CALCULATION OF DEVICES AND ELECTRONIC EQUIPMENT OWN NOISE (ACTIVE RC FILTER, RAUKH‘S CIRCUITS)

Autor/autori: Valentin GUTU (Repunblica Moldova)

Rezumat: Actuala lucrare este dedicata metodei de calcul a zgomotului propriu al dispozitivelor si echipamentelor electronice de selectie a semnalelor prin frecventa. Drept obiect ale acestor calcule sunt utilizate filtrele active RC , in varianta practica schemelor de realizare Raukh. Aceste scheme de realizare permit obtinerea filtrelor active cu diferite functii de transfer, ca trece-jos (FTJ), trece-sus (FTS) si trece-banda (FTB). Metoda de calcul propusa in aceasta lucrare este bazata pe un sir de elemente din teoria generala a cuadripolilor „zgomotosi”. Astfel, filtrul activ RC este prezentat ca o conexiune a doi cuadripoli, elementul activ (amplificatorul operational) - sursa de tensiune comandata prin tensiune - STCT si circuitul pasiv RC , iar proprietatile lor de zgomot sunt prezentate ca un generator sumar IZ (figure 5, a si b) . Lucrarea contine rezultatele calculului teoretic conform metodei propuse si ale masurarilor experimentale care confirma posibilitatea utilizarii acestei metode practica inginereasca (figure 8).

Cuvinte cheie: filtre active, functie de transfer trece-jos, trece-sus, trece-banta, amplificator operational, cuadripol, zgomot propriu, zgomot termic, caracteristici de zgomot, densitatea spectrala, circuit echivalent, generator echivalent de zgomot.

Abstract: This paper is dedicated to the method of calculation to its own noise of electronic devices and equipment for selection of signals by frequency. As the concrete object of the calculations presented in this paper are active RC filters in practice Raukh version. This scheme allows the realization of active filters to obtain the transfer function high-pass (HPF), low-pass (LPF) and passband (PBF). The calculation method proposed in this paper is based on elents of the general theory of quadripoles „noisy”. Thus, active RC filter is presented as a sumary quadripole obtained from connecting the active element (operational amplifier) ? voltage - controlled voltage source ? VCVS and passive RC circuit, and a his noise properties ? through a summary generator noise, IZ (figure 5, a and b). The paper containe the results of theoretical calculations and experimental measurement, which confirm the possibility to utilize thise methode of calculation in engineering practice (figure 8).

Keywords: active filter, pass-low, pass-high, pass-band transfer function, operational amplifier, quadripoles, own noise, termal noise, noise caracteristics, spectral density, equivalent circuit, noise equivalent generator

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