Design and implementation of low-power IIR digital filter systems

Abstract

A method for the design of linear-phase IIR digital filters for low-power applications is proposed. In this method, the digital filter is implemented as a cascade arrangement of 2nd-order sections. Each section is designed through optimization techniques so that all sections in cascade satisfy as far as possible the overall required specifications. This process is repeated until a multisection filter is obtained which satisfies the required specifications under the most critical circumstances imposed by the application at hand. The minimum number of sections required to process a particular input signal can then by switched on through the use of a simple adaptation mechanism and, in this way, the power consumption can be minimized. This design structure is achieved by formulating the design of the k-1 sections as constraints. As an example, a low-power filter system is compared with a fixed-order linear-phase IIR filter of the same performance. It is shown that a power reduction of at least 10% can be achieved.