The Island-Gate Varactor—A High-Q MOS Varactor for Millimeter-Wave Applications

摘要

ara> A new accumulation MOS varactor with island-shaped poly gate layout is proposed to improve the quality factor ( $Q$-factor) at high frequency, which can be readily employed for CMOS-based millimeter-wave applications. Measured results up to 67 GHz show significant improvements in the $Q$-factor and the series resistance $R_{s}$ over the conventional multi-finger MOS varactors with the same ground rule and gate area. The proposed island-gate MOS varactor is expected to improve the overall $Q$-factor of the LC tank of millimeter-wave oscillators.