Singularity error - Simulink

An error occurred while running the simulation and the simulation was terminated Caused by: Derivative of state '1' in block 'XXXXXX/Receiver/pre-amp/CTLE mode 2/Transfer Fcn15' at time 3.3003349235944607E-9 is not finite. The simulation will be stopped. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)

Please help.

[Birdman]

Share your model.

[Harvijay Raj]

Hi Birdman, I am assuming you are from Mathworks. Unfortunately my designs are proprietary and I can not post in public domain. If you could setup some kind of webex, I can share my screen and show you what is going on. is that ok?

If there is local Sandiego based (Qualcomm) rep then I can share locally.

Regards, Harvijay

[Birdman]

Ok, especially I want to see all transfer functions.

[Harvijay Raj]

I am working on Serdes model, I have quite a few Xfer func that you might be interested in seeing.

[Harvijay Raj]

So r u from Mathworks? R u setting up some remote debug session?

Answer 1

[Suhan]

Hi,

The singularity issues occur due to model instabilities. Instabilities may occur in a model due to a wide variety of reasons and one of them is the reference is too quick that the plant does not have enough time to respond and runs into singularities. This can be eliminated by putting in a filter on the reference signal.

Below is information on three tools that may assist you in further improving the model stability, if you are not already familiar with them:

1. Solver Profiler: The Solver Profiler can help you visualize your model dynamics and see where they may be unstable. Using the Solver Profile is described at this link: https://www.mathworks.com/help/simulink/ug/examine-solver-behavior-using-solver-profiler.html

2. Log the Simulink states, so you may view their values after running the simulation (perhaps stop the simulation before the error or use the above approach to remove the error): https://www.mathworks.com/help/simulink/examples/logging-states-in-structure-format.html

3. Use Stepping Options to pause the simulation and view signal values before the error occurs: https://www.mathworks.com/help/simulink/ug/simulation-stepper-interface.html