Balanced-type surface acoustic wave filter.

摘要

A balanced-type surface acoustic wave filter is provided which can attain a balanced-type of high frequency circuit without connecting a balance-unbalanced conversion circuit. A substrate of tantalic acid lithium substrate with 36 degrees rotation, Y cut, and X propagation is used, and aluminium is used for electrode to form resonators 101, 102. Then, two resonators 101 in a serial arm and two resonators 102 in a parallel arm are connected in the form of symmetry and lattice to form a balanced-type surface acoustic wave filter. In this configuration, antiresonance frequency in the latticed arms and resonance frequency in the serial arms are substantially equal to each other. <IMAGE>