General feed-forward input filter compensation method

For several reasons a switching regulator is always preceeded by an input filter, and this impairs all essential parameters of the regulator. The extended injected- absorbed current analysis method culminates in a truly general switching cell model, which, embedded in a closed-loop structure, results in a general model of a switching regulator. This model, preceeded by an equivalent filter network, consisting of an equivalent voltage generator and an output impedance, is analysed and the results demonstrate that a suitable feed-forward loop can entirely eliminate the undesirable effects of the filter. It is shown that the compensation depends on the cell parameters. Guidelines for future investigations are formulated.