Efficient Implementation of Reconfigurable Warped Digital Filters With Variable Low-Pass, High-Pass, Bandpass, and Bandstop Responses

• Published in: IEEE transactions on very large scale integration (VLSI) systems Vol. 21; no. 6; pp. 1165 - 1169
• Main Authors: Darak, S. J., Prasad, V. A., Lai, E. M.-K
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-06-2013; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Bandpass; Bandwidth; Circuit properties; Coefficient decimation; Coefficients; Complexity theory; Cutoff frequency; Delay; Design engineering; Digital filters; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Finite impulse response filter; Frequency filters; Logic gates; Prototypes; Sound filters; Transformations; variable digital filter (VDF); Very large scale integration; warped filter; Second order; warped filter; Updating; Implementation; Cut off frequency; All pass filter; Digital filter; First order; Electric power consumption; variable digital filter (VDF); Delay time; Reconfigurable architectures; Coefficient decimation
• ISSN: 1063-8210; 1557-9999
• DOI: 10.1109/TVLSI.2012.2203158

In this brief, an efficient implementation of reconfigurable warped digital filter with variable low-pass, high-pass, bandpass, and bandstop responses is presented. The warped filters, obtained by replacing each unit delay of a digital filter with an all-pass filter, are widely used for various audio processing applications. However, warped filters require first-order all-pass transformation to obtain variable low-pass or high-pass responses, and second-order all-pass transformation to obtain variable bandpass or bandstop responses. To overcome this drawback, the proposed method combines the warped filters with the coefficient decimation technique. The proposed architecture provides variable low-pass or high-pass responses with fine control over cut-off frequency and variable bandwidth bandpass or bandstop responses at an arbitrary center frequency without updating the filter coefficients or filter structure. The design example shows that the proposed variable digital filter is simple to design and offers substantial savings in gate counts and power consumption over other approaches.