Design and simulation of 4th order active band- pass filter using multiple feed back and Sallen-key topologies


In this paper, an active fourth order band pass analog filter is designed and simulated. The filter is designed such that it has butter worth response. The topologies that will be used to implement the filter are the multiple feed back (MFB) and Sallen-Key in order to compare between them to decide the best one. The filter is designed for radio frequency identification (RFID) system reader to reject all signals outside the band (10-20) kHz and to amplify the low antenna signal. This is because the identification number signals which are transmitted from the tag of RFID are (12.5 kHz) and (15.65 kHz).So the pass band of the filter is taken to be (10-20) kHz. The values of the resisters and capacitors of the filter circuit using the Sallen-Key and MFB topologies are calculated and the circuits are then simulated with the MULTISIM program to reach the final conclusion which describes the result of simulation compared to the simulation of the transfer function of the filter using MUTLAB program.