Title :
Compact Quadruplet Bandpass Filter Based on Alternative J/K Inverters and
Resonators
Author :
Zhang, Songbai ; Zhu, Lei ; Li, Rui
Author_Institution :
Sch. of Electr. & Electron. Eng., Nanyang Technol. Univ., Singapore, Singapore
fDate :
5/1/2012 12:00:00 AM
Abstract :
This letter presents the proposal and synthesis design of a novel compact microstrip quadruplet bandpass filter (BPF) based on alternative J/K inverters and λ/4 resonators. The proposed quadruplet bandpass prototype is firstly derived from the conventional one with lumped LC resonators and the J-inverters. The mainline coupling is implemented by cascading four λ/4 resonators via the alternative J and K inverters, resulting in the achievement of the generalized Chebyshev in-band response. Meanwhile, the first and fourth resonators are cross-coupled via magnetic coupling so as to simultaneously produce transmission zeros below and above the desired passband. Finally, a microstrip quadruplet BPF at 2.5 GHz with a fractional bandwidth of 12.0% is designed, and the measured results of the fabricated filter show consistent match with its theoretical ones.
Keywords :
Chebyshev filters; band-pass filters; coupled circuits; invertors; microstrip filters; resonator filters; λ/4 resonator; BPF; Chebyshev in-band response; J/K inverter; compact microstrip quadruplet bandpass filter; fabricated filter; fractional bandwidth; frequency 2.5 GHz; lumped LC resonator; magnetic coupling; synthesis design; transmission zero; Band pass filters; Couplings; Filtering theory; Inverters; Microstrip resonators; Prototypes; Hybrid inverters; microstrip bandpass filter (BPF); quadruplet filter; quarter-wave resonator;
Journal_Title :
Microwave and Wireless Components Letters, IEEE
DOI :
10.1109/LMWC.2012.2193124