A balun may include series-coupled balanced-signal lines. In some examples, a balun may include a first transmission line having a first unbalanced signal port on which an unbalanced signal may exist relative to circuit ground; a second transmission line having a first balanced-signal port may be connected...http://www.google.es/patents/US7692512?utm_source=gb-gplus-sharePatente US7692512 - Balun with series-connected balanced-signal lines
