Negative impedance converter

About: Negative impedance converter is a research topic. Over the lifetime, 5801 publications have been published within this topic receiving 87636 citations.

Influence of matrix type on negative capacitance effect in nanogranular composite films FeCoZr-insulator

Abstract: We observed an inductive contribution to impedance in granular (Fe0.45Co0.45Zr0.10)x(Al2O3)(1-x) and (Fe0.45Co0.45Zr0.10)x(PZT)(1-x) nanocomposite films deposited in Ar + O2 atmosphere. The films with x » 0.30 (in dielectric regime) demonstrated negative capacitance effect which were explained by hopping conductance of electrons over FeCoZr nanoparticles covered with complicated CoFe-oxides and embedded into dielectric matrix. In particular, at the determined conditions such a structure of nanocomposite resulted in the increase of hopping electron mean life time on nanoparticles and delay its returning jump under subjection of alternating electric field that created the possibility for positive angles of the phase shifts q and properlynegative capacitance (inductive-like contribution) effect.DOI: http://dx.doi.org/10.5755/j01.eee.19.4.1693

Impedance control network resonant step-down DC-DC converter architecture

Abstract: In this paper, we introduce a step-down resonant dc-dc converter architecture based on the newly-proposed concept of an Impedance Control Network (ICN). The ICN architecture is designed to provide zero-voltage and near-zero-current switching of the power devices, and the proposed approach further uses inverter stacking techniques to reduce the voltages of individual devices. The proposed architecture is suitable for large-step-down, wide-input-range applications such as dc-dc converters for dc distribution in data centers. We demonstrate a first-generation prototype ICN resonant dc-dc converter that can deliver 330 W from a wide input voltage range of 260 V–410 V to an output voltage of 12 V.

Bidirectional VSC converter with a resonant circuit

Abstract: The invention relates to a VSC-converter for converting direct voltage into auxiliary voltage and vice versa, which comprises a series connection of at least two current valves ( 5, 6 ) arranged between two poles ( 7, 8 ), a positive and a negative, of a direct voltage side of the converter, each current valve comprising several series connected circuits ( 12 ), each of which circuits comprising a semiconductor component ( 13 ) of turn-off type and a rectifying component ( 14 ) connected in anti-parallel therewith, an alternating voltage phase line ( 16 ) being connected to a midpoint ( 15 ), denominated phase output, of the series connection of current valves ( 5, 6 ) between two of said current valves while dividing the series connection into two equal parts. Each of the series connected circuits ( 12 ) of the respective current valve comprises, in order to make possible a good voltage distribution between the semiconductor components ( 13 ) of turn-off type included in the respective current valve, a snubber capacitor ( 17 ) connected in parallel with the semiconductor component ( 13 ) of turn-off type included in the circuit. The converter ( 1 ) further comprises a resonance circuit ( 18 ) for recharging the snubber capacitors ( 17 ) of the current valves.

A DC-DC buck converter chip with integrated PWM/PFM hybrid-mode control circuit

Abstract: This paper proposes a DC-DC buck power converter chip with a novel integrated PWM/PFM hybrid-mode control The DC-DC converter chip with synchronous rectifier not only uses current-mode feedback control but also possesses constant-frequency-mode control and hybrid-mode control functions at the same time Furthermore, the operational modes of the converter can be selected by an external voltage signal In the part of constant-frequency-mode control, as the inductor current is below zero, the synchronous rectifier switch of the converter will be automatically turned off in order to reduce the loss of the reverse inductor current About the hybrid-mode control, the operational modes of the converter can be judged by the proposed PWM/PFM hybrid-mode control circuit When the converter is operated in CCM, the constant-frequency-mode control is applied and when the inductor current is in DCM, the converter is operated under the variable-frequency-mode control At this moment, the switching frequency of the converter is designed to decrease proportionally with the load to reduce the high switching loss at light load The synchronous rectifier switch will also be turned off in order to reduce the reverse conduction loss All the above functions are integrated in one chip Simulation and experimental results verify that the converter chip works functionally The power converter chip with PWM/PFM hybrid-mode control proposed here is very suitable for the portable electronic products with the requirements of low voltage, low power, high efficiency, and wide load range

An integrated device having MOS transistors which enable positive and negative voltage swings

Abstract: A semiconductor circuit integrated with CMOS circuits for receiving a TTL input voltage and generating a large negative and positive voltage swing with respect to p-type or n-type substrate is disclosed. This invention is based on elimination of the electro-static discharge (ESD) protection circuit which is a requirement for any integrated circuit. Eliminating the ESD protection circuit also eliminates the clamping feature of the ESD protection circuit and therefore the circuit can be driven to negative voltages for PMOS circuits and to positive voltages for NMOS circuits. This provides the possibility of connecting the drain of a a P-channel type metal oxide silicon field effect (PMOS) transistor, which is fabricated on a p-type substrate within an n-well, to a voltage below the the substrate voltage. Also, in a n-channel type metal oxide silicon field effect (NMOS) transistor which is fabricated on a n-type substrate within a P-well, the drain can be connected to voltages higher than the substrate voltage. Utilizing this feature of a MOS transistor provides a way to design an integrated circuit which can handle negative voltage swings as well as positive voltage swings.