Stackable, passively-tunable, cost-reduced inductor

Abstract

An inductor (100) optimized for surface-mount vacuum-pickup automated circuit assembly eliminates the expense of an inductor housing. The inductor has a hollow rectangular ferrite core (101) and a winding defined by a stripline (102) deposited on the core surface. Winding ends are formed by conductive vias (103) in the core that open onto the core surface, where they connect and mount the inductor to a circuit board (150). A flat sheet (104) adhered to one face of the core provides a surface for vacuum pickup and for labeling of the inductor. The core of a passively tuneable inductor (200) defines multiple unconnected winding segments (102-103). Segment ends mount the inductor to the circuit board and connect the segments to circuit board striplines (254) that are laid out in a pattern to interconnect a number of the segments into a winding. The inductor is tuned by changing the stripline layout and thereby varying the number of interconnected segments. The core of an electromagnetic interference choke (300) defines two windings wound axially in parallel and radially in opposite directions. The core of a choke (500) that permits stacked mounting defines additional conductive vias (503) for connecting the windings of a second choke (300) mounted on the core to the circuit board. For electromagnetic isolation, the windings of the two chokes are oriented orthogonally to each other.