Interpolation on the ω axis

Finding real rational weighting functions for robust control analysis and design; connections to boundary interpolation and circuit synthesis

“…While Youla in [41] floats the idea of using his methods for interpolation in Π + , it appears that Wohlers [40] was the first to refine the method to use as a frequency response interpolation process and showed how this yielded a PR interpolant. Smilen's paper [38] and its successors due to Zeheb and Lempel [45] and Beccari [8] develop these ideas of the Youla construction further in producing transformerless circuit sections yielding syntheses for impedances interpolating frequency response values in a very systematic procedure. Particularly, the work of Zeheb and Lempel [45] yields a lossless two-port terminated by a single resistor.…”