Vertically Integrated Combline Filters in Multilayer PCB

Abstract

Vertical stacking of planar line resonators in multilayer media is an effective footprint reduction technique for high order filters, but strong broadside line coupling often negates the possibility of narrowband filters. It is shown that vertically stacking combline resonators with rotated centerlines leads to moderate bandwidth filters. Four variations of a 5th order filter are demonstrated, achieving 1.92 – 3.3 dB IL over 10% FBW around 10 GHz while occupying between 6.62 – 22.47 mm2 surface area on a 7 layer PCB.