A W-Band 0.01 mm² Cavity Resonator Employing Slot-Loaded Shielded Folded Ridged Quarter-Mode in CMOS Technology

This letter proposes a $W$ -band compact cavity resonator for future applications of on-chip bandpass filters (BPFs), oscillators, phase shifters, and so on. To mitigate the leakage from the open sides of a folded ridged quarter-mode substrate integrated waveguide (SIW) cavity, shielding structures made of vias are employed. Two parallel inductive slots are etched on the top metal layer for further size reduction. Later, the one-port cavity is converted to a two-port cavity resonator and utilized in the design of $W$ -band BPF. The proposed design is implemented in a commercial complementary metal-oxide-semiconductor (CMOS) technology, fabricated, and measured. The active size of the proposed cavity resonator is only 99 $\mu \text{m}\,\,\boldsymbol {\times }\,\,99\,\,\mu \text{m}$ ( $0.054 \boldsymbol {\lambda }_{\mathbf {g}}\,\,{ \boldsymbol {\times }}\,\,0.054{} \boldsymbol {\lambda }_{\mathbf {g}}$ ), and the measured insertion loss ( $\vert S_{21}\vert$ ) is 2.26 dB.