A New Technique for The Design Of Selective
FIR Filters With Non-Linear Phase, and Arbitrary Amplitude Characteristics
Q. Al-Zoubi and M. Abo-Zahhad
Department of Electronics Engineering,
Hijjawi Faculty of Engineering
Technology,
Yarmouk University, Irbid, Jordan
Email: zahhad@yahoo.com
Abstract
A
highly efficient method for the synthesis and design of lowpass FIR filters
with low loss and non-linear phase characteristics in the passband and
selective amplitude in the stopband is proposed in this paper. It is based
on a separate approximation of the real and imaginary parts of the filter
frequency response. The design process starts by specifying the amplitude
and phase at a set of frequencies in the passband and a set of transmission
zeros in the stopband. The passband amplitude and phase specifications
are interpolated by a general polynomial H1(l). Another polynomial H2(l),
that has no phase contribution, is determined to interpolate the stopband
requirements. Then, the amplitude specifications in the passband are predistorted
to take into consideration the effect of H2(l). The filter transfer function
is formulated as the multiplication of the two polynomials. Several design
examples with various constraints are presented to explain the main properties
of the design algorithm and to demonstrate that the proposed design method
leads to a significant saving in the arithmetic computations. Comparing
with the existing exact linear phase methods, this method is simple and
effective in the design of filters with better stopband characteristics.
