The aim of this diploma thesis is to design active frequency filters based on passive RLC prototype. Three methods of the design of active filters and active functional blocks of electronic circuits working in current or mixed mode are used to this purpose. These blocks allow to process electrical signals with frequencies up to low tens of megahertz. In addition they feature for instance with high slew rate and low supply voltage power. Active high-pass and low-pass 2nd order filters are designed using simulation of inductor by active subcircuit method. Grounded and subsequently floating synthetic inductor is made with the current conveyors in the first case and with the current operational amplifiers with single input and differential output in the second case. This method advantage is relatively simple design and disadvantage is great quantity of active functional blocks. Active filters based on passive frequency ladder 3rd order filter while only one floating inductor is connected, are designed with circuit equation method. In the first design differential input / output current followers are used and in the second case current-differencing buffered amplifiers are used. This method benefits by smaller active blocks number and disadvantage is more complex design of the active filter. Active filter based on passive prototype of low-pass 3rd order filter with two floating inductors is designed with Bruton transformation method. Final active filter uses current operational amplifiers with single input and differential output which together with other passive elements replace frequency depending negative resistor, which arise after previous Bruton transform. This method usage is advantageous if the design consists of larger quantity of inductors and less number of capacitors. High-pass 2nd order filter is simulated by tolerance and parametrical analyses. Physical realisation utilising current feedback operational amplifier which substitute commercially hardly accessible current conveyors is subsequently made. Measurements of constructed active filter show that additional modifications, which allow better amplitude frequency characteristics conformity, are necessary.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:218107 |
| Date | January 2009 |
| Creators | Pisár, Peter |
| Contributors | Vrba, Kamil, Kubánek, David |
| Publisher | Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií |
| Source Sets | Czech ETDs |
| Language | Slovak |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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