Negative group delay and “fronts” in a causal system: An experiment with very low frequency bandpass amplifiers

Mitchell, Morgan W.; Chiao, Raymond Y.

doi:10.1016/s0375-9601(97)00244-2

Cited by 153 publications

(176 citation statements)

References 20 publications

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“…N EGATIVE group delay (NGD), although being counterintuitive, has been proved its feasibility in electronic circuits using a simple bandpass amplifier at low frequency in [1]. In microwave regime, conventionally, bandstop structures are used to realize NGD circuitry; based on either series or shunt RLC resonators, many active and passive NGD circuitries have been proposed and demonstrated with or without tunability [2]- [5].…”

Section: Introductionmentioning

confidence: 99%

A Dual-Purpose Reconfigurable Negative Group Delay Circuit Based on Distributed Amplifiers

Gharavi

Daneshrad

et al. 2013

IEEE Microw. Wireless Compon. Lett.

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A dual-purpose reconfigurable negative group delay circuit based on distributed amplifiers Abstract-In this letter, a novel reconfigurable negative group delay distributed amplifier (NGD-DA) circuit is proposed. This NGD-DA offers a new method to realize negative group delay. By properly choosing the gain coefficient of each tap for the DA, we can synthesize the negative group delay at the reverse port of the DA in the frequency band of interest, while maintaining a flat gain at the forward port; this results in a dual-purpose DA. Moreover, the proposed NGD-DA is reconfigurable; the phase response at the reverse port can be simply controlled by adjusting the tap gain coefficients, and therefore the bandwidth as well as the amount of negative group delay can be manipulated. The proposed active NGD circuit is validated through theoretical explanation and experimental results.Index Terms-Dispersion engineering, distributed amplifier (DA), dynamic power supply, negative group delay (NGD), superluminal group velocity, transversal filter.

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Section: Introductionmentioning

confidence: 99%

A Dual-Purpose Reconfigurable Negative Group Delay Circuit Based on Distributed Amplifiers

Gharavi

Daneshrad

et al. 2013

IEEE Microw. Wireless Compon. Lett.

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“…According to the desired value of the total transmission gain 21 S , the transistor characteristic g m must be equal to:…”

Section: Theoretical Approach On the Lc-effect Neutralization Techniquementioning

confidence: 99%

“…4. These graphs illustrate the neutralization of the transmission gain S 21 and phase p 21 . One can see that with LH active circuit parameter variations of 10%, S 21 and p 21 relative variations only of about 1.5% are found.…”

Section: Validation With Spice Simulationsmentioning

confidence: 99%

“…(4) Since the early 1990s, the possibility to generate negative group delay (NGD) phenomenon has been confirmed in electronic domain thanks to the topology of circuit proposed by Chiao and his co-workers [19][20][21][22]. The first NGD circuit composed of an operational amplifier in feedback with passive networks mainly composed of resistor(s), inductance(s) and capacitance(s) as described in [23][24].…”

Section: Introductionmentioning

confidence: 99%

“…However, such NGD circuit operates only up to some hundreds kHz [23][24][25]. It was stated that the NGD effect does not contradict the causality principle [19][20][21][22][23][24][25][26]. In addition, the left-handed (LH) lumped passive circuit capable to generate NGD effect for microwave signals up to GHz has been introduced by the group of Mojahedi [15][16].…”

Section: Introductionmentioning

confidence: 99%

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Neutralization of LC- and RC-Disturbances with Left-Handed and NGD Effects

Ravelo

2013

AEM

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This paper focus is on the neutralization technique of the unwanted parasitic effects on radio frequencies (RF) and digital electronic circuits. Most of parasitic effects induced in these circuits can be modeled by RC-and LC-networks. For canceling these disturbing effects, we can proceed with operation as transfer function neutralization in the considered operating frequency bands. The neutralization presented in this paper is developed by using first, a lefthanded (LH) and negative group delay (NGD) circuits inspired from metamaterials. The theoretical approach illustrating the RC-and LC-effects neutralization is described. Synthesis relations enabling to determine the elements of required LH and NGD circuit correctors in function of the perturbation parameters are established. Numerical and experimental demonstrators are presented to validate the technique proposed.

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An atom optics experiment to investigate faster-than-light tunneling

et al. 1998

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We describe a series of atom optics experiments underway a t T oronto for investigating tunnelling interaction times of various sorts. We begin by discussing some outstanding issues and confusions related to the question of whether or not superluminal tunnelling can be construed as true faster-than-light \signal propagation," a question which w e answer in the negative. We then argue that atom optics is an arena ideally suited for addressing a variety of remaining questions about how, where, and for how long a particle interacts with a tunnel barrier. We present recent results on a modied \delta-kick cooling" scheme which w e h a ve used to prepare Rubidium atoms with one-dimensional de Broglie wavelengths on the order of an optical wavelength, along with simulations showing that from these temperatures, we will be able to use acousto-optically modulated dipole-force barriers to velocity-select ultracold atom samples ideal for future tunnelling experiments.

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Negative group delay and “fronts” in a causal system: An experiment with very low frequency bandpass amplifiers

Cited by 153 publications

References 20 publications

A Dual-Purpose Reconfigurable Negative Group Delay Circuit Based on Distributed Amplifiers

A Dual-Purpose Reconfigurable Negative Group Delay Circuit Based on Distributed Amplifiers

Neutralization of LC- and RC-Disturbances with Left-Handed and NGD Effects

An atom optics experiment to investigate faster-than-light tunneling

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