IMPROVED LBR 2-PAIR EXTRACTION METHODS FOR LOW-SENSITIVITY DIGITAL-FILTER REALIZATIONS

In this paper, we present two improved lossless bounded-real (LBR) two -pair extraction methods using an allpass input function, which signif icantly reduce roundoff errors during the extraction process and reduc e the amount of computation nearly to a half. Both methods are based o n the induced allpass transfer function from the given BR function, wh ich is obtained by replacing the value of the terminating multiplier w ith 1 or -1. The first method is an LBR two-pair extraction based dire ctly on the allpass input function induced from the given input transf er function. The second extraction method is based on two new real pol ynomials obtained by further decomposing the induced allpass input fun ction. Even with two polynomials, the involved polynomial division and parameter calculation are simpler in the second method. Consequently, numerical errors are further reduced in the second method. The benefi ts of employing the two improved methods are confirmed through simulat ion examples.