LADDER-TYPE FILTER AND COMMUNICATION MACHINE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a ladder-type filter where the number of parts can be reduced, and cost of circuit and occupation space can be reduced and to provide a communication machine. SOLUTION: A ladder-type filter 100 contains a wide band filter 80 and a narrow band filter 82 and switches the output terminal of the wide band filter 80 to an output terminal side and a narrow band filter 82-side. In a signal processing circuit 90 of a communication apparatus, the output signal of a mixing circuit 92 is inputted to the wide band filter 80 of the ladder-type filter 100. The output signal of the wide band filter 80 is outputted directly from the output terminal or is outputted via the narrow band filter 82 by switching the switch 96. The wide band filter 80 and the narrow band filter 82 are desirably formed as one substrate.