| Περίληψη: | The subject of this M.Sc. Thesis is the hardware implementation of biological models. More specifically, the aim of thesis is to develop a novel topology for emulating an electrical-analogue of a fractional-order mechanical impedance which represents the human respiratory system using approximated fractional-order capacitors and inductors. Also, the fractional impedance model of wood tissue is presented and evaluated using fractional-order capacitors. These fractional-order elements are realized using differentiator/integrator blocks constructed from appropriately configured Operational Transconductance Amplifiers (OTAs). The main reasons for using this technique is that it simultaneously offers the following attractive characteristics: (a) resistorless implementation, (b) electronic adjustment of frequency characteristics through the bias current and (c) implementation using only grounded capacitors.
The system implementation of human respiratory system and wood tissue is performed using MOS transistors operating in the subthreshold region and in strong inversion, respectively. The use of low-level bias currents allows for system design with low power consumption and, simultaneously, enables the implementation of large values of resistors that are necessary for the realization of large time constants.
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 and MOS transistor models provided by the AMS CMOS 0.35μm technology.
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