PURPOSE: To suppress a TTE level and reduce a ripple in a passing band by setting the conversion loss of an input transducer greater than that of an output transducer.
CONSTITUTION: Interdigital type input and output transducers 2 and 3 are provided on one surface of a ceramic substrate 1. For example, the input transducer 2 has 13 couples and the output transducer 3 has 3 couples so that R0 (reciprocal of output conductance of output transducer) >2RI (reciprocal of conductance of circuit coupled with output transducer). For example, only the input transducer 2 is weighted in order to video intermediate filter characteristics. Then, the impedance values of both transducers are so set that conversion loss of the input transducer is larger than that of the output transducer.
KODAMA RIICHI
EHATA YASUO
IZUMI HIROHIKO
