Browse Prior Art Database

EFFICIENT, ADAPTIVE PRECISION FIXED POINT DIGITAL FILTER

IP.com Disclosure Number: IPCOM000007448D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2002-Mar-27

Publishing Venue

Motorola

Related People

Authors:
Michael W. Loos

Abstract

The use of infinite impulse response (IIR) fil- ters is prevalent in audio applications. IIR filters gen- erally offer reduced filter order for an equivalent fil- ter transfer function as compared to finite impulse response filters (FIR). One of the drawbacks of efft- cient, high order IIR fixed point filter implementa- tions is their tendency to be subject to zero input limit cycles. That is, even when the input to the filter is zero the output can still (potentially) be non- zero. This zero input limit cycling is due to the quan- tization of the output of and subsequent feedback states to the fixed point precision of the processor, In audio applications these limit cycles can, under certain circumstances, be audible to the listener.