volume | PIER Journals

2013-11-21

Compact LPF with Sharp Roll off and Wide Stopband Using Coupling Stepped Impedance Triangular Resonator

Zebao Du,

Dr. Zebao Du

Department of RFIC

Institute of Microelectronics, Chinese Academy of Sciences

China

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Hao Yang,

Dr. Hao Yang

Department of RFIC

Institute of Microelectronics, Chinese Academy of Sciences

China

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Haiying Zhang,

Dr. Haiying Zhang

Department of MMICs and Compound Semiconductor Devices

Institute of Microelectronics, Chinese Academy Science

China

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Min Zhu

Dr. Min Zhu

Department of RFIC

Institute of Microelectronics, Chinese Academy of Sciences

China

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Progress In Electromagnetics Research Letters, Vol. 44, 29-34, 2014

doi:10.2528/PIERL13102203

Abstract

A lowpass filter with sharp transition and wide stopband using a novel coupling stepped-impedance triangular resonator is presented. The L-C equivalent circuit is developed for designing this type filter and analyzing the mechanism for improving roll-off and rejection property. The stopband width, passband edge, roll-off rate and overall suppression level are affected by coupling capacitance. The effect of coupling capacitance is analyzed using calculated frequency response. Coupling triangular stubs provide adequate coupling capacitance resulting in balance among transition property, stopband width and suppression level easily. A single LPF unit is designed and fabricated with cutoff frequency of 860 MHz. The single LPF unit exhibits 40-dB suppression level from 1.11 GHz to 2.28 GHz. A cascaded LPF with three asymmetric units provides 40-dB suppression level from 1.1 GHz to 6.76 GHz, and roll-off rate of 154 dB/GHz with compact size as small as 0.23λ_g × 0.05λ_g, where λ_g is guided wavelength at cutoff frequency.

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Zebao Du, Hao Yang, Haiying Zhang, and Min Zhu, "Compact LPF with Sharp Roll off and Wide Stopband Using Coupling Stepped Impedance Triangular Resonator," Progress In Electromagnetics Research Letters, Vol. 44, 29-34, 2014.
doi:10.2528/PIERL13102203

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