This paper presents an approximation of low-pass filter responses with adjustable stop-band attenuation in order to designing a high quality filter. The filter is based on QBernstein polynomial, which can be adjusted attenuation in stop-band by varying three parameters of the transfer function. A coarse attenuation in stop-band is provided by adjusting two parameters (epsilon and alpha) and a fine attenuation step is determined by Q parameters. The results of simulation were shown the filter, given attenuation in stop-band better than conventional filter at a second-order. Moreover, this paper proposes the filter which provides both flat magnitude and group delay characteristics in the pass-band. Therefore, it can useful for the high quality filter network as an audio crossover network.
