Design of active filters simulating mesh current equation of LC ladder filters

The well known "leap frog" active filter synthesis technique does not solves satisfactorily the simulation of double loaded passive filters with finite zeros. There are also difficulties in applying the method to high pass and bandstop filters. All these problems can be overcome through the active RC filter synthesis method based on mesh current emulation of LC ladder filter networks. In this paper, a unique emulation model that uses coupled feedforward Tow-Thomas biquads is employed to implement all classes of LC low pass and high pass filters. Applying standard low pass to bandpass frequency transformation to integrators and lossy integrators, bandpass and bandstop filters are easily obtained from the low pass or high pass active filter prototypes.