Experimental results and die area efficient self-shielded on-chip vertical solenoid inductors for multi-GHz CMOS RFIC

On-chip circular vertical solenoid inductors have been designed and fabricated using standard 6-metal layer CMOS process. Compared to the 4.1 nH circular planar spiral inductor on the same chip, the 4.8 nH solenoid inductor gives about 20% increase in maximum quality-factor (QF) and 50% increase in self-resonant frequency (SRF), but only occupies 20% of the area. The inductor impedance can be modeled by a simple RLC circuit valid beyond 20 GHz.