Frontiers in Physics (Mar 2022)

A Tunable low Pass Filter Based on Transmission Lines With Tunable Input/Output Impedance

  • Zhonghai Zhang,
  • Yuekai Zhao,
  • Lin Chen,
  • Zhihua Fang,
  • Aiting Wu,
  • Pengquan Zhang

DOI
https://doi.org/10.3389/fphy.2022.872204
Journal volume & issue
Vol. 10

Abstract

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A tunable low pass filter (TLPF) based on the tuning of input/output impedance was presented in this letter. The TLPF mainly consisted of improved quarter-wavelength stubs. The input/output impedance of the improved quarter-wavelength stubs can be tuned in a certain range. The design procedure of this TLPF was derived from the filters based on the quarter-wavelength transmission stubs. Through the tuning of the input/output impedance of the transmission lines, the cut-off frequency of the TLPF can be adjusted in a certain range. The TLPF has relatively good designability and can be easily changed to meet other performance levels. Finally, a TLPF was designed, fabricated, and measured. The measured results verify the effectiveness of the design method.

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