DESIGN OF CONJUGATE QUADRATURE MIRROR FILTERS

If we specify f1(n), g0(n), and g1(n) as a function of f0(n), we can derive a compact design procedure:
  1. Design a (2L - 1) tap half-band linear phase low-pass filter p(n) (use Parks-McClellan or Kaiser Window approach).

  2. Factor P(z) = Fo(z) F0(z-1) by finding roots.

  3. Compute the remaining filter impulse responses as follows:

    f1(n) = (-1)nf0(L-1-n)
    g0(n) = f0(L-1-n)
    g1(n) = f1(L-1-n)
What are the advantages of this approach?

There are several popular approaches to implementing such digital filterbanks. This general area of research is known as multirate signal processing. What are the merits of a frequency domain approach?