Active R ladders: High frequency, high order, low sensitivity active R filters without external capacitors

Active
R
filter techniques which make use of the pole of an operational amplifier to produce the state variables without the need for inductors or external capacitors may be employed to simulate all of the elements of both singly and doubly terminated reactance ladders. Although the design techniques are very simple and follow directly from passive synthesis techniques, the resulting filters offer high-order circuits with low sensitivity. However, the primary advantage of these active
R
filters is the ability to design filters which operate in a considerably higher frequency range than obtainable with standard active
RC
designs. While still primarily of research interest due to dynamic range problems and temperature sensitivity problems, active
R
ladders may be adequately compensated to allow many applications in specialized signal processing environments.