Design method for a lumped-element bandpass filter with two resonators and its application to multiplexers

A design method for a lumped-element bandpass filter is presented that simplifies construction of a multiplexer. Each filter consists of a series resonator and a shunt resonator. The input impedance of each filter designed in this study is near open-circuited at the resonance frequencies of the other channels. Owing to this property, all the filters can be connected together at a common port in parallel without any additional peripheral circuitry to build a multiplexer. This property is because of the combination of a series resonance circuit and a shunt resonance circuit of the filter. To verify the design method, a multiplexer with three channels is fabricated with lumped elements together with distributed elements. Measured results are in good agreement with prediction. The measured insertion loss is less than 0.5 dB at each channel, whereas return loss at each port is better than 15 dB and suppression of other channel signals is better than 20 dB. The isolation between channels is better than 20 dB.

[1]  G. R. Wagner,et al.  High temperature superconducting space-qualified multiplexers and delay lines , 1996 .

[2]  S. J. Fiedziuszko,et al.  Low loss multiplexers with planar dual mode HTS resonators , 1996 .

[3]  Roger J. Forse,et al.  Design of HTS, lumped-element, manifold-type microwave multiplexers , 1996 .

[4]  L. Accatino,et al.  Hybrid circuit-full-wave computer-aided design of a manifold multiplexers without tuning elements , 2002 .

[5]  W. K. Chen,et al.  Computer-aided design of a singly-matched (S-M) multiplexer with a common junction , 1993 .

[6]  Raafat R. Mansour,et al.  Design considerations of superconductive input multiplexers for satellite applications , 1996 .

[7]  Kai Chang,et al.  Encyclopedia of RF and microwave engineering , 2005 .

[9]  Chun Hsiung Chen,et al.  Modeling of symmetric composite right/left-handed coplanar waveguides with applications to compact bandpass filters , 2005, IMS 2005.

[10]  Raafat R. Mansour,et al.  Feasibility and commercial viability issues for high-power output multiplexers for space applications , 2000 .

[11]  Tatsuo Itoh,et al.  Multiplexers using unit-cell filters of CRLH TLs , 2010, 2010 Asia-Pacific Microwave Conference.

[12]  Kai Chang,et al.  A 10-35-GHz six-channel microstrip multiplexer for wide-band communication systems , 2006 .

[13]  Tie Jun Cui,et al.  Design and Analysis of Super-Wide Bandpass Filters Using a Novel Compact Meta-Structure , 2007, IEEE Transactions on Microwave Theory and Techniques.

[14]  T. Itoh,et al.  Composite right/left-handed transmission line metamaterials , 2004, IEEE Microwave Magazine.

[15]  P.M. LaTourrette,et al.  Extended-Junction Combline Multiplexer , 1978, 1978 IEEE-MTT-S International Microwave Symposium Digest.

[16]  R. Levy,et al.  A Generalized Multiplexer Theory , 1979 .

[17]  J.A. Ruiz-Cruz,et al.  Full-wave design of H-plane contiguous manifold output multiplexers using the fictitious reactive load concept , 2005, IEEE Transactions on Microwave Theory and Techniques.

[18]  Wai-Cheung Tang,et al.  Innovations in microwave filters and multiplexing networks for communications satellite systems , 1992 .