Stability of parametric, analog low-pass filters

The paper presents the necessity and potential possibilities of an introduction of time-varying functions /spl omega//sub 0/(t) and /spl beta/(t) instead of constant functions /spl omega//sub 0/ and /spl beta/ in the second order building elements of the structure of low-pass filters and constant component filters. The need of shortening of the settling time requires, according to the principle of indeterminacy, varying in time the filter parameters. This, in turn, may destabilise the system. In the paper, the stability conditions are defined for the second order parametric system which can be used as a building element of low-pass or constant component filters. It is shown that stability of higher order parametric filters can be examined as constant parameter filters if lim/sub t/spl rarr//spl infin///spl omega//sub 0/(t)=0.