Nonlinear Theory and Its Applications, IEICE
Online ISSN : 2185-4106
Special Section on Analysis, Design and Optimization of Nonlinear Circuits
Fractional-step Tow-Thomas biquad filters
Todd J. FreebornBrent MaundyAhmed Elwakil
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2012 Volume 3 Issue 3 Pages 357-374


In this paper we propose the use of fractional capacitors in the Tow-Thomas biquad to realize both fractional lowpass and asymmetric bandpass filters of order 0<α12≤2, where α1 and α2 are the orders of the fractional capacitors and 0<α1,2≤1. We show how these filters can be designed using an integer-order transfer function approximation of the fractional capacitors. MATLAB and PSPICE simulations of first order fractional-step low and bandpass filters of order 1.1, 1.5, and 1.9 are given as examples. Experimental results of fractional low pass filters of order 1.5 implemented with silicon-fabricated fractional capacitors verify the operation of the fractional Tow-Thomas biquad.

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© 2012 The Institute of Electronics, Information and Communication Engineers
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