Design and analysis of UWB band pass filter with ring filter

To realize an ultra wideband (UWB) bandpass filter (BPF) in wireless communications, a device is developed using a new ring filter. The ring filter is compact, with low insertion loss, sharp rejection and a constant group delay within the UWB pass band. The ring filter is made to control the attenuation pole frequency by adjusting both the ring and the stub impedance. A center frequency and a bandwidth of the 5-stage UWB BPF are designed based on the transmission line model. The circuit conditions of two attenuation poles at either side of the passband are given together with controlling them.