FILTER CIRCUIT AND RADIO DEVICE

摘要

A divider (103) divides an input signal into two types of divided signals: an equi-amplitude signal and an equi-phase signal. Buffers (104, 105) suppress interference between the two types of divided signals. A filter (106) performs frequency selection so as to transmit only a divided signal of a predetermined band. A differential amplifier (107) outputs a difference between amplitude components of the divided signal which has been frequency-selected and the divided signal which has not been frequency-selected by the filter (106). Thus, it is possible to maintain attenuation characteristic or transmission characteristic at a higher frequency band.