Topology (electrical circuits)

About: Topology (electrical circuits) is a research topic. Over the lifetime, 33316 publications have been published within this topic receiving 397651 citations. The topic is also known as: topology.

A supercapacitor-based energy-storage system for elevators with soft commutated interface

Abstract: Power variations and energy criteria have been the main motivations for developing regenerative drive converters for elevators. A better performing solution for power smoothing can be easily found by using a supercapacitor-based storage device, connected to the intermediary circuit of a variable-speed-drive system. In this paper, power and energy considerations are being accounted for in the design of the storage tank and regarding the maximum power demand from the feeding network. For the power-conversion circuit, which is necessary to compensate the voltage variations of the supercapacitors during charge and discharge, a high-efficiency converter, topology is proposed, which allows the bidirectional energy flow under soft-commutation conditions. Additionally it offers a good flexibility for the optimal sizing of the supercapacitor voltage level. The typical behavior of the special converter is given, together with an analysis of the advantages related to the specific application.

Low-Power 2.4-GHz Transceiver With Passive RX Front-End and 400-mV Supply

Abstract: An ultra low power 2.4-GHz transceiver targeting wireless sensor network applications is presented. The receiver front-end is fully passive, utilizing an integrated resonant matching network to achieve voltage gain and interface directly to a passive mixer. The receiver achieves a 7-dB noise figure and -7.5-dBm IIP3 while consuming 330 muW from a 400-mV supply. The binary FSK transmitter delivers 300 muW to a balanced 50-Omega load with 30% overall efficiency and 45% power amplifier (PA) efficiency. Performance of the receiver topology is analyzed and simple expressions for the gain and noise figure of both the passive mixer and matching network are derived. An analysis of passive mixer input impedance reveals the potential to reject interferers at the mixer input with characteristics similar to an extremely high-Q parallel LC filter centered at the switching frequency

CCTOP: a Consensus Constrained TOPology prediction web server

Abstract: The Consensus Constrained TOPology prediction (CCTOP; http://cctop.enzim.ttk.mta.hu) server is a web-based application providing transmembrane topology prediction. In addition to utilizing 10 different state-of-the-art topology prediction methods, the CCTOP server incorporates topology information from existing experimental and computational sources available in the PDBTM, TOPDB and TOPDOM databases using the probabilistic framework of hidden Markov model. The server provides the option to precede the topology prediction with signal peptide prediction and transmembrane-globular protein discrimination. The initial result can be recalculated by (de)selecting any of the prediction methods or mapped experiments or by adding user specified constraints. CCTOP showed superior performance to existing approaches. The reliability of each prediction is also calculated, which correlates with the accuracy of the per protein topology prediction. The prediction results and the collected experimental information are visualized on the CCTOP home page and can be downloaded in XML format. Programmable access of the CCTOP server is also available, and an example of client-side script is provided.

The MICROMIXER: a highly linear variant of the Gilbert mixer using a bisymmetric Class-AB input stage

Abstract: This paper outlines the basic theory of a development of the Gilbert mixer. The bipolar junction transistor (BJT) differential pair widely used as the RF input stage is replaced by a bisymmetric Class-AB topology based on translinear principles. It does not have inherent gain compression, affording a greatly extended signal capacity. The linearity of variants of the basic form is excellent, providing two-tone intermodulation intercepts as high as +30 dBm, without the expenditure of high bias currents. It can operate on supplies as low as 2.2 V, with a power consumption of under 5 mW. The input impedance of this mixer is accurately controllable (typically 50 /spl Omega/) and provides a true broadband match. The noise figure depends on design details and is generally not as low as in mixers specifically optimized for noise performance, although acceptable for many receiver applications. Inductively degenerated variants can be tuned to a narrowband match at microwave frequencies and provide full-mixing SSB noise figures as low as 6.5 dB, Practical realizations are in use in applications to 1.9 GHz.

Topology management in ad hoc networks

Abstract: The efficiency of a communication network depends not only on its control protocols, but also on its topology. We propose a distributed topology management algorithm that constructs and maintains a backbone topology based on a minimal dominating set (MDS) of the network. According to this algorithm, each node determines the membership in the MDS for itself and its one-hop neighbors based on two-hop neighbor information that is disseminated among neighboring nodes. The algorithm then ensures that the members of the MDS are connected into a connected dominating set (CDS), which can be used to form the backbone infrastructure of the communication network for such purposes as routing. The correctness of the algorithm is proven, and the efficiency is compared with other topology management heuristics using simulations. Our algorithm shows better behavior and higher stability in ad hoc networks than prior algorithms.