ABSTRACT
Various electronic circuits can be found to implement any given transfer function. Cascade filters and ladder filters are two of the basic approaches for obtaining a practical circuit. Cascade realizations are much easier to design and to tune, but ladder filters are less sensitive to element variations. There are many ways to implement filters. These could be passive LC filters, cascade active filters using operational amplifiers, active filters using operational transconductance amplifiers, or switched capacitor or switched current filters. While several passive realizations of first-order filters are possible, the active circuits shown are inexpensive and avoid any loading of the other filter sections when the individual circuits are cascaded. The foregoing circuits provide a variety of useful first- and second-order filters. There are many methods to implement filters. Filters can be implemented by using op-amps, LC ladder circuits, transconductance amplifiers, as well as switched capacitors.
