| Περίληψη: | Subject of this M. Sc.Thesis is the design of a generalized fractional (1+α) order filter. This structure offers the four standard types of filter functions, i.e. lowpass (LP), highpass (HP), bandpass (BP) and bandstop (BS). The selection of the type of the filter function is achieved through a digital logic, expressed by an appropriate combination of bits. These bits offer the advantages of the attractive design flexibility and precision to the whole system, by programming the order as well as the cutoff frequency of the filter. In addition, easy understanding and use merge through the appropriate combination of bits for each case. The contribution made in this Thesis is that capacitorless realizations of fractionalorder filters, using current-mirrors as active elements, are introduced for first time in the literature. In addition, these filters offer electronic adjustment of their frequency characteristics through digital programming of the corresponding bias currents and the realized scaling factors. Initially, the procedure for approximating this type of filter by an appropriate integer-order multifeedback topology is presented and the respective design equations are summarized. The basic operations required for implementing the generalized filter are integration and summation. Thus, the topology is realized through fully differential capacitorless lossy and lossless integrators topologies, which employ current-mirrors as active elements, offering the advantage of electronic adjustment of their time-constants. A two-integrator loop filter is realized using these integrators, confirming the above. Furthermore, the programmability of capacitorless current-mirror integrators is presented through Current-Division Networks (CDNs) and appropriate switching schemes, offering flexibility and providing compatibility, precision, easy control as well as modularity to the whole system. Extending this concept into a general topology, it is feasible to design a generalized fractional-order filter, which would be controlled through an appropriate digital logic corresponded to a specific number of bits. The system implementation is done using MOS transistors operating in the strong inversion region. The design of the circuits has been performed through the Virtuoso Schematic Editor of the Cadence software and the simulation results have been derived through Virtuoso Analog Design Environment provided by the AMS CMOS 0.35μm technology.
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