volume | PIER Journals

Abstract

A compact, ultra-broadband coplanar-waveguide (CPW) bandpass filter (BPF) is demonstrated. The proposed CPW-BPF is essentially designed by exploiting CPW short-stub and open-stub structures. Technically, the proposed filter comprises shunt short-stub and series open-stub structures that are connected in a cascade topology. The higher and lower cutoff frequencies are mainly related to the electrical length of the shunt short stub and the series open stub, respectively. In addition, the stopband rejection is enhanced through an incorporation of CPW bandstop structures. The proposed filter design is verified through experimental demonstration. The corresponding lumped equivalent and transmission-line equivalent circuits are provided for circuit design purpose. Compared with the classical CPW-BPFs, the proposed filter is of a relatively simple and compact configuration. The demonstrated CPW-BPF has about 110% 3-dB fractional bandwidth, sharp selectivity, and great stopband rejection.

1. Chen, H. and Y. Zhang, "A novel and compact UWB bandpass filter using microstrip fork-form resonators," Progress In Electromagnetics Research, Vol. 77, 273-280, 2007.
doi:10.2528/PIER07082302 Google Scholar

2. Razalli, M. S., A. Ismail, M. A. Mahdi, and M. N. Bin Hamidon, "Novel compact microstrip ultra-wideband filter utilizing short-circuited stubs with less vias," Progress In Electromagnetics Research, Vol. 88, 91-104, 2008.
doi:10.2528/PIER08102303 Google Scholar

3. Razalli, M. S., A. Ismail, M. A. Mahdi, and M. N. Bin Hamidon, "Novel compact "via-less" ultra-wide band filter utilizing apacitive microstrip patch," Progress In Electromagnetics Research, Vol. 91, 213-227, 2009.
doi:10.2528/PIER09020403 Google Scholar

4. Hong, J.-S. and M. J. Lancaster, Microstrip Filters for RF/Microwave Applications, Wiley, 2001.

5. Lin, F. L., C. W. Chiu, and R. B. Wu, "Coplanar waveguide bandpass filter --- A ribbon-of-brick-wall design," IEEE Trans. Microw. Theory Tech., Vol. 47, 1589-1596, Jul. 1995. Google Scholar

6. Kuo, Y.-K., C.-H. Wang, and C. H. Chen, "Novel reduced-size coplanar-waveguide bandpass filters," IEEE Microw. Wireless Compon. Lett., Vol. 11, No. 2, 65-67, Feb. 2001.
doi:10.1109/7260.914304 Google Scholar

7. Lin, Y.-S., W.-C. Ku, C.-H. Wang, and C. H. Chen, "Wideband coplanar-waveguide bandpass filters with good stopband rejection," EEE Microw. Wireless Compon. Lett., Vol. 14, No. 9, 422-424, 2004.
doi:10.1109/LMWC.2004.832069 Google Scholar

8. Gao, J., L. Zhu, W. Menzel, and F. Bogelsack, "Short-circuited CPW multiple-mode resonator for ultra-wideband (UWB) bandpass filter," IEEE Microw. Wireless Compon. Lett., Vol. 16, No. 3, 104-106, Mar. 2006.
doi:10.1109/LMWC.2006.869870 Google Scholar

9. Chen, N.-W. and K.-C. Fang, "An ultra-broadband coplanar waveguide bandpass filter with sharp skirt selectivity," IEEE Microw. and Wireless Compon. Lett., Vol. 17, No. 2, 124-126, Feb. 2007.
doi:10.1109/LMWC.2006.890337 Google Scholar

10. Dib, N. I., L. P. B. Katehi, G. E. Ponchak, and R. N. Simons, "Theoretical and experimental characterization of coplanar waveguide discontinuities 49-53 for filter applications," IEEE Trans. Microw. Theory Tech., Vol. 39, 873-881, May 1991.
doi:10.1109/22.79116 Google Scholar

11. Simons, R. N., Coplanar Waveguide Circuits, Components, and Systems, Wiley Interscience, 2001.

12. Liu, A. Q., A. B. Yu, and Q. X. Zhan, "Broad-band band-pass and band-stop filters with sharp cut-off frequencies based on series CPW stubs," IEEE MTT-S Int. Microwave Symp. Digest, 353-356, Jun. 2006.
doi:10.1109/MWSYM.2006.249525 Google Scholar

Dr. Shao-Ning Wang

Dr. Nan-Wei Chen