Negative Group Delay Circuit Research Articles

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.

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 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.

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.

Analysis of Septuple-Band NGD Circuit Using an E-Shaped Defected Microstrip Structure and Two T-Shaped Open Stubs

In this article, a compact distributed septuple-band negative group delay circuit (NGDC) is proposed and analyzed. It is mainly composed of a high–low–high step-impedance microstrip line with an E-shaped groove and two T-shaped open stubs. This NGDC was first simulated and then fabricated by using a conventional printed circuit board (PCB) process with the substrate of RO4350. To investigate the operational mechanism of the NGDC, an equivalent circuit, consisting of nine transmission lines, four series–parallel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonant circuits, and two T-type series <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonant circuits, has been developed and analyzed. It is found that the theoretical group delay characteristic calculated from the equivalent circuit agrees well both with the simulated data by using ADS as well as HFSS and with the experimental results. The measured seven NGD resonant frequencies occur at 2.03, 2.84, 8.14, 8.74, 13.0, 16.02, and 18.46 GHz, and the corresponding NGD values read −3.65, −3.04, −1.73, −3.23, −1.16, −1.20, and −1.47 ns. The dimensions of the presented passive NGDC are only 25 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times22$ </tex-math></inline-formula> mm without using any lumped components.

Measurement Characterization of Band‐Pass NGD Time Domain of a 101O‐Topology Passive Circuit

AbstractThe negative group delay (NGD) is one of less familiar electronic functions. So far, the time domain (TD) experimentation of NGD circuits remains a challenging task. This paper investigates an innovative TD measurement of a band‐pass (BP) NGD passive circuit. The topology of the considered BP NGD distributed circuit constituted by transmission line structure having a 101O‐geometrical shape is introduced. After the design description of the 101O‐structure, the NGD response illustrates from simulation and measurement based on S‐parameters. The NGD center frequency, bandwidth, and value are approximately 3.6 GHz, 33 MHz, and −4.9 ns, respectively. The TD measurement experimentation is based on the sine carrier‐modulated microwave signal generation with 50‐ns duration. The 101O‐NGD circuit input and output signals are plotted with innovative synchronization. It was shown from the TD‐simulated and measured results that the BP NGD effect induces an output envelope about 4.2 ns advanced of the test signal input.

Reconfigurable negative group delay circuit with tunable group delay flatness

A reconfigurable negative group delay circuit (NGDC) with tunable group delay flatness is presented. The proposed NGDC is composed of an amplifier, three series resistors connecting with two transmission lines, two varactors, and a diode. By shorting different resistors through the diode, different negative group delay (NGD) times can be obtained. Two varactors are utilized to tune the flatness of the group delay. For verification, an NGDC is designed, fabricated, and measured at the center frequency of 1.0 GHz. The measured NGD time is tuned from −2.0 to −5.8 ns. The flat-NGD bandwidth varies from 2.2% to 8.8% with ±8% group-delay fluctuation. And the insertion loss varies from 6.5 to 13.8 dB.

Band Pass Negative Group Delay demonstration on a VHF RLC parallel passive lumped circuit

This paper demonstrates the bandpass (BP) negative group delay (NGD) function on a passive RLC-parallel lumped network at Very High Frequencies (VHF). After the topological description of the RLC cell, the BP NGD analysis is introduced. The NGD circuit is modelled theoretical by means of voltage transfer function (VTF) expression. The analytical equations illustrating the BP NGD specifications as the NGD center frequency, NGD value, NGD bandwidth and the VTF attenuation are established in function of the R, L and C component parameters. A proof of concept is designed, fabricated as a SMD on printed circuit board, and measured. As expected, the different models (calculated, simulated and measured) present a BP NGD and are significantly corelated. The POC prototype (resp the calculated and simulated model), presents an NGD value of - 8 ns (resp -12 ns) and attenuation of - 10 dB (resp -8 dB) around a 225 MHz (resp 240 MHz) NGD center frequency. Uncertainties analysis (UA) of BP NGD specifications is also studied in order to show the influence of quality and tolerance of components for NGD circuit. The theoretical formulas of NGD specification UAs in function of R, L and C tolerances are derived. UAs with respect to 1%, 2% and 5% relative tolerances of R, L and C components constituting the POC designed circuit are performed.

Reconfigurable Non-Foster Elements and Squint-Free Beamforming Networks Using Active Transversal Filter-Based Negative Group Delay Circuit

A new type of reconfigurable negative group delay (NGD) circuits based on active transversal filter topology is introduced in this work. By incorporating varactors with the NGD circuit at the input and output ports of active transversal filter based on distributed amplifiers (DAs), one can notably enhance the tunability for both amplitude and phase responses, thereby enabling NGD characteristic synthesis with a wider reconfigurable range. In this article, the proposed reconfigurable NGD circuits are applied to create both tunable non-Foster elements and tunable squint-free beamforming networks, which are verified by experiment. Furthermore, a general <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> -stage transfer function for the proposed reconfigurable NGD circuit is derived, in which a two-stage particular case is given as an illustrative proof-of-concept example. Based on the reconfigurable NGD circuits, a prototype of a tunable negative capacitor is fabricated and measured, of which the capacitance can be tuned from −1.0 to −4.0 pF over a bandwidth of 100 MHz at 1 GHz or around 10% relative bandwidth. In addition, such an NGD circuit is utilized to create a low-dispersion superluminal transmission line, which enables a reconfigurable series antenna feedline for squint-free beam steering. Experimental results show that the main beam of the NGD antenna array has a tuning range from −15° to 15° within a squint-free bandwidth of 100 MHz at 2 GHz or within a relative bandwidth of around 5%.

Novel Tee-Shaped Topology Theory of Low- and High-Pass NGD Double-Type Function

Recent investigation reports that certain electronic circuits operate with the unfamiliar negative group delay (NGD) function. It is fundamentally stated that the NGD circuits can be classified in different types. For example, we have the simplest ones as LP and HP NGD circuit types. So far, all the NGD studies are focused on simple type function. In step up of the research about the NGD electronic circuit engineering, this paper develops an original theory of electronic circuit topology operating with double NGD-type behavior. The study consists in the theorization of three-port circuit simultaneously generating LP and HP NGD function types. The proposed three-port innovative circuit under study is innovatively composed of resistive-capacitive (RC) network of Tee-shaped topology. Moreover, the LP and HP double-NGD circuit is a first order cell which does not contain any inductive component. The LP and HP NGD analyses of the Tee-topology is based on the 3-D S-matrix modelling. Analytical investigation based on classical circuit theory is elaborated to determine the S-matrix model from the equivalent admittance matrix. The identification of the double-NGD function is established from the LP- and HP-NGD canonical forms. Hence, the specific double-NGD characteristics are defined in function of the R and C elements constituting the three-port topology. To validate the developed double-NGD theory, a proof-of-concept (PoC) of SMD lumped component-based three-port circuit is designed, simulated, fabricated and tested. The calculated, simulated and measured results from the three-port circuit PoC prototype in very good agreement confirm the double-NGD behavior. The proposed innovative NGD three-port circuit design is useful in the future for the synchronization of signals propagating through multi-way communication system.

Thermal Wave Variation Anticipation Under Minute Scale Time-Advance With Low-Pass NGD Digital Circuit

Over the emerging industry 4.0 era, the building control system performance depends on the development of smart sensor technology. Nowadays, the building control engineers challenge on the design of high-capacity smart sensor susceptible to operate with high speed of data processing. In this context, this paper introduces a pioneer research work on the negative group delay (NGD) circuit original application for room temperature anticipation useful for smart-building control. The real-time anticipation of sensor data by using a low-pass (LP) NGD digital circuit is studied. This approach enables minimizing the latency time for optimizing control action. The unfamiliar LP-NGD digital circuit design method and theoretical formulation are described for anticipating thermal wave experimentation in real-time. The digital circuit equation coefficients are computed regarding the time-advance of anticipated thermal completely arbitrary waveform signal. The main interest of using the NGD method-based for thermal wave anticipation regarding temperature variation from heater and freezer control is demonstrated. The anticipation feasibility is illustrated from the minute scale time-advance LP-NGD digital circuit implemented on the STM32® microcontroller unit. The NGD characterization is performed from frequency domain analysis and cosine waveform pulse transient test. Then, the -30 seconds to -10 seconds real-time-advance of temperature variation is verified by calculation and experimentation. The present study result opens a promising NGD method application for the advanced fault control of a future industrial system by anticipating system failures.

Design Method of Constant Phase-Shifter Microwave Passive Integrated Circuit in 130-nm BiCMOS Technology With Bandpass-Type Negative Group Delay

The miniaturization and application development are the expected challenges on the today engineering design research on bandpass (BP) type negative group delay (NGD) circuit. To overcome this technical limit, an innovative contribution on integrated circuit (IC) design method of BP-NGD application to design constant phase shifter (PS) in 130-nm BiCMOS technology is developed in the present paper. The BP-NGD PS microwave passive IC is topologically consisted of cascade of CLC- and RLC-resonant networks. After the S-matrix modelling, the synthesis design equations enabling to calculate each lumped component values constituting the BP-NGD PS BiCMOS are established. The design equations are expressed knowing the targeted specifications as phase shift and operating frequency. The BiCMOS design methodology including the key steps as design rule checking (DRC), layout versus schematic (LVS) and post-layout simulation (PLS) is described. The miniaturized BP-NGD PS design feasibility is verified with schematic and layout simulations with IC CMOS standard commercial software tool. A proof-of-concept (POC) of 130-nm BiCMOS BP-NGD PS operating at the center frequency <i>f</i>₀=1.9 GHz and bandwidth &#x0394;<i>f</i>=0.1 GHz is designed and simulated. After DRC, the chip layout of miniaturized BP-NGD PS POC presents 0.407 mm&#x00B2; size. The BP-NGD PS POC exhibits constant phase shift notable value of about &#x03C6;₀=-90&#x00B0;+/-0.4&#x00B0; under <i>S</i>₂₁(<i>f</i>₀)=-6+/-1 dB transmission coefficient with good flatness and reflection coefficients (<i>S</i>₂₁(<i>f</i>₀) and <i>S</i>₂₁(<i>f</i>₀)) widely better than -10 dB. The design robustness is confirmed by 1000-trial Monte Carlo uncertainty analyses with PLS results. Because of the potential integration in wireless sensor networks (WSNs), the BP-NGD PS under study is a promising candidate for the improvement of the future 5G and 6G transceiver design.

Frequency Switchable and Tunable Negative Group Delay Circuits based on Defected Microstrip Structures

Frequency Switchable and Tunable Negative Group Delay Circuits based on Defected Microstrip Structures

Suitability of passive RC-network-based inductorless bridged-T as a bandpass NGD circuit

PurposeThe purpose of this paper is to study, a bridged-T topology with inductorless passive network used as a bandpass (BP) negative group delay (NGD) function.Design/methodology/approachThe BP NGD topology under study is composed of an inductorless passive resistive capacitive network. The circuit analysis is elaborated from the equivalent impedance matrix. Then, the analytical model of the C-shunt bridged-T topology voltage transfer function is established. The BP NGD analysis of the considered topology is developed in function of the bridged-T parameters. The NGD properties and characterizations of the proposed topology are analytically expressed. Moreover, the relevance of the BP NGD theory is verified with the design and fabrication of surface mounted device components-based proof-of-concept (PoC).FindingsFrom measurement results, the BP NGD network with −151 ns at the center frequency of 1 MHz over −6.6 dB attenuation is in very good agreement with the C-shunt bridged-T PoC.Originality/valueThis paper develops a mathematical modeling theory and measurement of a C-shunt bridged-T network circuit.

Investigation on four‐port mono‐capacitor circuit with high‐pass negative group delay behavior

AbstractMost of the recent studies on unfamiliar negative group delay (NGD) circuit were focused on the classes of low‐pass (LP) and bandpass (BP) topologies. So far, few research works are currently available in the literature on the high‐pass (HP) NGD class. This paper introduces an original HP‐NGD circuit theory of four‐port passive topology constituted by a single lumped capacitor. The S‐matrix equivalent model of the innovative topology is established from the admittance matrix. The basic analytical frequency‐dependent responses are expressed. Then, the GD model is derived in function of the capacitor. It was analytically found that the four‐port mono‐capacitor passive circuit is susceptible to behave as an unfamiliar class of HP‐NGD function. An innovative HP‐NGD analysis is explored in addition to the expression of synthesis design equation in function of the expected NGD cut‐off frequency which is linked to NGD optimal value. The validity of the established HP‐NGD theory is verified with a proof of concept (POC) circuit. As expected, the POC enables HP‐NGD behavior to show a good correlation between analytical model which is confirmed by the simulation.

High-pass NGD characterization of resistive-inductive network based low-frequency circuit

PurposeThe purpose of this paper is to provide the high-pass (HP) negative group delay (NGD) circuit based (RL) network. Synthesis and experimental investigation of HP-NGD circuit are developed.Design/methodology/approachThe research work methodology is organized in three phases. The definition of the HP-NGD ideal specifications is introduced. The synthesis method allowing to determine the RL elements is developed. The validation results are discussed with comparison between the calculated model, simulation and measurement.FindingsThis paper shows a validation of the HP-NGD theory with responses confirming NGD optimal frequency, value and attenuation of about (9 kHz, −1.12 µs, −1.64 dB) and (21 kHz, −0.92 µs, −4.81 dB) are measured. The tested circuits have experimented NGD cut-off frequencies around 5 and 11.7 kHz.Research limitations/implicationsThe validity of the HP-NGD topology depends on the coil self-inductance resonance. The HP-NGD effect is susceptible to be penalized by the parasitic elements of the self.Practical implicationsThe NGD circuit is usefully exploited in the electronic and communication system to reduce the undesired delay effect context. The NGD can be used to compensate the delay in any electronic devices and system.Social implicationsApplications based on the NGD technology will be helpful in the communication, transportation and security research fields by reducing the delay inherent to any electronic circuit.Originality/valueThe originality of the paper concerns the synthesis formulations of the RL elements in function of the expected HP-NGD optimal frequency, value and attenuation. In addition, an original measurement technique of HP-NGD is also introduced.

Low loss negative group delay circuit using self‐packaged suspended line

A matched negative group delay (NGD) circuit with ultra-low insertion loss by using self-packaged multi-layer suspended line is proposed. Two transmission paths with different electric-lengths are used to produce positive phase slope, which would bring a negative group delay, while a coupled line is used for matching, and the commonly applied absorption resistors are not required. The NGD circuit has been fabricated and measured, and the design has been demonstrated with a measured NGD time of −2.84 ns, a NGD bandwidth of 34 MHz, a low insertion loss/signal attenuation (S21) of no more than 2.73 dB, and a S11 attenuation of about 27.8 dB. Both self-packaging and metallized air cavities are used to reduce the wave leakage, and the multiple via holes usually used for electromagnetic shielding are saved, which greatly reduce the fabrication complexity.

A Novel Multifunctional Negative Group Delay Circuit for Realizing Band-Pass, High-Pass and Low-Pass

A novel multifunctional negative group delay circuit is proposed. The circuit can realize three different negative group delay functions, including band-pass, high-pass and low-pass, which meet different conditions with capacitance, inductance and resistance. Analytical design equations are provided. The effects of different element values on the bandwidth, cut-off frequency and the minimum negative group delay of the circuit are analyzed. According to this design method, the negative group delay circuit is designed and fabricated. Simulation and measurement results are in agreement. It has good negative group delay characteristics. The feasibility of the design method is verified.

Design Engineering of Tri‐Band Ulu‐Shape NGD Circuit

AbstractThis paper investigates a negative group delay (NGD) design of Ulu geometrical shape circuit. The NGD basic topology is constituted by a coupled line coupler with two‐port terminated by open‐ended stub. The S‐matrix model of the topology is presented. The design equations allowing to determine the NGD circuit parameters in function of the NGD function specifications, NGD center frequency, NGD values and insertion loss are presented. As proof of concept, a microstrip circuit is designed and fabricated. As expected, the tested results confirm that the circuit behaves as bandpass NGD function. The modeled, simulated and measured results are in good correlation. The POC operates with tri‐band NGD behavior with center frequencies around 0.645, 1.285, and 1.87 GHz with NGD values of about −3.5, −2, and −1 ns, respectively.

Bandpass NGD function design for 5G microwave signal delay synchronization application

This paper introduces a design method of simple bandpass (BP) negative group delay (NGD) topology. The fundamental specifications of BP NGD function are defined. The NGD passive topology consists of parallel resistance associated with an open-ended microstrip stub. The NGD properties and characterization with respect to the constituting stub parameters are established. The validations are performed with theoretical calculated and simulated GD, transmission and reflection coefficients. The BP NGD circuit can be useful for the improvement of phase linearity and GD equalization of future 5G microwave devices.