Patent ID: 8878631
Filing Date: 2014-11-04
Classification: H03H,Y10T

Abstract:
1. Method for improving the selectivity of a low-pass filter with a cut-off frequency, formed by a symmetric network comprising a plurality of coupling inductors and associated respective LC resonators, the LC resonators being inserted between the respective coupling inductors and ground, wherein the method comprises: the following steps: centering a first LC resonator of the plurality of LC resonators in a center of the symmetric network with respect to the other LC resonators of the plurality of LC resonators, said first LC resonator resonating at a frequency which, compared to the resonant frequencies of the other LC resonators, is closest to the cut-off frequency; inserting one negative resistance in series with the first LC resonator such that the low pass filter comprises a single negative resistance, and optimizing the values of the components of the LC resonators of the symmetrical network in order to match the low-pass filter within the band of operation and in order to reject the unwanted band to the desired level.