A 800-to 3200-MHz wideband CPW balun using multistage Wilkinson structure

A novel ultra-wide band CPW(Coplanar Waveguide) balun having the structure of multistage Wilkinson power divider is proposed. It has an 180 phase inverting structure between signal line and ground planes of CPW transmission line. The 3-stage Wilkinson power divider is transformed directly into the ultra-wide band balun without any cost of the size and performances. The measurement shows the right S-parameters as a power divider and the proper out of phase as a balun. The measured amplitude and phase unbalances at output ports are +/- 0.5dB and +/- 6 degrees, respectively over 800-3200MHz, while the maximum insertion loss is 0.8dB.