Unconditionally Stable Non-Foster Element Using Active Transversal-Filter-Based Negative Group Delay Circuit

Zhang, Tiedi; Xu, Ruimin; Wu, Chung-Tse Michael

doi:10.1109/lmwc.2017.2745487

Cited by 46 publications

(53 citation statements)

References 9 publications

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“…In order to improve the matching bandwidth of the amplifier, non-Foster elements are needed. In recent years, non-Foster elements implemented by NGD circuits were proposed in References [20,21]. Figure 2a,b gives the traditional configurations of NGD circuits.…”

Section: Analysis Of Matching Network For Low Noise Amplifiermentioning

confidence: 99%

A Broadband Switch-Less Bi-Directional Amplifier with Negative-Group-Delay Matching Circuits

et al. 2018

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A broadband switch-less bi-directional low noise amplifier based on negative group delay (NGD) matching circuits with a non-Foster characteristic is proposed. To validate the feasibility, two circuits were designed and compared, which are matched by NGD circuits and traditional lumped elements respectively. The structure proposed in this paper has a measured relative bandwidth (RBW) of 32.6% rather than 5.1% for the traditional one. From 797 MHz to 1095 MHz, the input and output return losses (RL) are more than 10 dB with a noise factor (NF) of about 3.5 dB and peak gain of 12.2 dB. Meanwhile, the reverse isolation and stability factor (SF) are greater than 20 dB and 1, respectively. The group delay (GD) value is 0.5 ns ± 0.25 ns in the operating frequency band, which is much flatter and lower compared to that of the traditional one.

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Section: Analysis Of Matching Network For Low Noise Amplifiermentioning

confidence: 99%

A Broadband Switch-Less Bi-Directional Amplifier with Negative-Group-Delay Matching Circuits

et al. 2018

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“…Other RF and microwave applications were proposed as compensation of oscillators, filters, and communication systems [19]. The NGD circuits were also integrated in the phased array antenna system [20] and to design non-Foster elements [21][22]. Despite these initiative applications, further research work for understanding and interpretation of the NGD function is necessary.…”

Section: Introductionmentioning

confidence: 99%

“…It can analytically be identified by transfer function (TF) and topological analysis that the fundamental classification of this RF and microwave NGD circuits, available in the literature, belongs to the BP NGD category [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. It can also be remarked that these diverse BP NGD circuits [17][18][19][20][21][22][23][24][25][26][27][28][29][30] operate, generally, with use of resonant RLC-networks. The theoretical approaches proposed in the most of NGD theory state that NGD center frequencies are equal to the resonance frequency.…”

Section: Introductionmentioning

confidence: 99%

Original Theory of NGD Low Pass-High Pass Composite Function for Designing Inductorless BP NGD Lumped Circuit

Ravelo

Ngoho²,

Fontgalland

et al. 2020

IEEE Access

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This paper aims to develop an original circuit theory of inductorless NGD topology. The considered passive cell comprised of resistor and capacitor elements without inductor operates as a bandpass (BP) NGD function. The specifications of NGD functions are defined. Generally, the BP NGD fully lumped circuits available in the literature operate with resonant RLC-network. In the introduced research work, a lumped circuit was first time identified to exhibit the BP behavior without the presence of inductive component. The inductorless BP NGD topology is inspired from the combination of low-pass (LP) and high-pass (HP) NGD passive cells. Therefore, an original LP-HP NGD composite topology is obtained. The identified BP NGD topology is constituted only by passive RC-networks. Then, theoretical development of BP NGD analysis is explored. The inductorless circuit theory starts with the identification of BP NGD canonical form. Then, the expressions of NGD value, center frequency and attenuation in function of RC-network parameters are established. The synthesis equations allowing to determine the resistor and capacitor elements are derived. Proofs-of-concept are designed and prototypes are fabricated to verify the effectiveness of the developed LP-HP NGD composite theory. To validate the developed original circuit theory, two prototypes of RC-network based LP-HP NGD composite were designed, fabricated, simulated and tested. The two prototypes were synthesized with respect to two different NGD center frequencies 13.5 MHz and 22 MHz. As expected, the calculated, simulated and measurement results are in very good agreement with NGD value of about some negative nanoseconds. In the future, the characterized inductorless topology enable to overcome the traditional limitations of RLC-network based BP NGD circuits because of inductance self-effect limitation. INDEX TERMS Bandpass (BP) negative group delay (NGD), Low-pass/high-pass (LP-HP) NGD composite, Circuit theory, Inductorless passive topology.

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“…By cascading with a TL, the NGD function enabled to synthesize a frequency independent phase shifter [19]. The NGD circuits were implemented to realize non-Foster reactive elements [20], [21] which are used to design an arbitrary-angle squint-free beamforming in series-fed antenna arrays [22]. The NGD function was more recently used to design a tunable delay shifter [23].…”

Section: Introductionmentioning

confidence: 99%

Negative Group Delay Theory on Li Topology

Ravelo

Wan

et al. 2020

IEEE Access

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This paper investigates an innovative negative group delay (NGD) theory of ''li'' geometrical shape topology. The li-topology is an outstandingly simple and fully distributed circuit comprised of a coupled line (CL). The li S-parameter model taking into account the CL coupling coefficient, delay and attenuation is established. The NGD analysis showing the possibility to generate NGD condition with respect to the li topology parameters is developed. The NGD characteristics as NGD value, center frequency, bandwidth, transmission and reflection coefficient are expressed. The li-NGD theory is validated with two proofs-of-concept implemented in microstrip technology. Calculated models, simulations and measurements are in good correlation. As expected, bandpass NGD presenting center frequency at approximately 2.56 GHz and 0.92 GHz with NGD level of approximately −0.9 ns and −3.7 ns were realized with the small and large li prototypes. Outstanding time-domain analyses explaining the bandpass NGD meaning, with innovatively low attenuation output, were also presented. The time-domain results highlight li-output pulse signal envelopes in time advance without violating the causality. INDEX TERMS Distributed circuit, li-topology, microwave theory, negative group delay (NGD), S-matrix modelling.

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Unconditionally Stable Non-Foster Element Using Active Transversal-Filter-Based Negative Group Delay Circuit

Cited by 46 publications

References 9 publications

A Broadband Switch-Less Bi-Directional Amplifier with Negative-Group-Delay Matching Circuits

A Broadband Switch-Less Bi-Directional Amplifier with Negative-Group-Delay Matching Circuits

Original Theory of NGD Low Pass-High Pass Composite Function for Designing Inductorless BP NGD Lumped Circuit

Negative Group Delay Theory on Li Topology

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