3rd order Butterworth passive filter for the audible frequency range

This project presents the design of a third-order Butterworth filter using passive components for the audible frequency range. The design process involves determining the filter specifications, selecting the appropriate filter topology, and calculating the component values for the filter circuit. The designed filter was simulated using the circuit simulation software LTSpice and its frequency response was analyzed. The simulation results were compared with the theoretical calculations and were in good agreement. The designed filter provides a quite steep roll-off in the stopband and a flat passband response for frequencies in the cutoff frequency range of 300 Hz - 20 kHz. The passband attenuation was in the order of -6dB. After doing a search for components in the electronic component supplier’s database, denomination of the passive components was altered to the nearest existing denominations. Consequently, the corner frequencies on the bode plot were only slightly raised, while the passband power and roll-off rate remained unchanged.