Demo program for low power active filter

Abstract

In this paper, using Lab VIEW graphical programming environment are made a number of virtual instruments which are used at the demo/study of low power active filters with operational amplifiers (op-amp). There are analyzed the active first order low pass, high pass and band pass filters. The results are included in two papers. The first one contains the simulation of active filters. The different values of passive components (feedback or input resistor and capacitors) around the op-amp can be selected with numerical controls for each type of filter. The effect is seen using the Bode characteristic (frequency response curve for filter). The AC (alternating current) frequency characteristic is best described in term of a Bode plot where the gain is plotted on a log scale on the vertical axis and the frequency is plotted on a log scale on the horizontal axis. The op-amp ideal frequency response curve (Open Loop) it is also displayed in the chart. The values of Open Loop Gain and Frequency Cut-Off are also set with numerical control. The validity of the program is done by comparing simulation results with data obtained by calculation using the theory. The program is designed in a modular manner and it can be used successfully in education and training courses.