Advances in Radio Science www.adv-radio-sci.net 1684-9965 1684-9973 6 Kleinheubacher Berichte 2007 2008 10.5194/ars-6-125-2008 http://www.adv-radio-sci.net/6/125/2008/ http://www.adv-radio-sci.net/6/125/2008/ars-6-125-2008.html http://www.adv-radio-sci.net/6/125/2008/ars-6-125-2008.pdf 125 127 2008-05-26 Miniaturisation of combline filters for switched-mode power amplifier systems E. Serebryakova K. Blau M. Hein Dept. for RF and Microwave Techniques, Technische Universität Ilmenau, Ilmenau, Germany This paper presents a coaxial combline filter for a class-S power amplifier for an operating frequency of 450 MHz. According to the measurement results, the filter provides a bandwidth of 26 MHz, an insertion loss of 0.55 dB, and a second pass-band only at 2.8 GHz. As the filter dimensions are crucial for the envisaged application, different ways to miniaturise the filter are proposed and their features and disadvantages discussed. Cohn, S. B.: Dissipation loss in Multiple-Coupled Resonators Filters, Proc. IRE, 47, 1342–1348, 1959. Ishizaki, T. and Uwano, T.: A stepped impedance comb-line filter fabricated by using ceramic lamination technique, IEEE MTT-S 2, 617–620, 1994. Jayaraman, A., Chen, P. F., Hanington, G., et al.: Linear High-Efficiency Microwave Power Amplifiers Using Band-pass Delta-Sigma Modulators, IEEE Microwave and Guided-Wave Letters, 8, 3, 21–123, March 1998. Kurzrok, R. M.: Design of Comb Line Band-Pass Filters, IEEE MTT, 14, 351–353, 1966. Matthaei, G. L., Jones, E. L., and Young, L.: Microwave filters, impedance-matching networks, and coupling structures, Dedham, Mass, Artech House Books, 1980.