A W-Band Compact Substrate Integrated Waveguide Bandpass Filter With Defected Ground Structure in CMOS Technology

This brief proposes the first on-chip bandpass filter (BPF) based on substrate integrated waveguide (SIW) for W-band applications. Slot-loaded, folded ridge and quarter mode technology is used to reduce the cavity size. The coupling characteristic of two folded ridged quarter mode substrate integrated waveguide (QMSIW) cavities implemented in CMOS technology is investigated. A simplified equivalent lumped-element circuit model of the proposed wide-band BPF approach is provided and applied to study the coupling characteristic of slot-loaded folded ridged QMSIW cavity. Then, a novel coupling method using a defected ground structure is proposed to realize a proper coupling intensity for BPF design. Finally, the proposed BPF 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 405
$\mu \text{m}\,\,\times185\,\,\mu \text{m}$
(
$0.22{\lambda }_{\mathrm{ g}} \times 0.1 \lambda _{\mathrm {g}}$
), and the measured insertion loss (
$\vert|\text{S}_{21}~\vert|$
) is 3.15 dB with a central frequency of 85.5 GHz.