I'm simulating a semi-simple circuit with switches, resistors and caps and a voltage source. I need accuracy on the order of 10e-9 volts, when my voltage source drops below 10e-6, in another section that is slightly attenuated from the voltage source I should see something on the order of 100e-9 and all I see is zero. I have played with the solver settings in simulink and the solver configuration block settings but I haven't been able to get better accuracy. In fact, when I started changing the solver parameters to fixed step or changing the tolerance in the simulink solver configuation, the simulation would not run and stayed on a time step of ~10e-4. So my question is How can I get better accuracy. In spice simulators you can force the tolerances on voltage or solver tolerances.