Koaksialna zasnova merilnega upora na tiskanem vezju

MEH PEER, JAŠA VID (author), Zajec, Peter (mentor)

Zanesljiva in s pogreški neobremenjena meritev toka je v modernih polprevodniških napravah nadvse pomembna, vendar zaradi široke frekvenčne pasovne širine in amplitude, ki ju narekuje oblika merjenega toka, težko uresničljiva. Če upoštevamo še cenovni vidik, je merjenje toka z uporabo merilnega upora izmed poznanih načinov merjenja često najprimernejše – navkljub dodatnemu ojačevalnemu vezju za ojačitev majhnega padca napetosti. Tematika diplomskega dela je osredotočena na analizo, izvedbo in ovrednotenje merilnega upora s koaksialno zasnovo. Ta je prirejena čim večji kompatibilnosti s pretvorniškimi napravami, zgrajenimi na tiskanem vezju. Vse komponente merilnega upora morajo biti torej nameščene na tiskanem vezju ali biti njegov del. V diplomskem delu sem zasnoval osem merilnih uporov, ki se med seboj razlikujejo po postavitvi površinsko nameščenih (SMD) uporov in njihovimi povezavami na dvostranskem tiskanem vezju. Ker je impedanca omenjenih povezav primerljiva impedanci vgrajenih SMD uporov, je poznavanje njihove upornosti in induktivnosti ključno že v postopku zasnove. Pri tem uporabljena in osnovana teoretična pričakovanja posamezne izvedbe sem preveril, sprva s poenostavljenim in v nadaljevanju nadgrajenim simulacijskim pristopom. S simulacijami sem najprej pridobil parametre posamezne tiskanine, na podlagi katerih sem, zgolj z upoštevanjem diagonalnih elementov njihove impedančne matrike, izračunal mejno frekvenco. Njeno točnejšo vrednost sem določil z upoštevanjem idealiziranih in realnih lastnosti vgrajenih SMD uporov. Rezultati simulacij so bili pridobljeni v programskem paketu Ansys in v naslednjem koraku primerjani z rezultati meritev opravljenih z vektorskim analizatorjem vezij – Bode 100. Na podlagi rezultatov simulacij in meritev sem potrdil teoretično osnovane predpostavke in dokazal, da je možno izdelati prototipno vezje SMD koaksialnega merilnega upora, ki omogoča delovanje na frekvenčnem območju do minimalno 5,6 MHz.

• Language: Slovenian
• Keywords: merilni upor, impedančna karakteristika, koaksialna zasnova
• Work type: Bachelor thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2022
• PID: 20.500.12556/RUL-139142
• COBISS.SI-ID: 119907843
• Publication date in RUL: 31.08.2022

Secondary language

• Language: English
• Title: Coaxial design of a measuring resistor on a printed circuit board

Abstract

Reliable and error-free current measurement is extremely important in modern semiconductor devices, but difficult to implement due to the wide frequency bandwidth and amplitude dictated by the shape of the measured current. If we also consider the price aspect, current measurement using a measuring resistor is often the most suitable among the known measurement methods despite the additional amplifying circuit to amplify the small voltage drop. The topic of this diploma thesis is focused on the analysis, implementation and evaluation of the measuring resistor with a coaxial design. The coaxial measuring resistor is designed for maximum compatibility with converter devices on printed circuit boards. All components of the measuring resistor must therefore be installed on the printed circuit board or be a part of it. I designed eight measuring resistors, which differ from each other in the placement of surface-mounted (SMD) resistors and their connections on a double-sided printed circuit board. Since the impedance of the mentioned connections is comparable to the impedance of the SMD resistors in the circuit, knowing their resistance and inductance is already crucial in the design process. The theoretical expectations of each implementation were checked and tested at first with a simplified simulation model and subsequently an upgraded one. Through simulations I first obtained the parameters of all the different printed circuit board designs, on the basis of which I calculated the cutoff frequency simply by taking into account the diagonal elements of their impedance matrix. Its more accurate value was then determined by taking into account the idealized and real properties of the used SMD resistors in the circuit. The results of the simulations were obtained in the Ansys software package and in the next step compared with the results of the measurements made with the Vector Network Analyzer - Bode 100. Based on the results of the simulations and measurements I confirmed the theoretically based assumptions and proved that it is possible to make a prototype circuit of an SMD coaxial measuring resistor, which enables operation in a frequency range up to a minimum of 5.6 MHz.

• Keywords: measuring resistor, impedance characteristic, coaxial design