Design of Costless and Adjustable Inductors Embedded in Array Packages

High performance, costless and tunable embedded inductors for applications in system-in-package design are proposed. Square segmented spiral inductors in the chip pad area of the standard two-layer array packages provide multiple selections of adjustable inductances without penalty of signal routing density. The inductor performance was extracted using 3D electromagnetic field solvers and wideband circuit optimization. A 4 mm² spiral inductor can be achieved for inductance selection from 1 nH through 12 nH. In this range, an inductor of 7.6 nH with maximum Q-factor 37 can be obtained and its performance is comparable to that of LTCC or MCM-D.