Experimental analysis of spiral integrated inductors on low cost integrated circuit processes

Integrated spiral inductors are investigated to obtain an optimal design for low cost IC processes. For this study, different inductor structures were fabricated to determine the best topology suited for optimizing the Q factor. The inductor structures studied include patterned ground shield, hollow spiral and stacked inductors. A new design for stacked inductor using two metal layers is developed to reduce the resistive loss of integrated inductors. The hollow spiral inductors and planar spiral inductors have 4.5 turns and 8 turns, respectively. A patterned ground shield is found to enhance the Q factor from 1.9 up to 3.8 in hollow spiral inductors, and from 1.6 up to 2.5 in planar inductors. The new stacked spiral inductors show slightly lower peak inductance values and resonance frequencies. Nevertheless, due to the reduction of resistive loss of inductor traces, the Q factors of the new stacked structure of inductors are improved by about 14%.