Inductor design for monolithic DC-DC converters

Optimal design of passives is important for realization of monolithic DC-DC converters. This paper discusses ideas for integrating inductors onto a silicon chip. Expressions for trace resistance and inductance estimation of on-chip spiral inductors is compared. Based on these expressions, planar spiral inductors are designed for use in monolithic DC-DC buck converters. An out-of-plane technology that uses a surface micromachining technique, known as plastic deformation magnetic assembly, is used to erect high quality inductors with small footprints. Experimental results from buck converters with each inductor are presented.