PURPOSE: An active low pass filter for high frequency is provided to improve a cut-off characteristic and a group delay characteristic by using resistances, capacitors, and operation amplifiers. CONSTITUTION: An output terminal of the second low pass filter(200) is connected with an input terminal of a group delay compensation portion in order to compensate group delay. In the group delay compensation portion, the first capacitor(C1') is connected directly with the first resistance(R1'). The second capacitor(C2') is connected between a connection point of the resistance(R1') and the first capacitor(C1') and an output stage of the third operation amplifier(30). The third resistance(R3') is connected between a connection point of the first capacitor(C1') and an inverse input terminal of the third operation amplifier(30) and an output stage of the third operation amplifier(30). The second resistance(R2') is connected between an output stage of the low pass filter and an inverse input terminal of the fourth operation amplifier(40).
