Bandpass Negative Group Delay Research Articles

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.

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.

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.

Bandpass NGD Time- Domain Experimental Test of Double-Li Microstrip Circuit

This paper details a time-domain (TD) test to visualize impacts on the double-li microstrip circuit behavior of its bandpass (BP) negative group delay (NGD). To determine the central frequency and the bandwidth of the input signal to use during the TD test, a frequency domain (FD) S-parameter analysis of the circuit has been done. This preliminary analysis, carried out first with the aid of simulations and then with the aid of measurements, shows a NGD for a frequency band of 15 MHz (resp. 8 MHz) around 2.345 GHz (resp. 2.364 GHz). To observe in the TD the NGD impact around 2.345 GHz, TD experimentations have been performed using a 2.345 GHz sine carrier shaped by Gaussian pulses. During these TD tests, the BP NGD signature was verified thanks to the output envelopes which presents rising and falling edges in time-advance compared to the input ones. It was also experimentally shown that the output is normally delayed when the input sine carrier is outside of the li-circuit NGD frequency bands.

S-matrix-based bandpass negative group delay innovative model of inverted parallel arm distributed topology

This paper develops an innovative model of bandpass (BP) negative group delay (NGD) inverted arm topology of parallel lines. The S-matrix model is established from impedance and admittance matrix operations of elementary transmission lines constituting the topology. Parametric analysis is performed to assess the influence of inverted arm structure sizes on the BP NGD specifications. To validate the theoretical concept, a proof of concept is designed in microstrip technology. The calculated and simulated results are in very good agreement. NGD value, center frequency and bandwidth of about −8 ns, 3.6 GHz and 4 MHz, respectively, are observed with insertion loss better than 1 dB and reflection loss better than 18 dB. The innovative NGD physical structure could be an important asset to reduce propagation delay in the upcoming telecommunications systems as the 5G system.

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.

Design and Test of Innovative Three-Couplers-Based Bandpass Negative Group Delay Active Circuit

An innovative design method of bandpass (BP) negative group delay (NGD) active circuit is developed. The BP NGD topology consists originally of octopole and hexapole coupled line (CL) couplers. The NGD active circuit is validated by a prototype implemented in hybrid technology. The measured results are in good agreement with simulations. The CL-based passive circuit generates BP NGD performance with simulated and measured results showing NGD level of approximately -12 ns having 1.97 GHz center frequency with -11 dB transmission coefficient and -16 dB reflection coefficient. To compensate the loss, active circuit was fabricated by cascading the passive circuit with a microwave amplifier. Subsequently, the previous BP NGD performance is achieved with 0 dB gain. Moreover, a notable active microwave device characterization is performed with the NGD prototype via nonlinear measurements. It was found that the tested NGD prototype operates with 10-dB noise figure, 21 dBm P1dB compression, 29 dBm and 41 dBm OIP3.

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.

Robustness study of bandpass NGD behavior of ring-stub microstrip circuit under temperature variation

Abstract This paper explores an original study of bandpass (BP) negative group delay (NGD) robustness applied to the ring-stub passive circuit. The proof of concept (PoC) circuit is constituted by a ring associated with the open-end stub implemented in microstrip technology. An innovative experimental setup of a temperature room containing the NGD PoC connected to a vector network analyzer is described. Then, the electrothermal data of S-parameters are measured by varying the ambient or room temperature range from 20 to 60°C, i.e. 40°C maximal variation. The empirical results of the group delay (GD), transmission and reflection coefficient mappings versus the couple (temperature, frequency) highlight how the temperature affects the BP NGD responses. An innovative electrothermal calibration technique by taking into account the interconnection cable influence is developed. The electrothermal robustness analysis is carried out by variations of the NGD center frequency, cut-off frequencies and value in function of the temperature.

NGD investigation on medusa‐shape interconnect structure

This paper explains why the electromagnetic coupling between interconnect main Ω-shape and straight I-lines of printed circuit board (PCB) can be source of bandpass (BP) negative group delay (NGD) behavior. The investigation on the NGD effect is established from an innovative microstrip circuit having medusa shape. The medusa topology analytical description is based on the equivalent circuit and S-matrix model. Then, the group delay (GD) response enabling to explain the existence of the BP NGD function is defined. As proof-of-concept (POC), the influences of the medusa circuit constituting interconnect line (IL) lengths and interspaces on the BP NGD behavior are illustrated by parametric study. The NGD behavior is explained by the variations of the NGD value and NGD center frequency. More importantly, two NGD medusa prototypes were designed, fabricated, simulated and tested. The BP NGD responses of the two-medusa circuit POCs are validated by a very good agreement between the calculations, simulations and experimentations. The test results confirm that the medusa circuit POCs generate BP NGD responses with NGD level and center frequency of about −1.6 ns and 2.76 GHz respectively.

Bandpass NGD investigation of O-shape fully distributed structure with S-matrix modelling

PurposeThe aim of this paper is to provide the theoretical conceptualization of a bandpass (BP) negative group delay (NGD) microstrip circuit. The main objective is to provide a theorization of the particular geometry of the microstrip circuit with experimental validation of the NGD effect.Design/methodology/approachThe methodology followed in this work is organized in three steps. A theoretical model is established of equivalent S-parameters model using Y-matrix analysis. The GD analysis is also presented by showing that the circuit presents a possibility to generate NGD function around certain frequencies. To validate the theoretical model, as proof-of-concept (POC), a microstrip prototype is designed, fabricated and tested.FindingsThis work clearly highlighted the modelled (analytical design model), simulated (ADS simulation tool) and measured results are in good correlation. Relying on the proposed theoretical, numerical and experimental models, the BP NGD behaviour is validated successfully with GD responses specified by the NGD centre frequency: it is observed around 2.35 GHz, with an NGD value of about −2 ns.Research limitations/implicationsIt is to be noticed the proposed GD analysis requires limitations of the theoretical NGD model. It is depicted and validated through a POC demonstrating that the circuit presents a possibility to generate NGD function around certain frequencies (assuming constraints around usable frequency and bandwidth).Practical implicationsThe NGD O-shape topology developed in this work could be exploited in the future in the microwave and radiofrequency context. Thus, it is expected to develop GD equalization technique for radiofrequency and microwave filters, GD compensation of oscillators, filters and communication systems, design of broadband switch-less bi-directional amplifiers, efficient enhancement of feedforward amplifiers, design method of frequency independent phase shifters with negligible delay, synthesis method of arbitrary-angle beamforming antennas. The BP NGD behavior may also be successfully used for the reduction of resonance effect for the electronic compatibility (EMC) of electronic devices.Social implicationsThe non-conventional NGD O-circuit theoretical development and validation through experimental POC could be exploited by academic and industrial developers in the area of wireless communications including, but not restricted to, 5-generation communication systems. The use of the remarkable NGD effect is also useful for the mitigation of electromagnetic interferences between electronic devices and more and more complex electromagnetic environment (current development of Internet of Things[ IoT]).Originality/valueThe originality of this work relies on the new NGD design proposed in this work including the extraction of S-matrix parameters of the microstrip novel structure designed. The validation process based upon an experimental POC showed very interesting levels of NGD O-circuit (nanosecond-GD duration).

Innovative Study of Resistor Shunt‐Based Bridged‐T Topology With Bandpass Negative Group Delay Behavior

AbstractIn this paper, new bridged‐T network operating with bandpass (BP) negative group delay (NGD) function is introduced. The circuit design is innovatively based on an inductorless passive RC‐network. The innovative bridged‐T topology is implemented with a R‐shunt configuration. The analytical transfer function of voltages and equivalent impedance‐matrix are carefully calculated. The BP NGD analysis and design of the bridged‐T topology is developed. The BP NGD properties and specifications are analytically investigated. A proof of concept of R‐shunt bridged‐T prototype with a surface‐mounted device printed circuit board is designed, fabricated, and measured to verify the BP NGD behavior from theoretical equations and simulations. As expected, the theoretical, simulation, and measurements results are in very good agreement. From measurement results, the fabricated BP NGD C‐shunt bridged‐T reaches a delay of about −45 ns and a center frequency of about 0.5 MHz over a −3 dB attenuation.

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.

Bandpass NGD analysis of symmetric lumped Y-tree via tensorial analysis of networks formalism

This paper develops an original theory of bandpass (BP) negative group delay (NGD) function from three-port symmetric circuit. The BP NGD analysis is applied first time to three-port topology. The present study develops originally a BP NGD investigation of three-port circuit constituted by R, L and C lumped components. The equivalent S-matrix modelling is elaborated with the uncommon circuit theory. To validate the theory, a lumped circuit proof of concept is designed and simulated. A group delay value of about −0.3 ns is observed at the NGD centre frequency of about 76 MHz over 214 MHz bandwidth. For the further understanding on the BP NGD behaviour, a parametric study with the variations of the resistor, inductor and capacitor components of the Y-tree is performed. The results of the present study guarantee a potential microwave communication application of BP NGD function notably for systems operating with ISM and IEEE 802.11 standards.

Dielectric Resonator Negative Group Delay Circuit

AbstractThis study investigates an innovative theory on design of dielectric resonator (DR) based negative group delay (NGD) microwave circuit. The NGD circuit is mainly constituted by a cylindrical bulk of DR as a coupling element with a microstrip line. The developed theory is analytically established from the S‐parameters modeling of this innovative DR NGD topology. The NGD analysis and synthesis equations are formulated by considering the key parameters of the DR NGD cell. The NGD existence condition as a function of the DR and microstrip line parameters is also introduced. The behavioral response of the bandpass NGD function is verified with different designed proof‐of‐concepts (POCs). The developed NGD DR topology was validated with original circuit design by commercial simulations and experimentations with insertion and reflection losses lower than 4 and 10 dB, respectively. The POC prototypes operate with low attenuation losses in mono band and dual bands up to 10 GHz. Single NGD cells with DR coupled with “I” and “U” shape microstrip lines operating at different central frequencies were designed and implemented. Then, dual‐band NGD circuits operating at approximately 2.5 and 5 GHz were also tested. The possibility to widen the NGD bandwidth with double DR NGD circuits was investigated.

Electromagnetic Cavity Resonance Equalization With Bandpass Negative Group Delay

This article deals with an original equalization method of 3-D electromagnetic (EM) cavity resonance by using bandpass negative group delay (NGD) function. Based on the equivalent circuit, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> -matrix model of the equalized EM cavity is introduced. The design equations of the NGD function are established in function of the cavity physical parameters. The feasibility of the equalization method is validated with a 42×28×3.8 cm rectangular cavity containing two communicating monopole antennas. By considering the TE110-mode, a significant equalization is realized with improvement of transmission coefficient flatness from 4 dB to less than 0.3 dB. In addition to the magnitude, the NGD equalization method enables to outstandingly reduce spikes of 3-D EM cavity group delay. With the proof of concept, the GD is reduced from more than 4 to 1 ns.

Design and Test of Crab-Shaped Negative Group Delay Circuit

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Editor’s notes:</i> Negative group delay (NGD) function is used to solve the delay issue of RF and microwave devices. This article presents a novel NGD circuit based on the distributed topology of a “crab-shaped” geometry structure. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">—Fei Su, Intel Corp.</i>

Bandpass NGD TAN of Symmetric H-Tree With Resistorless Lumped-Network

This paper introduces an innovative passive topology of bandpass (BP) negative group delay (NGD) electrical circuit implemented with symmetric H-tree network. The multi-port topology of BP NGD circuit is originally represented by a resistorless H-tree constituted by lumped LC-passive network. Until now, the NGD electronic circuits available in the literature are implemented by two-port circuits which are using either resistive elements or distributed microstrip topologies. In the present investigation, the feasibility of the modelling, design, fabrication and test of unfamiliar BP NGD original H-tree circuits. The main objective of the study is to identify analytically the existence of the BP NGD function with the resistorless H-tree circuit. Because of its simplicity and the analytical equation compactness, the uncommon approach of tensorial analysis of networks (TAN) is used in the paper. After the branch and mesh analyses, the impedance matrix of the resistorless H-tree is elaborated. Hence, the resistorless H-tree equivalent S-matrix is established by means of impedance to scattering matrix transform. The BP NGD analysis in function of the inductance and capacitance parameters constituting the H-tree circuit is presented. Then, the main steps of the BP NGD investigation are described. The existence of BP NGD behavior in function of the adequate transmission parameters is identified by the consideration of the canonical form. To validate the BP NGD behavior, a proof of concept (POC) of LC-network based resistorless and symmetrical tree prototype is designed, fabricated and measured. Comparison results between well-correlated TAN calculation, simulation and experimentation are discussed.

Bandpass Negative Group Delay Theory of Fully Capacitive Δ-Network

A particularly original negative group delay (NGD) theory of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> -topology is developed in the present paper. The NGD three-port topology is a passive circuit purely constituted by capacitors network. The model of the proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> -topology impedance 3-D matrix is analytically established in function of the capacitor elements. Then, the S-matrix model is derived by using the Y-to-S transform. By considering the S-matrix frequency responses, a bandpass (BP) NGD analysis of the capacitive <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> -topology is originally elaborated. It is theoretically demonstrated that the passive <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> -topology is susceptible to behave as a BP NGD circuit under an analytical condition between the constituting capacitor values. The design feasibility of the BP NGD function is experimentally verified with lumped capacitor components-based <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> -circuit proof of concept. An electronic circuit board constituted by purely capacitive-network <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> -circuit is fabricated as an original <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula> -circuit prototype. The tested board is constituted by arbitrary chosen capacitors, 100 nF, 10 nF and 0.1 nF. As expected, the calculation, simulation and measurement results, which are in very good agreement, confirm the BP NGD behavior. It is observed from measurement that it generates NGD of about −18.1 ns at a frequency of about 0.55 MHz and, lower and upper cut-off frequencies of about 0.33 MHz and 1.71 MHz. It is noteworthy that the transmission and reflection coefficients at very low frequency are independent of the capacitor values and analytically equal to 2/3 and 1/3, respectively.