deba

Hi Sheldon,
From PXF you need to carry out the summation mentioned in Eq. (14) of the paper to calculate the ISFs.
J.Kim etal., "Impulse sensitivity analysis of Periodic Circuits", ICCAD 2008.
There are other simulations methodologies published to calculate the ISFs indirectly. Below paper mentions a time domain technique
M. Jeeradit etal., "Characterizing sampling aperture of clocked comparators"
But if the spectre saves the "PPV" waveforms then one need not resort to methods mentioned above. For oscillators, "ppv=yes" option saves the "PPV" waveforms. But for comparators/other driven circuits it doesn't save.
My guess is for oscillators one is looking at the amount of final phase shift due to an impulse arriving at time τ. That is Γ(τ) = h(t0,τ) = h(∞,τ). But for comparators, t0 is of finite value.
