Negative Group Delay Research Articles

Design of multi-band circuit with negative group delay and lower insertion loss characteristics

A novel multi-band pass negative group delay (NGD) circuit with lower insertion loss is proposed in this paper. Firstly, a single-band NGD circuit cell is designed as the fundamental component of the multi-band circuit. Secondly, this paper utilizes a tri-band circuit as an illustrative example to demonstrate the implementation of multi-band circuit. The scattering parameters are utilized to analyze the proposed two-port circuits. The circuit was subjected to theoretical analysis based on the relevant principles of microwave circuits. Finally, by simulating the circuit on ADS software, the impact of each component on the performance of the circuit is obtained. The proposed circuits are fabricated and measured, from the measured results, the single-band cell can generate a group delay of −3.73 ns at 138.1 MHz, with an associated insertion loss of only 2.5 dB. The group delay value of the multi-band circuit in the three bands are −3.99 ns, −3.47 ns and −3.12 ns, and the maximum insertion loss is only 3.31 dB. The bandpass NGD measured results agree well with the theoretical prediction. The proposed NGD bandpass circuit can be applied for signal delay correction.

Highly narrowband miniaturized microstrip diplexer for qubit mobile communication networks utilizing SIR and T-shaped resonators with negative group delay performance

Highly narrowband miniaturized microstrip diplexer for qubit mobile communication networks utilizing SIR and T-shaped resonators with negative group delay performance

Log‐periodic antenna effect on modulated signals in regions of negative group delay

Log‐periodic antenna effect on modulated signals in regions of negative group delay

Double‐order negative group delay filtering function: A brilliant capability of the bilinear double‐order transfer function

AbstractIn this work, the capability to generate the negative group delay (NGD) phenomenon at those frequencies higher than a certain value, that is, the NGD high‐pass (HP) filtering function, of the bilinear double‐order transfer function has been demonstrated. Based on the Type‐I bilinear double‐order filter circuit, our theory has been verified by strong agreements between the formulae and their proof‐of‐concept (POC) circuit‐based simulation results. Both formula‐based and POC circuit‐based simulations give the minimum group delay of −5 ms yet the cut‐off frequency of 10 and 9 rad/s, respectively. Such slight deviation is caused by the approximation error of the bilinear double‐order impedance. By employing two orders, the bilinear double‐order transfer function has been found to be the basis transfer function for the NGD filtering function with the highest degree of freedom. Based on our design equation for the NGD filtering function, it can be seen that the distances between zero and pole and the characteristic frequency of the bilinear double‐order transfer function are governed by such characteristic frequency itself, the cut‐off frequency of the NGD filtering function, and the fractional order of the Laplacian operator. In addition, the effects of the fractional order of the Laplacian operator, the fractional order of the transfer function, and the ratio of the abovementioned distances to the characteristics of the newly found double‐order NGD filtering function have been studied in detail.

Compact Broadband Negative Group Delay Circuit with Flatness and Bandwidth Enhancement

Compact Broadband Negative Group Delay Circuit with Flatness and Bandwidth Enhancement

Luminosity Sensing Application of Negative Group Delay Predictor

Luminosity Sensing Application of Negative Group Delay Predictor

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.

Negative group delay SSPP mode based on coupled periodic cells

To realize negative group delay (NGD) of spoof surface plasmon polaritons (SSPPs), two coupling strips are introduced within the U-shaped cell for SSPP waveguide. Furthermore, two such cells are coupled to form a double-structured NGD unit. At lower frequencies, the constructed unit can implement both TE and TM modes with the NGD feature, and the maximum NGD values of – 0.42 ns for TE mode is achieved at 1.83 GHz. Since the TM mode is alongside the stopband, a wide NGD band of 2.01–3.25 GHz is yielded, with a small NGD value. However, as this unit is applied to SSPP waveguides to compensate for positive delays, the measured NGD maximum is 2.81 ns at 1.93 GHz and 9.65 ns at 2.42 GHz, due to the influence of waveguide structure on the NGD unit. The proposed unit structure exhibits promising applications in delay equalization and dispersion compensation for microwave system.

Compact compressor based on unparallel gratings

The pulse compressor is one of the essential components in a high-power laser system, which is often bulky. Here, we propose a compact compressor based on a Treacy compressor with two unparallel gratings and a mirror. Two gratings provide a negative group delay dispersion, and the mirror has two functions. One is to make the beam enter the compressor twice, and the other is to make the optical path between the grating pair folded to reduce the volume of the compressor. The relation between the group delay dispersion and the incident angle in three-dimensional space is derived. The results show that a small spatial incident angle can produce a large negative dispersion when the perpendicular distance between the gratings is the same. The parameter limits of the designed structure are also discussed, and the volume of compact compressor under the simulated parameters is two-thirds of the conventional compressor when the constraints are satisfied. This work is applicable to the optimal design of grating-based compressors with different parameters.

A note on the bandwidth of negative group delay filters

SummaryAn updated definition of group delay bandwidth in analog filters is introduced in this work. Unlike existing definitions, this new definition considers simultaneously the value of the group delay and filter gain, leading to minimized distortion in the filter output. In addition, it offers the capability of handling wide‐band signals without introducing errors in the shape of their envelopes. Selected first‐ and second‐order filters are studied and simulation results are provided to validate the efficiency of the new definition.

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

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

Elementary Negative Group Delay Filter Functions

A theoretical study of the behavior of some elementary first- and second-order functions, which are suitable for realizing negative group delay, is performed in this work. As both the gain and phase responses are simultaneously considered, important derivations related to the actual bandwidth of operation are derived accompanied by useful design tips. The presented theory is supported by simulation and experimental results obtained through the utilization of typical active-RC filter structures, as well as from a field-programmable analog array device.

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.

Self‐equalized linear‐phase microstrip bandpass filter based on negative group delay parallel‐coupled three‐line units

AbstractA self‐equalized linear‐phase microstrip bandpass filter (BPF) utilizing negative group delay (NGD) parallel‐coupled three‐line (PCTL) units is presented in this letter. The NGD PCTL unit possesses an NGD valley in its frequency response of group delay (GD). By a combination of two or more NGD valleys, the sharp positive GD peaks at passband edges of a conventional coupled‐line BPF are counterbalanced, resulting in a linear phase response over the entire passband. A prototype of linear‐phase BPF in S‐band is designed by replacing two coupled‐line units in a three‐pole conventional BPF with the proposed NGD PCTL units. Measured passband GD fluctuation of the BPF utilizing NGD PCTL units is 0.5 ns while that of the BPF using conventional coupled‐line units is 1.7 ns, a considerable improvement of 70.5% is achieved with no increase in overall time delay. The out‐of‐band suppression is well retained, and the circuit size is 0.18 λg2.

Small attenuation negative group delay of spoof surface plasmon polaritons

Spoof surface plasmon polariton (SSPP) waveguides can be used to effectively construct on-chip microwave systems due to the single-side conductor structure. SSPP waveguides usually exhibit normal dispersion, which can introduce large group delays to transmission signal and impair waveform shapes. However, the negative group velocity (NGV) effect may occur in the split modes of coupled surface plasmon polariton waveguides. In this regard, the synthesis wave model of forward and backward transmission waves is applied, which generates a quadrupole vortex wave transmission. In this paper, the SSPP unit structure with folded multi-split rings is proposed to achieve anomalous dispersion with NGV feature in the fundamental mode. The SSPP unit can be equivalent to an epsilon-negative medium, and a maximum negative group delay (NGD) can be reached at the frequency where the NGV begins to appear. For the corresponding SSPP waveguide, a NGD band with lower attenuation can be achieved at the stopband edge. While the SSPP unit structures are loaded as dispersive materials in a microstip line, the similar NGD performance can be obtained. Clearly, the SSPP NGD with lower attenuation provides a new delay equalization method for ultra reliable and low latency communications (URLLC), and can also be used as an effective dispersion compensation means.

Power-Law Negative Group Delay Filters

A study of the behavior of the power-law negative group delay filters, accompanied by a comparison with their integer-order counterparts, is performed in this work. Employing a curve-fitting based approximation technique, the resulting integer-order rational transfer function is versatile in the sense that it has the same form independent of the order and/or the type of the filter. Its implementation is performed by following three alternative approaches, each one offering different advantages. The findings of this work are supported by simulation and experimental results using suitable platforms.

Negative Group Delay Prototype Filter Based on the Reciprocal Transfer Function of a Low-pass Butterworth Filter Capped at Finite Out-of-band Gain

Negative Group Delay Prototype Filter Based on the Reciprocal Transfer Function of a Low-pass Butterworth Filter Capped at Finite Out-of-band Gain

Transient Characterization of New Low-Pass Negative Group Delay RC-Network

Transient Characterization of New Low-Pass Negative Group Delay RC-Network