Title :
Extended-stopband bandpass filter using both half- and quarter-wavelength resonators
Author :
Lin, Shih-Cheng ; Lin, Yo-Shen ; Chen, Chun Hsiung
Author_Institution :
Dept. of Electr. Eng., Nat. Taiwan Univ., Taipei
Abstract :
A novel quasielliptic microstrip bandpass filter (BPF) using both half- and quarter-wavelength resonators is proposed. With the quarter-wavelength (lambda/4) resonators placed in the interstage, the filter spurious passband can be pushed up to 3 f0 where f0 stands for the passband center frequency. To improve the stopband characteristics, a modified stopband-extended filter is implemented, utilizing the multiple transmission zeros placed at specified frequencies to achieve good frequency selectivity and out-of-band rejection. The modified filter provides a 22.5-dB rejection level from 1.14 f0 to 5.2 f0
Keywords :
band-pass filters; band-stop filters; elliptic filters; microstrip filters; resonator filters; extended stopband bandpass filters; filter spurious passband; half-wavelength resonators; multiple transmission zeros; passband center frequency; quarter-wavelength resonators; quasielliptic microstrip bandpass filter; Band pass filters; Filtering theory; Frequency; Impedance; Microstrip filters; Microstrip resonators; Microwave filters; Passband; Resonance; Resonator filters; Cross-coupled bandpass filter (BPF); extended stopband; half-wavelength resonator; microstrip; quarter-wavelength resonator;
Journal_Title :
Microwave and Wireless Components Letters, IEEE
DOI :
10.1109/LMWC.2005.860014
