Variable inductance multilayer inductor with MOSFET switch control

A variable monolithic inductor having a stacked spiral inductor connected with MOSFET switches is proposed and fabricated in a 0.18 /spl mu/m, one-poly-six-metal (1P6M) standard CMOS process. By controlling a voltage of the MOSFET switch, the proposed three-stacked inductor demonstrates a continuously variable inductance of from 8 to 23 nH at 2.4 GHz, and due to its stacked structure, it takes less than 50% of the chip area compared with conventional single layer inductors. With its compact size and variable inductance feature, the proposed variable inductor is a prospective key component for the multiband RF circuits such as electrically controllable matching circuits and wide tuning range voltage controlled oscillators (VCOs).