Digitally programmed fractional-order Chebyshev filters realizations using current-mirrors

Fractional-order filter realizations with Chebyshev characteristics, approximated by appropriate integer-order topologies, are realized in this work. The employed active blocks were current-mirrors and the derived filters offer the following attractive characteristics: capability of operating in a low-voltage environment, circuit simplicity and resistor-less realization. In addition, a digitally controlled current division network is employed to perform electronic adjustment of the cut-off frequency as well as the order of the filters. The performance of the proposed fractional-order filters is evaluated through the Analog Design Environment of the Cadence software and the Design Kit provided by the AMS 0.35μm CMOS process. The obtained simulation results for orders 1.2, 1.5, and 1.8 confirm that both pass-band and stop-band characteristics of the filters are preserved, while the transition from pass-band to stop-band is performed in fractional-order steps.

[1]  Ahmed S. Elwakil,et al.  Field programmable analogue array implementation of fractional step filters , 2010, IET Circuits Devices Syst..

[2]  Shantanu Das,et al.  Extending the concept of analog Butterworth filter for fractional order systems , 2012, Signal Process..

[3]  Ahmed M. Soliman,et al.  Fractional Order Butterworth Filter: Active and Passive Realizations , 2013, IEEE Journal on Emerging and Selected Topics in Circuits and Systems.

[4]  Ahmed S. Elwakil,et al.  On the practical realization of higher-order filters with fractional stepping , 2011, Signal Process..

[5]  S.A. Mahmoud,et al.  New digitally controlled CMOS balanced output transconductor based on novel current-division network and its applications , 2004, International Conference on Electrical, Electronic and Computer Engineering, 2004. ICEEC '04..

[6]  Ahmed M. Soliman,et al.  Fractional order filter with two fractional elements of dependant orders , 2012, Microelectron. J..

[7]  Costas Psychalinos,et al.  0.5‐V fractional‐order companding filters , 2015, Int. J. Circuit Theory Appl..

[8]  Costas Psychalinos,et al.  Low-voltage CMOS adjustable current mirror , 2010 .

[9]  Debasmita Mondal,et al.  Experimental studies on realization of fractional inductors and fractional‐order bandpass filters , 2015, Int. J. Circuit Theory Appl..

[10]  B. T. Krishna,et al.  Active and Passive Realization of Fractance Device of Order 1/2 , 2008 .

[11]  T. Freeborn,et al.  Approximated Fractional Order Chebyshev Lowpass Filters , 2015 .