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This paper presents a miniature-size band-reject filter on a Coplanar Waveguide (CPW) transmission line using series connected complementary split ring resonators (CSRRs) and series capacitive gaps for X-band applications. The band-reject filter has highly miniaturized dimensions and is capable of solving almost all the basic limitations to which the conventional band-reject filters are mostly susceptible. The series connected CSRRs are etched on the signal planes of the CPW transmission line on silicon substrate enabling CMOS compatibility with planar IC technology. It is a concept resulting in higher bandwidth, low insertion loss of 0.5 dB with high rejection of 40 dB in the stop bands better than similar designs. The optimized design of the proposed device is performed using the parametric study of filter characteristics. The proposed devices RF analysis and circuit model are simulated using Ansoft High-Frequency Structural Simulator (HFSS) v13® and Agilent Advanced Design System (ADS) 2009. Measured results are in good agreement with their simulated counterparts and the measured performance is encouraging in all respects. [ABSTRACT FROM AUTHOR]

Abstract: A band reject filter with tuning capability is presented on a CPW transmission line on silicon substrate using comb line and RF MEMS variable capacitor, enabling compatibility with planar IC technology. A conventional CPW on a substrate consists of a central strip conductor with semi-infinite ground planes on either side. A comb line is etched on the signal line of the CPW and the MEMS bridge capacitor is put on the same line in shunt. Tunability of the filter is achieved by putting the MEMS bridge in either up or down state. The rejection at the centre frequency of stop bands are around −40.24dB for down state and −38.21dB for up state of the bridge. A low insertion loss, as low as −0.68dB, is obtained in the pass band. The proposed device structure is simulated using ANSOFT HFSS v13® for RF analysis and COVENTORWARE (2008)® for mechanical and electromechanical characterization, both static and transient analysis. [Copyright &y& Elsevier]