Square toroid transformer for hybrid integrated circuit

Claim 1

A hybrid transformer device for use in a hybrid integrated circuit, comprising in combination: (a) a nonconductive substrate having a planar surface; (b) first and second groups of parallel metal strip conductors adherent to the planar surface, each having an inner end and an outer end; (c) dielectric material on intermediate portions of each of the strip conductors between the inner and outer ends thereof, the inner and outer ends extending beyond the dielectric material; (d) a unitary rectangular magnetic core coated with dielectric material and having only first, second, third and fourth arms forming a continuous closed rectangular toroid, the first and third arms being parallel and the second and fourth arms being parallel, the first group of strip conductors being under the first arm and the second group of strip conductors being under the third arm; (e) a layer of adhesive material bonding the rectangular magnetic core to the dielectric material above the strip conductors; and (f) a first group of bonding wire conductors looping over the first arm and having first and second ends wire bonded to an outer end of a strip conductor of the first group and an inner end of an adjacent strip conductor of the first group, respectively, forming a primary winding, and a second group of bonding wire conductors looping over the third arm and each having first and second ends wire bonded to an inner end of a strip conductor of the second group and an outer end of an adjacent strip conductor of the second group, respectively, forming a secondary winding.