A Compact Configurable EBG Filter on PCB

Abstract

A novel design for configurable electromagnetic bandgap (CEBG) filter on printed circuit board (PCB) is presented. The CEBG filter is implemented in FR4 substrate with surface mounted lumped capacitors. Working frequency of the filter can be controlled by adjusting the value of the capacitor. The CEBG filter is unique in that it creates resonance by introducing a surface mounted capacitor instead of relying on modification of a periodic lattice in the substrate and in that it can cover large frequency range with a compact size. A particular example of a frequency controllable filter is implemented by CEBG process and experimentally demonstrated on the same EBG substrate and with different lumped capacitors. The results show a filter with a size of $2.50\times 3.00\times 1.00$ mm $^{3}$ in PCB achieving performance of an unloaded quality factor (Qu) of 81, an insertion loss (IL) of 3.48 dB at 3.22 GHz, and a Qu of 105, an IL of 2.93 dB at 4.07 GHz using a capacitor of 3.3 and 2.2 pf, respectively.