A novel compact microstrip bandpass filter with two transmission zeros

A novel compact microstrip bandpass filter composed of two quarter-wavelength (λ4 ) resonators is proposed. By introducing an additional capacitive coupling between two λ4 resonators, two transmission zeros at upper and lower stopbands may be suitably created. The proposed filter has good rejection at twice the center frequency with a very small circuit area. Specifically, a compact microstrip bandpass filter centered at 2.4 GHz is implemented with an area of approximately λ8 x λ4.

[1]  R.J. Wenzel.  Understanding transmission zero movement in cross-coupled filters , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[2]  Jen-Tsai Kuo,et al.  Miniaturized 3 GHz cross-coupled planar microwave filters , 2004 .

[3]  Chi-Yang Chang,et al.  Miniaturized microstrip cross-coupled filters using quarter-wave or quasi-quarter-wave resonators , 2003 .

[4]  M. Makimoto,et al.  Miniaturized hairpin resonator filters and their application to receiver front-end MICs , 1989 .

[5]  R. J. Forse,et al.  Hairpin-comb filters for HTS and other narrow-band applications , 1997 .

[6]  Chi-Yang Chang,et al.  Folded quarter-wave resonator filters with Chebyshev, flat group delay, or quasi-elliptical function response , 2002, 2002 IEEE MTT-S International Microwave Symposium Digest (Cat. No.02CH37278).

[7]  Ying Wang,et al.  Predistortion technique for cross-coupled filters and its application to satellite communication systems , 2003 .

[8]  S. K. Kim,et al.  Cross-coupled band-pass filter using HTS microstrip resonators , 2001 .

[9]  Jiasheng Hong,et al.  Couplings of microstrip square open-loop resonators for cross-coupled planar microwave filters , 1996 .

[10]  Michael J. Lancaster,et al.  Cross-coupled microstrip hairpin-resonator filters , 1998 .

[11]  Jen-Tsai Kuo,et al.  A microstrip elliptic function filter with compact miniaturized hairpin resonators , 2000, IEEE Microwave and Guided Wave Letters.

[12]  Chi-Yang Chang,et al.  A novel coupling structure suitable for cross-coupled filters with folded quarter-wave resonators , 2003 .