Variable band-pass filter unit and communication apparatus using the same

摘要

A variable band-pass filter unit which is free from deterioration in throughput or incapability of communication even if jamming signals are inputted. A variable band-pass filter circuit has at least two variable trap circuits. The variable trap circuits are constituted by the combination of resonators and variable capacitance diodes for band blocking. The variable band-pass filter circuit passes only a desired signal between variable trap frequencies of the variable trap circuits. Only a desired frequency band is made variable in accordance with frequency hopping.