A Low Substrate Loss, Monolithically Integrated Power Inductor for Compact LED Drivers

In this paper, a low substrate loss, monolithically integrated power inductor for compact LED drivers is designed and experimentally demonstrated. A 5.2 mu H inductor is embedded at the backside of the silicon substrate, and the low-k, insulating material SU-8 is used to reduce the substrate loss. The inductor achieves a DC resistance of 2.3 Omega and a peak Q factor of 22 at 3.4 MHz. The inductor, controller, and LED array are flip-chip bonded on a silicon slab for discrete implementation of the monolithically integrated LED driver which achieves an overall power efficiency of 73%.