719 research outputs found

    The Beauty of Symmetry: Common-mode rejection filters for high-speed interconnects and balanced microwave circuits

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    Common-mode rejection filters operating at microwave frequencies have been the subject of intensive research activity in the last decade. These filters are of interest for the suppression of common-mode noise in high-speed digital circuits, where differential signals are widely employed due to the high immunity to noise, electromagnetic interference (EMI) and crosstalk of differential-mode interconnects. These filters can also be used to improve common-mode rejection in microwave filters and circuits dealing with differential signals. Ideally, common-mode stopband filters should be transparent for the differential mode from DC up to very high frequencies (all-pass), should preserve the signal integrity for such mode, and should exhibit the widest and deepest possible rejection band for the common mode in the region of interest. Moreover, these characteristics should be achieved by means of structures with the smallest possible size. In this article, several techniques for the implementation of common-mode suppression filters in planar technology are reviewed. In all the cases, the strategy to simultaneously achieve common-mode suppression and all-pass behavior for the differential mode is based on selective mode-suppression. This selective mode suppression (either the common or the differential mode) in balanced lines is typically (although not exclusively) achieved by symmetrically loading the lines with symmetric resonant elements, opaque for the common-mode and transparent for the differential mode (common-mode suppression), or vice versa (differential-mode suppression).MINECO, Spain-TEC2013-40600-R, TEC2013-41913-PGeneralitat de Catalunya-2014SGR-15

    High-selectivity single-ended and balanced bandpass filters using ring resonators and coupled lines loaded with multiple stubs

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    © 2018 Elsevier GmbH High-selectivity single-ended and balanced bandpass filters (BPFs) using dual-mode ring resonators and coupled lines loaded with multiple stubs are proposed in this paper. With the help of the loaded short-circuited and open-circuited stubs, six deep transmission zeros (TZs) from 0 to 2f0 (f0: center frequency of the passband) can be realized in both of single-ended and balanced BPFs to improve the stopband suppressions. The functions of the loaded short/open stubs and calculated analysis of TZs’ positions have been presented. For further demonstration, two examples of single-ended BPF and balanced BPF with high common-mode suppression are designed and fabricated, whose center frequencies are both at 2.1 GHz. Their measured 3-dB fractional bandwidths are 23.7% and 24.7% (differential-mode), respectively. The simulated results and measurements of these two filters are in good agreement

    Multilayered balanced dual-band bandpass filter based on magnetically coupled open-loop resonators with intrinsic common-mode rejection

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    A new dual-band balanced bandpass filter based on magnetically coupled open-loop resonators in multilayer technology is proposed in this paper. The lower differential passband, centered at the Global Positioning System (GPS) L1 frequency, 1.575 GHz, was created by means of two coupled resonators etched in the middle layer of the structure, while the upper differential passband, centered at a Wi-Fi frequency of 2.4 GHz, was generated by coupling two resonators on the top layer. Magnetic coupling was used to design both passbands, leading to an intrinsic common-mode rejection of 39 dB within the lower passband and 33 dB within the upper passband. Simulation and measurement results are provided to verify the usefulness of the proposed dual-band differential bandpass filter.Ministerio de Ciencia, Innovación y Universidades TEC2017-84724-

    Compact Wideband Balanced Bandpass Filters With Very Broad Common-Mode and Differential-Mode Stopbands

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    [EN] Compact balanced bandpass filters based on a combination of multisection mirrored stepped-impedance resonators and interdigital capacitors are presented in this paper. The considered filter topology is useful to achieve wide bandwidths for the differential mode, with broad stop bands for that mode, as well as very efficient common-mode suppression. By conveniently adjusting the transmission zeros for both operation modes, the differential- and common-mode stopbands can be extended up to significantly high frequencies. Filter size and this differential- and common-mode stopband performance are the main relevant characteristics of the proposed balanced filters. The potential of the approach is illustrated by the design of a prototype order-5 balanced bandpass filter, with central frequency f0=1.8f_{0} = 1.8 GHz, 48% fractional bandwidth (corresponding to 55.4% ¿3-dB bandwidth), and 0.04-dB ripple level. The filter is automatically synthesized by means of an aggressive space-mapping software tool, specifically developed, and two (pre- and post-) optimization algorithms, necessary to determine the transmission-zero frequencies. The designed filter is as small as 0.48lambdagtimes0.51lambdag0.48lambda _{g} times 0.51lambda _{g} , where lambdaglambda _{g} is the guided wavelength at the central filter frequency, and the differential-mode stopband extends up to at least 6.5 GHz with more than 22-dB rejection. The common-mode suppression is better than 28 dB from dc up to at least 6.5 GHz.This work was supported in part by MINECO-Spain under Project TEC2013-40600-R, Project TEC2016-75650-R, and Project TEC2016-75934-C4-1-R, in part by the Generalitat de Catalunya under Project 2014SGR-157, in part by the Institucio Catalana de Recerca i Estudis Avancats (who awarded F. Martin), and in part by by FEDER funds.Sans, M.; Selga, J.; Vélez, P.; Bonache, J.; Rodríguez Pérez, AM.; Boria Esbert, VE.; Martin Antonlin, F. (2018). Compact Wideband Balanced Bandpass Filters With Very Broad Common-Mode and Differential-Mode Stopbands. IEEE Transactions on Microwave Theory and Techniques. 66(2):737-750. https://doi.org/10.1109/TMTT.2017.2785246S73775066

    Simple and compact balanced bandpass filters based on magnetically coupled resonators

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    A simple strategy is proposed to design differential-mode bandpass filters with good common-mode (CM) rejection using simple resonators. Specifically, the CM rejection is enhanced by using conventional open-loop resonators as well as folded stepped-impedance resonators without the addition of printed or lumped elements along the symmetry plane of the filter or the use of defected ground solutions. The novelty of the present proposal is that a good CM rejection is achieved by the use of magnetic coupling instead of the more commonly employed electrical coupling. Magnetic coupling inherently yields poorer CM transmission as requested by good differential filters. The resonators, due to their geometrical simplicity, can easily be cascaded to implement high-order filters. The use of simple geometries also simplifies the design methodology and makes final tuning based on electromagnetic simulation simpler or unnecessary.Miisterio de Economía y Competitividad TEC2010-16948, TEC2013-41913-P, CSD2008-00066Junta de Andalucía P12-TIC-143

    Common-mode suppressed differential bandpass filter based on open complementary split ring resonators fabricated in microstrip technology without ground plane etching

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    A differential (or balanced) bandpass filter based on open complementary split ring resonators (OCSRRs) coupled through admittance inverters is presented in this article. Pairs of OCSRRs are symmet- rically placed in a mirror configuration between the strips of the differential line and are modeled by means of two series connected parallel resonators. For the differential (odd) mode, there is a virtual ground at the connecting plane between the OCSRR pairs, and the structure is roughly described by the canonical model of a bandpass filter, consisting of a cascade of shunt resonators coupled through admittance inverters. It is demonstrated that, through a proper design of the OCSRR stages, the common mode noise in the vicinity of the differential filter pass band can be efficiently suppressed. Due to the differential mode operation of the filter, it is not necessary to incorporate metallic vias to ground the OCSRRs. Moreover, as compared to other differential filters based on OCSRRs, defected ground structures are not present in the proposed filters. To illustrate the potential of the approach, two balanced bandpass filters are designed, fabricated, and characterized

    Ultra-compact (80 mm2) differential-mode ultra-wideband (UWB) bandpass filters with common-mode noise suppression

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    This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) bandpass filters with common-mode noise suppression. To a first-order approximation, the differential-mode filter response is described by the canonical circuit model of a bandpass filter, i.e., a cascade of series-connected resonators alternating with shunt-connected parallel resonant tanks. Thus, the series branches of the balanced filter are implemented by means of inductive strips and patch capacitors, whereas the shunt sections are realized through mirrored stepped-impedance resonators (SIRs) and low-impedance (i.e., capacitive) short transmission-line sections. For the differential mode, the symmetry plane is a virtual ground, the wide strip sections of the SIRs are effectively grounded, and the SIRs behave as grounded inductors parallel connected to capacitors. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIRs act as shunt-connected series resonators, thus providing transmission zeros at their resonance frequencies. By properly tailoring the location of these transmission zeros, rejection of the common mode over the differential filter passband can be achieved. To illustrate the potential of the approach, an order-5 balanced bandpass filter covering the regulated band for UWB communications (3.1-10.6 GHz) is designed and fabricated. The filter exhibits common-mode rejection above 10 dB over the whole differential filter passband, with differential-mode insertion losses lower than 1.9 dB and return losses better than 10 dB. Since the proposed design approach is based on planar semi-lumped components, filter size is as small as 10.5 mm X 7.6 m

    Ultra-compact (80 mm 2) differential-mode ultra-wideband (UWB) bandpass filters with common-mode noise suppression

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    This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) bandpass filters with common-mode noise suppression. To a first-order approximation, the differential-mode filter response is described by the canonical circuit model of a bandpass filter, i.e., a cascade of series-connected resonators alternating with shunt-connected parallel resonant tanks. Thus, the series branches of the balanced filter are implemented by means of inductive strips and patch capacitors, whereas the shunt sections are realized through mirrored stepped-impedance resonators (SIRs) and low-impedance (i.e., capacitive) short transmission-line sections. For the differential mode, the symmetry plane is a virtual ground, the wide strip sections of the SIRs are effectively grounded, and the SIRs behave as grounded inductors parallel connected to capacitors. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIRs act as shunt-connected series resonators, thus providing transmission zeros at their resonance frequencies. By properly tailoring the location of these transmission zeros, rejection of the common mode over the differential filter passband can be achieved. To illustrate the potential of the approach, an order-5 balanced bandpass filter covering the regulated band for UWB communications (3.1-10.6 GHz) is designed and fabricated. The filter exhibits common-mode rejection above 10 dB over the whole differential filter passband, with differential-mode insertion losses lower than 1.9 dB and return losses better than 10 dB. Since the proposed design approach is based on planar semi-lumped components, filter size is as small as 10.5 mm ×\, 7.6 mm.Ministerio de Ciencia e Innovación TEC2010-17512, TEC2013-40600-R, TEC2013-41913-P, CSD2008-00066Gobierno Catalán 2014SGR-15

    Differential-mode to common-mode conversion detector based on rat-race hybrid couplers : analysis and application to differential sensors and comparators

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    Altres ajuts: M. Gil acknowledges the Universidad Politécnica de Madrid Young Researchers Support Program (VJIDOCUPM18MGB) for its suppor
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