Negative Group Delay Circuit Research Articles

Compact Broadband Negative Group Delay Circuit with Flatness and Bandwidth Enhancement

Compact Broadband Negative Group Delay Circuit with Flatness and Bandwidth Enhancement

Multi‐band pass negative group delay circuit with low insertion loss

AbstractA novel multi‐band pass negative group delay circuit has been designed and proposed. The circuit consists of three types of components: capacitance, inductance, and resistance. An n‐order bandpass negative group delay circuit was analyzed and presented, and taking a three‐frequency bandpass negative group delay circuit as an example, the influence of different component values on the circuit group delay and insertion loss was analyzed. The actual test results of this circuit are consistent with the simulation results, and it can achieve the function of a multi‐bandpass circuit. In actual testing, the circuit frequencies with negative group delay are 49, 82, and 102 MHz, with corresponding group delay values of −2.177, −2.058, and −1.903 ns and corresponding insertion loss values of −5.810, −5.835, and −5.866 dB.

Familiarity analysis and time-advance experimental study of LP-NGD RC-circuit intended to operate with Unity-normalized gain

PurposeThe purpose of this paper is to develop a familiarity analysis of resistive-capacitive (RC) network active circuit operating with unfamiliar low-pass (LP) type negative group delay (NGD) behavior. The design method of NGD circuit is validated by simulation with commercial tool and experimental measurement.Design/methodology/approachThe present research work methodology is structured in three main parts. The familiarity theory of RC-network LP-NGD circuit is developed. The LP-NGD circuit parameters are expressed in function of the targeted time-advance. Then, the feasibility study is based on the theory, simulation and measurement result comparisons.FindingsThe RC-network based LP-NGD proof of concept is validated with −1 and −0.5 ms targeted time-advances after design, simulation, test and characterized. The LP-NGD circuit unity gain prototype presents NGD cut-off frequencies of about 269 and 569 Hz for the targeted time-advances, −1 and −0.5 ms, respectively. Bi-exponential and arbitrary waveform signals were tested to verify the targeted time-advance.Research limitations/implicationsThe performance of the unfamiliar LP-NGD topology developed in the present study is limited by the parasitic elements of constituting lumped components.Practical implicationsThe NGD circuit enables to naturally reduce the undesired delay effect from the electronic and communication systems. The NGD circuit can be exploited to reduce the delay induced by electronic devices and system.Social implicationsAs social impacts of the NGD circuit application, the NGD function is one of prominent solutions to improve the technology performances of future electronic device in term of communication aspect and the transportation system.Originality/valueThe originality of the paper concerns the theoretical approach of the RC-network parameters in function of the targeted time-advance and the input signal bandwidth. In addition, the experimental results are also particularly original.

Balanced bandpass filter with common-mode reflectionless and linear-phase characteristics based on negative group delay circuit

In this paper, a balanced bandpass filter (BPF) with common-mode reflectionless and linear-phase characteristics is proposed, which consists of a balanced 3-order bandpass filtering network and two common-mode absorptive networks to obtain the common-mode reflectionless and suppression performance. The negative group delay circuits are loaded on the proposed balanced BPF to realize the full-passband linear-phase filtering performance. The flatter the group delay of the BPF (the fluctuation of the group delay within the passband tends to 0), the better the phase-frequency linearity, which will realize the undistortion transmission of the communication systems. For demonstration, a balanced linear-phase BPF prototype operating at 1.5 GHz is designed, simulated, and manufactured. The results demonstrate that the group delay fluctuation is reduced from 1.20 ns to 0.11 ns by 90.8 %, the differential-mode insertion loss is 1.04 dB, the minimum common-mode suppression is 59.3 dB within the passband and the common-mode reflectionless band is 1.22–1.91 GHz. The developed topology requires high precision in the processing, and the proposed balanced BPF can be applied to digital microwave communication systems to improve the transmission quality and reduce the bit error rate.

Balanced Linear-Phase Bandpass Filter Equalized with Negative Group Delay Circuit

Balanced Linear-Phase Bandpass Filter Equalized with Negative Group Delay Circuit

Positive‐to‐negative tunable delay circuit designed with NGD RC network

SummaryDespite the performed progressive research work, the interpretation of the negative group delay (NGD) function remains not familiar to non‐specialist design and fabrication circuit engineers. The functionality misunderstanding limits the NGD circuit applications compared to other classical electronic functions. The present paper deals with the design of a tunable circuit by operating with positive and negative delay behaviors. The topology of the tunable circuit by using a low‐pass (LP) type NGD circuit is described. The design formulas for calculating the circuit resistor and capacitor parameters from the desired delay are expressed. The design feasibility of the tunable circuit composed of LP‐NGD cell and RC‐circuit is validated with a proof‐of‐concept (PoC) implemented on a test board. Two different signals with pulse and arbitrary waveforms having tens‐milliseconds duration were considered during the validation tests. As expected by tuning a varistor from 0.4 kΩ to 1 kΩ, the negative delay behavior varying from about −0.4 ms was verified thanks to the time‐advanced effect due to the LP‐NGD property. Then, the output signal delay was observed to become positive when the varistor was tuned from 1 kΩ to 3 kΩ.

Systematic design of negative group delay circuits

In this brief, we introduce and verify some general opamp based structures to obtain negative group delay circuits. First order and second order negative group delay circuits are verified and all are noninverting circuits. As both the transfer functions and the group delay are simultaneously considered important derivations related to the actual bandwidth of operation are derived. LTSpice circuit simulations and experimental results using Gaussian input signals are provided to verify the theory.

Single CFOA-based active Negative Group Delay circuits for signal anticipation

The group delay of a signal prior to data monitoring is a crucial consideration in today’s real-time applications, especially for those that involve long sensor arrays or high-order filters. In this article, nine new second-order Negative Group Delay (NGD) circuits based on Current Feedback Operation Amplifier (CFOA) are proposed, and their transfer functions are demonstrated. These circuits have a wide range of applications, from audio to mechanical signals and sensor signal anticipation. An example design procedure is provided for one of the introduced circuits. A time-domain analysis is performed using both a single-tone sinusoidal and a band-limited audio recording in the frequency range of 1 Hz to 500 Hz. The article assesses the change in the signal using Root Mean Square Error (RMSE) and cross-correlation. Furthermore, the relationship between the NGD value and the operation range of the circuit is investigated and verified experimentally. The results show that an NGD value of approximately 100μs can be achieved with an amplitude error of 0.86% for a single-tone input and 1.54% for an audio recording, and an operation range of about 650 Hz.

On the fractional domain analysis of negative group delay circuits

SummaryIn this work, the analysis of negative group delay circuits in fractional domain has been conducted. The low pass and the high pass negative group delay circuits constructed based on passive network have been chosen as our candidate circuits. For performing the analysis in fractional domain, the novel Caputo–Fabrizio derivative‐based fractional impedance have been introduced to both circuits. The crucial parameters, the necessary conditions, and the existence conditions of both candidate negative group delay circuits have been formulated. The simulations have been conducted based on the formulated results where the comparisons with the conventional prototypes have been made. The verifications by the proof‐of‐concept circuits have also been performed. In addition, the effects of variation in the order of fractional impedances have been investigated. In summary, it has been found that considering these negative group delay circuits in the fractional domain, which effectively taking unavoidable nonidealities that cannot be modeled in conventional domain into account, significantly alters their characteristics especially the low pass circuit. However they can retain their low pass and high pass negative group delay functions.

Design of a quint-band passive NGDC by using Taguchi’s optimization method

This article presents a quint-band passive negative group delay circuit (Q-NGDC) by using Taguchi’s optimization method for the first time. This Q-NGDC mainly consists of a semi-circle and a multi-stub resonator, and it is evolved from a simple NGDC (Type I) to a well-designed one (Type VI) through three optimization stages. It is found that, with the application of Taguchi’s method (TM) in conjunction with full-wave simulations, the efficiency of the designed passive multi-band NGDC has been improved significantly. The proposed Q-NGDC was fabricated and tested, and the experimental results show that the five operation bands have been achieved at the center frequencies of 1.76, 2.80, 3.84, 4.42, and 5.28 GHz, with the corresponding group delay values of −1.85, −2.15, −1.45, −1.6, and −1.1 ns. The measured transmission coefficients are −4.4, −7.8, −9.7, −9.3, and − 8.9 dB. Furthermore, the proposed NGDC shows the best figure of merit (FOM) at each resonant frequency with a relatively small size. The proposed NGDC can be potentially applied to WCDMA, 5G communication, Zigbee (IEEE802.15.4), and Wi-Fi (IEEE802.11n) systems.

All-Pass NGD FIR Original Study for Sensor Failure Detection Application

This paper deals with original design, implementation, test, and potential application of finite impulse response (FIR) with uncommon all-pass negative group delay (AP-NGD) circuit. The counterintuitive AP-NGD numerical circuit theory is established. Design method of first order AP-NGD circuit is introduced with respect to the specified time-advance. The first order difference equation was synthesized, designed, and implemented in STM32 Microcontroller Unit, and experimented to validate the AP-NGD characteristics. The AP-NGD FIR prototype was tested in the time-domain with Gaussian and arbitrary waveform sensored signals. Calculated and experimented results in very good agreement with the most significant time-advance -10 s ever experimented before are obtained. The potential industrial application of the NGD predictor for sensor fault diagnosis in real-time is described.

Compact and Wideband Flat Negative Group Delay Circuit Investigation

This paper introduces a dual transmission structure with bandpass (BP) negative group delay (NGD) wideband flat behavior. The flat BP-NGD topology is analytically modelled from equivalent circuit composed of transmission line (TL) and stepped-impedance resonator connected by two resistors. As proof of concept (POC), by tuning TL characteristic impedances, the influences of circuit physical variables on NGD flatness are illustrated by parametric study. The flat BP-NGD POC circuit with a size of 48.2 mm×90.8 mm (0.2λg 0.38λg) is designed, fabricated, and measured. A very good agreement is confirmed by simulation and experimentation results of 680 MHz over 290 MHz (42.6%) NGD bandwidth (BW) around 0.7 GHz NGD center frequency. Also, the flat BP-NGD BW reaches 223 MHz (31.8%) over 569 MHz to 792 MHz with ±0.05 ns group-delay fluctuation with insertion and reflection losses better than 14 dB.

Group delay compensation based on negative group velocity effect of spoof surface plasmon polaritons

Negative group velocity (NGV) exists only in the anomalous dispersion band with resonance absorption. In this paper, it is verified that spoof surface plasmon polaritons (SSPPs) with spiral-shaped periodic units have the NGV characteristics near cutoff frequency. The negative group delay of this NGV SSPP can be used to achieve the compression of the pulse signal, and also to compensate the positive group delay with high efficiency. Of course, this group delay compensation scheme based on NGV may introduce an absorption loss, which is the characteristic of all passive negative group delay circuits.

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%.

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.

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.

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.

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

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.