60 GHz planar filters and transmission lines characterization in 0.25µm BiCMOS technology

In this article, three main aspects of passive millimeter-wave integrated filter realization are exposed. Firstly, the importance of the transmission line choice is discussed by comparing microstrip and coplanar waveguide (CPW) in BiCMOS 0.25µm technology. 50-Ω transmission lines exhibit similar losses around 0.6 dB/mm at 60 GHz. Secondly, two filter topologies, a dual-behavior resonator based filter and a dualmode ring based filter, are compared in terms of insertion losses, surface area and out-of-band rejection. They are both designed using microstrip lines and exhibit a similar 3dB fractional bandwidth (FBW3dB) around 12% with a 60 GHz center frequency. Finally, a miniaturization method is presented using Metal-Insulator-Metal (MIM) capacitive loading. A loaded filter is then realized and characterized. Similar electrical performance are demonstrated with a size reduction factor of 2.3.