User:Constant314/Tow-Thomas active filter



The Tow-Thomas active filter is one of many active filter circuits. It is a derivative of a state variable filter. The topology is discussed by Chen, Wait, Huelsman & Korn and Lindquist.

Some variations can implement transmission zeroes. It's input resisters are connected to virtual ground summing junctions which allow the topology to perform summing as well as filtering. Some variations have complimentary outputs. The combination of summing, filtering and having complimentary outputs makes the topology a useful building block in leapfrog filters.