FIR digital filter redesign via sampled-data H ∞ discretization in low-frequency domain
Shuaiying Wang, Peng Li · Transactions of the Institute of Measurement and Control · 2024
In this paper, a finite impulse response (FIR) digital filter is redesigned to approximate a delayed analog one via sampled-data H ∞ discretization in low-frequency domain. First, based on a continuous-time lifting technique, an infinite-dimensional error system is obtained by comparing the delayed analog filter with the FIR digital filter accompanied by an ideal sampler in front and a zero-order holder behind. Then, a finite-dimensional error system, which is satisfied with an equivalent H ∞ norm with infinite dimensional in low-frequency domain, is acquired by a fast sampling/holding approximation and a discrete-time lifting technique. Furthermore, the FIR digital filter is attained with stability and H ∞ performance for the finite-dimensional error system in low-frequency domain. Finally, a numerical example is presented to show the validity and superiority of the FIR digital filter redesign.