HSIM simulation accuracy for switch-cap circuit

[yuwenhuan]

hsim simulator

I am trying to simulate delta-sigma modulator with HSIM (it is said it is faster than Spectre). However when I look at the voltage across the sampling cap, there is around 0.5 mV numerical error (Spectre gives right result). It seems like the voltage keeps going to the right value at first, but never makes the last step. I try to tweak the simulation options, but cannot make it work. Here is the option I used:

.param HSIMOUTPUT=psfbin
.param HSIMANALOG=3
.param HSIMSPEED=0
.param HSIMSPICE=3

Any suggestions? Thanks a lot.

 

[Blackuni]

hsim simulations

Hi,


Hsim is a fastspice i.e event based simulator. so it will be faster than normal spice. But u hve tweak settings to get better results.

try this too
set Hsimvdd to appropriate value, also reduce the simulation time step.

I believe u r initial conditions are same as spectre.

then move into interactive mode check the voltage across the cap. u can also check wthr the voltage is propagated frm some othr node or not.

let me for any Qs.

Thanks,

 

[yuwenhuan]

hsim accuracy

I have tried to tweak HSIMMAXALLOWEDDV and HSIMTAUMAX, the final settling voltage does change. But I still cannot make it reach less than 100 uV error, which is needed in my simulation. Thanks.

 

[leo_o2]

h-sim simulator

If accuracy is required, don't use HSim. You can employ other spice type fast simulator. Spectre-turbo is one of them.

 

[yuwenhuan]

hsim param hsimspeed=0

It seems HSIMVPRECISION=5 solves my problem. Thanks.