Precizni dvostrani usmerivači malih signala realizovani u tehnici strujnog procesiranja

REZIME: Obrada analognih signala može se izvoditi u tehnici naponskog ili strujnog procesiranja. Iako je naponsko procesiranje imalo dominantniju ulogu u obradi signala dugi niz godina, pojavom strujnih prenosnika, strujno procesiranje dobija na značaju u poslednjih dvadesetak godina zbog više svojih prednosti koje su dokazane na primerima preciznih dvostranih usmerača za male signale obrađenih i u ovoj tezi. Pre svega prednost se ogleda u povećanju širine propusnog opsega zbog upotrebe opterećenja male impedanse. Predmet disertacije je realizacija preciznih dvostranih usmerača za signale malih amplituda u tehnici strujnog procesiranja. Precizno usmeravanje je važna funkcija obrade signala koja ima izuzetnu važnost kod mnogih mernih uređaja kao što su voltmetri i ampermetri za naizmenične signale, detektori polariteta signala, detektori vršne vrednosti, detektori amplitudno-modulisanih signala, kola za usrednjavanje signala itd.. Nakon opisa tehnike strujnog procesiranja i prikaza translinearnog principa, kao polazne osnove za realizaciju brojnih nelinearnih kola u bipolarnoj tehnologiji, razmatran je koncept strujnog prenosnika sa posebnim osvrtom na strujnom prenosniku druge vrste sa bipolarnim tranzistorima. Opisan je i koncept operacionog prenosnika, a sa posebnom pažnjom obrađen je operacioni prenosnik druge vrste sa strujnim kormilarenjem. Dat je i prikaz uporedne analize preciznih dvostranih usmerača realizovanih u tehnici naponskog procesiranja kao i u tehnici strujnog procesiranja, sa prednostima i manama jednih u odnosu na druge. U disertaciji su predstavljena dva modela preciznog dvostranog usmerača za male signale, od kojih prvi model koristi operacioni prenosnik, četiri strujna ogledala i dva strujna izvora, dok je drugi model realizovan sa dva operaciona prenosnika i dve diode sa predpolarizacijom. Osobine realizovanih usmerača su znatno bolje u odnosu na usmerače realizovane sa istim elektronskim komponentam u tehnici naponskog procesiranja. Kroz simulacionu i eksperimentalnu proveru dokazano je da je moguće realizovati precizni dvostrani usmerač u tehnici strujnog procesiranja koji radi u širokom frekventnom opsegu, za signale male amplitude, upotrebom dve diode umesto četiri, kako je to do sada uglavnom rađeno. Takođe je pokazano da ovakav usmerač ima sve bitne osobine bolje od osobina usmerača realizovanog u tehnici naponskog procesiranja.SUMMARY: The processing of analog signals can be performed in the voltage or current processing technique. Although the voltage processing has had a more dominant role in signal processing for many years, with the adventages of current conveyors, current processing has become more important over the past twenty years due to its manifold advantages, which have been proved by examples of precision full wave rectifiers for small signals dealt with in this thesis. The first advantage is the in increase of the bandwidth due to the use of a small impedance load. The subject of the doctoral thesis is the realization of full-wave rectifier for small amplitude signals in a current mode processing techniques. Precise rectification is an important function of signal processing and it is highly significant in many measuring devices, such as voltmeters, ammeters for alternating signals, detectors, signal polarity detectors, peak detectors, amplitude-modulated signal detectors, averaging circuits, etc... The dissertation presents the description of a current processing technique and translinear principle as an initial point for the realization of numerous nonlinear circuits in bipolar technology. This is followed by a speculation on a concept of current conveyor, where a special focus is placed on a different type of current conveyor with bipolar transistors. In addition, the concept of operational conveyor is given with an emphasis on a different type of operational conveyor with current steering output stage. The thesis also presents a comparative analysis of full-wave rectifiers, which are realized in both, voltage and current processing techniques, as well as their advantages and disadvantages compared to each other. The dissertation presents two models of precision full-wave rectifier for low-level signals, as well as the realization of the rectifiers out of which one uses an operational conveyor and four current mirrors and two direct current sources, while another one has two operational conveyors and two diodes with polarization before of them. The characteristics of such rectifiers are significantly better compared to the rectifiers with the same electronic components in voltage processing technique. Through simulation and experimental verification it has been proved that the full-wave rectifier in a current processing technique can be realized for wide frequency range, for low amplitude signals, by using two diodes instead of four, as it has been mostly done so far. It was also shown that such rectifiers have better characteristics than the rectifiers realized in voltage processing mode