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A class of digitally programmable n th‐order filters
Author(s) -
Alzaher Hussain,
Tasadduq Noman,
AlEes Osama
Publication year - 2012
Publication title -
international journal of circuit theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.364
H-Index - 52
eISSN - 1097-007X
pISSN - 0098-9886
DOI - 10.1002/cta.764
Subject(s) - digital biquad filter , filter (signal processing) , transfer function , active filter , electronic engineering , cmos , flexibility (engineering) , amplifier , analogue filter , topology (electrical circuits) , computer science , voltage , engineering , low pass filter , digital filter , mathematics , electrical engineering , statistics
SUMMARY A family of new high‐order filters capable of providing all filter functions without changing the circuit topology is proposed for integrated circuit applications. The proposed filters are based on simple active elements, namely, digitally controlled current amplifiers (DCCAs) and unity gain voltage buffers (VBs). Gains of DCCAs are digitally programmed to adjust the coefficients of transfer functions. R2R ladders are also utilized to increase the tuning flexibility of the proposed filters. A filter replicating the famous KHN biquad is extended to realize general n th‐order filters. Comparison with the recent works shows that the proposed approach results in more efficient realizations compared with its counterparts based on other current‐mode active elements. Experimental results obtained from a fourth‐order filter implemented using devices fabricated in a 0.35‐µm CMOS process are provided. Copyright © 2011 John Wiley & Sons, Ltd.