Novel coplanar-waveguide bandpass filters using loaded air-bridge enhanced capacitors and broadside-coupled transition structures for wideband spurious suppression

Shih Cheng Lin, Tsung Nan Kuo, Yo Shen Lin, Chun Hsiung Chen

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Novel inline coplanar-waveguide (CPW) bandpass filters composed of quarter-wavelength stepped-impedance resonators are proposed, using loaded air-bridge enhanced capacitors and broadside-coupled microstrip-to-CPW transition structures for both wideband spurious suppression and size miniaturization. First, by suitably designing the loaded capacitor implemented by enhancing the air bridges printed over the CPW structure and the resonator parameters, the lower order spurious passbands of the proposed filter may effectively be suppressed. Next, by adopting the broadside-coupled microstrip-to-CPW transitions as the fed structures to provide required input and output coupling capacitances and high attenuation level in the upper stopband, the filter with suppressed higher order spurious responses may be achieved. In this study, two second- and fourth-order inline bandpass filters with wide rejection band are implemented and thoughtfully examined. Specifically, the proposed second-order filter has its stopband extended up to 13.3 f0, where f0 stands for the passband center frequency, and the fourth-order filter even possesses better stopband up to 19.04 f0 with a satisfactory rejection greater than 30 dB.

Original languageEnglish
Article number1668354
Pages (from-to)3359-3368
Number of pages10
JournalIEEE Transactions on Microwave Theory and Techniques
Volume54
Issue number8
DOIs
StatePublished - Aug 2006

Keywords

  • Air bridge
  • Bandpass filter
  • Coplanar waveguide (CPW)
  • Microstrip
  • Quarter-wavelength resonator
  • Spurious suppression
  • Stepped-impedance resonator (SIR)

Fingerprint

Dive into the research topics of 'Novel coplanar-waveguide bandpass filters using loaded air-bridge enhanced capacitors and broadside-coupled transition structures for wideband spurious suppression'. Together they form a unique fingerprint.

Cite this