Minimax technique in SAW filter optimization

Minimax technique gives a powerful tool for comprehensive nonlinear optimization of SAW filter layouts. Due to the possibility of simultaneous optimization of electrode overlaps in the input interdigital transducer (IDT) and electrode positions in both IDTs, the needed filter selectivity is achieved at minimum time response duration. In addition, a minimax based optimization algorithm gives an opportunity to reduce a diffraction disturbance in narrow-aperture apodized IDTs by restriction of the minimum value of electrode overlaps. Due to IDT nonperiodicity the restriction by the values of 10-50% of the aperture usually decreases a filter out-of-band rejection only by 1-3 dB compared with equidistant analogs without such restriction