ON DIGITAL-SYSTEMS WITH NEGATIVE GROUP DELAY

The investigations to bc presented here have been motivated originally by a desired application of a subsystem with negative group delay as a part in the feedback path of a D/A-converter. After a short descript ion of this special problem we summarize the general properties of sys tems, having negative group delay in a certain band. The problem of de signing FIR- and IIR systems with the desired properties will be discu ssed next. Five methods will be presented for the design of systems, t he group delay of which approximates a negative constant value for Abs olute value of OMEGA less-than-or-equal-to OMEGA(c), while the magnitu de \H(e(jOMEGA))\ is approximately constant in that band. Solutions fo und in the different cases will be presented as well. Furthermore we i llustrate the transient behaviour of such a system using a typical exa mple.