Balun 90° large bande à base de circuit actif à temps de propagation de groupe négatif

National audienceCet article décrit le principe de fonctionnement d'un Balun 90° à base de dispositifs actifs à Temps de Propagation de Groupe (TPG) négatif. Ce Balun est composé d'un diviseur de puissance résistif et de deux branches de sortie, chacune composée de deux cellules actives à TPG négatif et d'une ligne de transmission. Après avoir analysé cette architecture, nous avons simulé un prototype fonctionnant de 3 à 6 GHz. Dans cette bande, nous avons obtenu des phases ayant une platitude de ± 10° et d'un gain au dessus de -3 dB avec de bons niveaux d'adaptation meilleurs que -10 dB aux accès et d'excellentes valeurs d'isolations

Application of negative group delay active circuits to reduce the 50% propagation Delay of RC-line model

International audienceThis paper presents a new method developed to reduce the propagation delay by using a negative group delay (NGD) active circuit. Analytical expressions are proposed to demonstrate the validity of our approach in the case of an RC-transmission line model. The synthesis method of NGD circuits versus the line length is detailed. For a 0.5 Gbit/s digital signal and a 2-cm-long RC-line model, time-domain simulations carried out with a high-frequency circuit simulator showed that the 50% propagation delay was reduced by 94%. Finally, potential applications of this method to compensate for time delays in different interconnect configurations (VLSI, package, on-chip, long-line, ...) are discusse

Déphaseur large bande à phase indépendante de la fréquence à base de circuit actif à temps de propagation de groupe négatif

National audienceUn nouveau principe de déphaseur actif à phase constante est proposé. Ce déphaseur est obtenu par l'association de dispositifs à Temps de Propagation de Groupe (TPG) positif et négatif de même valeur absolue. Pour le concevoir, nous avons ainsi associé une ligne de transmission classique avec un circuit actif à TPG négatif développé récemment. Après réalisation d'un prototype en technologie planaire hybride, nous avons mesuré une phase constante (indépendante de la fréquence) de -90° ± 5° sur une bande relative d'environ 75 % autour de 1,7 GHz. Les niveaux de gain et d'adaptation mesurés sont également en très bon accord avec les simulations. Finalement, des perspectives d'applications sont décrite

Equalization of Interconnect Propagation Delay with Negative Group Delay Active Circuits

International audienceIn this paper, we propose a technique to compensate the propagation delay and losses in VLSI interconnects by using negative group delay (NGD) active circuits. This study uses the RLC models of interconnect lines currently considered in VLSI circuits. The circuit proposed here is based on a cell consisting of a Field Effect Transistor (FET) in parallel with a series RL passive network. We also describe the synthesis method to achieve simultaneousely a significant negative group delay and gain. Simulations allow us to first verify the performance of the NGD circuit and also show a restoration of the distorted signal shape as well as a reduction of propagation dela

Nouvelle technique de compensation des dégradations introduites par des lignes d'interconnexions

National audienceUne nouvelle technique de compensation de dégradations des signaux dues à une ligne d'interconnexion modélisée par des circuits RC et RLC est présentée. Cette technique est basée sur la mise en cascade de ces lignes avec un dispositif à Temps de Propagation de Groupe (TPG) négatif (ou Negative Group Delay : NGD). Après avoir rappelé la théorie de ce circuit NGD et celle des modèles RC d'une ligne d'interconnexion, nous proposons une étude des deux dispositifs cascadés. La réduction du délai de propagation a été analytiquement mise en évidence. Les simulations confirment cette réduction du retard jusqu'à plus de 80 % en valeur relative et montre la remise en forme des signaux dégradés

Application of negative group delay active circuits to the design of broadband and constant phase shifters

Application of negative group delay active circuits to the design of broadband and constant phase shifters, B. Ravelo, M. Le Roy, and A. Perennec, Microwave and Optical Technology Letters, Vol. 50, No. 12, December 2008, pp.3078-3080, Copyright © 2008, Published online in Wiley InterScience (www.interscience.wiley.com).The definitive version is available at www3.interscience.wiley.comInternational audienceThe new phase-shifter configuration described in this report uses a negative group delay (NGD) active circuit. In this topology, a classical transmission line is set in cascade with an NGD circuit whose phase slopes are alike, but opposite, to get a constant and broadband phase shift. The proposed approach was validated through the design and measurement of a phase shifter, which exhibited a constant phase of 90° +- 5° over a 75% relative bandwidth around 1.6 GHz. Moreover, as the group delay of the NGD circuit compensated the transmission line one, the overall circuit group delay was kept to a small value in the operating frequency band

Negative group delay active topologies respectively dedicated to microwave frequencies and baseband signals

©Copyright 2008 European Microwave Association http://www.eumwa.org/en/publications/international-journal/journal.htmlInternational audienceThis paper proposes and describes in details the synthesis, design and implementation of two different active topologies exhibiting negative group delay (NGD) in different frequency bands. With the first of them, gain and NGD in microwave frequency band are simultaneously achieved; the basic cell consists in a field effect transistor (FET) cascaded with a shunt RLC series network. The second topology brings also gain and NGD but is particularly dedicated to baseband signals; this circuit is also built with a FET; but this time in feedback with an RL series network. For both approaches, analytical formulas demonstrating the existence of gain and NGD are proposed together with details about the associated equations, at first for a single cell and then for multi-stage circuits. After implementation of each topology in a two-stage configuration, the results from experiments in frequency-domain are carefully compared to those from simulations; the same thing is done in time-domain for the baseband-dedicated device. Time-domain simulations and measurements highlight the high capability of both topologies to compensate or control various dispersive effects. Indeed for both circuits, in case of Gaussian-pulse or -modulated signal, the maximum of the output signal exhibits a time advance compared to the input one of respectively more than 40% and 60% of the standard devia-tion of the input signal. Moreover, this high relative time-advance is obtained with gain and a pulse compression phe-nomeno

Study and Application of Microwave Active Circuits with Negative Group Delay

This chapter is available on the following open access link: http://www.intechopen.com/books/microwave-and-millimeter-wave-technologies-modern-uwb-antennas-and-equipment/study-and-application-of-microwave-active-circuits-with-negative-group-delayA simple topology of an NGD active circuit consisting of a FET terminated by a shunt RLC-resonant network and dedicated to the microwave signals was proposed and extensively studied. To our knowledge, in this chapter, the first experimental time-domain demonstration of a circuit able to exhibit simultaneously gain and NGD in microwave domain is proposed. By injecting in the NGD circuit a sufficiently smoothed input short-pulse modulating a sine carrier, one gets an output having an envelop peak in advance compared with the input one. Of course, this phenomenon does not contradict the causality principle. It is also worth emphasizing that the tested circuit respects all required criteria of classical active microwave devices such as gain, matching and stability. As predicted in theory (Ravelo et al., 2007a, 2007b, 2007c and 2008a), for a prototype implemented in planar technology, we have measured in time-domain a pulse peak advance of about -2 ns or 24% of the 1/e-input pulse half-width without attenuation. It is also interesting to note that through this experimentation, the input noise contribution did not destroy the occurrence of time-domain advance induced by the NGD active circuit. Moreover, in this chapter, thanks to the S21-magnitude form, the understudied NGD circuit is able to exhibit a pulse compression phenomenon with a possibility of amplification. Then, it should be worth using the presented NGD active topology to compensate for dispersion effects and especially to reduce the intersymbol interference in certain telecommunication channels. As a potential application of this NGD circuit, a new principle of frequency independent phase shifter is proposed. By cascading a classical transmission line with this NGD circuit, a constant phase value is obtained. The efficiency of this principle was demonstrated by measurement. Indeed, a constant phase value of 90°±5° was obtained within a 76% relative frequency band centred at about 1.5 GHz. The impacts of the PS parameter variations and sensitivity analysis are stated. The main benefits of this NGD active PS concerns its compactness and also the facility to generate very low group delay, and the broad band characteristics. Besides, a two-stage NGD PS was also designed; the simulation results showed a bandwidth enhancement of the constant phase up to 125%. Some fields of applications such as the design of broadband active balun for RF front end architectures are discussed. As ongoing research, design of reconfigurable devices dedicated to telecommunication applications is envisaged. Future investigations will be devoted to the design of NGD devices able to operate at higher frequencies through the use of distributed elements. In this optic, the implementation of MMIC devices based on distributed elements is envisaged

Broadband Balun Using Active Negative Group Delay Circuit

International audienceIn this paper, a broadband balun using an active circuit with negative group delay (NGD) is proposed. The unit cell of the active NGD circuit is based on a Field Effect Transistor (FET) in cascade with an RLC series network. First, a comparison between measurements of a two-stage prototype of this active topology and simulations validate the synthesis method of this innovative device. Then, thanks to the NGD circuit, a constant phase can be generated if this circuit is associated with a classical transmission line. By implementing such phase shifters into the two branches of a resistive splitter, we obtain a new balun topology. The NGD balun simulation results show a rather constant differential output phase (180°±9°), insertion losses above -2.4 dB and an excellent isolation below -59 dB for all three ports, for a bandwidth from 3.5 GHz to 5.5 GHz