A Compact Low-Pass Filter Using Dielectric-Filled Capacitor on SISL Platform

This letter proposes a compact low-pass filter (LPF) using dielectric filled capacitor based on the substrate integrated suspended line (SISL) platform. A dielectric filled capacitor with high capacitance density is presented for the first time. Using this type of capacitor, a three-order lumped element LPF with a cutoff frequency of 120 MHz is designed, fabricated, and tested. The measured results agree with the simulated ones. The circuit size of the implemented SISL LPF is only 0.005 λg × 0.013 λg, which is very small when compared to the state of art. The measured insertion loss of SISL LPF in the passband is 0.12 dB and the stopband is from 0.35 to 2.27 GHz with a suppression level greater than 20 dB. A seven-order LPF is also designed to further demonstrate the good property of the proposed capacitor.