Characterization and modeling of accumulation-mode MOS varactors

The characterization and modeling of an accumulation-mode MOS varactor implemented in a standard 0.13 /spl mu/m CMOS process is discussed. An experimental model based on the physical parameters of the device is verified. The model has been extracted, using S-parameter measurements, from different MOS varactor structures and is valid in both accumulation and depletion regions. The model has been verified both directly using the extracted values and indirectly by comparing the measured and simulated tuning curves of 5-6 GHz voltage controlled oscillators designed in the same process.