| Περίληψη: | This M.Sc. Thesis has focused its interest, on the implementation of fractional-order
shadow filters, a new family of filters, which provides the benefits of scaling and electronic
control over the filters’ parameters. The design of such filters for control systems, and
biological/biomedical applications is the core of this work.
The first applications, which were related to filtering, were implemented with integer order filters. The need of improving the characteristics of these circuits introduced
fractional-order filters. Initially, the filter’s characteristics are studied, with the ideal
and approximate transfer functions being compared in the frequency domain. The
approximation of Laplacian operator with rational polynomials is achieved, exploiting
approximation techniques and specifically Oustaloup approximation method.
Subsequently, using the aforementioned study as background, the concept of shadow
filters is presented. The simplicity of the design procedure is important in terms of the
cost and time spent to build such a filter.
As the exploitation of fractional calculus in the branch of engineering is one of the
recently developed research disciplines, there is no commercial production of fundamental
elements that could directly build a fractional-order circuit. Towards this purpose, RC
networks Cauer and Foster are utilized, which emulate the behavior of a fractional-order
capacitor. Finally, the topologies of fractional-order shadow filters are imolemented,
using Current Feedback Operational Amplifier, as basic active element.
The theoretical analysis, as well as the approximation processes, for each case study
are performed using the MATLAB software. The performance evaluation of the proposed
circuits is based on simulation results obtained using the Cadence software and the
Design Kit provided by the Austria Mikro Systeme (AMS) CMOS 0.35 μm technology
process.
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