Design And Implementation Of Microwave Filters Based On Coplanar Waveguide

Crowded spectrum resources make multi-band and miniaturization become the tendency of modern wireless communication systems, so do filters, which have an effect on frequency-selecting play a key role in modern wireless communication. The coplanar waveguide has characteristics of flexible design and esay integration which are suitable for designing multi-band filters and on-chip filters. This thesis summarizes the history of coplanar waveguide(CPW), the research status of coplanar waveguide filters, the traditional theory for designing filters and the theory for designing cross-coupled filters. By using the theory of filters with immittance inverters, three multi-band CPW filters and two on-chip filters were designed and fabricated. The main contents of this thesis are:Firstly, quasi-static conformal mapping techniques were used to determine the characteristic impedance and effective dielectric constant of coplanar waveguide transmission lines, the results of conventional CPW and CPW on a double-layer dielectric substrate agree with the simulated results of the complete full-wave electromagnetic simulation tool.Secondly, three multi-band CPW filters were designed. By using a composite coupling structure for CPW/microstrip, a new dual-band bandpass filter(DBBPF) stacking inverted Y-shaped CPW resonators and rectangular ring resonators is proposed; a novel uniplanar quasi-elliptic function dual-passband CPW filter with CPW stepped impedance resonators(SIR) and spiral-shaped CPW defected ground structure(DGS) resonators is presented; by adding half-wavelength microstip resonators, a tri-band filter was proposed. Complete full-wave electromagnetic simulation tool is used to optimize these important parameters and obtain good performace of three multi-band filters. Good agreement between simulated and measured results demonstrates the validity of three multi-band filters.Finally, two 60 GHz CPW on-chip filters were designed on Si substrate. By using quarter-wavelength CPW transmission lines and dumb-bell-shaped DGS resonators, a three order bandpass filter is proposed; with hybrid coupling between SIR, an asymmetric CPW bandpass filter is proposed, transmission zeros are located on both sides of this passband to make the selectivity of this filter better. We study on the process of the peel-off method for fabricating on-chip filters based on Si substrate and two CPW on-chip filters were fabricated by ourselves.