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Design of cross-coupled planar microstrip band-pass filters using a novel adjustment method
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Paper Abstract

In this paper the design of a cross-coupled planar microwave band-pass filter using open-loop square microstrip resonators, with two symmetrically placed attenuation poles, is presented. The design starts from the following specifications: central frequency 3GHz, 150MHz bandwidth, 1dB ripple in the pass-band corresponding to return loss of 6.8dB.The adjustment method using additional ports placed on each resonator of the filter is used, allowing the interconnection of the filter structure with external lumped elements. Connecting a reactive element (capacitor) from such an additional port to ground allows a fine tuning of the resonator. Connecting a reactive element between two such additional ports allows a fine change in the coupling coefficient between these resonators. After adding four extra ports and connecting the external elements (capacitors), it is possible to use fast circuit simulation software to optimize the filter's response. Then all these capacitors have to be gradually eliminated, by compensating their effects through fine changes back in the layouts. If some specific issues are properly handled, this procedure improves considerably the quality of the final design of the filter. After a thorough optimization of the layout, the filter was fabricated and measured. The results of measurements are in good agreement with the specifications of the filter, showing this way the efficiency of the applied optimization method.

Paper Details

Date Published: 20 February 2015
PDF: 5 pages
Proc. SPIE 9258, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies VII, 92580J (20 February 2015); doi: 10.1117/12.2070649
Show Author Affiliations
Muhammed Salah Sadiq Alkafaji, Politehnica Univ. of Bucharest (Romania)

Published in SPIE Proceedings Vol. 9258:
Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies VII
Ionica Cristea; Marian Vladescu; Razvan Tamas, Editor(s)

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