A transformer-based circuit has at least a first port and a plurality of second ports. The transformer-based circuit includes a first winding conductor and a plurality of second winding conductors. The first winding conductor is electrically connected to the first port, and has a plurality of sectors connected in series to thereby form a plurality of loops, where the loops are arranged in a concentric-like fashion. The second winding conductors are magnetically coupled to the first winding conductor; besides, the second winding conductors are electrically connected to the second ports, respectively. Overall layout patterns of the second winding conductors are identical to each other. The first winding conductor acts as one of a primary winding conductor and a secondary winding conductor, and each of the second winding conductors acts as the other of the primary winding conductor and the secondary winding conductor.