Event Details
Design of Nearly Linear-Phase Infinite-Duration Impulse-Response (IIR) Digital Filters Using Unconstrained Least-pth Minimax Optimization
Presenter: Sunil B Nagaraj
Supervisor: Dr. T. Aaron Gulliver
Date: Mon, September 20, 2010
Time: 14:30:00 - 15:30:00
Place: EOW 430
ABSTRACT
Abstract:
The design of infinite-duration impulse-response (IIR) digital filters such that the passband group-delay is nearly a constant is explored. Specifically, a parameterized design method using an unconstrained least-pth minimax algorithm is proposed. In the proposed parameterized method, the IIR filter is assumed to be a cascade of second-order biquadratic sections whose transfer functions are expressed in polar form. An error function is formulated based on the difference between the actual complex frequency response of the filter and the desired frequency response. Then,by using a least-pth minimax algorithm, the required design is obtained. In the new method filter stability is achieved by using a parameterization scheme based on the so-called sigmoid function that incorporates a mechanism by which an arbitrary prescribed stability margin can be achieved. The optimization engine used in the least-pth minimax algorithm is an unconstrained quasi-Newton algorithm based on the Broyden-Fletcher-Goldfarb-Shanno updating formula. It incorporates a nonuniform adaptive variable sampling technique with adaptive variable weights to prevent spikes in the error function.