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This paper presents correction structures compensating for the impact of linear weakly time-varying systems on bandlimited signals. The proposed structures can be used for the postprocessing and preprocessing of linear weakly time-varying systems which complements and generalizes the literature on iterative postcorrection methods. Furthermore, the precorrection of mixed-signal systems is discussed by investigating the computationally efficient preprocessing of nonuniform zero-order-hold signals in digital-to-analog converters.

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In this paper, methods for the design of time-varying finite impulse response (FIR) filters which facilitate the correction of time-varying systems are presented. The two possible cases where an undesired time-varying system requires either prepro cessing or postprocessing are considered. In particular, we show how the methods from [1], [2] can be used for the precorrection of time-varying systems. Though, these presented methods allow for the correction of systems exhibiting periodically recurring time varying behavior, these techniques can also be applied to the non periodic case. A mixed-signal application is presented to verify the viability of the presented precorrection case. To this end, a system model for non-uniform zero-order-hold (ZOH) signals in a digital-to-analog converter (DAC) is introduced. Finally, numerical simulations are performed to illustrate the increase of performance when the proposed precorrection is employed.

In this paper, a low complexity algorithm for the design of a time-varying correction filter of finite impulse response (FIR) type is presented. Using the obtained filter design to correct a preceding time-varying system, a correction performance in the least-squares sense can be ensured. The adaptation of the filter design requires a moderate computational complexity and is suitable for real-time applications. Thus, a correction of nonperiodically time-varying systems can be achieved where design methods, which rely on computationally intensive operations, e.g. numerical integration, can not be applied. At the same time, its application is not limited to weakly time-varying systems as iterative solutions are, which can correct for weakly time-varying behavior by gradually reducing the induced signal error over multiple stages.