A filter circuit which transmits all the frequencies without any attenuation, but provides some phase shift between input and output signals is called:

Attenuation means a reduction in amplitude of the signalLow pass filter will pass LOW frequencies and attenuated high frequenciesThe bandpass filter will attenuate both low and high frequencies and will pass only a band of frequenciesHigh pass filter attenuates low frequencies and passes high frequenciesAn All pass filter does not attenuate any FREQUENCY, it passes all frequencies An all-pass network is the network that is the combination of the minimum and non-minimum phase systems and have the unity magnitude for all frequencies and imparts only 180-degree phase shift.It is used for phase equalization in communication systems. Therefore, it is also called phase equalizer or delay equalizer.As GAIN magnitude is independent of frequency, the circuit passes all frequencies.