On the importance, realisation, experimental verification and measurements of active-R and active-C filters

Abstract Active-R filters are an offshoot of active-RC filters where the internal dynamics of an operational amplifier (OA) is employed in the elimination of external capacitors with several significant advantages. Some advanced level active-R topologies are discussed from the design point of view and in terms of greater flexibility over filter parameters. A few filter circuits are designed and their performance experimentally verified. Components simulation by an OA: R method is also performed and tested. A technique for realisation of a 20 A biquad is used to generate different types of filter functions which are experimentally verified. To overcome the difficulties of switched capacitor filters, a design method avoiding these but retaining the advantages of monolithic implementation with filter parameters set by ratios of capacitors, is used and termed active-C filters. Experimental verifications and measurements on designed active-C filters are presented.