Frequency-Domain Implementations of Variable Digital FIR Filters Using the Overlap-Save Technique

The paper introduces frequency-domain implementations of variable digital filters using the overlap-save method. Expressions for implementation and design complexities are derived for real-valued impulse responses. Design examples include implementations of a variable bandwidth (VBW) filter alone as well as a cascade of a VBW filter and a variable fractional delay (VFD) filter. Compared to a time-domain implementation and a filter bank approach, the proposed structures can reduce the implementation complexity significantly and achieve savings up to 95% in the multiplication rate and up to 89% in the addition rate.