That's true for IIR filters but not FIR filters, which modern (This century) signal processing uses. A 1024-point windowed sinc will have linear phase across th

That's true for IIR filters but not FIR filters, which modern (This century) signal processing uses. A 1024-point windowed sinc will have linear phase across the entire passband, that's one of the main reasons we use FIR filters.