Design of symmetric lossless LC filter with analysis of critical element changes

The paper presents the design of analog filter based on a new class of all-pole approximation. The approximating function is derived using Legendre orthogonal polynomial with the appropriate weights and the usage of two Legendre multiplication factors (at the origin and at the passband edge frequency). The design procedure is illustrated on LC ladder filter (inductors L, capacitors C) and analysis of the critical element changes of the 11th-order filter. The whole process of the design and optimization is automated using software Mathematica.