A high-Q quasi-planar filtering solution for 60-GHz applications

A low insertion loss 2.2% bandwidth two-pole cavity filter was fabricated at 60 GHz by bonding metallized lids on each side of a 250-μm silicon substrate. The lids are made by dry etching of a 500-μm silicon substrate. The same process is used to etch via holes on the intermediate substrate. The position of these via holes fixes the external coupling and the coupling between the resonators. The measured unloaded quality factor is lied on the height of the cavity (1.05 mm) and is around 1100.