Analiza stabilnosti prijenosne linije opterećene negativnim kondenzatorima s operacijskim pojačalom

master's thesis

• Title (english): Stability Analysis of Transmission Line Loaded with OPamp-based Negative Capacitors
• Author: Eugen Štimac
• Mentor: Silvio Hrabar (mentor)
• Committee member: Silvio Hrabar (predsjednik povjerenstva)
• Committee member: Zvonimir Šipuš (član povjerenstva)
• Committee member: Igor Krois (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2014-07-14, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

Problem stabilnosti koji se javlja kod metamaterijala znači da su primjene metamaterijala zbog toga ograničene. Uz teorijsku analizu spojeva dostupnih u literaturi, i nakon uvida u način rada negativnih pretvornika impedancije, proučeni su kriteriji stabilnosti NIC-eva. Simulirani su mnogi spojevi NIC-a s operacijskim pojačalom, te su uvedene mnoge promjene ne bi li se poboljšala stabilnost i time dobio širokopojasan metamaterijal.
Uz najbolju varijantu spoja, maksimalni broj ćelija koje generiraju negativan kapacitet koji se mogao staviti na liniju kako bi se ostvarilo ENZ svojstvo iznosio je 78.
Daljnje simulacije su rađene na spoju NIC-a s operacijskim pojačalom koje koristi SPICE model širokopojasnog operacijskog pojačala tvrtke Texas Instruments, THS4303. Nakon što je analiziran utjecaj pojačanja pojačala i parazitnih duljina linija na rad NIC-a, izvršeno je mjerenje na stvarnom sklopu. Doveden je u pitanje kriterij za stabilnost NIC-a te su nužne dodatne provjere kako bi se vidjelo vrijedi li taj kriterij.

Abstract (english)

Stability issues which are present in metamaterial structures hinder its usage in many applications. After theoretical investigations of circuits avaiable in literature, and gaining insights in ways in which negative impedance converters work, stability criteria of NICs are observed. Many circuits invloving NICs made from operational amplifiers are simulated, and many changes to the original design are made, so that stability would be increased and a wideband metamaterial constructed.
A maximum number of cells that could be loaded on a transmission line so that it would show ENZ behavior was 78, with the best version of the simulated circuit.
Further simulations were done on NIC circuit which used SPICE model of THS4303 operational amplifier from Texas Instruments. After analyzing effect of opamp gain and parasitic line lengths on NIC work, measurments were made on a constructed circuit. Stability criterion for NIC circuits is proven to be wrong, and further investigations should be done.

• Keywords: Metamaterijal; negativan pretvornik impedancije; operacijsko pojačalo; negativan kapacitet; kriteriji stabilnosti.
• Keywords (english): Metamaterial; negative impedance converter; operational amplifier; negative capacitance; stability criterion.
• Language: croatian
• URN:NBN: urn:nbn:hr:168:079129
• Study programme: Title: Information and Communication Technology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka informacijske i komunikacijske tehnologije (magistar/magistra inženjer/inženjerka informacijske i komunikacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-02-06 12:24:00