Tunable and variable passive digital filters for multimedia signal processing

The paper introduces a class of tunable and variable digital filters, which are derived from passive digital filters. By changing the values of their filter coefficients, the frequency response characteristics of these passive digital filters can be tuned or varied. These tunable and variable passive digital filters include first-order and second-order lowpass and highpass digital filters, and second-order bandpass and bandstop digital filters. 2D and 3D tunable and variable passive digital filters can be obtained by cascading 1D filter sections. Simulation results are given to illustrate their frequency response tunability and variability. Due to their pseudopassivity property, these variable passive digital filters are oscillation-free under finite word-length operations.