A compact millimeter-wave dual-mode ring filter using loaded capacitances in CMOS 0.25µm technology

Two millimeter-wave dual-mode ring-based filters implemented in SiGe BiCMOS 0.25-μm technology are presented. Both filters are designed using specific synthesis. The nominal ring filter exhibits 13% of 3-dB fractional bandwidth (FBW
_3dB
), 5.6 dB of insertion losses at 61 GHz for a footprint of 0.74 mm
²
. The modified filter is a capacitively loaded ring filter showing 11.9% of FBWW
_3dB
, 5.0 dB insertion losses at 61.2 GHz with a footprint of 0.32 mm
²
. The modification allows a significant size reduction (2.3 times smaller) while maintaining equivalent electrical performance.