Linear Phase Quadrature Mirror Filter Banks
Linear phase filters delay all frequencies by equal amounts, and this
is often a desirable property in audio and other applications. A
filter phase response is linear in
whenever its impulse
response
is symmetric, i.e.,
![]() |
(12.35) |
in which case the frequency response can be expressed as
![]() |
(12.36) |
Substituting this into the QMF perfect reconstruction constraint (11.34) gives
![]() |
(12.37) |
When



![]() |
(12.38) |
We see that perfect reconstruction is obtained in the linear-phase case whenever the analysis filters are power complementary. See [287] for further details.
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Conjugate Quadrature Filters (CQF)
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Quadrature Mirror Filters (QMF)