Abstract: In this paper a procedure is proposed for designing high-degree band-pass filters based on insertion of redundancy ideal transformers with optimal transformation ratio t. There are numerous possible positions for inserting transformers in starting a band-pass filter, and the best one should be used in the design. An efficient numerically based procedure for getting optimal transformation ratio t in the closed form is given. The parameter t thus obtained provides a minimal ratio between the reactive element maximum and minimum values in the transformed network. The networks with a minimum spread of element values are very suitable for realization of filters with lumped and distributed elements.
Key words: Band pass filters, minimum spread, Chebyshev low pass, Cauer low pass.