PIEZOELECTRIC CERAMIC FILTER CIRCUIT AND PIEZOELECTRIC CERAMIC FILTER

摘要

Multiple piezoelectric ceramic filter elements have different center frequencies from each other and are cascade connected together. The piezoelectric ceramic filter elements satisfy the condition 0 ~dF0~ / BW3 < 0.8; where ~dF0~ is the absolute value of the frequency difference dF0 between the center frequencies, and BW3 is the band width, wherein the amplitude loss is 3dB or less. Thereby, a low insertion loss and an improvement in the group delay characteristics can be compatible at the same time.