The Experts below are selected from a list of 3030 Experts worldwide ranked by ideXlab platform
Rui Li - One of the best experts on this subject based on the ideXlab platform.
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synthesis design of ultra wideband bandpass filters with composite series and shunt stubs
IEEE Transactions on Microwave Theory and Techniques, 2009Co-Authors: Rui LiAbstract:This paper presents a direct synthesis procedure for efficient design of a class of ultra-wideband bandpass filters with composite series and shunt transmission-line stubs. The proposed single-stage bandpass prototype is formed by cascading two sets of series open-ended and shunt short-ended stubs through a multisection nonuniform transmission line. All the stubs are set with an identical electrical length, i.e., thetasc , at Lower Cutoff Frequency fc and the middle connecting line is composed of stepped-impedance transmission line with i sections, and each section has an electrical length thetasc. The proposed filter topology aims to construct an ultra-wide bandpass filter with Chebyshev equal-ripple responses and (i + 3) in-band transmission poles. Based on the derivation of the transfer function, a synthesis approach is established and systematically described to design this type of filters according to the specifications such as Lower/upper Cutoff frequencies. Next, a multistage bandpass filter prototype is proposed and the synthesis design procedure is also presented. The implementation is achieved by using hybrid microstrip line and slotline sections. Compared with traditional stub filters, the proposed filters achieve higher order transmission zeros and thus provide higher selectivity. As design examples, two single-stage and one three-stage bandpass filters are designed and fabricated to confirm the theoretical predictions.
Anders Jens - One of the best experts on this subject based on the ideXlab platform.
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An integrator-differentiator TIA using a multi-element pseudo-resistor in its DC servo loop for enhanced noise performance
2018Co-Authors: Häberle Matthias, Djekic Denis, Fantner, Georg E., Lips Klaus, Ortmanns Maurits, Anders JensAbstract:In this paper, we present an integrator-differentiator transimpedance amplifier (TIA) featuring a multielement pseudo-resistor (MEPR) in the DC feedback path for improved noise performance in the presence of non-zero DC input currents. The presented prototype is implemented in a standard 180 nm CMOS technology and achieves an inband transimpedance of 10 MΩ over a 2.7 MHz signal bandwidth. The MEPR resistor in the DC servo loop can be tuned between 700 k Ω and 100 MΩ enabling a precise adjustment of the TIA's Lower Cutoff Frequency. For a DC feedback resistance of 700 k Ω, the TIA provides an input referred noise floor of 180 fA/√Hz at zero input current, which only marginally increases to 220 fA/√Hz for the maximum bias current of 1 μA. The TIA consumes 0.6 mm 2 of chip area and 18.5 mW of power from a 1.8 V supply
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An integrator-differentiator TIA using a multi-element pseudo-resistor in its DC servo loop for enhanced noise performance
New York IEEE, 2018Co-Authors: Haeberle Matthias, Djekic Denis, Fantner, Georg E., Lips Klaus, Ortmanns Maurits, Anders JensAbstract:In this paper, we present an integrator-differentiator transimpedance amplifier (TIA) featuring a multielement pseudo-resistor (MEPR) in the DC feedback path for improved noise performance in the presence of non-zero DC input currents. The presented prototype is implemented in a standard 180 nm CMOS technology and achieves an inband transimpedance of 10 M Omega over a 2.7 MHz signal bandwidth. The MEPR resistor in the DC servo loop can be tuned between 700 k Omega and 100 M Omega enabling a precise adjustment of the TIA's Lower Cutoff Frequency. For a DC feedback resistance of 700 k Omega, the TIA provides an input referred noise floor of 180 fA/root Hz at zero input current, which only marginally increases to 220 fA/root Hz for the maximum bias current of 1 mu A. The TIA consumes 0.6 mm(2) of chip area and 18.5 mW of power from a 1.8 V supply
Josep M Guerrero - One of the best experts on this subject based on the ideXlab platform.
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second ripple current suppression by two bandpass filters and current sharing method for energy storage converters in dc microgrid
IEEE Journal of Emerging and Selected Topics in Power Electronics, 2017Co-Authors: Ling Yang, Yandong Chen, An Luo, Kunshan Huai, Xiaoping Zhou, Leming Zhou, Josep M GuerreroAbstract:With the increase in ac loads injected into the dc microgrid (MG) through inverters, the second ripple current (SRC) in the front-end energy storage converter (ESC) and the circulating current among the ESCs in dc MG become more and more serious. In this paper, the SRC suppression method by introducing two bandpass filters (BPFs) into the output voltage and inductance current feedback of the ESC is proposed. Compared with the traditional dual-loop control method, the proposed method effectively reduces the SRC and improves the dynamic performance in case of a Lower Cutoff Frequency in the outer voltage loop. Simultaneously, an adaptive droop control method by introducing the fine-tuning virtual resistances is adopted to reduce the output voltage deviation of parallel ESCs and improve the output current sharing among the ESCs. Considering the allowed range of deviation between the output voltage and the rated voltage for each ESC, the impacts of the line power loss and circulating current power loss caused by the introduced virtual resistances are analyzed in detail. While the sum of the line power loss and circulating current power loss reaches the minimum value, the appropriate control parameters are obtained. Simulation and experimental results verify the validity of the proposed method.
Nasser Masoumi - One of the best experts on this subject based on the ideXlab platform.
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Lower Cutoff Frequency improvement of planar ebg patterned pdn using edge termination
Electronics Letters, 2015Co-Authors: A Sadr, Nasser MasoumiAbstract:A designed, fabricated and tested electromagnetic bandgap (EBG) structure is proposed for resolving the problem of the Lower cut-off Frequency of conventional planar-type EBGs. Bandwidth enhancement is achieved by incorporating edge termination along the edges of the whole EBG-patterned power plane. Measurement results show that the Lower Cutoff Frequency is shifted downwards from 800 to 13 MHz. This structure also improves the upper Cutoff Frequency of 4.3 GHz for the conventional planar EBG to 5.2 GHz. Using this structure, simultaneous switching noise can be suppressed over the relative bandwidth of 63%, which is higher than the commonly used EBGs. The structure is easily fabricated with the current method of printed circuit board manufacturing processes and commonly used SMD resistors and capacitors.
Astoul A. - One of the best experts on this subject based on the ideXlab platform.
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A model of rotating convection in stellar and planetary interiors: II -- gravito-inertial wave generation
'American Astronomical Society', 2020Co-Authors: Augustson K. C., Mathis S., Astoul A.Abstract:Gravito-inertial waves are excited at the interface of convective and radiative regions and by the Reynolds stresses in the bulk of the convection zones of rotating stars and planets. Such waves have notable asteroseismic signatures in the Frequency spectra of rotating stars, particularly among rapidly rotating early-type stars, which provides a means of probing their internal structure and dynamics. They can also transport angular momentum, chemical species, and energy from the excitation region to where they dissipate in radiative regions. To estimate the excitation and convective parameter dependence of the amplitude of those waves, a monomodal model for stellar and planetary convection as described in Paper I is employed, which provides the magnitude of the rms convective velocity as a function of rotation rate. With this convection model, two channels for wave driving are considered: excitation at a boundary between convectively stable and unstable regions and excitation due to Reynolds-stresses. Parameter regimes are found where the sub-inertial waves may carry a significant energy flux, depending upon the convective Rossby number, the interface stiffness, and the wave Frequency. The super-inertial waves can also be enhanced, but only for convective Rossby numbers near unity. Interfacially excited waves have a peak energy flux near the Lower Cutoff Frequency when the convective Rossby number of the flows that excite them are below a critical Rossby number that depends upon the stiffness of the interface, whereas that flux decreases when the convective Rossby number is larger than this critical Rossby number.Comment: 18 pages, 6 figures, accepted in Ap
