A comparison of basic 94 GHz planar transmission line resonators in commercial BiCMOS back-end-of-line processes

Abstract

A comparative simulation study of planar 94 GHz resonators in a typical BiCMOS BEOL stack-up is presented, with the effect of chip passivation included. It is shown that Q-factors of between 3 and 15 can be obtained, depending on transmission medium and ground plane layer choice. Straight half-wavelength and shorted quarter-wavelength microstrip resonators are shown to outperform CPW, GCPW and hairpin resonators, with highest Q-factors obtained where the lowest available metallization layer is used as ground plane. Q-factors of above 10 may also be achieve in the absence of any ground plane in CPW, which may be implemented in processes (such as GaAs or GaN) where multiple metallization layers are not readily available.