High-Q MOS Varactors for Millimeter-Wave Applications in CMOS 28-nm FDSOI

Accumulation MOS varactors on the low-power CMOS 28-nm fully depleted silicon on insulator (FDSOI) are presented with a minimum gate length of 43 nm. This process enable to improve the varactors quality factor (Q-factor) at high frequency, which can be employed for CMOS-based millimeter-wave (MMW) applications. Measured results up to 110 GHz show relatively high Q-factor close to 10 and relatively low series resistance for a conventional multifinger MOS varactors. The proposed MOS varactor is expected to improve the overall Q-factor of the inductor capacitor resonator (LC) tank of MMW oscillators.