Reconfigurable Bandwidth Bandpass Filter With Enhanced Out-of-Band Rejection Using π-Section-Loaded Ring Resonator

Salman Arain, Photos Vryonides, Muhammad Ali Babar Abbasi, Abdul Quddious, Marco A. Antoniades, Symeon Nikolaou

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)
420 Downloads (Pure)


A novel ring resonator bandpass filter with reconfigurable bandwidth with central frequency at 2.4 GHz is demonstrated. Theoretical analysis for computing the resonant frequencies is shown, and the design approach of implementing π-section stubs connected to the ring to obtain the bandwidth reconfigurability is explained. The use of reconfigurable π-section allows the alteration of the stub's effective width and therefore the filter's bandwidth reconfigurability. p-i-n diodes are used as switching elements to achieve the narrowband/wideband response. Coupled line sections are used for suppressing the higher modes by generating out-of-band transmission zeros, resulting in a significantly enhanced out-of-band rejection. Measurements indicate that the 3-dB fractional bandwidth can be switched from 58.5% to 75% at a fixed center frequency of 2.4 GHz with an insertion loss better than 1.1 dB. Moreover, the -20-dB stopband performance is extended to 2.7f₀.

Original languageEnglish
Pages (from-to)1-3
JournalIEEE Microwave and Wireless Components Letters
Early online date07 Dec 2017
Publication statusEarly online date - 07 Dec 2017


  • Bandpass filter (BPF)
  • Bandwidth
  • Frequency control
  • Impedance
  • Optical ring resonators
  • p-i-n diode
  • P-i-n diodes
  • Passband
  • reconfigurable bandwidth
  • Resonant frequency
  • ring resonator
  • switchable bandwidth.

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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