Topic
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.
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01 Jan 2010
TL;DR: In this article, a comparison between two-level and multilevel converters for medium-voltage applications is presented, focusing on issues such as waveform quality, voltage and current stresses on the switching devices, switching frequency per device, and conversion losses.
Abstract: This paper presents a comparison between two-level and multilevel converters for medium-voltage applications. The comparison focuses on issues such as waveform quality, voltage and current stresses on the switching devices, switching frequency per device, and conversion losses (mainly, on-state and switching losses). The modular multilevel converter (M2C) is selected as viable representative of the multilevel family in this study, because it can be extended to a high number of levels and is able to function independent of operating condition. (5 pages)
46 citations
Patent•
17 Dec 2008TL;DR: In this paper, a multiple-input multiple-output DC-DC converter that is capable of power diversification among different energy sources with different voltage-current characteristics is presented. But the converter is not capable of bidirectional operation in buck, boost and buck-boost modes and provides a positive output voltage.
Abstract: A multiple-input DC-DC converter that is capable of power diversification among different energy sources with different voltage-current characteristics. The converter is capable of bidirectional operation in buck, boost and buck-boost modes and provides a positive output voltage without the need for a transformer.
46 citations
Patent•
19 Aug 1996TL;DR: In this article, the reactance component of the impedance is modeled as a resistor in series with a capacitor, and a response voltage is measured across the load to estimate a transfer function between them, which results in estimation of the actual resistance and capacitance components of the true impedance.
Abstract: Impedance across a load, such as a pair of face-to-face electrodes and/or a patient's transthoracic and transmyocardial impedance, respectively, is modeled as a resistor in series with a capacitor, wherein the reactance component of the impedance equals 2 π*frequency/capacitance. A reference square wave voltage is applied to the load in series with a selected load resistor, and a response voltage is measured across the load. Both the reference voltage and the response voltage are then used to estimate a transfer function between them. Equating this transfer function to a resistor-capacitor circuit model results in estimation of the actual resistance and capacitance components of the true impedance. Alternately, the impedance may be measured with a high current load, such as during a defibrillator discharge. In this case, the voltage input and outputs are sampled at a much faster rate for the resistance component estimation, with the capacitance initialization adapted for the specific type of defibrillator waveform input.
46 citations
TL;DR: Using a ferroelectric PbZrTiO3 gate stack, the range of the steep subthreshold swing in tunnel field effect transistors was extended by 3.5 orders of magnitude demonstrating an improvement in the swing (by approximately double the slope) as mentioned in this paper.
Abstract: Using a ferroelectric PbZrTiO3 gate stack, the range of the steep subthreshold swing in tunnel field-effect transistors was extended by 3.5 orders of magnitude demonstrating an improvement in the swing (by approximately double the slope). The drain conductance (gd) shows only 16% enhancement with large V DS (∼−1.5V) indicates internal voltage amplification with ferroelectric negative capacitance effect beneficial to small lateral drain-source bias voltages (−0.1 V). The concept of coupling the ferroelectric polarization is proposed. The power consumption is also discussed in low-power applications of steep subthreshold slope devices.
46 citations
TL;DR: In this article, the authors present a general mechanism that unifies the various instances of negative capacitance under a common framework and demonstrate that negative capacitation arises from dc/ac signal mixing across a nonlinear conductor.
Abstract: Received 4 June 2009; revised manuscript received 25 August 2009; published 20 October 2009 The existence of a negative static dielectric constant has drawn a great deal of theoretical controversy. Experimentally, one has never been observed. However, low-frequency negative capacitance has been widely reported in fields including physics, chemistry, biology, geology, and electronics. This wide variety of systems possesses an extremely diverse set of physical processes that, surprisingly, share similar characteristics. We present a general mechanism that unites the various instances of negative capacitance under a common framework. The mechanism demonstrates that the negative capacitance arises from dc/ac signal mixing across a nonlinear conductor. Verification of the model is performed in physically distinct samples: an electrorheological fluid, a fuel cell, and a solar cell. Furthermore, we argue that the negative capacitance, under appropriate conditions, can be associated with a negative-differential dielectric constant, possibly even in the static limit.
46 citations