volume | PIER Journals

2013-04-18

Compact Wide Stopband Quasi-Elliptic Function Lowpass Filter Using Quasi-Lumped Elements

Chen Miao,

Dr. Chen Miao

Nanjing University of Science and Technology

China

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Xin Xu,

Prof. Xin Xu

Nanjing University of Science and Technology , UESTC

China

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Wen Wu

Dr. Wen Wu

Nanjing University of Science & Technology

China

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Progress In Electromagnetics Research Letters, Vol. 39, 151-159, 2013

doi:10.2528/PIERL13032202

Abstract

This paper presents a novel quasi-elliptic function lowpass filter (LPF) by using quasi-lumped elements. The proposed LPF is firstly based on a seven-order Chebyshev response lowpass prototype. Then, a series branches of shunt resonant LC circuit is introduced in the filter design to provide a transmission zero close to the transition band, which can improve the roll-off rate of proposed LPF significantly. To implement the lumped elements of lowpass prototype, the high-impedance meander lines are employed to realized the inductors while inter-digital microstrip lines and the microstrip parallel-plate structures are used to realize the capacitors. To validate the proposed method, a LPF with 3 dB cutoff frequency fc at 1.9 GHz is designed and fabricated. The measured results show that the fabricated LPF has a sharp roll-off rate up to -142 dB/octave and -15 dB harmonic suppression from 1.1f_c to 9.7f_c. Moreover, the fabricated LPF also has a compact size of 0.1λ_gc × 0.11λ_gc. Good agreement can observed between the simulation and measurement.

Citation

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Chen Miao, Xin Xu, and Wen Wu, "Compact Wide Stopband Quasi-Elliptic Function Lowpass Filter Using Quasi-Lumped Elements," Progress In Electromagnetics Research Letters, Vol. 39, 151-159, 2013.
doi:10.2528/PIERL13032202

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