Patent ID: 6791431
Filing Date: 2004-09-14
Classification: H01P,H03H

Abstract:
A balancing/unbalancing (balun) structure for operating at frequency f1 comprising:a microstrip printed circuit board (PCB); a balun on the PCB comprising: two input ports for coupling to a differential signal; an isolated port connected to ground through a matched resistance; an output port for coupling to a single-ended signal corresponding to the differential signal; and a plurality of traces on the PCB connecting the two input ports, the isolated port and a tap point to the output port; and an f2 rejection filter on the PCB wrapped around the balun comprising: a first folded element having a transmission length of &lgr;2/4 and connected to the output port; a second folded element having a transmission length of &lgr;2/4 and connected to the tap point; and a third folded element connecting the tap point to the output port and having a transmission length of &lgr;2/4.