Z-foldable secondary winding for a low-profile, multi-pole transformer

Abstract

A high-frequency, low-profile transformer having at least one pair of magnetic poles includes a primary winding having a z-folded, continuous primary conductive film with a generally serpentine configuration disposed on a primary dielectric membrane and further includes a z-folded, continuous secondary winding constructed from a plurality of secondary conductive film portions disposed on a secondary dielectric membrane. Each of the secondary conductive film portions is configured to form a single continuous path enclosing each of the magnetic poles in such manner that each path encloses one pole of each pair of the magnetic poles of each adjacent layer of the secondary winding. Each path thus continues along a respective fold of the winding stack. The secondary winding layers are interleaved with the primary winding layers and electrically connected together. In one preferred embodiment, the transformer has two pairs of magnetic poles, and each path formed by each secondary conductive film has a shape characterized as two generally ovoid portions connected together at a relatively wide midportion. Low-resistance conductive bridges are used to electrically connect the secondary conductive film portions together along alternate folds of the winding stack.