Linear Technology Corporation

Jeffrey Kingan Witt

Leonard Shtargot

David Roy Ng

Edward William Olsen

Daniel Cheng

John Gardner

Christian Kueck

An integrated circuit package may include a semiconductor die, a heat spreader, and encapsulation material. The semiconductor die may contain an electronic circuit and exposed electrical connections to the electronic circuit. The heat spreader may be thermally-conductive and may have a first outer surface and a second outer surface substantially parallel to the first outer surface. The first outer surface may be affixed to all portions of a silicon side of the semiconductor die in a thermally-conductive manner. The encapsulation material may be non-electrically conductive and may completely encapsulate the semiconductor die and the heat spreader, except for the second surface of the heat spreader. The second surface of the heat spreader may be solderable and may form part of an exterior surface of the integrated circuit package.

Exposed, solderable heat spreader for integrated circuit packages

This invention uses new switching regulator structures to split single magnetic loops into multiple magnetic loops, with linked opposing magnetic fields, to cause a cancelling effect, resulting in a much lower overall magnetic field. This results in lower EMI. In one embodiment, synchronously switched transistors are divided up into parallel topside transistors and parallel bottomside transistors. The topside transistors are positioned to oppose the bottomside transistors, and bypass capacitors are connected between the pairs to create a plurality of current loops. The components are arranged to form a mirror image of the various current loops so that the resulting magnetic fields are in opposite directions and substantially cancel each other out. Creating opposite current loops may also be achieved by forming the conductors and components in apattern with a cross-over point.

Magnetic field cancellation in switching regulators

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Oakland, CA, United States of America

Jeffrey Kingan Witt