Patent ID: 7405642

Claim:
A three dimensional (3-D) transformer comprising: a first coil and a second coil that are insulated from each other, each coil comprising a first port, a second port, a top layer metal line, a plurality of inter-layer inner metal lines, a plurality of inter-layer outer metal lines and a bottom layer metal line, wherein each layer of the metal lines of the first coil and each layer of the metal lines of the second coil are correspondingly configured to an opposite side of each other, and the first port of each coil is connected to the top layer metal line of the coil, and each coil is arranged, in the same spiral direction, from a first end of the top layer metal line of the coil to the inner metal lines of the coil and down to the bottom layer metal line of the coil and then from a second end of the bottom layer metal line of the coil up to a top-most layer of the outer metal lines of the coil and then to the second port of the coil.