New quadrature mirror filter structures

This paper introduces new quadrature mirror filter (QMF) structures for the frequency domain analysis and synthesis of digital signals. The conventional QMF technique is first extended to cover complex quadrature mirror filters (CQMF) in which a digital signal is split into N adjacent complex subbands where the real and imaginary parts are subsampled by 1/2N with respect to the original signal. The computational complexity of QMF banks is then analyzed and a new scheme which reduces the computational complexity by about a factor of two over conventional QMF implementations is proposed. Finally, the filter design tradeoffs are discussed and the microprogramed implementation of QMF banks is evaluated.