Sub-fF 130 nm MOS Varactor Characterization Using 6.8 GHz Interferometry-Based Reflectometer

Nanometer-scaled communication devices for microwave and millimeter wave applications motivated innovative techniques in modeling and characterization. In this letter, an interferometry-based reflectometer (IBR), comprising Vector Network Analyser (VNA) and commercial devices, is implemented. Using sub-fF 130 nm thick-oxide accumulation MOS varactors from ST Microelectronics, IBR and VNA measurements are compared to a silicon-based model. A capacitance from 0.9 to 1.6 fF around 6.8 GHz is estimated. IBR demonstrates a root-mean-squared (RMS) error related to silicon-based model of 60 aF, while VNA has 70 aF in its best case. The mean accuracy is estimated at 40 aF and 11 aF respectively for VNA best case and IBR in C-V measurements. This letter demonstrates that IBR solution has smaller RMS error and better accuracy for C-V measurements than VNA.