The number of harmonics with shooting doesn't usually affect converge too much because it's mostly an output parameter (it has some impact on the number of time steps within the shooting interval, but usually not the convergence properties itself). No, you can't auto-detect the fundamental tone of a driven circuit. Note that the fundamental frequency isn't necessary the lowest frequency in the circuit - it's the lowest common frequency. Perhaps if you could explain the topology (or even the netlist) of your divider, that would help. I probably should have made that clear. For example, if your circuit contains a divide by 4 as part of the functionality, a fundamental frequency of 450MHz won't suffice, because 1.125G is not an integer multiple of 450MHz. In other words, all frequencies in the circuit need to be an integer multiple of the PSS (or HB) fundamental - that's because it needs to be able to do a Fourier analysis of the fundamental period, and you can't have fractional periods within that for any node in the circuit - it won't be able to represent the solution (or converge). So if there was a divide by 4, you'd need a fundamental of 225MHz to accommodate that. Andrew
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