Balanced type surface acoustic wave device

摘要

The present invention provides surface acoustic wave devices which do not require a balanced-to-unbalanced transformer circuit regardless of the type of the peripheral circuits of the balanced type surface acoustic wave filter, i.e. a balanced type device or an unbalanced type. A transmitting interdigital transducer and a receiving interdigital transducer are formed on a substrate comprising 41 DEG Y cut-X propagation lithium niobate. A balanced type surface acoustic wave filter is formed on a substrate comprising 36 DEG Y cut-X propagation lithium tantalate. The balanced type surface acoustic wave filter comprises two series-arm surface acoustic wave resonators and two crossed-arm surface acoustic wave resonators connected in a lattice. The substrate on which the transmitting interdigital transducer and the receiving interdigital transducer are formed and the substrate on which the balanced type surface acoustic wave filter is formed are located in a ceramic package. One of the input terminals of the transmitting interdigital transducer is grounded. The output terminals of the receiving interdigital transducer are connected to the input terminals of the balanced type surface acoustic wave filter.