Linear phase decimation filters have zero group delay deviation across frequency. The latency of these filters are in the order of around 10–20 samples at the output sample rate. The out-of-band attenuation is around 72 dB for the linear phase filters, across all sample rates. Figure 3-1 shows the linear phase response for 48-kHz sample rates. The dashed line indicates the minimum out-of-band attenuation level, which is around 74 dB. This implies that the strength of any aliased out-of-band noise component would be attenuated by at least 74 dB by the decimation filter chain. Linear phase filters delay all frequency components by the same amount and consequently do not cause any phase distortion. These filters are recommended for applications requiring where time domain waveform fidelity is paramount, like professional audio recording.

Figure 3-1 Linear Phase Decimation Filter Response