New configurations for RF/microwave bandstop and lowpass filters

This thesis presents new, compact configurations for RF/microwave bandstop and lowpass filters for embedded passive applications. A simple design methodology is presented for designing the folded-transmission line filters on a microstrip platform. Unlike the conventional stub-loaded filter designs, the proposed folded-line filters will have practical dimensions for a wide range of electrical specifications, making physical implementation realizable. Further compactness is achieved by folding the transmission lines in a multi-layered environment. A back-to-back microstrip with through-holes in the ground plane is considered for this purpose. Closed-form design equations for the frequency independent R, L, C components have been developed for implementation in the circuit model of the through-ground via. The proposed configurations offer significant footprint reduction compared to the conventional geometries. Several lowpass and bandstop filters are designed in single and multi-layered environments, and the theoretical response is validated by full-wave EM simulation as well as with measurement.Keywords: Bandstop/lowpass, RF/microwave, New configurations, Planar filter

EM Based Synthesis and Design of Bandpass Waveguide Filters Including Manufacturing Effects with FEST3D

This article aims at the industry interest on automated design tools that are able to take into account manufacturing effects. First, an efficient design strategy for bandpass waveguide filters including the rounded corners arising from low-cost manufacturing procedures is presented. This technique is based on a recent enhanced prototype and synthesis methodology able to consider the real structure parts. Using the resulting electromagnetic (EM)-based synthesis technique, an excellent structure is extracted, which requires, at most, only a slight final EM optimization. Second, this article presents analytical expressions providing error estimates for the different filter performances in terms of manufacturing tolerances. From such expressions, designers can determine the tolerance to be requested for a tuning-less implementation. Moreover, they can also be used to set the convergence criterion for the synthesis procedure. A fully automated design tool of bandpass waveguide filters able to consider manufacturing impairments has been developed and integrated in the commercial software Full-wave EM Simulation Tool 3D (FEST 3D)The authors thank Mrs. Eva Tarin, Mr. Oscar Monerris, and Mr. Jaime Armendariz for their work on the integration of the synthesis tool for H-plane waveguide filters in FEST 3D. This work was supported by Ministerio de Educacion y Ciencia, Spanish Government, under the Research Project ref. TEC2010-21520-C04-01.Soto Pacheco, P.; Boria Esbert, VE.; Carceller Candau, C.; Vicente Quiles, CP.; Gil Raga, J.; Gimeno Martinez, B. (2012). EM Based Synthesis and Design of Bandpass Waveguide Filters Including Manufacturing Effects with FEST3D. International Journal of RF and Microwave Computer-Aided Engineering. 22(1):93-103. https://doi.org/10.1002/mmce.2058893103221Reiter, J. M., & Arndt, F. (1995). Rigorous analysis of arbitrarily shaped H- and E-plane discontinuities in rectangular waveguides by a full-wave boundary contour mode-matching method. IEEE Transactions on Microwave Theory and Techniques, 43(4), 796-801. doi:10.1109/22.375226Zhou, J., Duan, B., & Huang, J. (2010). Influence and tuning of tunable screws for microwave filters using least squares support vector regression. International Journal of RF and Microwave Computer-Aided Engineering, 20(4), 422-429. doi:10.1002/mmce.20447Nikolova, N. (2008). Electromagnetic software in microwave engineering [Guest Editorial]. IEEE Microwave Magazine, 9(6), 10-12. doi:10.1109/mmm.2008.929880Boria, V. E., Gimeno, B., Marini, S., Taroncher, M., Cogollos, S., Soto, P., … Gil, J. (2007). Recent advances in modeling, design, and fabrication of microwave filters for space applications. International Journal of RF and Microwave Computer-Aided Engineering, 17(1), 70-76. doi:10.1002/mmce.20199Kozakowski, P., & Mrozowski, M. (2002). Gradient-based optimization of filters using FDTD software. IEEE Microwave and Wireless Components Letters, 12(10), 389-391. doi:10.1109/lmwc.2002.804561Boria, V. E., Bozzi, M., Bruni, F., Cogollos, S., Conciauro, G., Gimeno, B., & Perregrini, L. (2003). Efficient analysis of in-line waveguide filters and frequency-selective surfaces with stepped holes. International Journal of RF and Microwave Computer-Aided Engineering, 13(4), 306-315. doi:10.1002/mmce.10087Morro, J. V., Esteban, H., Boria, V. E., Bachiller, C., & Belenguer, A. (2008). Optimization techniques for the efficient design of low-cost satellite filters considering new light materials. International Journal of RF and Microwave Computer-Aided Engineering, 18(2), 168-175. doi:10.1002/mmce.20264Hunter, I. (2001). Theory and Design of Microwave Filters. doi:10.1049/pbew048eSoto, P., Tarin, E., Boria, V. E., Vicente, C., Gil, J., & Gimeno, B. (2010). Accurate Synthesis and Design of Wideband and Inhomogeneous Inductive Waveguide Filters. IEEE Transactions on Microwave Theory and Techniques, 58(8), 2220-2230. doi:10.1109/tmtt.2010.2052668Morini, A., Venanzoni, G., & Rozzi, T. (2006). A new adaptive prototype for the design of side-coupled coaxial filters with close correspondence to the physical structure. IEEE Transactions on Microwave Theory and Techniques, 54(3), 1146-1153. doi:10.1109/tmtt.2005.864112Morini, A., Venanzoni, G., Farina, M., & Rozzi, T. (2007). Modified Adaptive Prototype Inclusive of the External Couplings for the Design of Coaxial Filters. IEEE Transactions on Microwave Theory and Techniques, 55(9), 1905-1911. doi:10.1109/tmtt.2007.904329Cogollos, S., Marini, S., Boria, V. E., Soto, P., Vidal, A., Esteban, H., … Gimeno, B. (2003). Efficient modal analysis of arbitrarily shaped waveguides composed of linear, circular, and elliptical arcs using the BI-RME method. IEEE Transactions on Microwave Theory and Techniques, 51(12), 2378-2390. doi:10.1109/tmtt.2003.819776Levy, R. (1967). Theory of Direct-Coupled-Cavity Filters. IEEE Transactions on Microwave Theory and Techniques, 15(6), 340-348. doi:10.1109/tmtt.1967.1126471Balasubramanian, R., & Pramanick, P. (1999). Computer aided design ofH-plane tapered corrugated waveguide bandpass filters. International Journal of RF and Microwave Computer-Aided Engineering, 9(1), 14-21. doi:10.1002/(sici)1099-047x(199901)9:13.0.co;2-

Verification of Magnitude and Phase Responses in Fixed-Point Digital Filters

In the digital signal processing (DSP) area, one of the most important tasks is digital filter design. Currently, this procedure is performed with the aid of computational tools, which generally assume filter coefficients represented with floating-point arithmetic. Nonetheless, during the implementation phase, which is often done in digital signal processors or field programmable gate arrays, the representation of the obtained coefficients can be carried out through integer or fixed-point arithmetic, which often results in unexpected behavior or even unstable filters. The present work addresses this issue and proposes a verification methodology based on the digital-system verifier (DSVerifier), with the goal of checking fixed-point digital filters w.r.t. implementation aspects. In particular, DSVerifier checks whether the number of bits used in coefficient representation will result in a filter with the same features specified during the design phase. Experimental results show that errors regarding frequency response and overflow are likely to be identified with the proposed methodology, which thus improves overall system's reliability

Optimal design of single-tuned passive filters using response surface methodology

This paper presents an approach based on Response Surface Methodology (RSM) to find the optimal parameters of the single-tuned passive filters for harmonic mitigation. The main advantages of RSM can be underlined as easy implementation and effective computation. Using RSM, the single-tuned harmonic filter is designed to minimize voltage total harmonic distortion (THDV) and current total harmonic distortion (THDI). Power factor (PF) is also incorporated in the design procedure as a constraint. To show the validity of the proposed approach, RSM and Classical Direct Search (Grid Search) methods are evaluated for a typical industrial power system

RF MEMS Based Tunable Bowtie Shaped Substrate Integrated Waveguide Filter

A tunable bandpass filter based on a technique that utilizes substrate integrated waveguide (SIW) and double coupling is presented. The SIW based bandpass filter is implemented using a bowtie shaped resonator structure. The bowtie shaped filter exhibits similar performance as found in rectangular and circular shaped SIW based bandpass filters. This concept reduces the circuit foot print of SIW; along with miniaturization high quality factor is maintained by the structure. The design methodology for single-pole triangular resonator structure is presented. Two different inter-resonator couplings of the resonators are incorporated in the design of the two-pole bowtie shaped SIW bandpass filter, and switching between the two couplings using a packaged RF MEMS switch delivers the tunable filter. A tunning of 1 GHz is achieved for two frequency states of 6.3 and 7.3 GHz. The total size of the circuit is 70mm x 36mm x 0.787 mm (LxWxH)