Variable cutoff frequency FIR filters: a survey

Many signal processing applications require digital filters with variable frequency characteristics, especially the filters with variable bandwidth and center frequency. Due to their linear phase and inherent stability, finite impulse response (FIR) filters are the popular choice in the majority of the applications. Once a variable cutoff frequency (VCF) FIR lowpass filter is designed, variable bandwidth and center frequency filters with bandpass/highpass/bandstop response and reconfigurable filter banks can be realized from the same. In this paper, we present a comprehensive review of the existing variable cutoff frequency FIR filter design techniques, including the developments in the recent two decades. We provide the basic concepts, design, and architectural details for each of these techniques and the significant developments/incremental works thereof. Qualitative, as well as quantitative comparisons, are provided to assist the reader in choosing the most suitable VCF filter design technique for a particular application.