High-Order Dual-Port Quasi-Absorptive Microstrip Coupled-Line Bandpass Filters

In this article, we present the first demonstration of distributed and symmetrical all-band quasi-absorptive filters that can be designed to arbitrarily high orders. The proposed quasi-absorptive filter consists of a bandpass section (reflective-type coupled-line filter) and absorptive sections (a matched resistor in series with a shorted quarter-wavelength transmission line). Through a detailed analysis, we show that the absorptive sections not only eliminate out-of-band reflections but also determine the passband bandwidth (BW). As such, the bandpass section mainly determines the out-of-band roll-off and the order of the filter can be arbitrarily increased without affecting the filter BW by cascading more bandpass sections. A set of 2.45-GHz one-, two-, and three-pole quasi-absorptive microstrip bandpass filters are designed and measured. The filters show simultaneous input and output absorption across both the passband and the stopband. Measurement results agree very well with the simulation and validate the proposed design concept.

[1]  F. S. Coale,et al.  A Traveling-Wave Directional Filter , 1956 .

[2]  Roberto Gómez-García,et al.  Split-Type Input-Reflectionless Multiband Filters , 2018, IEEE Microwave and Wireless Components Letters.

[3]  E.M.T. Jones,et al.  Coupled-Strip-Transmission-Line Filters and Directional Couplers , 1956 .

[4]  Roberto Gómez-García,et al.  RF Reflectionless Filtering Power Dividers , 2019, IEEE Transactions on Circuits and Systems II: Express Briefs.

[5]  Roberto Gómez-García,et al.  Dual-Behavior Resonator-Based Fully Reconfigurable Input Reflectionless Bandpass Filters , 2019, IEEE Microwave and Wireless Components Letters.

[6]  Roberto Gómez-García,et al.  Tunable Input-Quasi-Reflectionless Multiplexers , 2018, 2018 IEEE MTT-S International Microwave Workshop Series on 5G Hardware and System Technologies (IMWS-5G).

[7]  K. Yamanaka,et al.  A reflection-absorptive harmonic-rejection filter for RF power amplifiers , 2010, The 40th European Microwave Conference.

[8]  Roberto Gómez-García,et al.  Mixed-Technology Quasi-Reflectionless Planar Bandpass Filters , 2018, 2018 48th European Microwave Conference (EuMC).

[9]  Matthew A. Morgan,et al.  Reflectionless Filter Structures , 2014, IEEE Transactions on Microwave Theory and Techniques.

[10]  M A Morgan,et al.  Theoretical and Experimental Study of a New Class of Reflectionless Filter , 2011, IEEE Transactions on Microwave Theory and Techniques.

[11]  Seong-Wook Jeong,et al.  Absorptive Filter Prototype and Distributed-Element Absorptive Bandpass Filter , 2018, 2018 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO).

[12]  Roberto Gómez-García,et al.  Reflectionless Adaptive RF Filters: Bandpass, Bandstop, and Cascade Designs , 2017, IEEE Transactions on Microwave Theory and Techniques.

[13]  Antonije R. Djordjevic,et al.  On a class of low-reflection transmission-line quasi-Gaussian low-pass filters and their lumped-element approximations , 2003 .

[14]  Matthew A. Morgan,et al.  Reflectionless Filter Topologies Supporting Arbitrary Low-Pass Ladder Prototypes , 2019, IEEE Transactions on Circuits and Systems I: Regular Papers.

[15]  Ahmed A. Kishk,et al.  Compact Wideband Reflective/Absorptive Bandstop Filter With Multitransmission Zeros , 2019, IEEE Transactions on Microwave Theory and Techniques.

[16]  Eric J. Naglich,et al.  Switched Allpass-to-Bandstop Absorptive Filters With Constant Group Delay , 2016, IEEE Transactions on Microwave Theory and Techniques.

[17]  Juseop Lee,et al.  Lumped-Element Realization of Absorptive Bandstop Filter With Anomalously High Spectral Isolation , 2012, IEEE Transactions on Microwave Theory and Techniques.

[18]  Yo-Shen Lin,et al.  Narrowband Coupled-Line Bandstop Filter With Absorptive Stopband , 2015, IEEE Transactions on Microwave Theory and Techniques.

[19]  William J. Chappell,et al.  Frequency-Tunable Low- $Q$ Lumped-Element Resonator Bandstop Filter With High Attenuation , 2016, IEEE Transactions on Microwave Theory and Techniques.

[20]  Dimitrios Peroulis,et al.  A PCB Technology-Based 22–42-GHz Quasi-Absorptive Bandstop Filter , 2018, IEEE Microwave and Wireless Components Letters.

[21]  Wei Hong,et al.  Half Mode Substrate Integrated Waveguide (HMSIW) Directional Filter , 2007, IEEE Microwave and Wireless Components Letters.

[22]  L. C. Tillotson,et al.  A non-reflecting branching filter for microwaves , 1948, Bell Syst. Tech. J..

[23]  A.C. Guyette,et al.  Perfectly-matched bandstop filters using lossy resonators , 2005, IEEE MTT-S International Microwave Symposium Digest, 2005..

[24]  S. B. Cohn,et al.  Directional Channel-Separation Filters , 1956, Proceedings of the IRE.

[25]  Matthew A. Morgan,et al.  Think Outside the Band: Design and Miniaturization of Absorptive Filters , 2018, IEEE Microwave Magazine.

[26]  Roberto Gómez-García,et al.  Balanced Symmetrical Quasi-Reflectionless Single-and Dual-Band Bandpass Planar Filters , 2018, IEEE Microwave and Wireless Components Letters.

[27]  Mohammad Khalaj-Amirhosseini,et al.  Twofold Reflectionless Filters of Inverse-Chebyshev Response With Arbitrary Attenuation , 2017, IEEE Transactions on Microwave Theory and Techniques.

[28]  Roberto Gómez-García,et al.  Symmetrical Quasi-Reflectionless BSFs , 2018, IEEE Microwave and Wireless Components Letters.

[29]  Dimitrios Peroulis,et al.  Theory and Design of Frequency-Tunable Absorptive Bandstop Filters , 2018, IEEE Transactions on Circuits and Systems I: Regular Papers.

[30]  Jeong Phill Kim,et al.  Improved Design of Single-Section and Cascaded Planar Directional Filters , 2011, IEEE Transactions on Microwave Theory and Techniques.

[31]  J. Breitbarth,et al.  Absorptive near-Gaussian low pass filter design with applications in the time and frequency domain , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).

[32]  Roberto Gómez-García,et al.  Symmetrical Quasi-Absorptive RF Bandpass Filters , 2019, IEEE Transactions on Microwave Theory and Techniques.