I don't understand this: the HT works as it should but in an .AC simulation, the phase shows up like this (wrapped):
Why doesn't it look like a constant -90deg phase, like in a differentiator?
The thing that also confuses me is that a regular low-pass FIR has the same phase, so does that mean the FIR also adds constant -90deg? Obviously not, and I can't see the explanation. Can someone please shed some light?