see such warning:
ailed to add item definition to cell "AFIC10275N_Level1_Rev0_DK:FSL_AFIC10275N_Level1_Rev0_MODEL"
Could not find cell "FSL_AFIC10275N_Level1_Rev0_MODEL" in library "AFIC10275N_Level1_Rev0_DK".

anyway, this do s-parameter simulation correctly.

-Model is not 100% compatible with ADS simulator engine:
answer: well, I had questioned about it from NXP company, and they answer their model support transient analysis.


-If you're using s-parameters, sampling points are out of min. and max. freq.
answer: I am doing transient analysis using large signal model not s2p file.

-The circuit itself has some floating nodes or extremely high or low valued components
-There are short circuits or open circuits

answer: I am using test circuit values. some nodes are float by default such as thermal nodes)

-You're using very short time step in simulator control
answer: time step is about 1us. carrier frequency is 1090MHz. pulsed RF input signal has pulse width 128us (10% duty cycle). this does not seem too low.

-Loads or terminations are non-realistic

answer: input and output load is 50 ohm.

thank you

I have checked the error log and I'm sure that the model has some problems.
Which version of ADS you've been using ?? Did you you know that you must install this generic DK before using particular component ?

It needs a registration. Without generic DK, simulations don't work.


OK, the problem is coming from the DK itself. It's buggy, call NXP support.

BigBoss said:

I have checked the error log and I'm sure that the model has some problems.
Which version of ADS you've been using ?? Did you you know that you must install this generic DK before using particular component ?

Models for ADS: Keysight Advanced Design System | NXP Semiconductors

It needs a registration. Without generic DK, simulations don't work.


OK, the problem is coming from the DK itself. It's buggy, call NXP support.
View attachment 177043

Click to expand...

Hi @BigBoss,
so so SORRY for such long delay to reply.
well I have told my question in NXP forum about this warning, the link is in the following:

NXP forum: warning

well, about my project, I have to say because of intellectual property I can not issue full project. so sorry about that. I am dong project for some company.

best regards,
thank you

mohamis288 said:

Hi @BigBoss,
so so SORRY for such long delay to reply.
well I have told my question in NXP forum about this warning, the link is in the following:

NXP forum: warning

well, about my project, I have to say because of intellectual property I can not issue full project. so sorry about that. I am dong project for some company.

best regards,
thank you

Click to expand...

Never mind, I have also observed this error. Even you do a simple DC simulation, ADS stops to run due to this bug.
You have to wait the response of NXP, you got nothing to do.

BigBoss said:

Never mind, I have also observed this error. Even you do a simple DC simulation, ADS stops to run due to this bug.
You have to wait the response of NXP, you got nothing to do.

Click to expand...

Hi @BigBoss,
fortunately, I've git permission from my company to publish my simulation project. so, I have uploaded the link in the following. let me know the solution for this error if there is any. I would appreciated any help.

[moderator action: removed link to external file server]

do not forget to use the NXP large-signal model library. the original project is located in the "firstSchematic" cell.
best regards,
thank you

mohamis288 said:

Hi @BigBoss,
fortunately, I've git permission from my company to publish my simulation project. so, I have uploaded the link in the following. let me know the solution for this error if there is any. I would appreciated any help.
do not forget to use the NXP large-signal model library. the original project is located in the "firstSchematic" cell.
best regards,
thank you

Click to expand...

I have mentioned earlier. This model has a bug and I have already observed that. So inspection your project is useless. You have to signal this error to NXP, they may hopefully correct.