Hardware experiments for low power active filters
Gheorghe-Eugen Subţirelu, Vaduva Alina · 2016
The paper deals with a hardware solution for the study of low power active filter with Bode plotting. By using a DAQ card and an experimental platform it shows how LabVIEW graphical programming environment can be used for manual or automated testing and analysis of the first order active filter with operational amplifier (op-amp). The hardware platform can provide a template to build real op-amp circuits to better understand (together with a previous one paper for developing the software simulation and demonstrations) the op-amp filters principles. The main contribution for this paper refers to a software / hardware solution for obtaining a manual / automat Bode plotting. For plotting the frequency response curve of a filters, it is often necessary to measure the output signal over a range of input frequency. The hardware experiments allows a range of test voltages with variable frequency to be input and the filters response measured, displayed and analyzed. The frequency scan range, scan rate and number of test points can be selected from front panel controls. Another contribution is a practical tool for the analysis of the response filter to various input signals (sine / square / triangular wave) and calculating the filter gain depending on the amplitude measured in units of peak, peak to peak or roots mean square signal level.