High-Q variable inductor using redistributed layers for Si RF circuits

We present a high-Q variable inductor using redistributed layers, whose inductance is of nH-order for GHz applications. The inductance can be varied by shielding the magnetic flux by means of a metal plate above the inductor. The metal plate is moved using a MEMS actuator. At 2 GHz, the measured inductance is varied from 4.80 nH to 2.27 nH, i.e., the variable range is 52.6%. The maximum value of quality factor is 50.1.