Band-Notched Balanced UWB BPF With Stepped-Impedance Slotline Multi-Mode Resonator

• Published in: IEEE microwave and wireless components letters 2012-04, Vol.22 (4), p.182-184
• Main Authors: Ching-Her Lee, Hsu, C-I G., Chung-Jung Chen
• Format: Article
• Language: English
• Subjects: Applied sciences; Balanced ultra-wideband (UWB) bandpass filter (BPF); Balancing; Band pass filters; Circuit properties; common-mode (CM) suppression; Delta modulation; differential-mode (DM) operation; Dubnium; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Frequency filters; Local area networks; Microstrip; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwaves; Noise levels; Oscillators, resonators, synthetizers; Passband; Rejection; Resonators; Slotline; slotline resonator; Ultra wideband technology; Wireless communication
• ISSN: 1531-1309; 2771-957X; 1558-1764; 2771-9588
• DOI: 10.1109/LMWC.2012.2188019

This letter presents a new 5 GHz band-notched balanced ultra-wideband (UWB) bandpass filter (BPF), which is designed using a stepped-impedance slotline multi-mode resonator (MMR). To obtain favorable uniform differential-mode (DM) response, a microstrip-to-slotline transition is used as the signal-feeding structure and the first three resonant modes of the slotline MMR are located in the UWB passband. Common-mode (CM) signal rejection is achieved by deploying the slotline MMR in such a way that the quarter-wavelength resonances occurring near the input and output sides of the resonator are well decoupled. Also featured in this design is the blocking of unwanted WLAN signals, which is achieved by loading the input feed-lines with a stepped-impedance microstrip stub to create a notch-band centered at 5.5 GHz. The designed BPF has a measured minimum DM insertion loss of 0.83 dB in the UWB passband, in which the measured CM suppression is larger than 18.85 dB.