Center-tap transformers in integrated circuits

摘要

Techniques for implementing transformers with center-taps are disclosed. Based on an overlay winding structure, according to one embodiment, the primary and the secondary of the transformer are respectively formed on two separate layers that are stacked on top of each other, wherein the secondary includes two segments, the two respective terminals of the two segments are coupled together to a component in a circuit to form a center-tap of the secondary. According to another embodiment, three or more separating windings are formed on separate layers. At least one of the windings is a conducting stripe wound in loops and includes a center-tap that extends across but not electrically connected to the loops of the conducting stripe by detouring the conducting stripe through other layers.