Niskopropusni električni filtri četvrtog reda s povratnom vezom, niskom osjetljivosti, niskim šumom i niskom distorzijom

master's thesis

• Title (english): Low-Sensitivity, Low-Noise and Low-Distortion Coupled Fourth-Order Low-Pass Filters
• Author: Andro Ćoza
• Mentor: Dražen Jurišić (mentor)
• Committee member: Dražen Jurišić (predsjednik povjerenstva)
• Committee member: Tomislav Pribanić (član povjerenstva)
• Committee member: Tomislav Petković (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2019-07-16, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Computing
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

Ovaj rad zasniva se na usporedbi klasičnog niskopropusnog filtra realiziranog s dvije bikvadratne sekcije povezane u kaskadu, te nove verzije istog filtra koja se zasniva na pozitivnoj povratnoj vezi. Prikazan je detaljni postupak projektiranja filtra s pozitivnom povratnom vezom, a posebni naglasak je dan na utjecaj faktora pojačanja povratne veze β. Projektirani filtar je 4. reda s aproksimacijom po Butterworthu i s graničnom frekvencijom od 1 kHz. U nastavku rada kompjuterskim alatom Pspice simulirana je realna izvedba filtra te je uspoređen novi filtar s kaskadnom verzijom. Uz pomoć Monte Carlo analize uspoređena je i osjetljivost utjecaja realnih pasivnih elemenata na parametre filtra. Kako bi se mogao i fizički testirati filtar projektiran je PCB a osnovna shema strukture prikazana je u radu. Zadnji dio rada jest mjerenje filtra na mrežnom analizatoru HP4195A, na kojem su provedena mjerenja amplitudno-frekvencijske karakteristike prijenosne funkcije, termičkog šuma na izlazu, te SFDR faktor kao i distorzija na izlazu.
Dobiveni rezultati pokazuju da ne postoji ni jedan segment u kojemu je filtar s pozitivnom povratnom vezom lošiji od onog realiziranog kaskadno. Štoviše, novi filtar je očekivano pokazao znatno bolje rezultate od klasične verzije. U oba slučaja bikvadratna sekcija se realizira istom GP2 sekcijom.

Abstract (english)

This thesis is based on the comparation of the low-pass filter realised with two second order biquads connected into a cascade and the new version of the same filter that is based on the positive feedback. A detailed procedure of the realisation of a coupled filter was depicted, with a special emphasis on the influence of the positive-feedback factor β. A realised filter is a low-pass fourth-order Butterworth approximation filter with the cut-off frequency of 1kHz. The continuation of this thesis presents the usage of the computer tool Pspice in the simulation of the physical realisation of a coupled filter compared with the cascaded one. With the help of the Monte Carlo analysis, the influence of the sensitivity to the realistic passive elements on the parameters of the filters was also compared. In order to also physically test the filter, the PCB was produced, and the schematic of the structure is presented in the body of the thesis. At the final part of the thesis the measuring of the filters on the HP 4195A Network Analyzer is presented. The latter instrument measures the amplitude-frequency characteristics of the transfer function, output thermal noise and SFDR factor, as well as distortion.
The results show that there is no single performance in which a cascaded filter is better than a coupled filter. Moreover, the new filter, as expected, showed significantly better results than the classic version of the filter. In both cases, biquad sections are formed with the same GP2 section.

• Keywords: Aktivni filtri; analogni električni krugovi; sinteza električnih krugova; niskopropusne bikvadratne sekcije s povratnom vezom; teorija filtara; strukture s povratnom vezom; osjetljivost; termički šum na izlazu; distorzija; IIP3; SFDR
• Keywords (english): Active filters; Analog Circuits; Circuit Synthesis; Coupled Low-Pass Biquads; Filtering Theory; Feedback Circuits; Sensitivity; Output Thermal Noise; Distortion; IIP3; SFDR
• Language: croatian
• URN:NBN: urn:nbn:hr:168:416757
• Study programme: Title: Electrical Engineering and Information Technology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije (magistar/magistra inženjer/inženjerka elektrotehnike i informacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2020-01-07 17:30:03