Broadband negative group delay networks forcompensation of microwave oscillators and filters

Demonstration of negative signal delay with short-duration transient pulse

“…In 1990s, this negative group delay (NGD) phenomenon was also confirmed with several electronic experiments [22][23][24][25][26][27][28][29][30][31]. Firstly, by using an operational amplifier in negative feedback loop with passive networks based on R, L and C,…”

“…Nevertheless, the main roadblock of this application for the numerous high speed submicron systems that such a topology is limited to some MHz. Hence, passive microwave NGD lumped circuits, capable to operate up to GHz, have been proposed by the groups of Lucyszyn [30], Broomfield [31] and of Eleftheriades [32][33]. But, due to the excessive inherent losses and the narrow bandwidth systematically associated to the generation of significant NGD value, this circuit is inoperable in many electronic systems.…”

Negative Group Delay Phenomenon Analysis Using Finite Unloaded Quality Factor Resonators

“…The effect of NGD is observed within a limited frequency band when the absorption or attenuation is at a maximum. Therefore, conventional approaches to realize the NGD circuits are based on bandstop structures using either series or shunt RLC resonators [4][5][6][7][8][9][10][11]. The NGD circuits have been used in various practical applications in communication systems, such as shortening or reducing delay lines [11], enhancing the efficiency of feedforward linear amplifiers [12,13], designing broadband and constant phase shifters [14], realization of non-Foster reactive elements [15], and minimizing beam-squint in series-fed antenna arrays [16].…”

Neutralization of LC- and RC-Disturbances with Left-Handed and NGD Effects

“…Several experiments confirmed the physical existence of the superluminal and NGD phenomena with negative refractive index media [32][33][34][35][36][37]. In the presence of losses, the NGD generated by NGD passive media is accompanied by excessive losses [15][16][38][39][40]. So, the applications are still limited in low frequencies.…”

“…The time delay limitation of NGD circuits is investigated in [45][46]. Based on the NGD function, different applications for the design of innovative oscillator [47], balun [48], phase shifters [49][50][51], pulse compression generator [52] and feed forward amplifier [53][54] were developed in electronic areas. In addition, further applications for the reduction of signal delays were also proposed based on the neutralization of the disturbing effects in the electronic systems [51] [55][56][57].…”