Hi gus,

I am trying to do the stability analysis for a V2 control constant on time buck converter. The attachment is the circuit I used. The only difference here is I don't have an Error Amp, instead, I connect Vref directly to the comparator.

I do the ordinary AC simulation, the result is kind of weird. There is double pole on LC resonance freq, which should not be the case for constant on time control. Also DC gain increases with inductor value, which doesn't make any sense.

I wonder ordinary AC simulation in Simplis is suitable for this kind of pseudo fixed freq circuit? Should I use Multi-Tone AC Analysis as they introduce on their website? Haven't try that since I don't have the DVM license.

BTW, is it convenient to do stability analysis in Spetre using PSS and PSTB? Looks like most people prefer Simplis.

Thanks