NOISE CALCULATION OF 4-TH ORDER LP FILTER WITH FEEDBACK

Zadatak ovog diplomskog rada bio je realizirati Butterworthov NP filtar 4. reda u kaskadnoj strukturi i strukturi s povratnom vezom s dva operacijska pojačala. Analiza je izvršena uz pomoć programskog paketa „Matlab“. Određena je prijenosna funkcija, raspored polova i nula, frekvencijske karakteristike, vremenske karakteristike, vrijednosti parametara i elemenata filtra za obje realizacije, te proračun šuma za obje realizacije. Uz pomoć programskog paketa „LTspice“ provedena je provjera dobivenih karakteristika. Nakon provjere ispravnosti izrađena je tiskana pločica u „EasyEDA“ programskom paketu i izrađen je model filtra u laboratoriju. Ispitana je ispravnost modela uz pomoć osciloskopa i funkcijskog generatora. Mrežnim analizatorom je potvrđena ispravnost filtarskim sklopova i zadatak je uspješno izvršen.The task of this master degree graduate thesis was to design Butterworth 4th order low pass filter in a cascade structure and a feedback structure with two operational amplifiers. The analysis was performed with „Matlab“ software package. The transfer function, pole and zero distribution, frequency characteristics, time characteristics, values of parameters and filter elements for both realizations and spectral voltage density of noise were determined. With the help of the software package "LTspice", the obtained characteristics were checked. After checking the correctness, a printed circuit board was made in the "EasyEDA" software package and a filter model was made in the laboratory. The correctness of the model was examined with the help of an oscilloscope and function generator. More precise accuracy was tested by a network analyzer which confirmed the filters correctness, and the task was successfully done