A sequential weighted least squares procedure for design of IIR filters and two-channel IIR filter banks

This paper proposes a weighted least squares (WLS) optimization procedure for the design of infinite impulse response (IIR) filters and IIR two-channel quadrature mirror filter banks (FB). The original WLS design problem is converted to a sequence of WLS sub-problems. In each of the WLS sub-problems, only one second-order factor of the denominator and the numerator is updated and iteratively solved by a constrained WLS algorithm. Using the same IIR filter from a recent work, the proposed method shows a better performance in terms of all the measured errors. For the FB, the lowpass filter is designed using a ladder structure through an allpass filter and desirable performance is achieved using a low order allpass filter.