Lumped-element Lowpass Filter with High out-of-Band Rejection on Multilayer Printed Circuit Board

In this paper, a design method for the lumped-element lowpass filter with high out-of-band rejection based on the multilayer printed circuit board is presented. To enhance the stopband rejection of the filter, the lumped-element resonators are modified to reduce the parasitic effects, and a lowpass network is introduced to further lower the spurious levels. Comparison of the electromagnetic models and the corresponding simulation results demonstrates a significant improvement in out-of-band suppression, confirming the effectiveness of the proposed approach. This approach can be further extended to lumped-element filter design on LTCC and LCP technology.