Convergence Problem in ADS

A model is built in ads and run. Under DC analysis is is converged, but under transient analysis it is nor converged. and the message below appeared,

Pseudo transient does not converge

Step limit exceeded.

DC analysis converged with Convergence mode = Newton-Raphson.


Could someone tell me the possible reason and the posssible solution?

Thanks!

Convergence Problem in @DS

Try to increase the "Maximum iteration per time step" in Convergence tab. Also, you might change the integration method to "Gear"

try to post ur simulation file

khouly

ok,the simulation file is here.

Convergence Problem in @DS

I delete SRC1 and set the time in psec. It converges.

Thanks for the reply!But I think the problem is still not solved. The model was built according to a paper. It should work well in several ns. Maybe it is because of some mistake of my model.

Could someone give me some help to get some material about the transient analysis in ADS, I think it is also useful for me to debug my model.

I don’t know what model of drain current (IDS) your using, but if you are using the Curtice model you will have a problem of convergence, specially at values of VGS<=Vp (pinch off voltage). This is due because the equation that model the drain curre (IDS) is not cero at values of VGS<=Vp . I recommend you to do a DC analysis at values of VGS=<Vp. If IDS of your model is aprox cero, for VGS=<Vp, then your model is working well (at pinch off) and the problem is not there, but if the model do bizarre thinks like negative values of IDS or large values of IDS for VGS=<Vp, then you know that the problem is there and you will have problems of convergence, so, for a transient analysis you will need to decrease the input power, by doing this you will limit the swing of the input signal to values of VGS --> Vp<=VGS<=0.

Sorry for my English OK, is not good i know LOL.