A trifilar transformer comprising: a first winding; a second winding; and a third winding, wherein one winding is mutually coupled to each of the other two windings, and wherein said other two windings are substantially not coupled to each other. At least one of the first winding, the second winding and the third winding may comprise a figure-of-eight winding, e.g. a clockwise loop and an anti-clockwise loop. In some embodiments, the trifilar transformer may comprise: a first winding; a second winding concentric or interwound with the first winding; and a third winding formed from a first winding part in series with a second winding part, the first winding part having a shape corresponding to the first winding and the second winding part having a shape corresponding to the second winding.