Negative Group Delay Research Articles

High-pass negative group delay analysis of single capacitor three-port circuit

PurposeThis paper aims to develop high-pass (HP) negative group delay (NGD) investigation based on three-port lumped circuit. The main particularity of the proposed three-port passive topology is the consideration of only a single circuit element represented by a capacitor.Design/methodology/approachThe methodology of the paper is to consider the S-matrix equivalent model derived from admittance matrix approach. So, an S-matrix equivalent model of a three-port circuit topology is established from admittance matrix approach. The frequency-dependent basic expressions are explored to perform the HP-NGD analysis. Then, the existence condition of HP-NGD function type is analytically demonstrated. The specific characteristics and synthesis equations of HP-NGD circuit with respect to the desired optimal NGD value are established.FindingsAfter computing the frequency expressions to perform the HP-NGD analysis, this study demonstrated the existence condition of HP-NGD function type analytically. The validity of the HP-NGD theory is verified by a prototype of three-port circuit. The proof-of-concept (POC) single capacitor three-port circuit presents an NGD response and characteristics from analytical calculation and simulation is in very good correlation.Originality/valueAn innovative theory of HP-NGD three-port circuit is studied. The proposed HP-NGD topology is constituted by only a single capacitor. After the topological description, the S-matrix model is established from the Y-matrix by means of Kirchhoff voltage law and Kirchhoff current law equations. A POC of single capacitor three-port circuit was designed and simulated with a commercial tool. Then, a prototype with a surface-mounted device component was fabricated and tested. As expected, simulation and measurement results in very good agreement with the calculated model show the feasibility of the HP-NGD behavior. This work is compared to other NGD-type function with diverse number of ports and components.

Negative Group Delay Metamaterials Based on Split-Ring Resonators and Their Application

In this report, negative group delay (NGD) metamaterials based on split-ring resonators (SRRs) are discussed. A theoretical analysis is proposed to calculate the equivalent circuit parameters, NGD values, and S21 amplitudes of two types of SRRs. Metamaterials made from tantalum nitride are simulated, and the parameters of the two types of SRRs are discussed. Prototypes of metamaterials were fabricated and tested. Measured real-world results were found to be consistent with theoretical and simulated predictions. For EC-SRR, a negative group delay of up to −0.1 ns was achieved at 12–13 GHz. For SR-SRR of the same size as the out ring of EC-SRR, a negative group delay of up to −0.04 ns was achieved, with a loss lower than 2.7 dB. The proposed SRRs were applied to continuous transverse stub (CTS) antenna to reduce the beam walk. The simulation shows that the beam walk can be reduced using the proposed metamaterial.

OTA-C signal delay compensation circuit for transimpedance-mode audio signal processing systems

This paper proposes an operational transconductance amplifier-capacitor-based (OTA-C) negative group delay (NGD) circuit for transimpedance-mode systems. The application areas extend from audio to sensor signal anticipation. Post-layout simulated NGD value of about 200 μs to 100 ns is observed to be achievable with three different capacitor values without any resistive passive components. The operation range varies from 700 Hz to 700 kHz. The NGD and the operation range are shown to be flexible without gain dependency. An example design is built for a specific NGD value of 15 μs and time-domain analysis is done with both a single-tone sinusoidal and a band-limited audio record in the range of 1 Hz–7 kHz. The calculated Root Mean Square Error for audio input to the system is only 4.70%.

Fully Microstrip Three-Port Circuit Bandpass NGD Design and Test

This article presents design and test of three-port distributed circuit exhibiting double bandpass (BP) negative group delay (NGD) effect.

Research and Simulation of Negative Group Delay and Superluminal Propagation

Abstract In recent years, negative group delay circuits have attracted much attention due to their propagation characteristics and wide application prospects. In the history of human exploration, the exploration of the speed of light has never stopped. The theory of relativity points out that the speed of light in vacuum is the limit speed of signal propagation. However, it is found through research that phase velocity and group velocity appear faster than the speed of light, which does not violate the causal relationship. This paper first introduces the related concepts of negative group delay and superluminal phenomenon, the second focuses on the principle of negative group delay and superluminal phenomenon in-depth analysis and research, finally using the principle of Multisim software, the bandwidth of two different job, different structure of circuit design, the virtual simulation experiment to negative group delay phenomenon and measurement data. It is of great significance to explore the field of faster-than-light and negative group delay in today's rapidly developing information age, and it can try to meet the high requirements for signal transmission. In the future, the interdisciplinary research direction of this research topic also has great development space.

CSRR DGS-Based Bandpass Negative Group Delay Circuit Design

The unfamiliar negative group delay (NGD) circuit is the less familiar function for most of RF and microwave design engineers. Among the existing types, the bandpass (BP) NGD type circuits are the most convenient for the wireless communication microwave technology. Therefore, it is particularly important to explore different microwave circuit topologies operating as BP-NGD function. An innovative design of BP-NGD topology constituted by defected ground structure (DGS) with complementary split ring resonator (CSRR) is developed in the present paper. The DGS-based BP-NGD structure design method is introduced in function of the CSRR geometrical elements followed by S-parameter parametric analyses. As proof-of concept (POC), the design method of the proposed BP-NGD passive fully distributed circuit is described. The effectiveness of the BP-NGD structure and the test feasibility are investigated by implementing two different prototypes represented by single- and double-wing DGS passive circuits. It is observed that significant BP-NGD function performances were validated by well-correlated simulations and measurements showing -1.9 ns NGD value around the center frequency, 2.46 GHz over 31 MHz NGD bandwidth. In addition, the tested BP-NGD prototypes present insertion loss better than 4 dB and reflection loss better than 16.7 dB. Because of its potential integration, the investigated BP-NGD circuit is potentially useful for the communication system performance improvement for example via delay effect reduction in the RF and microwave devices.

A Compact Passive Quad‐Band Negative Group Delay Circuit With Stepped Impedance Resonator and Defected Microstrip Structure

AbstractBased on two‐stage stepped impedance resonator (SIR) and defected microstrip structure (DMS) with an E‐shaped slot, a novel compact passive quad‐band negative group delay circuit (NGDC) is proposed whose resonation frequencies and group delay performance are mainly determined by the SIR and the DMS. In order to help reveal the working mechanism of the quad‐band NGDC, an equivalent circuit of the NGDC is developed. It is composed of the transmission lines and serial‐parallel LC networks, and its S‐parameters are derived by using the theory of transmission matrix. The theoretical and simulated results for the transmission characteristics of the NGDC agree well with each other. To validate the design concept, a prototype of the proposed quad‐band NGDC was fabricated and measured. The measured results show that at the frequencies of 2.64, 7.88, 13.08, and 18.18 GHz, the negative group delay values achieve −5.4, −3.1, −1.18, and −1.14 ns, with |S21| values of −17.2, −20.5, −12.8, and −18.1 dB, respectively. Compared with the recently reported works, the proposed NGDC exhibits the largest number of operation frequency bands. Furthermore, it does not use lumped resistors and has miniaturized dimension.

Differential Negative Group Delay Circuit Topology with Reverse Nested Double U-shaped Defected Ground Structure

Differential Negative Group Delay Circuit Topology with Reverse Nested Double U-shaped Defected Ground Structure

Planar Tunable Negative Group Delay Circuit with Low Reflection Loss

Planar Tunable Negative Group Delay Circuit with Low Reflection Loss

Implementation of broadband optical receiver amplifier with low group delay variation

Considering the ever-increasing growth of data traffic in communication systems, optical receiver amplifiers are now emerging as a key feature of various optical receivers. This article presents a broadband optical receiver amplifier for high-speed and low latency communication systems. The proposed amplifier is based on the distributed amplifier configuration, and employs the negative group delay technique to reduce the group delay variation. The experimental results of the proposed amplifier show a 15 dB average gain, 3 dB noise figure, and 8 ps group delay variation at frequency ranging from DC to 40 GHz. To the best of our knowledge, the proposed distributed amplifier (DA) demonstrates the lowest group delay variation among the reported forward optical module distributed amplifiers (DAs) for high data rates applications.

Enhanced and controllable reflected group delay based on Tamm surface plasmons with Dirac semimetals

The reflected group delay from a multilayer structure comprising a one-dimensional photonic crystal coated with a bulk Dirac semimetal (BDS) separated by a spacer layer is investigated theoretically. It is shown that the group delay of the reflected beam in this structure can be significantly negatively enhanced and switched from negative to positive. The enhanced group delay originates from the steep phase change caused by the excitation of the optical Tamm state at the interface between the BDS and spacer layer. Moreover, positive and negative group delays can be actively tuned through the Fermi energy and the relaxation time of the BDS. We believe that this enhanced and tunable delay scheme has important research significance for the fabrication of optical delay devices.

Design and Experimentation of Inductorless Low-Pass NGD Integrated Circuit in 180-nm CMOS Technology

This article introduces an innovative design of a low-pass (LP) negative group delay (NGD) integrated circuit (IC) in the 180-nm CMOS technology. The LP-NGD circuit is an inductorless topology constituted by RC-network with CMOS metal-insulator-metal (MIM) capacitor and polygate resistor. The design methodology is illustrated by considering the chip layout process. Then, the first run simulation is performed with the design rule check (DRC) and 2.5 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\times }$ </tex-math></inline-formula> 2.2 mm layout versus schematic (LVS) approaches. The feasibility of the CMOS LP-NGD IC circuit implementation is validated with chip-onboard (CoB). The proof of concept (PoC) of the LP-NGD miniaturized circuit was tested in both S-parameter and time domain (TD). As expected, the calculated, simulated, and experimented results of CoB showing NGD of about −10 ns over 12 MHz and −10 dB attenuation are confirmed. The active CMOS LP-NGD technology compensates the insertion loss to 2.4 dB, the GD reaches −11 ns, and the reflection loss reaches −20 dB. Moreover, TD investigations were also performed to show the feasibility of generating pulse and arbitrary waveform signal time advance through the designed and fabricated LP-NGD CoB prototypes.

A Compact Dual-Band Differential Negative Group Delay Circuit With Wideband Common Mode Suppression

A compact dual-band differential negative group delay (DNGD) circuit with wideband common mode suppression is proposed. Two small 180° phase shift swap structures of double-sided parallel striplines (DSPS) are adopted to realize intrinsic wideband common-mode suppression. The dual-band DNGD characteristic is achieved by the DSPS coupled asymmetrically with two different-length open-circuited resonators. The DNGD times and center frequencies of the lower and upper bands can be tuned independently. To verify the proposed DNGD circuit topology, a prototype is designed, fabricated, and measured. From the measured results, DNGD times are −1.60 ns and −1.43 ns at the center frequencies of 1.227 GHz and 1.575 GHz, respectively. The differential insertion loss is lower than 3.55 dB, the differential return loss is larger than 13.3 dB and the common-mode suppression is over 30.8 dB in both DNGD bands.

Tunable Superluminal and Subluminal Reflected Group Delay in an Air-Weyl Semimetal Film-Weyl Semimetal Substrate Layered System

In this work, we theoretically investigate the superluminal and subluminal reflected group delay from an air-Weyl semimetal film-Weyl semimetal substrate layered structure by using 4*4 magneto-optical matrix. We show a tunable transition between positive and negative group delays of reflection pulse in such a layered structure controlled by the properties of the Weyl Semimetal layer and reveal its mechanism to control the propagation properties of the light pulse reflected from such structure. It is demonstrated that the reflected group delays are tunable from positive to negative values and vice versa, which are adjusted by tuning the incident angle, thickness of Weyl semimetal film, tilt parameter, and Fermi energy. The control of the magnitude and the sign of the reflected group delay of light propagation represent a key point in slow and fast light technologies. Our results are helpful to control the pulse propagations and are useful for design of Weyl semimetal-based delay devices.

A self‐packaged SCPW negative group delay circuit and its integration with power divider

In this article, a matched branch line-loaded negative group delay (NGD) circuit without resistor is presented firstly, and then an Wilkinson power divider with NGD characteristic is implemented by integrating the NGD circuit and the power divider by using self-packaged suspended coplanar waveguide (SCPW) technology. The self-packaged SCPW power divider with NGD characteristic has been fabricated, and the design has been demonstrated by measurement, which indicates that the proposed power divider with NGD characteristic has a measured signal attenuation (S21) of 10.92 dB, a S11 attenuation of 32.1 dB, an NGD time of −2.42 ns, and an isolation of no less than 39 dB at the center frequency, while simple circuit topology, self-packaging and compact circuit size have also been achieved.

Low-Pass NGD Numerical Function and STM32 MCU Emulation Test

This article introduces an original microcontroller unit (MCU) design of numerical low-pass (LP) negative group delay (NGD) function. The innovative theory of the numerical LP-NGD function is developed based on the first-order analog transfer function discretization. The infinite impulse response (IIR) LP-NGD is fundamentally formulated in function of the desired NGD value, cutoff frequency, gain, and the MCU sampling frequency. A STM32 MCU proof-of-concept (POC) is tested to implement the IIR LP-NGD function. Different real-time tests with visualization of input and output analog signals from the MCU LP-NGD POC were performed. As expected, time-advance demonstration tests with milli-second short- and several hour long-duration time-scale with arbitrary waveform signals from temperature and humidity sensors. The signal time-advance is not in contradiction with the causality. The proposed digital MCU function opens a potential future industrial application of LP-NGD function via sensored signal anticipation.

A Novel Dual-Band Negative Group Delay Circuit With a Stepped-Impedance Structure

A novel dual-band negative group delay (NGD) circuit employing an active stepped-impedance structure is presented in this letter. A theoretical analysis on the dual-band NGD response of the proposed structure is presented. The characteristic impedances and phases of the transmission lines are calculated to implement the circuit’s I/O transmission function. This calculation is performed by defining the desired NGD values at two arbitrary frequencies as the operating condition. The theoretical analysis demonstrates that there is no dependence between the group delay (GD) values at different frequencies. Prototypes of the proposed circuit with the same or different GDs are designed, fabricated, and measured to demonstrate the performance of the proposed structure. The experimental results show that the proposed dual-band NGD circuit is capable of generating −1 ns GD at 0.7 and 1.3 GHz or different GDs (−0.3 and −2 ns). The corresponding maximum and minimum transmission gains are 2 and −8 dB, respectively.

Wideband Flat Negative Group Delay Circuit With Improved Signal Attenuation

A novel wideband flat negative group delay (NGD) circuit with improved signal attenuation is proposed. The proposed negative group delay circuit (NGDC) is composed of three transmission lines and two parallel branches, which are consisted of two series transmission lines with a resistor linking to a T-type stub. The complete closed-form design equations are presented. For verification, an NGDC is designed, fabricated, and measured at the center frequency of 2.14 GHz. From the measured results, NGD time of −1.11 ns at the center frequency is obtained with an insertion loss of 9.75 dB and return loss of 22.3 dB. The flat-NGD bandwidth reaches 6.1% from 2.072 to 2.202 GHz with ±11.5% group-delay fluctuation.

A Self-Equalized Linear-Phase Absorptive BPF Using Negative-Group-Delay Admittance Inverters

In this letter, a microstrip negative-group-delay (NGD) admittance inverter (J-inverter) is proposed to implement a self-equalized linear-phase absorptive bandpass filter (ABPF). It is revealed that this NGD J-inverter, being composed of a coupled-line loaded with a lumped resistor and an open-circuited stub, has an NGD pit in its frequency response. The superposition of the NGD pits associated with a specific number of the NGD J-inverters is utilized to counterbalance the group delay (GD) peaks at the lower and upper edge of the ABPF passband. A three-order ABPF prototype with a passband of 1.5–2.5 GHz is designed using six NGD J-inverters. Measured GD fluctuation within the 3-dB bandwidth is reduced to 0.18 from 0.59 ns compared with the ABPF using the conventional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> /4 J-inverter. The sharpness of the out-band roll-off has been retained. The measured input–output return loss is better than 12 dB over 0.6–3.5 GHz.

Pre-Detection Sensing With Multistage Low-Pass Type Negative Group Delay Circuit

This paper reveals a fascinating pre-detection technique of sensor signals by means of counterintuitive negative group delay (NGD) electronic function. The sensor signal pre-detection technique is unconventionally developed thanks to the engineering of low-pass (LP) type NGD circuit. The NGD pre-detection basic principle is introduced. After topological description, the LP-NGD cell design method in function of negative time delay specification is formulated. An innovative analysis of time-advance property related to multi-stage LP-NGD cell is elaborated. To demonstrate the LP-NGD pre-detection technique feasibility, a proof of concept (POC) is designed with fabricated 3-stage LP-NGD printed circuit board (PCB) prototype integrating 4 LED detectors. The NGD pre-detection experimental setup is described. Extraordinary pre-detection with −0.5 s negative time propagation visible with LED on-lightning is demonstrated by considering a sinc pulse input signal. The developed NGD pre-detection technique can be useful in the future for the anticipation of industrial equipment damages and failure pre-detection sensor system in real-time.