Analytical Design of Dual-Band Negative Group Delay Circuit With Multi-Coupled Lines

Xiang Zhou,Qizheng Ji,Ningdong Li,Glauco Fontgalland,Blaise Ravelo,Binhong Li,Fayu Wan,Xiaofeng Hu

doi:10.1109/access.2020.2988096

Abstract

This paper develops an innovative design method of a multi-coupled line (CL) topology of low-loss dual band negative group delay (NGD) circuit. The proposed is conceived using three transmission lines (TLs) with different length in which integrate two couplers. The three traveling paths are designed to generate the dual-band NGD effect, where the CLs allow lowering the signal attenuation. The NGD circuit S-parameter model as a function of the TLs physical lengths and coupling coefficient are established. To validate the NGD circuit proof-of-concept, it is fabricated and measured. The NGD values of approximately -4.06 ns and -3.83 ns are measured at center frequencies of 2.43 GHz and 3.02 GHz, respectively. The measured transmission coefficient is better than -2.9 dB and the measured reflection one is better than -12 dB into the NGD band. The measurement results of the NGD circuit are in good agreement with the simulations results.

Highlights

Theoretical analysis and experimental researches in the microwave field demonstrated that the existence of negative group delay (NGD) phenomenon was reasonable at certain passive circuits [1]–[5]
The low-pass, high-pass, bandpass, and stop-band NGD circuit cells were designed to understand the basic NGD properties and synthesis methodology in [26]. Most of these existing active NGD microwave circuits based on the use of low noise amplifiers (LNAs) and field effect transistors (FETs) associated with lumped RLC resonant networks have recently been proposed and developed [27]–[30]
Some topologies of the passive NGD circuits implemented by distributed elements such as transmission line (TL) and coupled line (CL) were developed [31]–[34]

Summary

INTRODUCTION

Theoretical analysis and experimental researches in the microwave field demonstrated that the existence of negative group delay (NGD) phenomenon was reasonable at certain passive circuits [1]–[5]. The low-pass, high-pass, bandpass, and stop-band NGD circuit cells were designed to understand the basic NGD properties and synthesis methodology in [26] Most of these existing active NGD microwave circuits based on the use of low noise amplifiers (LNAs) and field effect transistors (FETs) associated with lumped RLC resonant networks have recently been proposed and developed [27]–[30]. It was found that these active NGD circuits would unavoidably suffer from design inflexibility restrictions on lumped components as well as increasing design difficulties in the microwave band To overcome these limitations, some topologies of the passive NGD circuits implemented by distributed elements such as transmission line (TL) and coupled line (CL) were developed [31]–[34].

TOPOLOGICAL ANALYSIS

GROUP DELAY FREQUENCY-DEPENDENT EXPRESSION

CONCLUSION