Coupled line negative group delay circuits with very low signal attenuation and multiple-poles characteristics

This paper presents a novel design of negative group delay circuit (NGDC) with very low signal attenuation (SA) and multiple-poles in group delay (GD) characteristics. The very low SA is obtained due to high characteristics of coupled lines. Theoretical analysis shows that the multiple-poles in GD characteristics can provide wider negative GD bandwidth and be obtained by connecting coupled lines resonators with slightly different center frequencies separated by quarter-wavelength transmission lines. For experimental validation, the NGDCs with 2-poles and 3-poles in GD characteristics are designed, simulated, and measured. The measurement results have a good agreement with theoretical predictions.