Novel design approach for transversal notch filter using recursive principles

In this paper, a new transversal active filter is presented. Basic principle consists of combining the signals coming from two branches. One branch is passive and the other includes a band-pass filter. The transversal combination leads to a stop-band response. For the band-pass filter, we have chosen a recursive topology that uses the same amplifier/power combiner association process. We first present a low-noise MMIC active recursive filter implemented at X-band. Layout, measured noise figure and s-parameters of this filter are presented. Then, the theoretical background of the transversal filter is given. We first apply the technique by using the results of the low-noise measured recursive filter. We further show the improvement provided by the method with the analytical optimization of the filter in terms of noise.