in this paper, an algorithm suitable for
the computer aided design (CAD) has been
developed to estimate and model the main
characteristic parameters of an apodized SAW filter.
The design of SAW filters on different substrates
consisting of two apodized interdigital transducers
(IDTs) without using multistrip coupler is
presented. The analytical model is described using
REMEZ algorithm. The design criteria for an
apodized SAW filter components are discussed in
terms of number of fingers, minimum stopband
attenuation, maximum passband ripples, and design
frequency range requirements. In other words, the
upper and lower hermitian frequency response,
impulse response/apodization, and phase response
are demonstrated with aid of the computer
algorithm. The technique has been applied to the
design of multiband linear phase SAW filters. The
uses Hermitian function relations can be applied to
realize an even or odd number of up to fifteen
passbands with equal or unequal widths, as
required. The results obtained in this work, provide
an adequate basis for understanding the parameters
effects, and optimization processes of an apodized
SAW filter. A comparison between the obtained
results and the experimental published results shows
a good agreement. |
