Silicon high frequency test structures improvement for millimeter wave varactors characterization optimization and modeling

Nowadays, thanks to the capabilities offered by advanced CMOS and BiCMOS technologies for the design above 60GHz, the improvement of millimeter wave varactors is mandatory. Innovative test structures must be designed to characterize these varactors with low capacitance values (down to aF scale) and an influent parasitic environment. High frequency varactors characterization with reduced pad size and modified metal stack added to an optimized test structure positioning has been validated up to 110GHz.